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Community Acquired Pneumonia Dr Vincent Ioos Medical Intensive Care Unit Pakistan Institute of Medical Sciences

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Definition Infection of the lung parenchyma that has been acquired in the community Before hospital admission or within 48 hours hospital acquired pneumonia, health care associated pneumonia acute bronchitis and exacerbation of COPD obstructive pneumonia, TB

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Diagnosis Lack of sensitivity of clinical signs and symptoms But good Positive Predictive value of the presence of crakles Good Negative Predictive Value of RR>30/mn, HR>100/mn, T>37,9C Fever frequently absent in older patients CXR Leucopenia : poor prognosis Microbiological diagnosis : better treatment when pathogen oriented but contreversies on the value of tests

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Should we get a CXR ? Patient with severe infection : presence of pneumonia allows proper empiric antibiotic therapy If patient is not severely ill : helps in deferentiating CAP from acute bronchitis or exacerbation of COPD, and assess if antibiotics are necessary or not

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Which pathogens ?

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Epidemiology Varies from one country to another 2 questions : Pathogens most likely to be responsible for CAP Pattern of resistance, especially for Streptoccus Pn. Epidemiological studies difficult : previous use of antibiotics, cost of C/S and serological studies, invasive procedures. Sentinel surveillance systems for specific pathogens : data from microbiology departments, from disease oriented register.

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Etiology Outpatients

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Etiology ward patients

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Etiology ICU patients

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In Pakistan Lack of datas Neighbooring countries World surveillance networks Peadiatric studies

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Shimia, Himachal Pradesh, India 70 patients with CAP, blood, sputum and pleural fluid c/s, Mycoplasma Pn. Ab 75,6 % proven etiology Streptococcus Pn 35,8% Klebsiella Pn 22% Staphylococcus Aureus 17% Mycoplasma Pn 15% E. Coli 11% Beta hemolytic Streptococci 7,5% GNB 5,9% Bansal S, Indian J Chest Dis Allied Sci. 2004, Jan-March ; 46(1) : 17-22

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New Delhi All India Institute of Medical Sciences, April 1997 December 1998 60 patients : blood C/S + Elisa Ab against L. Pneumophila (serogroups 1-7) 13% conventional bacterial etiology 15% serological evidence of recent infection with L. Pneumophila Chaudhry R, Trop Doct. 2000 Oct ; 30(4):197-200.

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Shangai 389 patients with CAP between 2001-2003 Bacterial culture, PCR, specific immunological assays Specific pathogen found in 39,8% : Haemophilus Inflenzae 51%, among them 88,3% amoxicilline S Mycoplasma Pn. 27% Chlamydia Pn. 11% Klebsiella spp. 10% Streptococcus Pn. 8% among them 75% Peni S, 25%Peni I Staphylococcus Aureus 4% Legionella Pn. 1,3% Moraxella Catharallis 0,6% Huang HH, Eur J Clin Microbiol Infect Dis. 2006 Jun ; 25(6):369-74

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Iran, Afghanistan PubMed : country name + pneumonia, Iran : 33 articles, no epidemiological data on CAP Afghanistan : 12 articles, one on epidemiology datas on CAP in Russian Soldiers

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Hoban DJ, Clin Infect Dis. 2001 May 15;32 Suppl 2:S81-93. 66 Laboratories in 1997, 81 in 1998 (17 in Asia-Pacific) Pneumococal isolates from bloodstream and respiratory tract infections 8252 respiratory tract isolates

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Network of microbiology departments in 26 countries 1998-2000 Streptococcus Pneumonia (8882 isolates), Haemophilus Influenzae (8523), Moraxella Catharralis (874)

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Streptococcus Pn. : 95% Amoxicilline S Quinolone resistance 1,1% Haemophilus : Beta Lactamase production 16,9%

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ARI in children, Pakistan 87 strains of Streptococcus pneumoniae from blood culture 97% resistant to at least one drug 31% R to Cotrimoxazole, 39% R to Chloramphenicol All isolates were susceptible to erythromycin, cefaclor, cephalothin, ceftriaxone, cefuroxime, rifampicin, vancomycin, and clindamycin Mastro TD, Lancet 1991 Jan 19 ; 337(8734):156-9.

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Critical microbes Legionella Pneumophila Influenza A +B Avian Influenza SARS CA-MRSA Epidemiological challenges or treatment different from standart regimen

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Which diagnostic methods ?

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Blood cultures (pros) Pretreatment blood cultures positive for a pathogen in 7 to 16 percent of hospitalized patients. Streptococcus pneumoniae : 2/3 of the positive blood cultures When positive, the microbial diagnosis is established. Only diagnostic test done, in most cases : major source of microbiologic data (resistance patterns of S. pneumoniae )

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Blood cultures (cons) The blood culture positivity rate is relatively low. High rate of false positive blood cultures (up to 10 percent). Eg Staphylococcus. Positive cultures rarely lead to modification or narrowing of antibiotic therapy

Slide 26 25 PMNs / LPF but < 10 SECs/LPF on Gram Stain Interpretation : Quantitation of growth (heavy, moderate or light, quantitative threshold 10 7 CFU), clinical correlation, correlation with the Gram's stain">

Sputum : standard quality criterias Deep cough specimen obtained prior to antibiotics, To be sampled only if macroscopically purulent sputum, Cultures performed rapidly after collection, preferably within two hours Good" sputum sample : > 25 PMNs / LPF but < 10 SECs/LPF on Gram Stain Interpretation : Quantitation of growth (heavy, moderate or light, quantitative threshold 10 7 CFU), clinical correlation, correlation with the Gram's stain

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Invasive sampling Protected brush specimen Bronchalveolar Lavage In case of failure of the initial treatment If epidemiology or clinical presentation suggest a specific pathogens that is not covered by usual treatment strategy If patient is intubated (ICU)

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Pleural Tap Rarely positive Evidences empyema

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Urinary antigens (pros) Urine specimens avalable when patients cannot supply expectorated sputum. Results of urine antigen testing immediately available. Retains validity even after the initiation of antibiotic therapy. High sensitivity compared to blood cultures and sputum studies.

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Urinary antigens (cons) The sensitivity and specificity may be less in patients without bacteremia. No microbial pathogen available for antibiotic sensitivity testing.

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Urinary Antigen LP Legionella Pneumophila Only for serotype 1 (the most frequent 80%) Sensitivity 86%, specificity 93% Positive 1 to 3 days after the onset of disease

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Urinary antigen (SP) Sensitivity 77-89% if CAP with blood culture +, Sensitivity 44-64% if blood culture False positive test rare Rapid diagnosis, still positive after 7 days of antibiotics, persists several weeks.

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Diagnostic yield of microbiological tests Prospective study : 262 hospitalized patients with CAP. Sputum for Gram staining, culture, and detection of pneumococcal antigen; blood for culture and serologic tests; urine for legionella and pneumococcal antigens; and specimens obtained by bronchoscopy. A pathogen was identified in 158 (60 percent) patients Adequate sputum samples obtained in only 44 patients : Gram's stain + positive sputum culture in 36/44 patients (82%). Van der Eerden MM, Eur J Clin Microbiol Infect Dis 2005 Apr;24(4):241-9.

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Diagnostic yield of microbiological tests S. pneumoniae most commonly identified (97 of 158). Urinary pneumococcal antigen test positive in 52/97 (54%) patients with pneumococcal pneumonia. Blood cultures were positive in 40 of 254 (16%) patients. Bronchoscopy : additive diagnostic value in 18/37 patients (49%) who did not expectorate sputum and in 14 of 27 patients (52 percent) who failed treatment within 72 hours after admission. Van der Eerden MM, Eur J Clin Microbiol Infect Dis 2005 Apr;24(4):241-9.

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PCR Multiplex Real-time PCR Respiratory viruses and atypical bacteria (eg, M. pneumoniae, L. pneumophila, Legionella spp, C. pneumoniae, influenza A and B virus, respiratory syncytial virus, parainfluenza viruses, human rhinovirus, metapneumovirus, adenovirus, and human coronaviruses) 105 adults : etiology determined 50% with conventional techniques 80% with PCR But increased cost. ? Less antibiotic use. Templeton KE, Clin Infect Dis 2005 Aug 1;41(3):345-51.

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Minimal approach 2 blood cultures and Tracheal Aspirate culture if patient is intubated before antibiotics are given Urinary Legionella Pn. Antigen

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Where should the patient be managed ? At home In the ward In the ICU saving lifes and saving money Identify low risk patient to save money (and hospital beds !) Identify high risk patient to save life

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Saving lifes : the high risk patient

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Saving money, avoid unnecessary hospitalisation Large cohorts for validation (38,039 adults retrospectively, 2,287 adults for prospective validation)

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Fine scoring system ClassPoints II 70 III71 - 90 IV91 - 130 V> 130 Fine et al. N Engl J Med 1997; 336: 243-50

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Fine et coll. NEJM 1997

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Decision IV, V : admit the patient I : no admission II, III : no admission if score results from the age + 1 other criteria. Admit systematically if : Hypoxemia SaO2