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Microbiology of Respiratory Infection II. Dr Michael Lockhart. Respiratory Infections. Infections of throat and pharynx Infections of middle ear and sinuses Infections of trachea and bronchi Infections of the lungs. Infections of throat and pharynx. Sore throat Diphtheria Candida/thrush
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Microbiology of Respiratory Infection II Dr Michael Lockhart
Respiratory Infections • Infections of throat and pharynx • Infections of middle ear and sinuses • Infections of trachea and bronchi • Infections of the lungs
Infections of throat and pharynx • Sore throat • Diphtheria • Candida/thrush • Vincent’s angina
Infections of throat and pharynx • Diagnosis: • Well taken throat swab
Sore throat • VAST MAJORITY (OVER TWO THIRDS) - VIRAL • DO NOT NEED ANTIBIOTICS
Bacterial sore throat • The most common BACTERIAL cause is Streptococcus pyogenes (also known as Group A streptococci) • Clinical: Acute follicular tonsillitis • Treatment:Penicillin
Streptococcal sore throat • Acute complications: • Peritonsillar abscess (quinsy) • Sinusitis/ otitis media • Scarlet fever
Streptococcal sore throat • Late complications • Rheumatic fever • 3 weeks post sore throat • fever, arthritis and pancarditis • Glomerulonephritis • 1-3 weeks post sore throat • haematuria, albuminuria and oedema
Diphtheria • Corynebacterium diphtheriae • Clinical: Severe sore throat with a grey white membrane across the pharynx. The organism produces a potent exotoxin which is cardiotoxic and neurotoxic.
Diphtheria • Epidemiology : Rare, but increased in certain parts of the world eg Russia • Treatment: Antitoxin and Supportive and Penicillin/erythromycin
Candida/Thrush • Candida albicans • Clinical: White patches on red, raw mucous membranes in throat/ mouth • Cause: endogenous • Treatment: Nystatin
Vincent’s angina • Mixture of organisms (Borrelia vincenti and Fusobacterium sp.) • Clinical:Foul smelling mouth and throat ulcers • Treatment: penicillin
Respiratory Infections • Infections of throat and pharynx • Infections of middle ear and sinuses • Infections of trachea and bronchi • Infections of the lungs
Infections of middle ear and sinuses • Often viral with bacterial secondary infection • Most common bacteria: Haemophilus influenzae, Streptococcus pneumoniae and Streptococcus pyogenes. • Treat: Amoxycillin
Respiratory Infections • Infections of throat and pharynx • Infections of middle ear and sinuses • Infections of trachea and bronchi • Infections of the lungs
Infections of trachea and bronchi • Acute epiglottitis • Acute exacerbations of COPD • Cystic fibrosis • Pertussis (whooping cough)
Acute epiglottitis • Haemophilus influenzae • Clinical: severe croup in children aged 2-7 years, may progress to respiratory obstruction and death.
Acute epiglottitis • Microbiology of Haemophilus influenzae • Habitat - upper respiratory tract • Microscopy- small gram negative bacillus • Culture - Chocolate agar -small translucent colonies • Identify - “X and V test”; H influenzae requires both factors X and V to grow.
Acute epiglottitis • Diagnosis: blood culture (?throat swab) • Treatment: ITU and ceftriaxone
COPD • Acute exacerbations of COPD. • Exacerbations of this chronic condition are often associated with bacterial infection.
Acute exacerbations of COPD • Often follow viral infection, or fall in atmospheric temperature with increase in humidity (often in winter) • Clinical: Patients present with increased breathlessness. The volume and purulence of sputum is increased.
Acute exacerbations of COPD • The most common organisms associated are: • Haemophilus influenzae • Streptococcus pneumoniae • Moraxella catarrhalis • NB All three organisms are present in normal upper respiratory tract flora.
Acute exacerbations of COPD • Treatment: • Give antibiotics if ↑sputum purulence. If no ↑sputum purulence then antibiotics not needed unless consolidation on CXR or signs of pneumonia. • 1ST LINE Amoxicillin 500mg tds 2ND LINE Doxycycline 200mg on day 1 then 100mg daily (5 days) • With time becomes increasingly difficult to treat, due to acquisition of more resistant organisms.
Cystic fibrosis • Inherited defect • leads to abnormally viscid mucus which blocks tubular structures in many different organs including the lungs.
Cystic fibrosis • Chronic respiratory infection is a major problem. • Causal bacteria: • Staphylococcus aureus and Haemophilus influenzae • Pseudomonas aeruginosa • Burkholderia cepacia
Pertussis (whooping cough) • Bordetella pertussis • Clinical: Acute tracheobronchitis • cold like symptoms for two weeks • paroxysmal coughing (2 weeks) • repeated violent exhalations with severe inspiratory whoop, vomiting common • residual cough for month or more
Pertussis (whooping cough) • Diagnosis: • pernasal swab (charcoal blood agar/ Bordet-Gengou medium) • serology • clinical ( by the stage of paroxysmal coughing organism numbers much reduced) • Treatment: most effective in the first 10 days of illness, also reduces spread to susceptible contacts • Vaccination
Respiratory Infections • Infections of throat and pharynx • Infections of middle ear and sinuses • Infections of trachea and bronchi • Infections of the lungs
Infections of the lungs • Community acquired pneumonia • Nosocomial pneumonia • Legionnaires disease • Pneumocysitis carinii pneumonia (PCP) • Fungal chest infection • Tuberculosis
Community acquired pneumonia • Clinical: cough, sputum production, dyspnoea, fever. • Chest x-ray with infiltrates. • Acquired in the community
Community acquired pneumonia • Causative organisms: • Streptococcus pneumoniae 70% • Atypicals/viruses 20% • Staphylococcus aureus 4% • Other bacteria 1% • Haemophilus influenzae 5%
Community acquired pneumonia • Streptococcus pneumoniae • Microbiology: • Microscopy - gram positive cocci • Culture - Alpha haemolytic colonies, typically “draughtsmen” ie with sunken centre. • Identify - “Optochin” sensitive • Treatment - generally penicillin sensitive
Community acquired pneumonia • “Atypicals” - old term for pneumonias not attributable to any of the common bacterial causes of pneumonia. • Refer to Dr McIntyre’s talk
Community acquired pneumonia • Treatment , follow the Tayside Critical Care Pathway for the Management of Community-Acquired Pneumonia