PNEUMONIA
Pneumonia, an infection of the lung parenchyma, is classified as community-acquired (CAP), hospital-acquired (HAP), ventilator-associated (VAP), or health care–associated (HCAP). Although the HCAP category initially referred to CAP caused by a multidrug-resistant (MDR) pathogen, it now describes pts with at least two or three risk factors for infection with MDR pathogens (Table 134-1).
| MULTIDRUG-RESISTANT GRAM-NEGATIVE BACTERIA AND MRSA | NOSOCOMIAL MRSA | COMMUNITY-ACQUIRED MRSA | 
|---|---|---|
| Hospitalization ≥2 days in previous 90 days Use of antibiotics in previous 90 days Immunosuppression Nonambulatory status Tube feedings Gastric acid suppression Severe COPD or bronchiectasisb | Hospitalization ≥2 days in previous 90 days Use of antibiotics in previous 90 days Chronic hemodialysis in previous 30 days Documented prior MRSA colonization Congestive heart failure Gastric acid suppression | Cavitary infiltrate or necrosis Gross hemoptysis Neutropenia Erythematous rash Concurrent influenza Young, previously healthy status Summer-month onset | 
aCephalosporin/macrolide or respiratory fluoroquinolone. 
bRisk for Pseudomonas aeruginosa infection. 
Abbreviations: COPD, chronic obstructive pulmonary disease; MRSA, methicillin-resistant Staphylococcus aureus. 
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Citation
Kasper, Dennis L., et al., editors. "PNEUMONIA." Harrison's Manual of Medicine, 20th ed., McGraw Hill Inc., 2020. harrisons.unboundmedicine.com/harrisons/view/Harrisons-Manual-of-Medicine/623674/all/PNEUMONIA. 
PNEUMONIA. In: Kasper DLD, Fauci ASA, Hauser SLS, et al, eds. Harrison's Manual of Medicine. McGraw Hill Inc.; 2020. https://harrisons.unboundmedicine.com/harrisons/view/Harrisons-Manual-of-Medicine/623674/all/PNEUMONIA. Accessed October 31, 2025.
PNEUMONIA. (2020). In Kasper, D. L., Fauci, A. S., Hauser, S. L., Longo, D. L., Jameson, J. L., & Loscalzo, J. (Eds.), Harrison's Manual of Medicine (20th ed.). McGraw Hill Inc.. https://harrisons.unboundmedicine.com/harrisons/view/Harrisons-Manual-of-Medicine/623674/all/PNEUMONIA
PNEUMONIA [Internet]. In: Kasper DLD, Fauci ASA, Hauser SLS, Longo DLD, Jameson JLJ, Loscalzo JJ, editors. Harrison's Manual of Medicine. McGraw Hill Inc.; 2020. [cited 2025 October 31]. Available from: https://harrisons.unboundmedicine.com/harrisons/view/Harrisons-Manual-of-Medicine/623674/all/PNEUMONIA.
* Article titles in AMA citation format should be in sentence-case
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T1  -  PNEUMONIA
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ED  -  Fauci,Anthony S,
ED  -  Hauser,Stephen L,
ED  -  Longo,Dan L,
BT  -  Harrison's Manual of Medicine
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PB  -  McGraw Hill Inc.
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 Harrison's Manual of Medicine
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