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LOWER RESPIRATORY TRACT INFECTIONS

LOWER RESPIRATORY TRACT INFECTIONS. Prof T Rogers. PNEUMONIA. THE IMPORTANCE OF PNEUMONIA. A major killer in both developed and developing countries Accounts for more deaths than other infectious diseases Mortality rates vary but can be as high as 25%

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LOWER RESPIRATORY TRACT INFECTIONS

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  1. LOWER RESPIRATORY TRACT INFECTIONS Prof T Rogers

  2. PNEUMONIA

  3. THE IMPORTANCE OF PNEUMONIA • A major killer in both developed and developing countries • Accounts for more deaths than other infectious diseases • Mortality rates vary but can be as high as 25% • A major cause of death in children in developing countries • Incidence here (?) 2-5/1000 population

  4. PNEUMONIA • Neither radiological or microbiological criteria are specific for predicting the cause of pneumonia • A better approach is to first consider the clinical circumstances under which pneumonia acquired • Add the clinical background of the particular patient…

  5. Classification of pneumonia • Community-acquired • Hospital-acquired • Aspiration and anaerobic • Pneumonia in immunocompromised • AIDS-related • Geographically restricted • Recurrent

  6. COMMUNITY-ACQUIRED PNEUMONIA: INTRODUCTORY POINTS • More common at the extremes of age • Twice as common in winter months • A General Practitioner is likely to see up to 10 cases per yr • Represent <10% of all respiratory infection cases prescribed antibiotics • Most will be managed in the community

  7. TYPES OF COMMUNITY ACQUIRED PNEUMONIA • In a previously healthy individual • Here the infection may have been acquired by droplet spread from another • Alternatively, in patients with underlying diseases endogenous colonizing bacteria may be the cause • These are more likely to be resistant to first-line antibiotics

  8. SYMPTOMS OF PATIENTS WITH COMMUNITY-ACQUIRED PNEUMONIA(%)[Mc Farlane unpublished] • Cough 92 • Fever 86 • Breathlessness 67 • Pleural pain 62 • Headache 55 • New sputum production 54 • Muscle aches 44 • Nausea/vomiting 48

  9. COMMUNITY ACQUIRED PNEUMONIA: WHAT’S CAUSING IT?

  10. MICROBIOLOGICAL CAUSES (%) OF COMMUNITY ACQUIRED PNEUMONIA FROM HOSPITAL BASED STUDIES (N=3,000) CAPSevere CAP • No cause found 36 33 • Pneumococcus 25 27 • Influenza virus 8 2.3 • Legionella spp*. 7 17 • Haem. Influenzae 5 5 • Other viruses 5 8 • Psittacosis/Q fever 3 2 • Gram neg. bacilli 2.7 2 • Staph aureus* 2 5

  11. INVESTIGATIONS FOR DIAGNOSIS OF PNEUMONIA • Non-invasive: blood count, urea, albumin,LFT’s, sputum gram, chest X-ray, CT scan • Culture of sputum, blood, pleural fluid • Serology: pneumococcal, Legionella antigen • Invasive: induced sputum, bronchoscopy, open lung biopsy

  12. TYPICAL GRAM APPEARANCE OF Strep pneumoniae IN SPUTUM GRAM POSITIVE CHAINS DIPLOCOCCI

  13. Streptococcus pneumoniae (pneumococcus) • A gram positive coccus that grows in short chains • Alpha haemolytic on blood agar • Identified by its susceptibility to optochin • Polysaccharide capsule confers pathogenicity-at least 80 serotypes • There are multivalent vaccines for prevention of pneumococcal disease

  14. SOME COMPLICATIONS OF PNEUMOCOCCAL SEPSIS • Bacteraemia (10%+) • Empyema (1%) • Meningitis (<0.5%) • Mortality rates of 10-25% • Splenectomy or asplenia a major risk factor

  15. Pneumococcal vaccine is recommended for: • Age >65 years • Underlying chronic lung disease • Asplenia • Alcoholism • Diabetes mellitus • Chronic renal failure • HIV infection

  16. BTS Guidelinesfor the Management of Community Acquired Pneumonia in Adults Updated 2004 www.brit-thoracic.org/guidelines

  17. Treatment • Home treated-Amoxicillin 500mg or 1 g tds PO (or admitted for social reasons) • Hospital treated Amoxicillin 500mg or 1 g PO plus erythromycin 500mg qds po • Hospital treated severe Co-amoxiclav 1.2 g tds and erythromycin 500mg qds I/v , +/- rifampicin

  18. VIRUSES THAT CAUSE COMMUNTIY ACQUIRED PNEUMONIA

  19. INFLUENZA

  20. OTHER VIRAL CAUSES • Respiratory syncytial virus (RSV) • Parainfluenza viruses • Enteroviruses • (Cytomegalovirus)

  21. CAUSES OF ‘ATYPICAL’ PNEUMONIA • Mycoplasma pneumoniae • Chlamydia pneumoniae • Legionella pneumophila • Coxiella burnetii

  22. Mycoplasma pneumoniae • Has no cell wall, therefore doesn’t respond to beta lactams • Causes atypical pneumonia in adolescents and young adults • Dry hacking cough, low grade fever, headache feature • Isolation by culture of the organism is difficult therefore diagnosis is confirmed by a high CFT or rising titre of specific antibodies • Cold agglutinins also typical • Macrolides or tetracyclines most active

  23. Chlamydia pneumoniae • An obligate intracellular bacterium • Causes mild pneumonia but may cause protracted symptoms • Sore throat, hoarseness, URT symptoms feature • Serological diagnosis rather than culture • Tetracyclines, macrolides, quinolones active

  24. Legionnaires’ disease • A severe pneumonia due to Legionella pneumophila • Can be community or hospital acquired • Organism is acquired from environmental sources eg, humidified air conditioning, showers • Usually attacks debilitated individuals

  25. RISK FACTORS • Male sex • Advanced age • Cigarette smokers • Alcoholism • Chronic lung disease • Immmunosuppression, malignancy

  26. Legionnaires’ disease • Hyponatremia, confusion, nausea, vomiting, abnormal LFT’s a feature • Diagnosis often confirmed by urinary antigen test (specific for serogroup 1) • Can be cultured on special media • Must be notified to Public Health as it can cause outbreaks • Most active antibiotics are: macrolides, quinolones, rifampicin

  27. Antibiotic Treatment of Community Acquired Pneumonia • The priority is to cover pneumococcus • Penicillin, amoxycillin, cephalosporins, new quinolones and macrolides have all been used as monotherapy • Choice will be influenced by local resistance rates for pneumococcus

  28. Examples of antibiotics for CAI • Benzylpenicillin • Penicillin V • Ampicillin, amoxycillin, Augmentin • Cefuroxime, cefotaxime, ceftriaxone • Moxifloxacin (a quinolone) • Erythromycin, clarythromycin, azithromycin

  29. PATHOGEN PREFERRED THERAPY S pneumoniae amoxicillin 500 mg – 1.0 ga tds po or benzylpenicillin 1.2 g qds iv M pneumoniae C pneumoniae erythromycin 500 mg qds po or iv or clarithromycin 500 mg bd po or iv C psittaci/C burnetii tetracycline 250 mg – 500 mg qds po or 500 mg bd iv Legionella spp. clarithromycin 500 mg bd po or iv ± rifampicin c 600 mg od or bd, po/ iv

  30. Hinfluenzae Non- B-lactamase-producing: amoxicillin 500 mg tds po or ampicillin 500 mg qds iv B-lactamase-producing: co-amoxiclav 625 mg tds po or 1.2 gtds iv Gram negative enteric bacilli cefuroxime 1.5 g tds or cefotaxime 1-2g tds iv or ceftriaxone 2g od iv (Comment: the table in the 2001 version incorrectly stated bd) P.aeruginosa ceftazidime 2g tds iv plus gentamicin or tobramycin (dose monitoring) S.aureus Non-MRSA: flucloxacillin 1-2gqds iv ±rifampicin 600 mg od or bd, po/iv MRSA: vancomycin 1gbd iv (dose monitoring)

  31. ACID ALCOHOL FAST RODS SUGGESTING TUBERCULOSIS

  32. KLEBSIELLA PNEUMONIA (RARE)

  33. COMMUNITY ACQUIRED PNEUMONIA IN INFANTS AND CHILDREN • Group B streptococcus and E coli cause pneumonia in neonates • RSV an important pathogen in infants • Bordetella pertussis (cause of whooping cough) important in young children • As is Haemophilus influenzae type b

  34. SOME FEATURES OF NOSOCOMIAL PNEUMONIA • Often ventilator associated, therefore seen in ITU most commonly • Due to both endogenous organisms and others acquired by cross infection • MRSA, gram negatives predominate • High associated mortality because of co-morbidity and antibiotic resistance

  35. HOSPITAL ACQUIRED PNEUMONIA:Pseudomonas aeruginosa

  36. TREATMENT OF HOSPITAL ACQUIRED PNEUMONIA • Will depend on the local epidemiology of the unit/hospital • Often require good cover for MRSA and gram negative enterobacteria • Therefore vancomycin and carbapenem or Tazocin may be used

  37. PNEUMONIA IN THE IMMUNOCOMPROMISED HOST • Cause depends on the underlying immunodeficiency • More likely to present as a diffuse interstitial pneumonia • Treatment often empirical as establishing the cause is often difficult

  38. MAJOR CAUSES OF PNEUMONIA IN IMMUNOCOMPROMISED • Pneumocystis jiroveci (carinii) • Cytomegalovirus • Other respiratory viruses • Tuberculosis • Fungi

  39. Pneumocystis jiroveci(Lung biopsy) Cyst stage

  40. NOCARDIOSIS(Cause: Nocardia asteroides, acid fast rod)

  41. Geographically restricted pneumonias • Typhoid • Melioidosis • Brucellosis • Endemic mycoses: histoplasmosis • Helminthic: paragonimiasis

  42. Recurrent pneumonia • May be caused by local bronchial or pulmonary abnormality • Obstruction due to eg, foreign body, carcinoma, lymph node • Chronic obstructive lung disease: bronchiectasis • Neurological disorders: motor neurone disease • Structural: tracheo-oesophageal fistula • Aspiration (alcoholics): anaerobic organisms • Immunodeficiency state: hypogammaglobulinaemia

  43. EMPYEMA • May arise as an acute complication of pneumonia • Characterised by collection in pleural cavity, malaise, fever, pleuritic pain, leucocytosis • Chronic empyema usually occurs after failure to diagnose or treat adequately an acute empyema • May be loculated, or associated with a broncho-pleural fistula • Organisms are those causing the original pneumonia, or anaerobes • Treat by drainage of the collection and antibiotics after microbiological findings

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