community acquired pneumonia

1. Community Acquired Pneumonia Manav Bhavsar ICM Study Day 22nd June 2007

4. Definition CAP Diagnosis in hospital benefit chest radiography Symptoms & signs consistent with an acute LRTI associated with new radiographic shadowing for which there is no other explanation (e.g. not pulm oedema or infarction) The illness is the primary reason for hospital admission and is managed as pneumonia

5. Epidemiology 5-11 per 1000 population 83000 admission each year Fifth leading cause of death, mortality can be as high as 50% Most episodes occur in winter & autumn

6. Risk Factors Age – infants, young chidren, over 65 Smoking, alcoholism COPD, malignancy, bronchiectasis, CF Pre-existing chest infection, esp bronchitis Immunosuppression, AIDS, cytotoxic drug Cardiac failure Diabetes

7. Aetiology CAP: cause by small no. organism Bacterial common: Streptococcus pneumoniae [Ib] Viral: 13%, Influenza A & B, autumn & winter, recent travel or contact - Influenza type disease Low freq of legionella, mycoplasm, Chlamydia psittaci & Coxiella burnetii infection, mainly elderly

10. Clinical Features and Epidemiological features

11. Clinical & Radiological Feature Likely aetiological agent can’t be predicted from clinical or radiological feature [II] Term “atypical” pneumonia be abandoned as it incorrectly implies characteristic clinical features with inf caused by “atypical”pathogens [II] Radiological resolution often lags behind clinical improvement from CAP, esp folloeing legionella & bacteraemic pneumococcal inf [III]

12. Clinical & Radiological Feature Radiographic changes caused by atypical pathogens clear more quickly than those caused by bacterial infection [III] Radiological resolution is slower to resolve elderly and in multilobe involvement [Ib]

13. Investigations General chest radiograph [C] full blood count [B–] urea, electrolytes and liver function tests [C] C reactive protein (CRP) [B–] oxygenation assessment [C] Microbiological investigations

14. Microbiological Investigation Blood culture Sputum samples Serological Tests Urine Antigen test - S pneumoniae (BINAX NOW) and Leigonella

15. Blood Cultures Ideally obtained before antibiotic therapy starts [D] Severe CAP: result more likely lead change antibiotics Only about 11% will be positive, highly specific, unlikely to be contaminated by respiratory tract commensals A positive BC in absence of septicaemia or other focus of infection is a definitive test Positive BC are more often found S. pneumoniae and H. influenzae serotype B (the incidence of which has now been reduced by vaccination) BTS Guidelines Management CAP

16. Sputum Samples Non-severe CAP, C/S test samples as able to expectorate purulent samples & have not received prior antibiotic treatment [A-] Severe CAP, be performed for patients or those who fail to improve [A-] Laboratories should offer a reliable Gram stain in pt with severe CAP or complications & should adhere to strict and locally agreed criteria for interpretation and reporting of results [B+]

17. Serological Tests Paired serological tests be performed [D] patients with severe CAP who are unresponsive to ß-lactam antibiotics selected patients epidemiological risk factors whom a specific microbiological diagnosis is important for public health measures during outbreaks and when needed for the purposes of surveillance

18. Antigen Tests Pneumococcal antigen tests should be used for patients with severe CAP, if available locally [B+] Investigations for legionella infection are recommended for all patients with severe CAP, with specific risk factors, and for all with CAP during outbreaks [B+] Rapid testing & reporting legionella urine antigen available in at least one lab per region [B+] Legionella cultures routinely performed on invasive respiratory samples (e.g. obtained by bronchoscopy) from patients with CAP [D]

19. Atypical Pathogens Serological assays with complement fixation tests (CFTs), diagnosis for atypical and common respiratory viral pathogens [C] Chlamydial antigen detection tests should be available for invasive respiratory samples from patients with severe CAP or where there is a strong suspicionof psittacosis [D] The CFT remains the most suitable and practical serological assay for routine diagnosis of respiratory mycoplasmal and chlamydial infections [B–]

20. Severity Assessment Recommended as the key to planning, [D], where to treat, which test to carry out, which antibiotic regimen Certain adverse prognostic features asso with an increased risk of death, should be assessed in all pt [A–] None of the available predictive models or the algorithms allow unequivocal categorisation pt into definite risk groups & be regarded as an aid to clinical judgement [D] Regular reassessment of severity during course of illness is mandatory, Mx to be adjusted appropriately [D]

23. Management - General Oxygen therapy: aim to maintain PaO2 >8 kPa, SaO2 >92%. High conc oxygen [D] Oxygen therapy, careful COPD complicated ventilatory failure guided by repeated ABG’s [C] Assessed volume depletion - IV fluids [C] Nutritional support - prolonged illness [C] Temp, RR, HR, BP, mental status, SaO2 & FiO2 conc monitored initially at least twice daily & more freq severe CAP or on reg O2 [C] CRP be remeasured [B–] & CXR repeated [C] in patients not progressing satisfactorily

24. Antibiotics Choice, dose and route of adm depends on severity of disease, pathogen and local resistance patterns Agent chosen always cover most likely pathogens; S pneumoniae & H. influenza Nursing home acquired pneumonia – no changes in regimen [Ib] Eur Respir J 2001; 18(2):362-368

27. Antibiotics An alternative regimen intolerant of or hypersensitive to preferred regimen where there are local concerns over C difficile associated diarrhoea related to beta- lactam use Clarithromycin may be substituted for those with GI intolerance to oral erythromycin Levofloxacin & moxifloxacin only currently UK licensed fluoroquinolones with activity against S pneumoniae Switch from parenteral drug to equivalent oral preparation as soon as feasible

28. Non-invasive Ventilation Several studies, NIV in severe CAP can lead to initial improvement in SaO2 and fall in pulse, but over 50% later deteriorated requiring intubation ABG prior starting NIV not predictive of outcome There were a higher failure rate of those with an initial RR > 38/min & those aged > 40 years May have a place in the initial management, but very close observation needed to detect deterioration and need for intubation

29. Staphylococcus aureus Versatile, dangerous 10% CAP (ATS 2001) ? incidence by 200% CAPO database study (11 countries 2001-03) Nursing home MSSA is suspected, BTS recommends flucloxacilin with or without rifampcin ATS recommends a beta-lactum plus macrolide or fluroquinolone MRSA pneumonia - vancomycin or linezolid Cochrane Database of Systematic Reviews 2007 Issue 1

31. Other Therapies Vitamin C: may be in cases with low plasma value Cochrane Database of Systematic Reviews 2007 Issue 1 Pneumococcal vaccine: efficacy 50% corresponds to a NNT of 20,000 vaccinations per infection avoided, and perhaps 50,000 per death avoided Cochrane Database of Systematic Reviews 2003, Issue 4 Granulocyte colony stimulating factor (G-CSF): no current evidence Cochrane Database of Systematic Reviews 2007, Issue 2

32. References Guidelines for the Management of Community Acquired Pneumonia in Adults – 2001 guidelines Thorax 2001; 56 (suppl 4) Guidelines for the Management of Community Acquired Pneumonia in Adults – 2004 update www.brit-thoracic.org.uk