Treatment of Community-Acquired Pneumonia in Adult Inpatients with MRSA Risk Factors

Standard community-acquired pneumonia management applies to most hospitalised adults, but specific risk factors identify patients at meaningful risk for MRSA as a causative pathogen — a population requiring a different empiric approach from the outset.

Clinical scenario

Adult inpatient with community-acquired pneumonia and at least one of the following MRSA risk factors:

  • Prior respiratory isolation of MRSA
  • Recent hospitalisation with receipt of parenteral antibiotics in the last 90 days

Guideline evidence supports restricting empiric MRSA coverage to adults with CAP who have locally validated risk factors. Prior respiratory isolation of MRSA and recent hospitalisation with parenteral antibiotic exposure are the most consistently strong individual risk factors identified.

Treatment approach (partial)

When these risk factors are present, the standard CAP regimen is augmented with empiric MRSA-directed coverage, and nasal PCR together with cultures are obtained early to enable deescalation if the patient is clinically improving at 48 hours.

Clinical targets

Clinical improvement at 48 hours with negative cultures permitting deescalation to standard CAP therapy; clinical stability — resolution of vital sign abnormalities, ability to eat, and normal mentation — achieved by 5 days.

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References

DOI: 10.1164/rccm.201908-1581ST

  1. We recommend clinicians only cover empirically for MRSA or P. aeruginosa in adults with CAP if locally validated risk factors for either pathogen are present (strong recommendation, moderate quality of evidence).
  2. The most consistently strong individual risk factors for respiratory infection with MRSA or P. aeruginosa are prior isolation of these organisms, especially from the respiratory tract, and/or recent hospitalization and exposure to parenteral antibiotics.
  3. Finally, routine cultures in patients empirically treated for MRSA or P. aeruginosa allow deescalation to standard CAP therapy if cultures do not reveal a drug-resistant pathogen and the patient is clinically improving at 48 hours.
  4. We recommend that the duration of antibiotic therapy should be guided by a validated measure of clinical stability (resolution of vital sign abnormalities [heart rate, respiratory rate, blood pressure, oxygen saturation, and temperature], ability to eat, and normal mentation), and antibiotic therapy should be continued until the patient achieves stability and for no less than a total of 5 days (strong recommendation, moderate quality of evidence).
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