Prophylactic Antibiotics in Surgery
K Lakshman FRCS
Consultant Surgeon
Bangalore
Surgeons have been facing the dual problems of infection and bleeding from time
immemorial. Discovery of chemical disinfectants and antibiotics along with
principles of asepsis and antisepsis have helped keep surgical infections under
control. One of the tools employed towards minimizing wound and deep space
infections after surgery, is the use of prophylactic antibiotics. A clear
understanding of definitions of some of the terms used, is important, if uniform
policies for minimizing surgical infections have to be developed and adopted.
Definitions:
Stedman’s dictionary defines Prophylaxis as a process of ‘being on guard’ or ‘to
take precaution’. Implicit in the definition, is the fact that, there is no existing
infection to start with.
Discrepancies occur in the way surgeons define Surgical site infections (SSI).
With this difference, audit of wound infections will produce variable and
incomparable results. Table 1 outlines the currently accepted features of wound
infection.
Table 1: Wound Infection
Definition
1.
2.
3.
4.
Purulent discharge
Discharge showing organisms on Gram stain or Culture
Cellulitis of > 1cm
Follow-up – minimum of 1 month for skin and deep space infection
and 1 year for infection in implanted prostheses.
Superficial infection refers to infection in skin and subcutaneous tissues. The
term Deep infection is not universally accepted; it refers to infection in the fascial
planes of the abdominal wall. Deep space infections refer to infection in intraabdominal and intra-thoracic spaces. In reporting infections, criteria laid out for
detection and duration of follow-up have to be strictly adhered to. Without this,
under reporting of infection is common (Yerdl, 2001).
Several factors influence the incidence of surgical site infections (Al-Fouji, 1998).
Table 2 lists some of these factors. Control of these confounding variables is
important in studies, aiming to establish the value of prophylactic antibiotics.
Table 2: Factors influencing SSIs.
 Class of surgery
 Co-morbid conditions
 ASA grading
 Shaving
 Skin preparation
 Duration of surgery
Table 3: Class of Procedure
 Clean
Hernia repair
 Clean contaminated
Biliary tract, Stomach
 Contaminated
Gross spillage, Bowel
Resection
The degree of contamination at the time of surgery is a significant factor in the
causation of SSI. Wounds are classified as clean, clean-contaminated,
contaminated or dirty, depending on the estimated degree of contamination
(Table 3). Dirty wounds have gross faecal or purulent material contamination;
use of antibiotics in this situation is treatment of established infection, and not
strictly, prophylaxis. It is universally accepted that prophylaxis is used in cleancontaminated and contaminated operations. Clean operations with implanted
material also attract prophylaxis. Its use in clean operations without implanted
material is not universally accepted. The low incidence of infection without
antibiotics in this group of patients and the unfavourable cost-benefit ratio, have
lead to this controversy.
Principles of Prophylaxis:
Principles of prophylaxis address the selection of the antibiotic to be used and
the mode and time of administration of the antibiotic (Dunn DL, 2001).
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Clearly, the cost–benefit ratio, in terms of the cost of the antibiotic and the
‘cost’ in side effects like anaphylaxis, gastro-intestinal disturbance
(Harbarth S, 2001), bone marrow suppression and hepatic and renal
toxicity, must weigh in favour of the antibiotic.
The first 2-4 hours after making the surgical incision form the ‘golden
period’ for prophylaxis. It is important that blood levels of the antibiotic are
above minimum inhibitory levels from about 10 minutes before incision is
made to about 4 hours after the completion of the operation. If the surgery
lasts longer than four hours, it would be prudent to repeat the dose of the
antibiotic.
Contaminating organisms are endogenous; from the patient
himself/herself. With modern sterilization methods, exogenous
contamination is almost completely avoided. Endogenous sources include
the organisms on the skin and those in the viscera. Knowledge of the
‘normal’ organisms at various sites in the body is essential for choosing
the correct antibiotic for prophylaxis.
It is important to develop data locally regarding the organisms found at
various sites of the body. Extrapolating results of studies from other parts
of the world, may lead to the choice of the incorrect drug.
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Antibiotic levels are maintained for about 12 hours after the surgery; some
studies have protocols lasting 24 hours. Certainly any antibiotic course
lasting more than 48 hours becomes treatment and cannot be called
prophylaxis.
Antibiotics commonly used for treatment are avoided as the drugs for
prophylaxis; this is to avoid selecting out resistant organisms.
Availability, cost, side effects and allergies may preclude use of the first
choice antibiotic. It is, thus, important to have a second line drugs ready,
to be used if the need arises.
Suggested Regimen
It is incorrect to specify the use of a single prophylactic antibiotic regime to be
applied at different institutions. The principles laid down above have to be
followed by each institution, or at the most, institutions within a confined
geographical area, in drawing up an antibiotic policy. The following table has
been reproduced from a standard surgical textbook (Bailey and Love, 2001) as a
general guideline.
Source
Organism
Antibiotic
Oesophago-Gastric
Enterobact.
Enterococci
Cefuroxime+
?Metranidazole
Biliary
Enterobact.
Enterococci
Cefuroxime
Small Bowel
Enterobact.
Anaerobes
Cefuroxime+
Metranidazole
Colorectal
Enterobact.
Anaerobes
Vascular
S aureus
S epidermidis
Aerobic Gm –ve
S aureus / Epid
Aerobic Gm –ve
Anaerobes
Cefuroxime+
Metranidazole+
Bowel Prep.
Fluclox + Genta
Cefuroxime
Lower limb
amputations
Cefuroxime +
Metranidazole
Special Situations:
Most of the operations come under the principles and guidelines outlined above.
However certain special situations need a modified approach. These situations
include dental procedures in patients with implants (Segreti J, 1999), the asplenic
and other immuno-compromised patient (Brigden, 2001) and procedures in the
presence of valvular disease of the heart and implanted pace makers(Lee, 2001).
Detailed discussion of these situations is outside the purview of this paper. In
general, treatment is individualized. Risk stratification of the patient and the
procedure is done and decision taken regarding the use of antibiotic.
Our Practice:
We have been routinely using prophylactic antibiotics in all classes of operations.
Our reason in using antibiotics even in clean cases without implants has been to
‘cover’ variations in operating room techniques in different institutions. A single
dose of Cefuroxime 750mg IV is given at the time of induction of anaesthesia.
This ensures that the drug has been given under direct supervision. Also
unexpected delays in starting the surgery will not compromise the time interval
between administration of the antibiotic and the making of the incision. A similar
IV dose is repeated if the surgery lasts longer than 4 hours. In clean
contaminated cases, an additional dose is given 6 hours after the completion of
surgery. Metranidazole is added if anaerobes form a part of the potential
contaminating flora. If contamination from oral organisms is a possibility, a
combination of ampicillin and metranidazole or amoxicillin+Clavulenic acid is
used.
What is needed in future?
We need to generate data regarding the pattern of flora in various centres in our
country. Susceptibility pattern of these organisms have to be determined. We
also need to have a survey of current practice. It is likely that there are great
variations in the use of antibiotics both as prophylaxis and treatment. We need to
normalize this by drawing up a uniform policy for the use of antibiotics. Finally we
need to monitor how well this policy is being followed. The general experience in
this regard, even in developed countries, has been disappointing (Llemand S,
2001).
Conclusion:
This paper outlines the need for antibiotic prophylaxis. The principles governing
such use are explained. The importance of having locally drawn up guidelines
for antibiotic use is stressed. Finally, it is emphasized that monitoring the
adherence to guidelines and regular audit of SSI are necessary if the goal of
good surgical care to our patients, is to be achieved.
References:
Al-Fouji AR, 1998 in Postgraduate Surgery – A Candidate’s Guide 2nd Edition,
Butterworth-Heinmann, pp 180-182
Bailey and Love’s Short Practice of Surgery, 2000, 23rd Edition, Wound Infection,
Arnold, pp 93-95
Brigden ML, 2001, Detection, Education and Management of the Asplenic or
Hyposplenic Patient, Am Fam Phy, 63(3):499-506
Dunn DL, 2001, Diagnosis and treatment of infection in Surgery – Basic Science and
Clinical Evidence, Ed. Norton JA, Bollinger RR, Springer, pp 206-208
Harbarth S, Samore MH, Carmeli Y, 2001, Antibiotic prophylaxis and the risk of
Clostridium difficile-associated diarrhea, J Hosp Inf, 48(2):93-7
Lee TH, 2001, Prevention, Evaluation, and Management of Infective Endocarditis:
AHA/ACC Guidelines Summary, ACC/AHA Cardiology Guideline Summaries
Braunwald: Heart Disease: A Textbook of Cardiovascular Medicine, 6e W. B.
Saunders Company, pp 748-749
Llemand S, Albin C, Huc B, 2001, Antibiotic prophylaxis and surgery. Prescription
compliance in Franche-Comte with the national reference system, Ann Chir,
126(5); 463-471 (compliance to guidelines)
Segreti J, 1999, Is antibiotic prophylaxis necessary for preventing prosthetic device
infection?, Inf Dis Clin NA, 13(4): 871-877
Yerdl MA, Emin BA, Sukru D, 2001, Effect of Single-Dose Prophylactic Ampicillin and
Sulbactam on Wound Infection After Tension-Free Inguinal Hernia Repair With
Polypropylene Mesh, Ann Surg 233(1):