| MRSA | Pseudomonas | |
| Strong risk factors* | Known MRSA colonization | Known Pseudomonas colonization |
| Prior MRSA infection | Prior Pseudomonas infection | |
| Detection of gram-positive cocci in clusters on a good-quality sputum Gram stain | Detection of gram-negative rods on a good-quality sputum Gram stain | |
| Hospitalization with receipt of IV antibiotics in the prior 3 months | ||
| Other factors that should raise suspicion for infection¶ | Recent hospitalization or antibiotic use, particularly hospitalization with receipt of IV antibiotics in the prior 3 months | Recent hospitalization or stay in a long-term care facility |
| Recent influenza-like illness | Recent antibiotic use of any kind | |
| Necrotizing or cavitary pneumonia | Frequent COPD exacerbations requiring glucocorticoid and/or antibiotic use | |
| EmpyemaΔ | Other structural lung diseases (eg, bronchiectasis, cystic fibrosis) | |
| Immunosuppression | Immunosuppression | |
Risk factors for MRSA colonization, including:
|
CAP: community-acquired pneumonia; MRSA: methicillin-resistant Staphylococcus aureus; IV: intravenous; COPD: chronic obstructive pulmonary disease.
* The presence of these risk factors generally warrant empiric treatment in patients with CAP of any severity.
¶ The presence of these factors should raise suspicion for MRSA or Pseudomonas infection and generally warrants treatment in those who are severely ill; in others, the need for empiric treatment should take into account local prevalence, severity of illness, and overall clinical assessment.
Δ This factor is associated with community-acquired MRSA infection, which can cause severe toxin-mediated infection. Refer to the UpToDate topic on MRSA infections and treatment of CAP in patients with risk factors for MRSA infection for further detail.