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Community-acquired Pneumonia

Community-acquired Pneumonia. H. Nina Kim, MD MSc Harborview Medical Center University of Washington ID Fellows Orientation July 5, 2011. Community-acquired Pneumonia. Epidemiology & Terminology Site of care decision-making & Prognosis Microbiology Diagnosis Treatment Prevention.

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Community-acquired Pneumonia

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  1. Community-acquired Pneumonia H. Nina Kim, MD MSc Harborview Medical Center University of Washington ID Fellows Orientation July 5, 2011

  2. Community-acquired Pneumonia • Epidemiology & Terminology • Site of care decision-making & Prognosis • Microbiology • Diagnosis • Treatment • Prevention

  3. Alphabet Soup for Pneumonia • CAP: Community-acquired pneumonia • Outside of hospital or extended-care facility • HCAP: Healthcare-associated pneumonia • Long-term care facility (NH), hemodialysis, outpatient chemo, wound care, etc. • HAP: Hospital-acquired pneumonia • ≥ 48 h from admission • VAP: Ventilator-associated pneumonia • ≥ 48 h from endotracheal intubation

  4. Which of these patients does NOT have CAP? • 34 yo hospital employee, previously healthy, admitted for acute pneumonia. • 56 yo man admitted with CHF, noted to have pneumonia on the day after admission. • 76 yo bedridden man transferred from a nursing home for acute confusion, noted to have a new infiltrate on CXR.

  5. Epidemiology • Influenza & pneumonia = 8th leading cause of death in US in 20071 • 5 million cases per year in US – 20-25% require hospitalization • Of those hospitalized: mortality 10% in 30 days, 40% in 1 year2 • Almost 916,000 cases annually in pts >65 yo • Case fatality rate has not changed substantially in recent years 1cdc.gov/nchs/data/hestat 2Kaplan, et. al. Arch Intern Med. 2003;163:317-23.

  6. To Admit or Not?Pneumonia Severity & Deciding Site of Care • Objective criteria to risk stratify & assist in decision re outpatient vs inpatient management • Pneumonia Severity Index (PSI) • CURB-65 • Caveats • Other reasons to admit apart from risk of death • Not validated for ward vs ICU • Labs/vitals dynamic

  7. Criteria for Severe CAP(Admit to ICU) • Minor criteria • Respiratory rate ≥30 breaths/min • PaO2/FiO2 ratio ≥250 • Multilobar infiltrates • Confusion/disorientation • Uremia (BUN ≥20 mg/dL) • Leukopenia (WBC <4000 cells/mm3) • Thrombocytopenia (platelets <100,000 cells/mm3) • Hypothermia (core T <36C) • Hypotension requiring aggressive fluid resuscitation • Major criteria • Invasive mechanical ventilation • Septic shock with the need for vasopressors 2007 IDSA/ATS Guidelines for CAP in Adults.

  8. Microbiology • Causative organism established in 60% CAP in research setting, 20% in clinical setting • “Typical”: • S. pneumoniae, Haemophilusinfluenzae, Staphylococcus aureus, Group A streptococci, Moraxella catarrhalis, anaerobes, and aerobic gram-negative bacteria • “Atypical” - 20-28% CAP worldwide • Legionella spp, Mycoplasma pneumoniae, Chlamydophila (formerly Chlamydia) pneumoniae, and C. psittaci • Mainly distinguished from typical by not being detectable on Gram stain or cultivable on standard media

  9. Microbiology of CAP among hospitalized patients

  10. Age-specific Rates of Hospital Admission by Pathogen Marsten. Community-based pneumonia incidence study group. Arch Intern Med 1997;157:1709-18

  11. Typical vs Atypical CAP • N=24 C. pneumoniae N=13 Strep pneumoniae N=8 Both • CXR patterns • Bronchopneumonia: 88% C. pneumovs 77% Pneumococcal, P=0.67 • Lobar or air-space: 29% C. pneumovs 54% Pneumococcal Kauppinen et al. Arch Intern Med 1996; 156: 1851.

  12. Comorbidities & Associated Pathogens

  13. Zoonotic Exposures & Associated Pathogens

  14. Exposures & Associated Pathogens

  15. MRSAModern-day CAP pathogen • 51 Staphylococcus aureus CAP cases in 19 states reported 2006-2007 • 79% MRSA • Median age 16 yrs (range <1 to 81) • 47% antecedent viral illness • 11 of 33 (33%) tested had lab-confirmed influenza • 51% died a median of 4 days from symptom onset Lesson: Must consider MRSA coverage in severe CAP, esp during flu season! Kallen, Ann Emerg Med. 2009 Mar;53(3):358-65.

  16. Diagnosis: Cultures • Pre-abxBlood Cultures • Yield 5-15% • Stronger indication for severe CAP • Host factors: cirrhosis, asplenia, complement deficiencies, leukopenia • Pre-abxexpectorated sputumGs & Cx • Yield can be variable • Depends on multiple factors: specimen collection, transport, speed of processing, use of cytologic criteria • Adequate sample w/ predominant morphotype seen in only 14% of 1669 hospitalized CAP pts (Garcia-Vasquez, Arch Intern Med 2004) • Pre-abxendotracheal aspirateGs & Cx • Pleural effusions >5 cm on lateral upright CXR

  17. Diagnosis: Pop quiz • Name 2 ways a gram stain of respiratory specimen can be helpful in pt hospitalized with CAP. • True or False: Yield for culture is markedly affected by a single dose of abx for all CAP pathogens. • True or False: Failure to detect S. aureus or GNR in good-quality respiratory specimens (no abxexposure) is strong evidence against presence of these pathogens.

  18. Diagnosis: Other testing • Urinary antigen tests • S. pneumoniae • L. pneumophilaserogroup 1 • 50-80% sensitive, >90% specific in adults • Pros: rapid (15 min), simple, can detect Pneumococcus after abx started • Cons: cost, no susceptibility data, not helpful in patients with recent CAP (prior 3 months)

  19. Diagnosis: Other testing • Acute-phase serologies • C. pneumoniae, Mycoplasma, Legionella spp • Not practical given slow turnaround & single acute-phase result unreliable • Influenza testing • Hospitalized patients:Severe respiratory illness (T> 37.8°C with SOB, hypoxia, or radiographic evidence of pneumonia) without other explanation and suggestive of infectious etiology should get screened during season • NP swab or nasal wash/aspirate • Rapid flu test (15 min) • Distinguishes A vs B • Sensitivity 50-70%; specificity >90% • Respiratory virus DFA & culture - reflex subtyping for A • Respiratory viral PCR panel - reflex subtyping for A • Influenza A PCR panel

  20. How to obtain a nasopharyngeal swab

  21. 2010-2011 Influenza SurveillanceSeattle - King County www.kingcounty.gov/healthservices/health/communicable/immunization/fluactivity.aspx

  22. Outpatient Empiric CAP Abx • Healthy; no abx x past 3 months • Macrolide e.g. azithromycin • 2nd choice: doxycycline • Comorbidities; abx x past 3 mon • Respiratory fluoroquinolone: Moxifloxacin, levofloxacin 750 mg, gemifloxacin • Beta-lactam + macrolide • Regions with >25% high-level macrolide-resistant S. pneumo, consider alternative agents 2007 IDSA/ATS Guidelines for CAP in Adults.

  23. Case 29 yo previously healthy but morbidly obese woman admitted in March with 5 days of progressive SOB, intubated in field after being found home unresponsive, hypoxic with Sat 80%. Initial BP 100/80, HR 120. PaO2 60 on 80% FiO2. CXR reveals diffuse patchy infiltrates with some lower lobar consolidation R>L. Sputum could not be obtained but endotracheal aspirate shows 3+ polys and 3+GPC in clusters. Which of the following abx would you start empirically? • Ceftriaxone + azithromycin • Zanamavir + vancomycin + azithromycin • Oseltamavir + vancomycin + azithromycin • Oseltamavir + vancomycin + piperacillin-tazobactam • Oseltamavir + daptomycin + azithromycin

  24. Inpatient Empiric CAP Abx1 • Inpatients in ward • Respiratory fluoroquinolone • ß-lactam (cefotaxime/ceftriaxone or ampicillin/sulbactam) + macrolide • Inpatients in ICU • ß-lactam + macrolide • Respiratory fluoroquinolone for PCN-allergic pts • Pseudomonas • Anti-pneumococcal & anti-pseudomonalß-lactam + azithromycin + cipro/levofloxacin (750 mg) • Can substitute quinolone with aminoglycoside • PCN-allergic: can substitute aztreonam • CA-MRSA: Add vanco or linezolid* (or ceftaroline2) • CA-MSSA: Nafcillin 12007 IDSA/ATS Guidelines for CAP in Adults. 2File, et. al. CID 2010. 51(12): 1395-1405.

  25. Antiviral Therapy for Influenza • Comorbid conditions: • Chronic pulmonary • Cardiovascular (except HTN alone) • Renal, hepatic, hematologic, metabolic (DM) • Neurologic, neuromuscular (cerebral palsy, epilepsy, CVA, SCI) • Immunosuppression (caused by meds, HIV, infection) • Pregnant or post-partum (<2 wks) women • Persons <19 years on long-term aspirin • American Indians & Alaskan Natives • Morbidly obese (BMI ≥40) • Residents in NH or chronic-care facilities CDC Guidelines for Influenza 2010-2011

  26. Influenza pneumoniaWhat about the 48-hr rule? • Antiviral treatment within 48 hrs • Reduce likelihood of lower tract complications & antibacterial use in outpatients • Impact on hospitalized pts less clear • Possible exceptions to <48 h rule: • Immunocompromisedpatients • Severe, complicated or progressive illness • To reduce viral shedding for infection control in hospitalized patients

  27. Influenza pneumoniaSome things to keep in mind… • Influenza B • Oseltamavir 75 mg PO BID x 5 days • Zanamavir2 mg INH BID x 5 days • Influenza A* • H3N2 (general seasonal), Novel H1N1 (Swine flu) • Sensitive to neuraminidase inhibitors • Resistant to adamantane antivirals • H1N1 - general seasonal • High rate of oseltamavir resistance in 2008-2009 • Still susceptible to zanamavir • Resistant to adamantanes

  28. Drug-resistant Strep pneumoniaeß-lactam resistance • Risk factors • Age >65 yrs • ß-lactam x previous 3 mon • Medical comorbidities • Exposure to child in day care • Current levels of ß-lactam resistance do not generally result in treatment failure* with amoxicillin, ceftriaxone or cefotaxime • As opposed to macrolide (& less so fluoroquinolone) resistance

  29. Case-control study from Canada - review of fluoroquinolone (FLQ) use among Cx-proven TB cases. • Of 148 isolates of M. TB, 3 were FLQ resistant. • Patients who had received multiple FLQ prescriptions were more likely than patients who had received a single FLQ prescription to be infected with FLQ-resistant M. tuberculosis (15.0% vs. 0.0%; odds ratio, 11.4; P<.04) Long, Clin Infect Dis 2009. May 15; 48: 1355.

  30. Case 29 yo previously healthy but morbidly obese woman with severe CA pneumonia. Nasopharyngeal swab (+)influenza A, novel H1N1. Sputum Cx (+) MRSA. Creatinine 3.2 and requiring HD. On hospital day 14, still febrile – oxygenation requirements remain high – now on ARDS settings with high PEEP. Exam notable for persistent coarse BS throughout, deep sedation, very quiet abdomen – no bowel tones. No change in minimal respiratory secretions. In addition to resending BCx & ET Cx, what would you do next? • Send stool for C. diff toxin A/B by PCR. • CT with contrast, PE protocol. • Stop oseltamavir. • Transition to oral antibiotics.

  31. Follow-up ResponseExpected improvement? • Clinical improvement w/ effective abx: 48-72 hrs • Fever can last 2-5 days with Pneumococcus, longer with other etiologies, esp Staph aureus • CXR clearing • If healthy & <50 yo, 60% have clear CXR x 4 wks • If older, COPD, bacteremic, alcoholic, etc. only 25% with clear CXR x 4 wks • Switch from IV to PO • Hemodynamically stable, improving clinically • Able to ingest meds with working GI tract

  32. Question… What is far & away the most common reason for non-response to antibiotics in CAP? • Cavitation • Pleural effusion • Multilobar involvement • Discordant antibiotic/etiology • Host factors

  33. Inadequate Response to TherapyWhat to consider • Consider S. aureus, virus, resistant organism, TB, endemic fungi, Pneumocystis • More unusual pathogens: atypical mycobacteria, higher bacteria (Nocardia, actinomycetes), fungi • Noninfectious illness: • Lung neoplasms with bronchial obstruction • Lymphoma • Systemic autoimmune disorders • PE w/ infarct, pulm edema, ARDS • Consider other testing: • Lower tract sampling (bronchoscopy) • CT chest • PE work-up? • Serologic testing • Open lung biopsy

  34. PreventionTried & true… http://www2a.cdc.gov/eCards

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