Methods: Patients admitted to OSUWMC between January 1, 2009 and December 31, 2013 with MSSA bacteremia and treated with a β-lactam agent were evaluated. Patients were stratified by low (≤1) versus high (>1) vancomycin MIC. Data collected included baseline characteristics, source of bacteremia, definitive therapy selection and duration, and Pitt bacteremia score. The primary outcome was 30-day attributable mortality. Secondary outcomes included time to microbiologic clearance, 90-day MSSA bacteremia recurrence, hospital length of stay (LOS), and infection-related LOS. The Wilcoxon-rank sum and Fisher’s exact tests were utilized as appropriate.
Results: Among eligible patients, 317 patient charts were reviewed (MIC ≤ 1, n=127; MIC >1, n=190). The most common source of infection was an intravenous catheter or implanted device and the median Pitt Bacteremia Score was 1 in both groups. Attributable 30-day mortality was observed in 6 patients (5%) in the low MIC group vs 8 patients (4%) in the high MIC group (p=0.239). Time to microbiologic clearance was 3 (1-4) vs 3 (2-4) days (p=0.89); 90-day MSSA bacteremia recurrence was observed in 3 (2%) vs 2 (1%) patients (p=0.36); hospital LOS was 14 (9-23) vs 14 (10-23) days (p=0.50); and infection-related LOS was 12 (8-16) vs 11 (8-17) days (p=0.94), in the low vs high MIC groups, respectively.
Conclusion: In contrast to previous studies, 30-day attributable mortality was lower in this cohort and we failed to demonstrate a difference in it among other clinical outcomes between patients treated with a β-lactam for MSSA bacteremia with a high vs low vancomycin MIC. Additional studies are warranted.
J. Johnston, None
K. Stevenson, None
E. Reed, None
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