RESPIRATORY TRACT INFECTIONS
Etiology
viruses
rhinovirus
coronavirus
adenovirus
influenzavirus
parainfluenzavirus
respiratory syncytial virus
Coxsackievirus
Epstein-Barr virus
cytomegalovirus
fungi
Candida albicans
bacteria
Streptococcus pyogenes (GABHS)
Streptococcus pneumoniae
Haemophilus influenzae type b
Moraxella catarrhalis
Arcanobacterium haemolyticum
Staphylococcus aureus
Corynebacterium diphtheriae
Klebsiella pneumoniae
Mycoplasma pneumoniae
Chlamydia pneumoniae, psittaci
Legionella pneumoniae
oral anaerobic flora
rhinitis - common cold
pharyngitis
epiglottitis, laryngitis
tracheitis
bronchitis
pneumonia
sinusitis
otitis media
UPPER RESPIRATORY TRACT INFECTIONS
COMMON COLD, CORYZA, ACUTE RINOPHARYNGITIS
Etiology:
rhinoviruses, coronaviruses, …RSV, parainfluenza, influenza, enteroviruses, adenoviruses
secondary infection – S.pneumoniae, H.influenzae, M.catarrhalis, anaerobes
Clinics: familiar to everybody
Treatment: symptomatic
Complications:
- acute sinusitis
complications: orbitocellulitis, meningitis, brain abscess
- otitis media
complications: mastoiditis…meningitis, brain abscess
PHARYNGITIS, TONSILLITIS
Etiology:
viruses – EBV, adenoviruses, enteroviruses, HSV, other respiratory
bacteria – GABHS -S.pyogenes, N.gonorrhoeae, Arcanobacterium haemolyticum
Clinics:
local - sore throat, reddened and inflamed pharyngeal mucosa, reddened enlarged tonsills with/without exsudate
(patchy… confluent forming pseudomembranes), submandibular lymphadenopathy
systemic - fever, malaise, headache
Local + systemic symptoms ═ diagnostic clues to etiology:
Pharyngitis with mild sore throat, mild systemic symptoms and coryza - common cold, respiratory viruses
Pharyngitis with moderate to severe sore throat and systemic symptoms:
tonsillitis with/without exudate, acute onset, fever, in children vomiting and abdominal pain –
S.pyogenes(GABHS)
tonsillitis with confluent exsudate (pseudomembranes), palatal petechiae, cervical lymphadenopathy,
hepatosplenomegaly, insidious onset, low-grade fever, no effect of ATB –
Epstein-Barr virus, (CMV), infectious mononucleosis
nonexudative, catarrhal pharyngitis, nonproductive cough, myalgia, fever – influenza
pharyngitis with/without exudate, conjunctivitis, lymphadenopathy, fever - adenoviruses
vesicles (blisters) around the soft palate, which soon rupture leaving shallow ulcers, fever
Coxsackieviruses – herpangina
HSV pharyngitis
Diagnosis– to differentiate „strep throat“ and viral pharyngitis:
ESR, blood count, differential count of leukocytes, CRP
throat swab culture, rapid GABHS antigen detection tests
antistreptolysin O titre
ALT, AST
heterophilic antibodies (agglutinate sheep, bovinne, horse erythrocytes - Ericson, Paul-Bunnell, Monospot test)
Streptococcal tonsillitis:
raised ESR and CRP, leukocytosis, left shift
ASO titres > 400 IU - recent infection, fourfold rise in paired sera is evident of strep. disease. But may be
delayed for up to 4 weeks, useful for dg. sequelae.
Infectious mononucleosis:
atypical lympho-monocytes, raised ALT, AST, heterophilic antibodies, anti-EBV antibodies - anti EA, VCA,
EBNA
Treatment and complications:
Streptococcal tonsillitis
Treatment: PNC, alternatively ERY or CEF I., 10days!!
Complications:
suppurative: peritonsilar abscess (quinsy), lymphadenitis
nonsuppurative poststreptococcal sequelae: rheumatic fever, glomerulonephritis
Infectious mononucleosis:
Treatment: symptomatic - antipyretics, analgesics, nasal decongestant drops
Complications:
airway obstruction - elevated head, anti-inflammatory drugs, i.v.corticosteroids, intubation or tracheostomy is
rarely needed
peritonsilar abscess (quinsy)
thrombocytopenia, hemolytic anaemia, spleen rupture
Rare pharyngitis:
Plaut –Vincent´s angina – the synergistic action of the mouth spirochetae Borrelia vincenti and the anaerobe
Fusobacterium in persons with poor oral hygiene, extreme soreness of the mouth and gums with offensive
halitosis
tularaemia - oralglandular form
HIV – seroconversion illness – mononucleosis-like illness, with generalized lymphadenopathy and unusual
rash, few atypical mononuclear cells
Be aware of hematologic malignancies!
DIPHTHERIA - Corynebacterium diphtheriae – toxin
Clinical forms:
- pharyngeal diphtheria – tonsillitis with membranes, marked edema of the cervical lymph nodes („bull-neck“),
fever, sore throat
- laryngeal diphtheria
- nasal, cutaneous, conjunctival diphtheria
Resorption of toxin!
Diagnosis: non-immunized patient with anamnestic exposure, quickly developing exsudative tonsillitis or
respiratory distress
Laboratory: specimens from throat, larynx, nose for culture on special media, confirmation of toxin production
Complications: toxin
- early cardiac damage – myocarditis, conduction defects – heart failure †
- late neurological damage (demyelination) – palatal and ocular palsies, peripheral palsies, Guillain - Barré sy
- laryngeal, tracheal membrane – airway obstruction and suffocation †
Treatment:
antitoxin – hyperimmune globulin
antibiotics – benzyl-PNC, ERY, CEF I.
elective tracheostomy
Prevention:
diphtheria vaccine (toxoid)
ACUTE EPIGLOTTITIS
Acute and severe cellulitis of the epiglottis and surrounding tissues, with rapid progression and threatening
airway obstruction.
Children 1-5 years, average 3y, the incidence has decreased since the introduction of Hib vaccination.
Etiology: H. influenzae type b, rarely H. parainfluenzae or GABHS
Clinics: abrupt onset with sore throat, fever and toxicity, dysphagia, drooling, respiratory distress with
stridor, retractions of the chest wall
cherry-red epiglottis may be seen, this should not be attempted, not depress the tongue, fatal occlusion of the
airway may occur
Diagnosis: history and clinics → emergent transport to the hospital:
- direct inspection of the epiglottis only with trained personnel and equipment for maintaining the airway
- blood culture, respiratory secretions culture
- leukocytosis, left shift, CRP
- (lateral neck X-ray – „thumb sign“, in early, less toxic patients)
Treatment:
adequate airway - intubation, (corticosteroids)
antibiotics – CEF III, AMO/inh, CEF II, CHMF
Prevention: Hib vaccine
LARYNGITIS and CROUP
I. Acute viral laryngitis
self-limited illness of viral etiology, symptomatic treatment
II. Acute viral laryngotracheitis (croup)
Clinically distinctive syndrome, characterized by respiratory distress, inspiratory stridor and subglottic
swelling.
Children few months to 3 years.
Etiology: parainfluenza virus type 1,2,3, less freq. influenza, RSV, adenoviruses, Mycoplasma pn.
Clinics: often preceding common cold, pharyngitis, fever is variable, hoarseness, „barking“ cough (like a
„barking seal“)....at night abruptly respiratory distress with inspiratory stridor
Diagnosis: characteristic clinics (neck X-ray shows narrowing of the tracheal air shadow in the subglottic
region, not routinely done)
Laboratory: resp. secretions - virus isolation (not routinely), serology
Treatment:
sedation
humidification, humidified oxygen
corticosteroids
nebulized epinephrine
(intubation rarely necessary)
PERTUSSIS, WHOOPING COUGH
Etiology: Bordetella pertussis, parapertussis……..toxins!
(Viruses, chlamydiae and mycoplasma can mimic the cough.)
Clinics: IP 7-14days, a catarrhal cold with simple cough and slight fever develops (catarrhal phase), after 45days cough progresses to paroxysms (paroxysmal phase), followed by rapid inspiration causing „whoop“, with
cyanosis, they repeat 30-40times a day, are often terminated by vomiting or expelling a piece of thick sputum.
The infants may have apnoeic attacks. It lasts at least 2-3weeks.
Complications:
haemorrhage due to raised venous pressure during paroxysms – facial and subconjunctival petechiae,
intracerebral haemorrhage in infant
encephalopathy (combination of hypoxia and haemorrhage)
secondary pneumonia
malnutrition
Laboratory: absolute and relative lymphocytosis
Diagnosis:
culture of nasopharyngeal swab on Bordet-Gengou agar
serology
Treatment:
symptomatic: careful observation, a humidified atmosphere, cot oxygen tent, lifting and comforting during
paroxysms, cleaning away the mucus, minimizing inhalation of vomit, small frequent feeds, re-feeding when
necessary, antitussives have a limited effect
antibiotics – ERY
Prevention: vaccine – whole-cell killed vaccine (associated encephalopathy not supported by studies), subunit
vaccine
LOWER RESPIRATORY TRACT INFECTIONS
Laboratory diagnosis
Sputum microscopy – Gram-stain
Sputum culture - the common respiratory pathogens also occur in the normal upper resp. tract flora,
semiquantitative culture methods – pathogens reach higher concentrations than commensals ( > 10 6 CFU/ml)
Serology for retrospective diagnosis
Specimen collection from the lower RT:
- sputum obtained by coughing
- tracheal aspirate
- bronchoscopy with bronchoalveolar lavage or protected brush specimen – when suspicion of unusual
pathogens or in immunocompromised pts: tuberculosis, legionellosis, fungal infections, Pneumocystis
carinii infection
VIRAL INFECTIONS OF THE LOWER RT
Bronchiolitis
Etiology: RSV, ….parainfluenza 3, other respir. viruses
Infants up to 2 years, possible role of RSV in the etiology of SIDS, preterm infants and those with congenital
heart disease are at particular risk.
Clinics: initially common cold, loose cough, after 3-4 days respiratory distress occurs with tachypnea and
intercostal and subcostal retractions, exspiratory wheezing, rhonchi, crepitations resembling asthma,
…respiratory insufficiency, cyanosis….heart failure
X-ray: hyperinflation with or without infiltrates from atelectasis or concomitant pneumonia
Diagnosis:
RSV Ag in nasopharyngeal secretions – IFT, EIA
virus isolation
serology – CFR, IFT, EIA
Treatment:
oxygenation - cot-sized oxygen tent, ventilatory support
bronchodilators (salbutamol) to differentiate asthma
adequate hydration
virostatics - nebulized ribavirin
Complications: secondary bacterial infection…antibiotics
Prevention: vaccination
Influenza
( x flu-like disease)
Etiology: influenzaviruses type A, B, C (orthomyxovirus), the envelope contains 2 glycoproteins –
haemagglutinin H and neuraminidase N, both are antigenically variable, type A exists in many H a N subtypes
Epidemiology:
Epidemics are due to a great antigenic variability:
drift (A, B) – a little change in H or N antigen, responsible for the yearly winter epidemics, infection with an
epidemic strain provides antibody which will cross-react with closely related types and provides partial
immunity to infection by slowly evolving types from year to year
shift (A) – major change in H or N antigen, the population has little or no cross-reacting antibody to a new
subtype and a pandemy results.
Infects and kills ciliated epithelium, airways then susceptible to colonization and invasion by bacterial
pathogens.
Clinics: IP 1-5 days, abrupt onset of symptoms:
systemic – fever (1-5 days), shivering, headache, myalgia, arthralgia, severe malaise, loss of appetite
respiratory – dry cough, substernal burning, nasal and pharyngeal symptoms, hoarseness
eye – photophobia, painful eye movement
uncomplicated lasts 5-7 days
Laboratory: nonspecific
Diagnosis:
epidemic period
Ag in respiratory secretions – direct IFT
virus isolation in respiratory secretions
serology – CFR, IFT, EIA
Complications:
1. Pulmonary complications: (viral pneumonitis is common and usually mild)
a) severe „influenza“ viral pneumonia
- rapid progression of fever, cough, haemorrhagic sputum, dyspnea, hypoxemia, cyanosis, ....progressive
deterioration, high mortality despite intensive care
- physical exam and X-ray - pulmonary edema, similar to ARDS
b) secondary bacterial pneumonia – often elderly or with pulmonary disease
- after the period of improvement 1-4 days, relaps of fever with symptoms and signs of bacterial pneumonia –
productive cough, chest pain, dyspnea
- physical exam and X-ray consistent with bacterial pneumonia
- sputum Gram stain and culture – S. pneumoniae, H. influenzae, S. aureus
- ATB – AMP(AMO)/inh, CEF I, II
2. Other bacterial infection: sinusitis, otitis media
3. Reye‘s syndrome
Most often after influenza B, prior ingestion of aspirin and other salicylates is associated with an increased risk,
most patients under 16 years, mortality 20-40%.
After several days of influenza CNS signs such as lethargy or drowsiness occur, which may progress rapidly, the
liver is enlarged, liver function tests abnormal, treatment only supportive.
4. Myocarditis, pericarditis often subclinical
5. Myositis and myoglobinuria
after B, less A, painful leg muscles, elevated serum creatinkinase and urine myoglobin
6. (Meningo)encephalitis, Guillain - Barré syndrome, encephalopathy
Treatment:
Symptomatic: rest, warmth, adequate hydration, analgesics, vitamin C
Antivirotics:
amantadine, rimantadine – A, within 48h of onset, side-effects
neuraminidase inhibitors: zanamivir, oseltamivir – A,B
ATB for bacterial complications
Prevention:
Vaccination - vaccines are prepared each year from strains similar to those considered most likely to circulate in
the forthcoming season. Recommended for persons with chronic respiratory and cardiac disease, chronic renal
failure, diabetes and immunosuppression, residents of nursing homes, event. health care workers.
Chemoprophylaxis: for high-risk group persons, for whom vaccination is contraindicated, or in the 2 weeks
following vaccination before Ab develop
amantadine, rimantadine - A
neuraminidase inhibitors: zanamivir, oseltamivir – A,B
A) community – acquired (CAP)
B) hospital – acquired (HAP)
PNEUMONIA
A) Community – acquired pneumonia
Etiology: bacteria, viruses, fungi
Predisposing factors:
 Exposure (epidemiological data): family, job, hobby, travelling
 Age: very young and elderly
neonate: S. agalactiae
infant: RSV, influenza, S.pneumoniae, H.influenzae
children to teenagers: S.pneumoniae, viruses, H.influenzae (< 5y), Mycopl.pneumoniae (> 5y)
young adults (18-45y): Mycoplasma spp., Chlamydia pn., influenza
elderly: S.pneumoniae, Legionella, anaerobes, MycoTBC
 Underlying conditions:
alcoholism – S.pneumoniae, anaerobes, H.infl., Kl.pneumoniae, Mycotbc
disturbed consciousness, dysphagia - anaerobes
COPD – H.infl., S.pneumoniae, Moraxella cat.
cystic fibrosis – S.aureus, Pseudomonas
preceeding influenza – S.aureus, H.infl., S.pneumoniae
Diagnosis:

•
•
•
clinical features
X-ray
laboratory:
– blood count, CRP, ESR
– biochemistry incl. arterial blood gas analysis
microbiology:
– sputum Gram stain, culture, ATB sensitivity test
– blood culture
–
–
–
–
pleural effusion culture
serology – if no response to beta lactam ATB, test admission serum Ab to Legionella and
atypical pathogens (and repeat in 7-14 days) and cold agglutinins (for Mycoplasma infection)
bronchoscopy with bronchoalveolar lavage (or bronchial brushing) – microscopy, culture,
histology – if severe infection not responding to antibiotics
molecular diagnostic methods (PCR) in future
Assessment of severity → referral to hospital or home therapy:
factors associated with increased mortality:
• core factors - if > 2 present, refer to hospital
confusion
tachypnea > 30/min
hypotension < 90/60
tachycardia > 140/min
(= signs of sepsis and/or respiratory insuficiency)
•
age, underlying chronic illness (pulmonary, cardiac, renal, hepatic, diabetes, immunodeficiency),
bilateral or multilobar X-ray changes and signs of necrosis (cavitation), signs of complications:
pleural effusion, empyema
pericarditis
metastatic infection
sepsis, ARDS, MODS
Treatment
Choice of initial empirical antibiotic depends on severity:
not severe:
amoxicillin 500mg-1g q8h oral or clarithromycin 500mg q12h
if hospitalised: benzylpenicillin 5-10 mil IU/day i.v.
severe:
i.v. co-amoxiclav 1,2g q8h or cephalosporin I,II
plus erythromycin or clarithromycin (alternative - levofloxacine)
Adjustment of antibiotics according to microbiological results:
Legionella: erythromycin +/- rifampicin..........or ciprofloxacin
Staph. aureus: oxacillin or clindamycin
Supportive management:
rest, stop smoking, analgesics, humidified oxygen, adequate fluid intake
Lobar pneumonia, bronchopneumonia
Etiology: S.pneumoniae, H.influenzae, Moraxella cat., S.aureus, Kl.pneumoniae ant other gramnegative aerobes,
anaerobes
Clinics: rapid onset, high fever and rigors, dry cough, pleuritic chest pain, later sputum volume and purulence
increase
elderly patients – afebrile, confused
severe cases – sepsis syndrome...MOSF
on examination - signs of consolidation, bronchial breathing, dull percussion note, crepitations
X-ray:
lobar pneumonia - dense infiltration, consolidation of lung tissue filling the lobe
bronchopneumonia – patchy shadowing, air bronchograms
Laboratory diagnosis and treatment – see above.
Complications: pleural effusion, empyema
pericarditis
metastatic infection
sepsis, ARDS, MODS
Pneumonia associated with influenza epidemics (see in influenza)
1.
2.
influenza viral pneumonia
secondary bacterial pneumonia
Aspiration pneumonia
Reduced level of consciousness, seizure disordes, dysphagia due to esophageal or neuromuscular disease, poor
dentition. The right lower lobe more often affected.
Etiology: mixed (aerobic+anaerobic) oral flora
Acute chemical injury due to aspiration of gastric content.
Clinics: symptoms of pneumonia + putrid breath odour
severe cases – lung abscess, empyema
Treatment: G-PNC or AMO/inh or CEF + metronidazole
thoracic drainage of empyema, bronchoscopy
Atypical pneumonia
The term initially used to describe pneumonia which failed to respond to penicillin or sulphonamides and
bacteriology failed to provide a diagnosis, is no longer recommended.
„Atypical pathogens“ - Mycoplasma pneumoniae, Chlamydia pneumoniae, C. psittaci, Coxiella burnetii
Mycoplasma – all ages, commonest in school-age children and young adults, epidemics at 3-4 years interval
Chlamydia psittaci – birds: parrots, duck, poultry
Coxiella burnetii (Q fever) – sheep
Clinics: insidious onset, low-grade fever, sweating, fatigue, dry cough, poor physical findings - discrete
crepitations.
X-ray: anything from faint segmental opacity to a large and dense consolidation, often much greater than the
physical signs suggest. Small or moderate pleural effusion with pleuritic pain.
Laboratory: modest neutrophilia or normal blood count, elevated ESR, mildly elevated transaminases
Diagnosis: serology
cold agglutinins in Mycoplasma infection (may cause hemolysis)
Treatment:
erythromycin 2-3g/day or doxycycline 200mg/day, 10-14days
Legionellosis (Legionnaire´s disease)
Legionnaire´s disease – severe systemic infection with pneumonia
Pontiac fever – the milder nonpneumonic form
Etiology: Legionella pneumophila
Transmission by inhalation of contaminated aerosols generated from air condition, hot-water tap, shower outlets,
water-cooling towers and whirlpool spas. Can exist within free-living amoebae.
The middle-aged and elderly, particularly males, smokers, with underlying chronic respiratory disease.
Clinics: symptoms of severe pneumonia, fever, prostration, confusion, vomiting, diarhea, area of
consolidation or coarse crepitations
Laboratory: neutrophilia, ↑ ESR, signs of renal (↑ urea, creatinine) and hepatic dysfunction (↑ transaminases),
hyponatremia
X-ray: one or more large opacities
Diagnosis:
• clinical features – pneumonia + other organs involvement (GIT, kidney, liver, CNS)
• L.pneumophila serogroup 1 Ag in urine (ELISA)
• L.pneumophila serogroup 1 in sputum (IFT)
• culture (on request) of sputum, tracheal aspirate
• serology – late positivity!, retrospective dg.
Treatment: erythromycin i.v. 3-4g/day plus rifampicin 600-1200mg/d or ciprofloxacin i.v. 400-600mg/day
oxygenation, ventilatory support, supportive management
Prevention: chlorination of water supplies, heating of hot water over 60 o C, cleaning and disinfection of
whirlpool spas.
B) Hospital – acquired, nosocomial pneumonia
Occurs > 48 h after admission, different etiology, different treatment.
Ventilator associated pneumonia (VAP) – particular subgroup.
Risk factors: age, underlying chronic/acute illness, immobility, reduced level of consciousness, recent anesthesia,
dysphagia, instrumentation of respiratory/GIT tract, use of broad-spectrum ATB.
Etiology:
early onset – 2-5days – similar to CAP – S.pneum., H.infl. S.aureus
late onset - gram-negatives – Enterobacteriacae, Pseudomonas, Acinetobacter, S.aureus, anaerobes, rarely
Legionella sp.
Clinics: fever, purulent respiratory secretions, respiratory symptoms, new X-ray signs
Microbiology:
- tracheal aspirate widely used for detection of etiology, of doubtful value, as tracheobronchial colonization is
common in critically ill
- bronchoalveolar lavage or protected bronchial brushing specimen
- blood culture, pleural fluid culture
Antibiotic therapy must be guided by culture and sensitivity results.
FUNGAL INFECTIONS OF THE LOWER RT
Aspergillosis
In pre-existing cavities fungal hyphae may produce a ball-shaped growth, which irritates the cavity wall, causing
cough and hemoptysis.
X-ray – a round, space-occupying lesion surrounded by a narrow clear air space.
Treatment: itraconazole, amphotericin B
surgery – segmental or lobar resection
Histoplasmosis
Dry, hot areas, often from dried bird droppings.
X-ray resembles tuberculosis, nodular apical lesions, cavities
Treatment: amphotericin B, additional itraconazole, fluconazole, surgery for advanced disease
Blastomycosis – confined to the USA, similar disease to histoplasmosis
Coccidioidomycosis – rapidly progressive bronchopneumonia unresponsive to ATB