Lecture 11. “Surgical infection. Classification. Acute purulent infection. Osteomyelitis.” The microorganisms divides on pathogenic and nonpathogenic, but this division is conditional. Pathogenicity of a parasite — it is it ability to call infection disease in organism of the host. Pathogenicity of microorganisms dialectically is connected to immunity of an macroorganism. Even the agents with expressed pathogenicity not always can call disease. And on the contrary, at a significant drop of immunity of an organism under influence of those or other conditions the disease develops at the expense of a duplication of an agent, nonpathogenic for an organism with normal immunity. Modern hospital infection is called in basic just by these last biologicalecological groups of pathogens (nonpathogenic obligate and facultative parasites). The purulent processes are called by various microorganisms but the most often reason of their development are Staphylococci, Streptococci, Pneumococci, Gonococci, Blue pus bacilli, Escherichias etc. Quite often agent of purulent process happens a symbiosis of several aerobic microorganisms or even their combination with anaerobic microorganisms. It’s mixed infection. On clinical current and pathoanatomical to changes in tissues all kinds of surgical infection are divided on acute and chronic. Acute surgical infection is divided on acute purulent, acute anaerobic, acute specific – (tetanus, antrax) and acute putrifactive. The chronic surgical infection can be nonspecific and specific (tuberculosis, actinomycosis etc.). Classification of purulent surgical infection 1. On clinical current is distinguished acute purulent infection — general and local, and also chronic purulent infection — general and local. 2. On localization of a defeat selects a defeats of a skin, underskin fat; covers of a skull, its contents; neck, breast, chest wall; pleura, lungs, mediastinum, peritoneum and organs of abdominal cavity; pelvis and its organs; bones and joints. 3. On aetiology purulent surgical diseases are Staphylococcus, Streptococcus, Pneumococcus, etc. 4. On aetiology distinguishes also purulent mono- and polyinfection. SPREAD OF INFECTION Cellulitis Cellulitis is inflammation spreading along the subcutaneous or a fascial plane often as the result of infection with Streptcoccus pyogenes which has entered the tissue through an accidental wound, graze, or scratch, or following surgical incision. Unchecked this may lead to septicaemia after a rapid spread within the tissues. Initially red and itchy at the site of the innoculation, the skin swells and becomes tender, frequently being shiny. There may be local gangrene. Rest, elevation of the part, and the appropriate antibiotic should lead to resolution, but any underlying condition (e.g. diabetes) should be treated. LOCALLY—Celtulitis INFECTION REGIONALLY—Lymphangitis SPREADS Lymphadenitis GENERALLY (systemically) BLOODSTREAM—Bacteraemia Septicaemia TO OTHER BODY CAVITIES—Peritonitis PATIENTS Meningitis —LYMPHATIC SYSTEM Cellulitis in special sites Orbit.—Spreading infection from wounds of the paranasal sinuses will cause proptosis and impairment of ocular movements. Associated thrombophlebitis can extend to the meninges and, if the ophthalmic veins are involved, to the cavernous sinus. Early attention and the use of antibiotics (Penicillin) is vital in reducing morbidity. Neck.—Submaxillary cellulitis is often termed 'Ludwig's angina" and the great risk of infection spreading from tonsils or mastoids to the neck is that the cellulitis will involve the glottis with concomitant oedema, asphyxia and mediastinitis. Pelvic cellular inflammation.—The common cause is a lateral tear in the cervix during parturition. The pelvic inflammation as a result of the trauma incurred during childbirth may extend along the broad ligament appearing above the inguinal ligament. Anaerobic infection (actinomycosis) and Chlamydial infection may arise as secondary infections following the use of intra-uterine contraceptive devices. They will present as a cause of pelvic pain and the diagnosis requires the culture of endocervical pus. Metronidazole should be used whilst awaiting the results of cultures which should also exclude sexually transmitted infections (N. gonorrhoea or herpes virus infection). Localised infection will spread by lymphangitis to local or regional lymph nodes and by bacteraemia to distant organs. Bacteraemia and Septicaemia (overwhelming bacterial proliferation and toxins in the blood).—These terms describe the presence of organisms in the blood. The clinical features include a source of infection, hypotension, pyrexia and often rigors ('shaking of the bed'). Hepatic involvement and acute cortical necrosis of the kidneys may be associated with bacteraemia, also peripheral circulatory collapse. Intra vascular coagulation defects frequently accompany the later stages. Following at least three blood cultures treatment must be immediate and aggressive by means of a broad spectrum attack using a p-lactam antibiotic together with an aminoglycoside and metronidazole, (these should be given intravenously), with blood transfusions, plasma expanders and hydrocortisone. Bacteraemia can cause multiple metastatic abscesses in distant organs and these will require treatment. Abscess Formation An abscess is a collection of pus. Bacteria which cause pus (pyogenic bacteria) reach the infected area by: (1) Direct infection from without, e.g. penetrating wounds. (2) Local extension from some adjacent focus of infection. (3) Lymphatics. (4) Blood-stream (haematogenous). Pus is a collection of polymorphonuclear leucocytes from which the proteolytic enzyme causes liquefaction of the tissues. The tension within an abscess rises as plasma exudes into it and, unless the abscess is surgically drained, the pus will discharge eventually along the line of least resistance. The area immediately around the abscess which is infiltrated with leucocytes and bacteria is called the pyogenic membrane. Symptoms depend upon the site, size and tension of the abscess and the virulence of the bacteria causing it; the patient will suffer generalised illness, and throbbing pain with swelling. Signs of Pus— (a) GENERAL.—The temperature is elevated and bacteraemia with rigors may occur. (b) LOCAL.—The five classical local signs of inflammation are due to hyperaemia and inflammatory exudate : 1. Heat. 2. Redness of the skin over the inflamed area. 3. Tenderness. 4. Swelling. 5.Loss of function. Prevention.—An abscess can usually be prevented by timely and appropriate antibiotic treatment. Treatment. Once pus is diagnosed, the abscess must be incised and dependent drainage instituted as penetration by antibiotics is poor. In 'high risk' anatomical areas, as in the neck or axilla, Hilton's method should be used. This consists of incising the skin and superficial fascia, and opening the abscess by thrusting a pair of sinus forceps or a haemostat into the cavity. By separating the blades, a sufficiently large opening can be made to insert, if necessary, a finger in order to convert loculi into a single cavity, and to insert a drainage tube. Pus should be cultured in order to isolate and identify the organism and its sensitivity to antibiotics. The underlying cause needs to be ascertained and appropriate treatment, e.g. surgery, instituted. Errors in treatment.—If pus is not drained and antibiotics are continued, the inflammation continues to smoulder and a hard lump forms, called an 'antibioma'. In certain areas, e.g. the breast, it becomes difficult clinically to decide whether such a lump is malignant or inflammatory. Incising an aneurysm in mistake for an abscess. It has been done on many occasions IMAGING IN INFECTION There are four available techniques which allow surgical infections and collections of pus to be accurately diagnosed and clearly defined:— Conventional radiology, Isotope scanning. Ultrasound (US), Computed Axial Tomography, (CT). The clinical indications will usually determine the appropriate technique and the site of infection will influence the choice of investigation. Conventional radiology, for example, reveals fluid levels when air or gas is present as in subphrenic abscess or lung abscess, or pus suggested by an opacity filling a space (the nasal antrum or the pleural cavity). Isotope scanning.—Intravenous technetium accumulates at the site of infection and clearly demonstrates the position of brain abscesses, inflammation such as osteomyelitis, and hepatic abscesses. Gallium scans may be needed for mediastinal abscesses, pelvic and perinephric abscesses or subphrenic abscesses, but care in the interpretation is needed as gallium is taken up by normal breast tissue under certain circumstances. Ultrasound or CT scans of suspicious areas may show regular necrotic centres which will help to distinguish abscesses from tumours. Ultrasound (US) reliability depends upon close contact of the US probe and the skin. It cannot be used over surgical wounds, colostomy or ileostomy bags. Gas in the bowel obscures the underlying organs and therefore US is of the greatest use in liver, spleen and urinary bladder investigations whilst it is of considerable value in the diagnosis of gallbladder stones or empyema. The demonstration of bacterial vegetations upon a cardiac valve by echocardiography can be decisively diagnostic of endocarditis. Computed tomography (CT) scans are usually necessary for localising brain lesions and abscesses although isotope scans can demonstrate these also. PREVENTING INFECTION Antibiotic Prophylaxis is used to prevent bacteraemia and wound infection when instrumentation or surgery is performed upon a site with normal flora or where infection already exists (e.g. cystoscopy when bladder infection is known to be present). It should be maintained for a short period, seldom using more than three doses, the maximum duration being 48 hours. Prophylaxis should cover and control the known or likely pathogens. Prophylaxis may conveniently be given intravenously as a bolus after induction of anaesthesia or, ifintramuscular antibiotics are to be used, may be given one hour before surgery. Aminoglycosides such as gentamicin require that serum levels be monitored if they are used for more than 36 hours. If renal function is known to be satisfactory three doses only of 80120 mg given at 8 hour intervals may be used for a normal adult. Metronidazole may be given as one gram per rectum (suppository) with resulting excellent blood levels; the first suppository should be given 1 1/2 hours preoperatively. Topical antibiotics should be reserved for use in eye or ear surgery; skin antibiotics are seldom if ever indicated and can lead to severe antibiotic resistant infections. Antibiotic impregnated 'cement' or 'beads' for use in orthopaedic prosthetic operations are gaining favour; they act as a local reservoir giving slow release to the site of operation. Alternative regimes are based on single doses of cephalosporins, e.g. prior to the open reduction of fractures. Care should be taken with diabetics (superadded Candida and multi-resistant Gram-negative infections) and patients who are immunodeficient or immunesuppressed, e.g. receiving steroid therapy or receiving radiotherapy. Penicillin prophylaxis for up to one week is mandatory for the prevention of Clostridial gas gangrene at the time of lower limb amputation through the thigh in those patients who have diabetic or severe peripheral vascular disease. PREVENTING INFECTION IN SURGICAL PROCEDURES Abdominal procedures Colorectal surgery Ampicillin 500 mg I.V. 8 hourly x 3* + Metronidazole Appendicectomy Metronidaxole i gram rectally Peritonitis Ampicillin 500 mg Gentamicin 120 mg followed by 80 mg twice at 8 hour intervals with Metronidazole Biliary Ampicillin or a cephalosporin Urinary tract Amoxycillin 3 g or single dose of Instrumentation or Gentamicin 120 mg if previously surgery infected Obstetric surgery Vaginal hysterectomy, Ampicillin 500 mg I.M. termination of pregnancy Metronidazole I g rectally with history of pelvic once only inflammatory disease or abdominal caesarean Orthopaedic Compound fractures Ampicillin 500 mg 8 hourly with Flucloxacillin 500 mg 6 hourly (or Erythromycin 500 mg 6 hourly if Penicillin hypersensitive) Elective or prosthetic 48 hours only Ampicillin 500 mg 8 hourly surgery and Flucloxacillin 500 mg 8 hourly Lower limb amputation Penicillin 2 mega units at induction and thereafter 4 mega units daily for 5-7 days Patients with known 1. Dental surgery Amoxycillin 3 g orally and valvular disease, Probenecid I g, orally (if allergic prosthetic grafts of the 2. Urethral to Penicillin, Erythromycin 1-5 g cardio-vascular system catheterisation orally followed by 0-5 g 6 hours later). (e.g. aortic or aortic 3. Operations under If general anaesthesia or valve), history of general anaesthesia gastrointestinal investigation is rheumatic fever being performed a single dose of Gentamicin 1-5 mg per kg of body weight I.M. must be added Preventing Infection at Operation.—The open wound is at risk of contamination from airborne dust which carries bacteria derived from skin organisms of attendants and operating room personnel. Positive pressure, filtered ventilation of the operating theatre prevents bacteria gaining entry with the air. Ultra-clean ventilation (laminar flow and fine filters) has been shown to reduce wound infection rate by two-fold. Body exhaust suits carrying away the infected skin particles of the surgeons and assistants clearly reduces the number of infected particles near the wound and has been shown to reduce the wound infection rate by sevenfold. The patients own skin is a source of infection especially at abdominal operations and can be treated by pre-operative bathing, and skin preparation with alcoholic povidone iodine solution or 5% chlorhexidine in 70% alcohol. Povidone iodine compresses applied to the thigh for one hour prior to hip arthroplasty reduce the risk of self infection. At the time of operation, the use of a plastic adhesive film (Opsite®) through which the incision is made helps to prevent contamination during the operation itself. Surgical hand washing with hexachlorophane, chlorhexidine, or povidone iodine and the use of gloves, mask and change of clothes all contribute to reducing the risk of surgeon transmitted infection. Instruments.—Central hospital and theatre sterile supply departments use high temperature autoclaves (i32°C) for sterilising instruments, whilst equipment made of heat sensitive material may be sterilised at 8o°C in sub-atmospheric pressures ('low temperature steam') with or without a formalin injection cycle (e.g. for cystoscopes). Some endoscopes (e.g. colonoscopes) may require special procedures for disinfection; liquid gluteraldehyde is often useful for disinfection of cleaned instruments. Where viral infections (Hepatitis B) are implicated hypochlorites or steam disinfection are used while in operating theatres the infection control policy will clearly lay down guidelines for the disinfection of blood contaminated instruments before cleaning if possible. The exercise of proper professional care will usually prevent self-inflicted injuries with instruments that may be at risk of spreading Hepatitis B virus or HIV virus by blood contamination. Controlling Surgical Infection—Control of Infection Team.—Vigilance, education and definition of policies for controlling infection in surgical wards is best placed in the hands of a Control of Infection team consisting of a control of infection nurse or considerable seniority, a medical microbiologist and a surgeon. Not only is it necessary to monitor the type of infections and the resistance and distribution of the bacteria, but the in-service education on the principles of wound care, catheter toilet, aseptic dressing techniques can best be managed by such a team. Isolation of high risk patients, modification of antibiotic regimes, and the prevention of spread of any resistant infections will all require the combined speciality interest for the advice to be authoritative, acceptable and effective. Though the tissues do not react to each of the pyogenic bacteria in an exactly similar way, the typical local effect of pyogenic infection is the formation of a cavity filled with pus—an abscess—and the general or constitutional effect is the establishment of fever, leucocytosis and prostration. The constitutional reaction varies little in kind, though much in degree, whatever the pyogenic microorganism. The character of the local reaction, on the other hand, is more directly related to the type of invading bacterium. Frank suppuration, that is, a rapid solution of tissue and a free outpouring of leucocytes, is habitually excited by staphylococci; and a diffuse suppurative inflammation, cellulitis or phlegmon, characterized rather by edema and necrosis than by an abundant formation of pus, is typical of streptococcal infection. It is the frankly suppurative type of inflammation caused by the familiar staphylococci of the skin which commonly gives rise to abscess. The local signs of any suppurative inflammation are heat, redness, swelling and pain, with which must be included sensitiveness to touch or movement, that is, tenderness. Moreover, abscesses of sufficient size exhibit, to the practised touch, fluctuation, a wave-like impulse transmitted through a soft-walled sac of fluid in response to pressure. The combination of these various signs is unmistakable, but since any one or more of them may for various reasons be absent, the significance of each requires investigation. Difficult as it is to assign a relative order to their importance, pain, heat and fluctuation appear to be of the greatest clinical significance; redness of the least. They will therefore be considered in that order. Pain results from the stimulation of sensitive nerve fibers or their endings and may perhaps be attributed to distension by toxic substances of tissue supplied with such fibers. The skin is well furnished with sensory nerves; the subcutaneous tissues and muscles arc not. The periosteum, the serosa of points, the anterior rectus sheath, the parietal peritoneum and the pleura are potential sources of exquisite pain, but the abdominal and thoracic viscera are themselves comparatively insensitive, though when distended by suppuration within, such solid organs as the liver, spleen, and kidneys may become the seat of pain which must then be attributed to the rapid stretching of their capsules and, in some instances, tension upon their (parietal) peritoneal attachments. The severity of pain is usually proportional to the rapidity in development of the suppurative process. Thus an abscess which gathers slowly and distends the tissues gradually, occasions comparatively little subjective sensation while a very active process may be a source of agony. To some degree also the severity of pain is influenced by the toughness of the tissue in which the abscess develops. For such reasons, the minute infection (Paronychia) beneath the edge of the nail is painful out of all proportion to its extent, and the same is even more true of acute inflammation within the tough pulp of the finger tip (Felon). Subperiosteal inflammation, particularly in regions where fibrous tissue is solidly attached to rough bone, is notably painful. Perhaps the most agonizing of all are the abscesses within the thick walls of the long bones (Osteomyelitis). On the other hand, suppuration within yielding tissues may be almost unnoticed until, perhaps, it reaches and invades one of the sensitive surfaces already mentioned. Pain, then, is usually the most enlightening of all the symptoms of abscess. It is increased by pressure or movement. Its character, even in the absence of other local signs, may suggest the existence of an abscess and indicate its exact position. The throbbing pain of a felon and the deep agonizing pain of acute osteomyelitis are examples of this sort. On the surface of the body, pain is a less constant evidence of abscess than heat, redness and fluctuation, since tension of the inflamed sensitive skin is readily relieved by softening of the tissues and by even partial evacuation. Abscesses in the skin are more sore than painful, though they are often exquisitely tender to the touch. Heat is due to local hyperemia but may be detected in the absence of any redness whatever. In infections of the skin, the two signs go together, but beneath the surface, the hyperemia about an abscess may be evident to the touch when the skin is quite normal in color. Local heat is a very early and constant sign of even a relatively deep suppurative process It is to be sought by comparing the suspected region with a remote symmetrical part. In the presence of an abscess deep in the thigh, or even within the femur, the surface of the affected leg may be ever so slightly warmer than that of the other. The two thighs, in that case, or it may be the hands or arms in another, should be lightly and simultaneously touched by the sensitive palmar surfaces of the examiner's two hands, and the warmth of the opposite sides rapidly compared. Local heat and pain are almost pathognomonic of abscess, even though the suppuration is so situated that fluctuation can not be elicited, and in the presence of superficial, fluctuating collections of fluid, absence of heat distinguishes cysts and cold (tuberculous) abscesses from acute pyogenic infections. Fluctuation is a rather gross evidence of abscess. Since it merely points to the presence of the collection of fluid, it’s only valuable when some other sign of suppuration is detectable. Indeed it is chiefly an aid in confirming other findings and in marking, for purposes of treatment, the exact position of the lesion. Recognition of the fluctuant border of a collaction of pus may call attention to the point at which dependent drainage must be established. Even a collection of fluid too small to transmit an actual fluid wave may be detected in the midst of a considerable brawny induration as a crater-like area of softening, and so indicate beginning suppuration and a favorable location for drainage. Ordinarily, the sense of fluctuation is sought by placing the palmar surface of the fingers of each hand on the opposite sides of a swelling, or at a distance from each other upon a flat surface, when, upon pressing down with one hand, the impression of a fluid wave is received by the other. Swelling would appear at first sight to be an indispensable sign of abscess. Indeed it is usually present, and is quite apparent in such suppurations as are near the surface of the body as well as in deeper ones of any notable size. In some instances, however, tissues are destroyed and pus collects without causing any appreciable swelling. In others, the abscess occurs in unyielding tissues or in deeply seated organs concealed from sight and touch. Again, so many other processes—new growths and cysts—are responsible for tumor that other signs of suppurative inflammation are more reliable. Redness, or hyperemia, is a very constant part of the response of the tissues to irritation and is almost invariably present about an abscess. It is only noticeable, however, when the abscess is near the surface. Then it is the earliest sign of inflammation and precedes actual suppuration. But deeper abscesses may be betrayed by the heat of hyperemia before any superficial redness is visible. This is particularly true of infected operative or accidental wounds of considerable depth, which may appear on the surface to have healed in a very reactionless way. The Constitutional Symptoms of abscess become increasingly valuable and even indispensable to diagnosis when suppuration is remote and inaccessible. A painful, hot, red, swollen and fluctuant area would be recognized as an abscess even without the confirmation offered by fever and leucocytosis, but deeply seated pain, slight local tenderness upon deep pressure, and questionable local heat are only suggestive of suppuration unless constitutional symptoms are present. In most instances, the character of these general manifestations can be relied upon implicitly; it is only in quantity that they vary. Since fever and leucocytosis result from the reaction of the body to bacterial toxins, the virulence of the toxins is a prime factor in this response. Naturally, the factor of virulence is influenced by the degree to which toxic substances are absorbed into the general circulation, that is, by the nature of the tissue in which the abscess originates. In these respects, the richness of the blood and lymph supply in any region is a most important consideration. The tension under which pus is retained is another. Thus a suppurative process pent up in the vascular but unyielding medullary cavity of a long bone promptly causes high fever, leucocytosis, and prostration, but an abscess in the soft, yielding brain, which possesses almost no power of absorption, may for a long time occasion no constitutional symptoms whatever. An infection within the palm of the hand is a more potent source of fever than a similar process in the loose, avascular fat of the thigh or the abdominal wall. Differences of this sort are, however, matters of degree only. It almost never happens that an abscess of any consequence fails to cause some rise of temperature, though instances of failure of leucocytosis in the presence of overwhelming infection are not very rare. Furuncle. A furuncle, or boil, is a very familiar form of abscess, peculiar to the skin, and caused almost invariably by the staphylococcus aureus (or albus). Infection reaches the dermis by way of a hair follicle or sebaceous gland. Bacteria multiply rapidly at the point of entrance and here their toxins are sufficiently deadly to provoke, before the protective defenses of the body can be set up, a rapid necrosis of tissue. This slough is of such tough material as to resist for a time complete solution. It remains, therefore, as the core of the furuncle. About it, liquefaction of tissue and outpouring of a highly purulent exudate make pus, and thus an abscess is formed in and beneath the true skin. About the abscess, new vessels and young connective tissue keep the infected area surrounded by a layer of granulation, to which the name pyogenic membrane is given. If the cocci continue to develop, the pyogenic membrane is dissolved and the furuncle enlarges. New defenses, however, again are built around it. Should the process be prolonged, lymphoid and plasma cells begin to replace the polynuclear leucocyte. Eventually, the invading bacteria are robbed of their virulence or the contents of the abscess are evacuated, After incision or natural rupture, the cavity closes, partly by collapse and partly by ingrowth of new tissue. Finally, a scar covered by epithelium is left. If the furuncle is observed from its beginning, it will usually be noted that a pustule first appears about the base of a hair. In a few hours, a circumscribed dark red swelling surrounds it. Heat, redness and pain are evident. The swelling slowly increases until, from the fifth to the seventh day, a yellow, softened area appears at its apex. The furuncle is then said to "point" and there is formed the beginning of an opening from the abscess to the surface. Under favorable conditions, this opening enlarges, so that there may be discharged through it by pressure the sloughing "core" and pus. Sometimes the pus burrows beneath the upper layers of the epidermis, making a flat, blister-like pustule. This communicates by a narrow neck with the larger collection beneath. Such a furuncle has, on cross section, the shape of a collar-button, a name which is often given to it, and the importance of recognizing the lesion lies in this, that adequately to evacuate the deep portion of the pus sac something more than the mere exposure of the superficial pocket is required, ihe tiny opening into the deep pocket must be discovered and enlarged by incision. From the time the furuncle is evacuated, healing begins. The discharge, at first purulent, soon becomes serous and then drys up. Skin grows over the granulations which fill the cavity. The resulting scar is often invisible. One furuncle may lead to the appearance of many, suggesting, as indeed may be the case, that a "crop" has been sown by the outpouring upon the skin of countless virulent bacteria which have escaped from the original lesion. But of course the same result may arise from a loss of resistance to a particular bacterium widely distributed in the skin and heretofore held in subjection. The back of the neck is commonly the seat of this sort of process; the axillary skin is sometimes most stubbornly infected, the face is often invaded and the buttocks as well. Indeed, any part of the skin may be affected. When the furuncles are in considerable numbers, recurrent and spreading, the condition is known as furunculosis. Then the body appears to have lost, to a greater or less degree, its combative quality. Under these circumstances, a constitutional reaction in the form of moderate fever may be present, and instances of considerable debilitation, doubtless partly due to the annoyance and constant discomfort of the newly developing lesions, are sometimes observed. That furuncles have long been considered a serious affliction may be judged from the passage in the Bible wherein it is stated that "Satan went forth from the presence of the Lord, and smote Job with sore boils from the sole of his foot unto his crown," the most terrible affliction of which the devil could think, and one which was intended to try Job's fortitude to the utmost. It is clear in some instances and quite probable in many others, that furuncles afford entrance for the staphylococci which so frequently occasion acute infections of bone in children. Blood-borne staphylococcal infections of a similar source in persons of any age may invade the lungs, kidneys, and other organs, not infrequently leading to a fatal outcome. Treatment: The furuncle should be evacuated in such a way as to render unlikely a spread of infection into deeper tissues or into neighboring hair follicles. Thus it is unusual to incise a boil before it has become a pus sac about which a well organized pyogenic membrane is presumed to exist. And it is unusual even then to incise until continued enlargement and absence of a necrotic spot upon its surface indicate that it can not be ruptured by very gentle pressure. After opening, the furuncle is covered with a sterile absorbent dressing. Sometimes a little piece of guttapercha tissue is passed into it as a drain. Before evacuation, the skin about it is kept as clean as possible with soap and water, and is often greased with a bland ointment to keep the bacteria, as they are discharged from the opened abscess, from finding new lodgment. A boil may sometimes be aborted by the use of hot applications or the injection of a drop of pure carbolic acid into its core. The application of heat, by increasing active hyperemia, hurries on the process to the destruction of the bacteria or to frank suppuration. When multiple active furuncles are present, the condition presents considerable difficulty in treatment. The patient seems at times to lose all resistance and may develop serious secondary infections. Under these circumstances, vaccines are sometimes employed and may be useful. Many internal remedies have been tried. The administration of yeast has sometimes seemed to do good. The salts of tin are favored by a number of French investigators. On the whole, more reliance is to be placed on general hygienic measures, in persistence in the most painstaking care of the skin and in preventing the spread of sepsis from established furuncles to new regions. Carbuncle is a suppurative inflammation of the skin and subcutaneous tissue having the form of a many headed furuncle, and like it, is caused by the staphylococci. Its peculiar pathologic features and clinical course are due to the nature of the tissue—the skin of the back of the neck, the back, the hairy dorsal surface of the hand and fingers, and rarely the upper lip and scalp—in which it originates. In these regions, the skin is particularly thick and tough, and from the base of the hair follicles clefts of the true skin filled with fat—the columnae adiposae of Warren—extend downward for a considerable distance. At their base, these columns are firmly bound to the underlying fascia. Thus an infection which does not rapidly reach the surface is likely to follow the fibrous attachments of the columns downward to the deep fascia, whence it rises again to the skin through other columns. The process once begun, spreads rapidly by the customary solution of tissue and pus formation, reaching out continually along the deep fascia and mounting in new areas. A rather terrifying lesion often several inches in diameter may result. In its early stages, the carbuncle appears as a raised red area in whose center pustules are dotted like the holes of a pepper pot. As it extends, its oldest portion becomes a pussy grayish crater about which cyanotic skin, more tenacious of life than the deeper tissues, forms an irregularly indented border. Large and small openings and areas of slough surround the central crater, but in the newer, growing area the early appearance of yellow pustules scattered or grouped in a field of angry red is preserved and continued. Still beyond this zone is a region of brawny edema diminishing in hardness and depth as the normal skin is approached. The whole back of the neck and head from ear to ear may be occupied by such a lesion. Pain and tenderness are variable. Some carbuncles cause great suffering, while others are painless and remarkably insensitive. When the lesion occupies the back of the neck, the head is held rigidly bent forward. The patient is often prostrated, sometimes delirious, and since carbuncles are particularly apt to attack diabetics, the outcome is occasionally fatal. The small carbuncles which occur on the ulnar side of the dorsal surface of the hand and upon the back of the proximal phalanges of the fingers are misleading in appearance, since the many headed appearance of the typical lesion is sometimes lost. Nor is it always realized that carbuncles occur in these regions. Nevertheless they are exactly similar to the lesions of larger size in other localities. Carbuncles of the face and scalp have a remarkable tendency to invade the venous blood stream, leading to septic processes in the cerebral sinuses and in the lungs. Treatment will depend somewhat upon the general condition of the patient. Careful physical examination with reference to chronic disease of the heart, lungs or kidneys, and especially, examination of the urine for sugar, should always be made. If the patient is profoundly septic and the carbuncle is not too large, the whole may be excised by a circular incision carried down to the deep fascia. This ends the disease more certainly, perhaps, than the less radical operations of crossed incisions through the center of the carbuncle, the turning up of the flaps along the plane of the deep fascia to the outer limit of the suppurative process, and the wide open packing of the cavity which is usually employed. The anesthesia, should be as innocuous as possible. Exposure to the x-ray, especially in the earlier stages, is often curative, least so, unfortunately in diabetics. The carbuncle may soften early or be "aborted." The sulfonamides and penicillin have been found effective, particularly if infection is already present in the blood stream. DIFFUSE SUPPURATIVE INFLAMMATION This is a common, often severe and occasionally fatal disease. The names, Phlegmon and Diffuse Cellulitis, are given to those suppurative inflammations in which necrosis of tissue шау be extensive but pus formation is little marked; in which the inflammatory reaction is rather in the form of intense widespread vascularity and outpouring of serum than of local abscess formation; and in which the streptococcus pyogenes is the usual infectious agent. Lymphangitis is the name applied to an infection of similar origin confined to lymphatic channels. This may occur as an independent process or may appear as an extension away from a parent cellulitis. Almost invariably the superficial lymph vessels are the ones affected. PHLEGMON, OR DIFFUSE CELLULITIS Infection reaches the subcutaneous tissues by way of an injury which may be so small and apparently harmless as to have been unnoticed. Or it may spread from one of the common punctured, incised wounds of the fingers and toes. It is a frequent cause, as will appear later, of septic hand. The organism —almost invariably the streptococcus—causes a local necrosis with exudation. If the infection is very mild, the exudate is soon absorbed and little loss of substance occurs. If it is severe, destruction is extensive. When at last it has subsided, much necrotic tissue remains to be cast off and the area occupied by the septic process is largely converted into granulation tissue. As the resulting scar contracts, the overlying skin is likely to become adherent to underlying structures. This sequence of destruction, induration and shrinkage may impair the function of adjacent muscle or tendon. The appearance of such a lesion differs decidedly from that of a furuncle or carbuncle. Redness and swelling appear about the point of origin. The skin pits on pressure. The area of infection may extend up a limb or over the body, as the case may be. Near the starting point of the process, the skin is a deep angry red. At its advancing edge, which seldom is sharply defined, it is of a lighter color. Everywhere the inflamed tissue has, to the touch, a brawny feeling obscuring all landmarks. In the older portion of the lesion an area of fluctuation or of crater-like softening indicates the situation of advanced necrosis and the presence of a collection of thin pus. Blebs, and even great blisters containing a cloudy fluid, mark a particularly severe process, as if the tissues had been slightly burned. Extensive destruction of skin (sloughing) may expose raw skin and a thick, yellow, gelatinous subcutaneous layer from which a thin, cloudy fluid exudes in abundance. And if, as resolution of the exudate occurs, such an incision is carefully observed, it will be noted that larger and smaller bits of grayish tissue are continually coming from the wound. In the most severe infections, this sloughing is of great extent, involving large sheets of subcutaneous tissue and more or less of the skin itself. THE TREATMENT OF DIFFUSE SUPPURATIVE INFLAMMATION The General Principles of Treating Established Diffuse Suppurative Inflammation.—Since the discovery that hemolytic streptococci are susceptible to the action of sulfanilamide, various other sulfonamides have been found to have a similar action, some being superior to sulfanilamide in their effect upon certain bacteria. All tend to sterilize the blood stream, having a bacteriostatic effect on the organisms, but they do not kill the bacteria in the initial lesion which still requires surgical drainage. Identification of the causal organism is therefore more than ever necessary. The sulfonamides are given by mouth (the initial dose often intravenously) but when sterilized, can be powdered freely into open wounds, where, especially in fresh ones, they help to overcome infection, without interfering with healing. For established infection they—and penicillin—are unpredictably effective. An example of one of the most familiar types of diffuse cellulitis is an infection spreading from the tip of the elbow: a small contused wound may have been the starting point. In the course of a few days the disease will have spread up and down the arm, perhaps encircling it. Over the olecranon the skin may exhibit a very small area of necrosis. For several inches in every direction, it will be deep red and shiny. Swelling will be very great and of a porky firmness. The advancing borders will show a fainter color and softer edema shading imperceptibly into the normal tissues. No fluctuation will be discernible, but careful palpation may disclose a softened area in the center and perhaps other crater-like spots about it. Tender lymph nodes will probably be palpable in the axilla. Such a lesion can not possibly be drained in the ordinary sense. Yet if the areas of softening are incised, a considerable amount of thin pus will escape and perhaps small pieces of sloughing fascia. Twenty-four hours of immobilization, elevation and hot poulticing (which here finds its greatest usefulness) will show a marked improvement. The skin will everywhere be wrinkled, a sure evidence of receding edema, the redness will have decreased, the lymph nodes in the axilla will have subsided, and if a blunt instrument is passed into one of the incisions, it will probably be found that new pockets have become connected with the original openings. More exactly dependent drainage may then be indicated. The speed of recovery will depend upon the amount of dead tissue which must be cast off or absorbed, and upon the persistence of the organisms in scattered areas. Phlegmonous processes in certain regions, as in the case of the hand or foot, may penetrate into complicated tissue spaces or tendon sheaths. They may also become a starting point for lymphangitis. The treatment of this latter condition requires the nicest judgment, for though it is not of itself a suppurative condition, yet too often it leads infection to regions which may require drainage. A small area of infection about the hair follicles on the back of one of the fingers may, without warning, occasion a sudden extension of lymphangitis which winds up the back of the hand and arm to the axilla. Chills, high fever, and intense prostration may be present. In such a case, incision of the long streak or streaks of lymphangitis would certainly spread rather than restrain infection. Incision of the primary focus might and probably would be beneficial, but immobilization, elevation and poulticing will usually (certainly at the beginning) be more helpful. In all probability, there will be no breaking down of tissue, and unless the infection is of such virulence that death follows within twenty-four hours, the whole process will probably subside in a few days, leaving no trace. Indeed, any operative treatment which it requires is called for only by the lesions with which it is associated or by the complications it causes. Mastitis of infants is at least as common in the male as in the female. On the third or fourth day of life, if a breast of an infant is pressed lightly, a drop of colourless fluid can be expressed; a few days later there is often a slight milky secretion, which finally disappears during the third week. This is popularly known as 'witch's milk'. The explanation of this phenomenon is that the hormone which stimulates the mother's breast reacts also upon the mammary tissue of the foetus. Thus it is essentially physiological. Mastitis of puberty is encountered rather frequently, usually in males. The patient, aged about fourteen, complains of pain and swelling in the breast. In 80% the condition is unilateral but the opposite breast may be affected later. The breast is enlarged, tender and slightly indurated. Suppuration never occurs. The tenderness subsides in fourteen days or so, but induration often persists for several weeks. In some instances enlarged tender breasts may persist in males for a prolonged period even up to years. In such circumstances it may be justifiable to recommend local mastectomy, conserving the nipple. Mastitis of mumps is usually unilateral, and more common in females. Mastitis from milk engorgement is liable to occur about weaning time; and sometimes in the early days of lactation when one of the lactiferous ducts becomes blocked with epithelial debris. In the latter instance a sector only of the breast becomes indurated and tender. Bacterial mastitis, which is by far the most common variety of mastitis, nearly always commences acutely. Although often referred to as mastitis of lactation, it is incorrect to assume that acute mastitis in women is necessarily lactational. Of a hundred consecutive cases of breast abscess, thirty-two occurred in women who were not lactating; probably some were due to infection of a haematoma. In almost every case the infecting organism is a staphylococcus. In cases where the infection is acquired in hospital no less than 90% of the infecting staphylococci are insensitive to penicillin. Aetiology.—Mastitis of lactation is seen far less frequently than in former years. Usually the intermediary is the infant; after the second day of life 50% of infants harbour staphylococci in the nasopharynx. 'Cleansing the baby's mouth' with a swab is also an aetiological factor. The delicate buccal mucosa is excoriated by the process; it becomes infected, and organisms in the infant's saliva are inoculated on to the mother's nipple. There seems little doubt that in the great majority of cases the precursor of intramammary mastitis is failure of secretion to escape because one (rarely more) of the lactiferous ducts becomes blocked with epithelial debris—a hypothesis that is strengthened by the fact that, whether they are lactating or not, intramammary mastitis and abscess of the breast are relatively frequent in women with a retracted nipple. While stasis in some part of the lactiferous tree is a major factor in the production of this condition, undoubtedly the older hypothesis—ascending infection from a sore or an infected cracked nipple—must not be spurned. Once within the ampulla of the duct, staphylococci cause clotting of milk. Within the clot organisms multiply rapidly. Clinical Features.—The affected breast, or more usually mainly one part of it, presents the classical signs of acute inflammation, and what is aptly called 'the cellulitic stage' of a breast abscess has been reached. Treatment during the Cellulitic Stage.—The patient should rest in bed and, pending the results of bacterial culture of her milk, be given an antibiotic appropriate for a penicillin resistant staphylococcus, e.g. cloxacillin or flucloxacillin. Support to the breast and local heat will help to relieve the pain and permit examination of the inflamed breast daily, which is essential. Unless there is some strong reason to continue breast feeding it is better to wean. Suppression of lactation usually follows naturally upon the cessation of suckling but if necessary bromocriptine can be given, 2-5 mg bd for 14 days. Stilboestrol is no longer used for this purpose. If the mother insists on continuing breast feeding it is safer to use the unifected breast only and to empty the infected breast of milk, which may have a high bacierial content, by means of a breast pump. Boiling or pasteurisation of expressed milk not only destroys its content of antibodies but also greatly reduces its nutritional value to the infant. Formation of an 'Antibioma'.—It is absolutely essential that an antibiotic should not be given in the presence of undrained pus. In such circumstances, if an antibiotic is given the pus in the abscess frequently becomes sterile and a large brawny oedematous swelling remains in the breast and takes many weeks to resolve. Sometimes there is excessive fibrosis and this, with the absence of tenderness, had led to the mistaken diagnosis of carcinoma. It is better to explore the mass with a wide-bore aspirating needle than to cause an 'antibioma' with its attendant pain, chronicity, and ill health. Most 'antibiomas' are due to late, inadequate, and ineffective antibiotics. Indications for Operation.—The breast should be incised when, after emptying, an area of tense induration is felt and/or when oedema of the overlying skin is found. In contrast to the majority of localised infections, fluctuation is a late sign and incision must not be delayed until it appears. Usually the area of induration is sector-shaped, and in early cases about one-quarter of the breast is involved; in many later cases the area is more extensive. Drainage of an Intramammary Abscess.—The usual incision is sited in a radial direction over the affected segment. One parallel with the cutaneo-areolar margin has a better cosmetic value and does permit access to the affected area. The incision passes through the skin and the superficial fascia. A long haemostat is then inserted into the abscess cavity. Every part of the abscess is palpated against the point of the haemostat and its jaws are opened. All loculi that can be felt are entered. Finally, the haemostat having been withdrawn, a finger is introduced and any remaining septa are disrupted. Unless the abscess cavity is situated at the very highest sector of the breast a counter-incision should be made at the most dependent part of the breast and a drainage tube inserted. In this, almost more than any part in the body, dependent drainage is essential. Subareolar mastitis is not a true mastitis but results from an infected (sebaceous) gland of Montgomery, or from a furuncle on or near the areola. The inflammation develops insidiously, usually without constitutional symptoms. When the patient presents early, there is often an area of induration no larger than a pea. No matter how small, if a lump can be felt, pus is present, and the abscess should be drained without delay. Spontaneous rupture, if allowed to occur, does not cure the condition; it merely results in recrudescence or chronicity. Chronic intramammary abscess which follows inadequate drainage or injudicious antibiotic treatment is often a very difficult condition to diagnose: when encapsulated within a thick wall of fibrous tissue, the condition cannot be distinguished from carcinoma without the histological evidence from a biopsy. Chronic Subareolar Abscess (leading to a Mammillary fistula).—A recurrent subacute or a chronic abscess may occur apart from lactation in women of the child-bearing age. The condition is a frequent complication of long-standing retraction of the nipple the infection being restricted to a single obstructed duct system. The abscess ruptures and subsides, only to repeat the cycle over and over again at intervals of a few months when it forms a chronic mammillary fistula. A non-infective inflammation such as duct ectasia may also result in fistula formation. Treatment.—Antibiotic therapy followed by incision and drainage is useless. The fistula must be treated in the same way as a fistula-in-ano, i.e. the track is laid open and saucerised Retromammary Abscess.—Here the pus is situated in the cellular tissues behind the breast, and in the great majority of cases the abscess has no connection with the breast proper. Usually a retromammary abscess originates from a tuberculous rib, infected haematoma, or possibly from a chronic empyema, and treatment must be directed to the relief of these conditions. A submammary incision allows the breast to be retracted as necessary from the field of operation. ERYSIPELAS Of a character easily distinguishable from other forms of suppurative inflammation, erysipelas represents the most completely non-suppurative type of diffuse streptococcal infection. A lesion limited to the skin itself, it illustrates, apparently, the reaction of a particular tissue to infection, capable in other situations and in an altered state of virulence, of producing a very different result. It arises from gross or microscopic wounds, spreads rapidly, and almost invariably causes chills, high fever, and such severe constitutional disturbance that delirium is quite common. Sometimes there is a phlegmonous inflammation at its point of origin and at other times none. Facial erysipelas spreads over the nose and cheeks in the shape of a butterfly with outspread wings. In that case the infection appears to enter from small ulcerations within the nose. This form of disease may occur at any age, but the very young and old are particularly subject to it. Rarely it passes over the entire body in a wave or succession of waves; for though it is ordinarily self-limited, running a course of one to three weeks, relapses and reinfections are far from uncommon. Erysipelas appears as an intense blush upon the skin which becomes glazed and moderately swollen. Its advancing edge is elevated and quite sharply outlined. The exudate is in the form of an edema, well supplied with phago-cytic leucocytes, but, since there is little or no solution of tissue, non-suppurative. Indeed, solution and destruction of the skin is so little marked that once the infection dies out, repair is rapid and complete. Streptococci are present in the advancing margin of the lesion and may be found in the blebs which sometimes appear upon its surface. They disappear from its center as the disease spreads. Treatment.—Owing to the rapid progress of erysipelas over considerable areas, incision, which in any case would be likely to spread the infection to deeper parts, is out of the question. Indeed, no local treatment has much of any influence on the disease, though attempts have been made to limit its spread by establishing a zone of artificial vascularity about the lesion through painting the surrounding area with tincture of iodine or crude carbolic acid (and alcohol). Hitherto the greatest progress has been made by prophylaxis. The cleansing of accidental wounds in soiled skin, the prompt treatment of seemingly trivial infections have greatly cut down its incidence. The sulfonamides have revolutionized the treatment of erysipelas, greati; lowering its mortality in both infants and adults. At the moment, sulfadiazini is the drug of choice, and should be administered in full therapeutic dose. Complete bed rest is obligatory; fluids are forced orally—parenterally if necessary. Hot wet compresses may be applied to the affected part. Fever usually lessens within 12 to 24 hours, and the lesion often disappear in 5 to 8 days. Lymphadenitis.— Diffuse suppurative inflammation rapidly involves those lymph glands placed in the course of the lymphatic vessels which dram the diseased area. At first slightly swollen and tender, they may later become ereatly enlarged and inflamed, even at a considerable distance from the infection Thus a septic process, originating, perhaps, in an abrasion of the surface of the great toe, may be followed, within a few hours, or perhaps over night, by the appearance of a red streak which wanders up the c-uf and thigh toward the groin. Even now, the superficial group of lymph glands about the saphenous opening may be palpable as a mass of tender elastic lumps the size of a pea or larger. If the original focus upon the toe subsides the glands will usually subside as well. But it is not uncommon to observe enormous enlargement and diffuse suppuration in the glands of the groin some days or even weeks after the healing of a local lesion which may,indeed, have appeared insignificant. In the upper extremity, the cubital and epitrochlear glands may pick_up infection from a lymphangitis which is spreading toward the axilla. Ihe axillary group is very commonly involved but usually prevents the process from advancing further. The cervical glands take up infection spreading from the mouth, laws, face and scalp. The axillary, inguinal and cervical groups •ire therefore of great importance as filters, catching invading micro-organisms on their way to the general circulation, reacting like other tissues to bacteria and their toxins, and thus affording the body time and opportunity for defence against virulent and otherwise overwhelming infection. Considering the fre-auency of their involvmcnt, lymph nodes seldom undergo abscess formation. They soften reluctantly, breaking down so gradually that suppuration is exceedingly slow and incomplete. Treatment.—Should suppuration actually occur, judgment as to when and how to operate is difficult. Ultimately, a mass of persistently infected lymph nodes is likely to soften into a single or multilocular abscess, but all the glands of the axillary or inguinal groups, as the case may be, seldom undergo abscess formation at one time, or to the same degree. Incision into such a mass will disclose, if made too early, a little thin purulent fluid among a group of greatly enlarged glands, some of which are reduced to necrotic fragments while others are firm or only partly softened. Drainage is therefore ineffective and the attempt at complete excision, though occasionally successful, is more apt to spread the infection. Conservative measures, in the form of poultices or moist compresses, bring comfort, and result finally in complete breakdown of the glands or spontaneous healing. The sulfonamides are indicated in overwhelming infections, but have little effect upon the lesion itself. LYMPHANGITIS This very common disease appears in two forms: (1), the reticular, a generalized involvement of the cutaneous mesh of lymph spaces marked by a diffuse blush, and (2), the tubular, which is actually an infection of the subcutaneous lymph channels. The visible sign of the second is a red streak upon ?he kTwiich may advance with remarkable rapidity. If the local infection from which it takes origin subsides, tho lymphangitis is quickly resolved, the red streak disappears, and healing occurs leaving no visible trace. On the other hand if the original focus spreads into the subcutaneous tissues, the lymphangitis becomes swallowed up in the more diffuse process which advances along and about it and which then becomes a cellulitis. Lymphangitis almost necessarily loads to infection of the lymph nodes in its course. It may convey infection into tendon sheaths and joints, even into the general circulation. Such complications occur in only a small percentage of all cases. ANO-RECTAL ABSCESSES In 60% of cases the pus from the abscess yields a pure culture of Esch. coli; in 23% a pure culture of Staphylococcus aureus is obtained. In diminishing frequency, pure cultures of Bacteroides, a streptococcus, or B. proteus are found. In many cases the infection is mixed. In a high percentage of cases—some estimate it as high as 90%—the abscess commences as an infection of an anal gland. Other causes are penetration of the rectal wall, e.g. by a fish bone, a blood-borne infection, or an extension of a cutaneous boil. A large percentage of anorectal abscesses coincide with a fistula-in-ano. For this reason, anorectal abscess becomes a highly important subject. Moreover, as antibiotics cannot reach the contents of an abscess in adequate concentration, no reliance can be placed on antibiotic therapy alone. A fistula is much more likely if bacterial culture of the pus discloses bowel (as opposed to skin) organisms. Classification of Ano-rectal Abscesses.—A clear understanding of suppuration in this area is dependent on a concise knowledge of the anatomy. There are four main varieties—perianal, ischiorectal, submucous, and pelvirectal. 1. Perianal (60%).—This usually occurs as the result of suppuration in an anal gland, which spreads superficially to lie in the region of the subcutaneous portion of the external sphincter. It may also occur as a result of a thrombosed external pile. If the haematoma is not evacuated, it may become infected and a perianal abscess results. This is the most common abscess of the region. Persons of all ages are affected, and the condition is not uncommon, even in infancy and childhood. The constitutional symptoms and the pain are less pronounced than in the ischiorectal abscess because the pus can expand the walls of this part of the intermuscular space comparatively easily. Early diagnosis is made by inspecting the anal margin when an acutely tender rounded cystic lump about the size of a cherry is seen and felt at the anal verge below the dentate line. Treatment.—No time should be lost in evacuating the pus. Operation.—Thorough drainage is achieved by making a cruciate incision over the abscess and excising the skin edges—this completely removes the 'roof of the abscess. Healing commonly occurs within a few days. 2. Ischiorectal abscess (30%).—Commonly, this is due to an extension laterally through the external sphincter of a low intermuscular anal abscess (fig. IOI2B). Rarely, the infection is either lymphatic or bloodborne. The fat, which fills the ischiorectal fossa, is particularly vulnerable because it is poorly vascularised; consequently it is not long before the whole space becomes involved. The ischiorectal fossa communicates with that of the opposite side via the post-sphincteric space, and if an ischiorectal abscess is not evacuated early, involvement of the contralateral fossa is not uncommon. Should an internal opening into the anal canal ensue, a 'horseshoe' abscess develops enveloping the whole of the posterior part of the circumference of the anal canal. An ischiorectal abscess gives rise to a tender, brawny induration palpable on the corresponding side of the anal canal and the floor of the fossa. Constitutional symptoms are severe, the temperature often rising to 3839°C. Men are affected more often than women. Treatment.—Operation should be undertaken early—as soon as it is certain that an abscess is present in this area—remembering that antibiotic therapy often masks the general signs. Operation.—Stage I.—A cruciate incision is made into the abscess. A portion of skin is sometimes excised but deroofing is not necessary in every case. 3. Submucous abscess (5%) occurs above the dentate line (fig. i I37C). When it occurs after the injection of haemorrhoids it always resolves. Otherwise, it can be opened with sinus forceps when adequately displayed by a proctoscope. 4. Pelvirectal abscess is situated between the upper surface of the levator am and the pelvic peritoneum. It is nothing more or less than a pelvic abscess and as such is usually secondary to appendicitis, salpingitis, diverticulitis, or parametritis. Abdominal Crohn's disease is an important cause of pelvic disease that can present as perianal sepsis. A relevant point to remember is that rarely a supralevator abscess/fistula may be due to over-enthusiastic attempts to drain an ischiorectal abscess or to display a fistula, when a probe is forced through the levator ani/rectal wall from below. 5 Fissure Abscess.—This is the name given to a subcutaneous abscess lying in immediate association with an anal fissure. Drainage is achieved at the same time as the fissure is treated by sphincterotomy. ACUTE OSTEOMYELITIS Acute osteomyelitis used to be a common and serious, indeed often a fatal, disease in children. Over recent years there has been a fall in the incidence of the disease, probably due to an improvement in the general health of children. At the same time antibiotics have made the disease less serious: it need never now be fatal and should be curable. Aetiology.—The bacteria reach the bone by the blood-stream. A primary focus may be obvious in the form of a boil or an infected graze, but not uncommonly no obvious source of infection is evident. Rarely the disease may be secondary to a frank septicaemia or pyaemia. More commonly the blood-borne infection takes the form of a bacteraemia. It has been suggested that a lowered general resistance on the part of the patient, and local trauma, may predispose to this disease, but the evidence in support of these suggestions is unconvincing. The usual causative organism is the staphylococcus aureus. Other organisms which may be responsible include the streptococcus, pneumococcus, haemophilus influenzae, staphylococcus albus and a number of other organisms, no one of which is present commonly. Pathology.—The disease always, or nearly always, begins in the metaphysis. The infective process progresses through the thickness of the cortex via the Haversian canals and as it does so causes thrombosis of the vessels in the bone. As a consequence, by the time the infection reaches the subperiosteal region of the bone a variable amount of the cortex may have been infarcted. In the first 24 or 48 hours after the onset of the infection, an inflammatory exudate forms deep to the periosteum, elevating the membrane from the bone. Periosteal elevation is painful and, since the periosteum is inelastic, the inflammatory exudate deep to it is under tension. As a consequence the patient rapidly develops marked toxic signs. Approximately 48 hours after the first symptom, frank pus develops subperiosteally. Partly as a consequence of the resistance of cartilage to invasion by the septic process, and partly because of the very firm attachment of the periosteum (more accurately the perichondrium) to the epiphyseal plate, transgression of the plate itself and consequent interference with growth is rare. The inflammatory process progresses along the length of the medulla causing venous and arterial thrombosis as it does so. Subperiosteally, pus tracks both longitudinally and circumferentially around the bone, stripping the periosteum and interrupting the periosteal vessels. Thus progressively larger areas of the cortex become infarcted and involved in the inflammatory process. In the absence of treatment pus finally bursts through the periosteum and tracks through the muscles to present subcutaneously. Eventually the skin breaks down and pus discharges from a sinus which connects the bone with the«skin surface. The bone infarct in acute osteomyelitis is known as a Sequestrum. Surrounding the sequestrum, the elevated periosteum lays down new bone which entombs the dead bone within. This ensheathing mass of new bone is known as the Involucrum. In the places where pus has broken through the periosteum to form a defect in it, sinuses develop which are represented in the involucrum by holes known as Cloaca (Latin) = A drain. The development of such advanced pathology is now rarely seen since modern treatment if adequate, aborts the disease before pus has formed, and certainly before a significant amount of bone has died. Two factors are responsible for the chronicity of this disease: the presence of dead, infected bone which cannot be resorbed; and the fact that the intraosseous abscess cavity cannot be obliterated because it has rigid bony walls. As a consequence of these factors the body's normal defence mechanisms (leucocytes and antibodies) together with any antibiotics that may be given therapeutically are unable to reach all the bacteria in the bone. Accordingly, although the disease process may be sterilised in the living bone, recurrence is always likely. Clinical Features.—Pain is the presenting symptom. It is essential that an accurate history is taken so that the onset of the first complaint of local pain can be timed exactly. The significance of this feature of the history is discussed further under Treatment. The pain gradually increases in severity, and the child becomes increasingly febrile and toxic, at a rate dependent upon the toxicity and virulence of the infective organism. It is usual for the mother to seek medical advice within 48 hours of the onset of the first symptom. Physical Signs.—The essential physical sign is localised tenderness. When the doctor first examines the child, the child is likely to be irritable and to resent examination. It is imperative that the physician should be patient, and gently palpate the child's limbs until the exact area of maximum tenderness has been identified. If this tenderness lies over the metaphysis of a long bone, the diagnosis of acute osteomyelitis should be presumed until it can be proved otherwise. The adjacent joint may contain an effusion, raising the differential diagnosis of suppurative arthritis. The joint itself however is not tender and although the child resists movement of the limb, with patience it is possible to demonstrate that some movement of the joint is allowed. This contrasts with acute suppurative arthritis in which absolutely no movement is permitted. The temperature is raised, often markedly so, and an associated increase in the pulse rate occurs. Some days after the onset of the first symptom noticeable swelling and heat may be detected in addition to tenderness. Finally the area of the abscess (for such it is by this time) is fluctuant. It is absolutely essential that blood cultures should be undertaken before antibiotic treatment is commenced. In order to provide the maximum possible chance of a positive culture, three separate venipunctures should be made and from each venipuncture three aliquots' should be cultured separately. The child's body surface should be searched minutely for possible primary foci of infection and if these are found they should be cultured. Special Investigations.—Other investigations are of no diagnostic value early in the disease. The E.S.R. and white cell count are usually raised but this is entirely non-specific. X-ray.—There are no abnormal radiological features in the first few days of the infection. As time goes by, new bone can be seen deposited by the elevated periosteum, but this sign does not appear until more than 10 days after the onset of the disease and will then be demonstrable whether or not the disease has been sterilised: it depends entirely upon the presence or absence ofperiosteal elevation. Some rarefaction in the bone due to local hyperaemia will also occur after 2 or 3 weeks but again does not distinguish continuing osteomyelitis from the sterilised disease. The radiological appearances of chronic osteomyelitis are dealt with elsewhere. Treatment.—The child is admitted to hospital and the limb is splinted, but in such a way that easy access to the tender area is retained. The outline of the tender area is marked on the skin. If the patient is first seen within 48 hours of the appearance of the first symptoms, antibiotic treatment is begun immediately after appropriate samples have been taken for blood culture. Acute osteomyelitis is one of the few diseases in which it is justifiable to begin antibiotic treatment without waiting for bacterial sensitivity, a peculiarity which stems from the fact that if the disease can be sterilised within the first 48 hours, complete resolution can be guaranteed. If sterilisation fails or is not attempted in this time, the disease may become chronic, so generating life-long disability and a possible cause of death. The great majority (about 80%) of the isolates from osteomyelitis are Staphylococcus aureus and cloxacillin should be administered at a dosage of 100-200 mg/kg body weight in divided doses intravenously until the child is clinically well, has no fever and the local signs have decreased. Oral therapy, with flucloxacillin can then be given. In addition, benzyl penicillin should be given intravenously (0.25-1.0 million units every six hours). For penicillin-hypersensitive patients a cephalosporin may be given intravenously. In children under three Haemophilus influemae may be a responsible organism and especially affects the small bones of the hands and feet. At the present time ampicillin 250 mg q.d.s. intravenously is recommended. Unfortunately antibiotic resistance amongst organisms causing osteomyelitis creates problems. The staphylococci are usually resistant to benzyl penicillin and ampicillin and therefore require a penicillinase-stable penicillin. Most strains of Haemophilus influemae are currently susceptible to ampicillin but if failure to respond is thought to be due to a resistant organism, chloramphenicol should be substituted. Other antibiotics may be substituted if they are dictated by the sensitivity tests. If the patient is first seen 48 hours or more after the onset of the first symptom, the possibility arises that pus is present. If pus is present, it may be sterilised by antibiotics, but the general surgical principle applies to bone as to other tissues that an abscess requires surgical evacuation. The presence of pus may be difficult or impossible to detect with certainty since fluctuation is late to develop. Fluctuation cannot be demonstrated in the early stages of abscess formation because the periosteal membrane is tense, the involved bone is often deep to muscle, and the area is too tender to palpate firmly. Therefore the surgeon has to rely upon his general impression as to the severity of the disease and his knowledge of its duration in deciding either to treat the patient initially with antibiotics, or to combine this therapy with incision of the tender area. If it is decided to rely on antibiotic therapy alone in the belief that no pus is present, antibiotics should be given and the effect of this treatment upon the toxic signs and upon local tenderness should be watched very closely. If the antibiotic is controlling the disease, and if no pus is present, the temperature will subside to become normal within 2 or 3 days and tenderness will progressively disappear. If, on the other hand, the antibiotics are inappropriate to the sensitivities of the organism or pus is present, the temperature is likely to settle but not to normality: spikes up to 38°C will continue. If this occurs, the tender area must be explored surgically with a view to evacuating pus if any is present and to obtaining the organism for culture and sensitivity. Operation.—Operation is carried out under general anaesthesia and is preceded by exsanguination of the limb by elevation and the use of an inflatable tourniquet. An incision is made over the tender area and carried down to the bone where pus is usually found deep to the periosteum. The abscess cavity is fully opened and the pus evacuated. A swab is taken for culture and sensitivity at this stage. There is controversy as to whether or not this procedure should be followed by drilling the cortex in order to enable any pus that may be present in the medullary cavity to drain to the surface. The wound is then closed with interrupted sutures over a closed sterile suction drain. Antibiotics and local splintage are continued postoperatively. Complications.—These may be divided into two types, general and local. The general complications are septicaemia and pyaemia which may give rise to metastatic abscesses. Either complication, if uncontrolled, may prove fatal. Amyloid disease may develop as a complication of chronic osteomyelitis. The local complications include: (1) secondary involvement of the joint if the epiphyseal line is intra-articular, e.g. the hip joint in association with osteomyelitis of the proximal femur; (2) spontaneous fracture which is rare provided the limb is splinted and the disease adequately treated, (3) deformity which, surprisingly, is rare, and (4) chronic osteomyelitis. Acute Traumatic Osteomyelitis This condition arises as a result of infected wounds, for example compound fractures, and operations on bones. The constitutional disturbances are less severe than in acute (infective) osteomyelitis, as the causative wound provides some measure of drainage. Treatment consists of more extensive opening of the wound, removal of dead bone, and antibiotics. The prevention of this condition depends upon the adequate initial treatment of compound fractures and upon sterile operating conditions. CHRONIC OSTEOMYELITIS Pathology.—Acute haematogenous osteomyelitis may pass into chronic osteomyelitis if early treatment is not available, or is inadequate so that infected bone dies to form a sequestrum. The disease may take two forms. The pathology of the more common variety in which a large volume of bone is involved has been described under acute osteomyelitis. The incidence of this condition has been greatly reduced by the modern treatment of the acute infection, but some cases remain as a legacy of the preantibiotic era, and more will probably occur in the future if the acute infection is inadequately treated. The second variety is known as Brodie's abscess. The infection in this form of the disease is closely contained so as to create a chronic abscess within the bone composed of pus or jellylike granulation tissue surrounded by sclerotic bone. The lesion may be the sequel to a pyogenic septicaemia from which the patient has recovered, leaving a bone abscess which may remain dormant for years. On the other hand, it may be found in a patient who is known to have had osteomyelitis (but not septicaemia) affecting a bone other than the one in which the Brodie's abscess is discovered. Clinical Features.—Chronic osteomyelitis may remain quiescent for months or years, but from time to time acute or sub-acute exacerbations occur. An exacerbation is ushered in with constitutional upset and local evidence of inflammation, which may culminate in a discharge of pus, often from a preexisting sinus. An x-ray sometimes reveals a sequestrum which has separated from the surface of the bone or which lies in a cavity. Tomographs may help to demonstrate a sequestrum and a sinogram may delineate an abscess cavity in the bone. A Brodie's abscess causes intermittent local pain and occasionally transitory effusions in the adjacent joint during an exacerbation. Examination may reveal tenderness and thickening of the bone. A radiograph is diagnostic. The amount of bony sclerosis is variable, ranging from dense sclerosis extending a considerable distance round the cavity to, more commonly, a faint line of sclerosis at the junction of the abscess with the cancellous bone. The chronicity of a Brodie's abscess is the result of the physical characteristics of bone, because the abscess can never close by collapse of the walls as happens in soft tissues. Moreover, the infection kills the hard, bony walls of the abscess and provokes new bone deposition, thus preventing leucocytes, antibodies and antibiotics from reaching the contents of the cavity. Treatment of exacerbations in chronic osteomyelitis consists of immobilization of the limb and the administration of antibiotics. On this regime the exacerbation often subsides, but only to recur again later in life. Surgical intervention in chronic osteomyelitis has as its objective the removal of dead bone and the elimination of dead space. Dead bone in the form of a sequestrum may be detected by probing a sinus or by x-ray. Seams of dead bone dispersed within living bone cannot be detected with certainty but may be suspected if an x-ray shows an area of sclerosis. An appropriate antibiotic (which is chosen in the light of the sensitivity of the causative organism) is administered for some days prior to operation. Access to the bone is usually gained through a previous scar. The soft tissues are stripped from the bone, and the involucrum is removed to reach the sequestrum. If a cavity is present, the over-hanging walls are removed with an osteotome, until it is 'saucerised'. Sclerotic bone is removed en bloc if this is practicable. The wound is drained and closed in such a way as to eliminate dead space as far as possible. Modern approaches to this problem include insertion of gentamycin-impregnated beads following debridement of the affected area. These are removed 14 days later and the dead space obliterated by packing the cavity with cancellous bone chips, or filling it with a local muscle flap. So difficult is it to guarantee that an operation will cure chronic osteomyelitis affecting a large volume of bone, that operative intervention is not be be considered lightly unless a sequestrum is known to be present. If, however, a sequestrum is present and is removed, sinuses will often close and the disease may be cured. If only a cavity or sclerosis is present in the bone without a sequestrum, the attempt to 'saucerise' may fail and still leave a sinus. There are many patients for whom, if the discharge is slight and easily controlled by a dressing, it is preferable to retain the sinus and dressings permanently. Amyloid disease need be feared only when a copious discharge of pus has persisted for some years. Amputation may be advisable if exacerbations are frequent or prolonged, in order to rid the patient of recurring periods of painful disability, and to forestall the onset of amyloid disease. A Brodie's abscess should be treated by surgical evacuation and curettage of the cavity under antibiotic cover followed, if the cavity is of moderate size, by packing with cancellous bone chips. ACUTE SUPPURATIVE ARTHRITIS Like acute osteomyelitis, this used to be a common disease especially in children, but is now rare. Acute infection of a joint occurs as a result of: /. Direct infection, as by a penetrating wound or a compound fracture which involves the joint. 2. Local extension, from some neighbouring focus, such as acute arthritis of the hip joint from osteomyelitis of the femoral neck. 3. Blood-home infection, the usual organisms being the streptococcus, staphylococcus, and pneumococcus, and less commonly the gonococcus and B. typhosus. The knee joint, owing to its large size and exposed position, is the commonest joint to be involved by penetrating wounds, while suppurative arthritis from blood-borne infections is the more common cause in other joints. Clinical Features.—The patient complains of steadily increasing pain, inability to move the joint and malaise. On examination the patient is often severely toxic with a raised temperature and pulse rate. The joint is held in the position of its greatest capacity (the 'position of ease') and, if subcutaneous, it can be seen to be swollen. Palpation reveals increased heat, tenderness and an effusion. Movements are prevented absolutely by muscular spasm, and attempts at either active or passive movement cause severe pain. On this regime the exacerbation of the limb and the administration of antibiotics. On this regime the exacerbation often subsides, but only to recur again later in life. Treatment.— 1.Immobilisation.—The joint must be immobilised until the infection has been cured. As any case of suppurative arthritis may be followed by ankylosis, it is the duty of the surgeon to anticipate this possibility by immobilising the joint in the best position for ankylosis (i.e. the position of optimum function), as indicated in the table below. The limb is supported and fixed by a suitable splint or appliance in the correct position, an anaesthetic being administered if necessary. Traction is used in cases of septic arthritis of the hip to prevent dislocation. 2. Antibiotics are administered systemically as in acute osteomyelitis. 3. Aspiration is useful for both diagnostic and therapeutic reasons. The nature of the fluid can be ascertained, and the organism cultured to obtain its antibiotic sensitivity. Aspiration reduces the tension within the joint, thereby relieving pain, and limiting the stretching of ligaments and capsule. It has the disadvantage that a previously uninfected 'sympathetic' effusion may be infected if the needle traverses a septic focus on its way into the joint. On balance, the advantages outweigh this disadvantage. If frank pus is aspirated, the joint is opened. 4. Aspiration and Injection.—After fluid has been aspirated, antibiotics may be injected into the joint. Repeated injections of antibiotic into a joint are unnecessary, since systemic administration is adequate. 5. Arthrotomy and Drainage is only done if the joint is found on aspiration to contain frank pus, or if bone destruction has involved the articular surfaces so that some degree of ankylosis is all that can be expected when healing has occurred. The joint is opened, washed out, and closed suction drains are placed down to the sy no vial cavity. This technique is nowadays less often needed, because the disease, if diagnosed early, can be treated by antibiotics and aspiration. Extra-articular abscesses sometimes require to be opened and drained. In the case of the knee joint, pus is particularly liable to track upwards beneath the quadriceps, where its presence may be overlooked. 6. Excision.—Nowadays this too is rarely required, but if the condition of the patient deteriorates in spite of treatment, or if suppuration is prolonged, drastic surgical ablation of the diseased bone is necessary. Complications.—Early complications include destruction of articular cartilage, pathological dislocation, and necrosis of the epiphysis resulting from damage to the blood supply (especially in the case of the proximal femoral epiphysis). Late complications include secondary degenerative osteoarthritis, joint stiffness and fibrous or, particularly, bony ankylosis.