Appropriate Antibiotic Treatment for Pneumonia

Abstract

SIR— We read with great interest the article by Gonzalez et al. [1] that described a high mortality rate among patients treated with vancomycin for pneumonia caused either by methicillin-resistant Staphylococcus aureus (MRSA; 50%) or by methicillin-sensitive S. aureus (MSSA; 47%). In contrast, the authors have found that in the subgroup of patients receiving cloxacillin treatment for pneumonia caused by MSSA, the mortality rate was zero [1]. Among intubated patients receiving cloxacillin for pneumonia caused by MSSA, we found a mortality rate of 2.6%; in episodes caused by MRSA and treated with intermittent administration of vancomycin (with serum level monitoring), we found a mortality rate of 54.5% [2]. Moreover, 2 of our patients developed an MRSA episode even though they were receiving treatment with vancomycin. Postmortem cultures performed for 3 of these patients showed that MRSA strains persisted even though these patients had received vancomycin. The discrepancies between reports of microbiologic resistance and clinical outcomes may be due to the fact that sustained tissue levels above MIC are far more determinant of clinical outcome.