Vancomycin Minimum Inhibitory Concentration Does Not Predict Death, Recurrence or Readmission in Patients with Staphylococcus aureus Bacteremia in a Safety-Net Hospital
Methods: This was a prospective cohort study of all adult patients with SAB presenting to San Francisco General Hospital, the San Francisco County hospital, from 2008-2012. Subjects were identified by a hospital-wide infection surveillance system. The main predictor was vancomycin MIC, dichotomized as less than 2 mcg/mL or equal to 2 mcg/mL. The primary outcome was death within 90 days. Secondary outcomes were readmission or recurrence of disease within 90 days. Covariates included methicillin resistance, age, race, gender, severity of illness, co-morbidities, source of infection, injection drug use and all antibiotics administered over the study period with activity against Staphylococcus aureus. A survival analysis with a Cox proportional hazards model was used to estimate 90-day outcomes.
Results: Of 437 unique first time cases of SAB, 23 patients were excluded for incomplete data, leaving 414 individuals with SAB for the final analysis. Eighty-two (19.8%) patients had a vancomycin MIC = 2 mcg/mL. 60 subjects (14.5%) died, 124 (30.0%) were re-admitted and 10 (2.4%) had recurrence of SAB within 90 days. Multivariate regression showed equivalent risk of death (HR = 1.00, 95% CI (0.52, 1.91)), readmission (HR = 1.19, 95% CI (0.77, 1.85)) and recurrence (HR = 5.72 (95% CI (0.27, 123.56)) of SAB at 90 days for MIC < 2 versus MIC = 2.
Conclusion: In this prospective cohort study, in which antibiotic treatment course and length of hospital stay were comprehensively measured and loss to follow-up was minimized, vancomycin MIC was not predictive of mortality, disease recurrence or readmission at 90 days in the treatment of SAB.
A. Gahbauer, None
D. Deck, Forest Pharmaceuticals: speaker, Speaker honorarium
Merck: speaker, Speaker honorarium
B. Imp, None
S. Doernberg, None
H. Chambers, None