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etiology of pneumonia

Etiology: 1) community acquired a) Streptococcus pneumonia* b) Haemophilus influenza c) Moraxella catarrhalis d) Staphylococcus aureus e) Klebsiella pneumonia f) Legionella g) Anaerobes: 1] Bacteroides 2] Fusobacterium 3] Peptostreptococcus 2) nosocomial bacterial infections (60% gram-negative bacilli) a) Enterobacteriaceae 1] Escherichia coli 2] Klebsiella pneumonia 3] Enterobacter 4] Serratia b) Pseudomonas aeruginosa c) Staphylococcus aureus d) Streptococcus pneumonia e) Anaerobes 3) atypical bacteria a) Mycoplasma pneumoniae b) Chlamydia pneumoniae c) Chlamydia psittaci d) Coxiella burnetii e) Francisella tularensis f) Bordetella pertussis g) Yersinia pestis 4) aspiration pneumonia a) community-acquired: anaerobes & gram-positive cocci - poor dental hygiene is risk factor [4] b) nosocomial: 1] gram-negative organisms: a] E. coli b] Klebsiella pneumonia c] Pseudomonas aeruginosa 2] Staphylococcus aureus 5) Mycobacterium tuberculosis 6) virus a) influenza A & B b) adenovirus c) parainfluenza virus d) respiratory syncytial virus (children) e) varicella (chickenpox, more common in adults) f) Herpes virus (including cytomegalovirus) - immunocompromised & patients with burns g) rhinovirus ? 7) fungi a) Histoplasma capsulatum b) Blastomyces dermatitidis c) Coccidioides immitis d) Cryptococcus neoformans e) Aspergillus (nosocomial) f) Candida (nosocomial) 8) parasites: Pneumocystis carinii (AIDS) 9) rickettsiae * bacterial pathogens detected by multiplex PCR assay [5] - Hemophilus influenzae in 33% - Streptococcus pneumoniae in 20% - Staphylococcus aureus in 20% - gram-negative bacilli in 18% - Moraxella catarrhalis in 12% * also see community-acquired pneumonia for percentage of isolates Pathology: Pathogens associated with comorbid conditions 1) altered consciousness or aspiration: anaerobes 2) COPD: a) Streptococcus pneumonia b) Haemophilus influenza c) Moraxella catarrhalis 3) nursing home residents: - poor dental hygiene is risk factor [4] a) Enterobacteriaceae b) methicillin-resistant Staphylococcus aureus (MRSA) c) Mycobacterium tuberculosis d) respiratory viruses 4) immunodeficiency a) Pneumocystis carinii b) cytomegalovirus c) Mycobacterium tuberculosis d) Cryptococcus neoformans e) Nocardia 4) cystic fibrosis a) Pseudomonas aeruginosa b) Staphylococcus aureus 5) influenza epidemic: Staphylococcus aureus

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characteristics of etiologic agents of pneumonia

General

pulmonary

References

  1. Manual of Medical Therapeutics, 28th edition, Ewald & McKenzie (eds) Little, Brown & Co, 1995, pg 247-49
  2. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 775-78
  3. Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998
  4. Journal Watch 25(4):31, 2005 Quagliarello V, Ginter S, Han L, Van Ness P, Allore H, Tinetti M. Modifiable risk factors for nursing home-acquired pneumonia. Clin Infect Dis. 2005 Jan 1;40(1):1-6. Epub 2004 Dec 01. PMID: 15614684 Terpenning M. Prevention of aspiration pneumonia in nursing home patients. Clin Infect Dis. 2005 Jan 1;40(1):7-8. Epub 2004 Dec 01. No abstract available. PMID: 15614685
  5. Falsey AR et al. Real-life assessment of BioFire FilmArray pneumonia panel in adults hospitalized with respiratory illness. J Infect Dis 2023 Jun 27; [e-pub]. PMID: 37369370 https://academic.oup.com/jid/advance-article/doi/10.1093/infdis/jiad221/7209038