1070. Outcomes in Patients Treated with a Beta-Lactam for Methicillin-Susceptible Staphylococcus aureus (MSSA) Bacteremia Stratified by Vancomycin Minimum Inhibitory Concentration (MIC)
Session: Poster Abstract Session: Clinical Infectious Diseases: Bacteremia and Endocarditis
Friday, October 28, 2016
Room: Poster Hall
Background: Staphylococcus aureus is a common cause of bacteremia associated with significant morbidity and mortality. A limited number of studies have demonstrated increased 30-day mortality in patients treated with a β-lactam for methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia with a high vancomycin minimum inhibitory concentration (MIC). The question remains whether the evidence justifies modifying the management of these patients. Thus, we sought to compare the outcomes of patients treated with a β-lactam for MSSA bacteremia with a high vs low vancomycin MIC.

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.

Kristen Landry, MD1, Robert Leininger, MD2, Jessica Johnston, MS1, Kurt Stevenson, MD, MPH, FSHEA3 and Erica Reed, PharmD, BCPS-AQ ID4, (1)The Ohio State University Wexner Medical Center, Columbus, OH, (2)Cinicians in Infectious Diseases, Canton, OH, (3)Department of Internal Medicine, Division of Infectious Diseases, The Ohio State University, Columbus, OH, (4)The Ohio State University Wexner Medical Center, COLUMBUS, OH


K. Landry, None

R. Leininger, None

J. Johnston, None

K. Stevenson, None

E. Reed, None

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