β-lactam antibiotics vs. vancomycin for the early treatment of enterococcal bacteraemia: A retrospective cohort study.

BACKGROUND

The efficacy of vancomycin compared with ampicillin for enterococcal infections is unknown. This study aimed to compare their efficacy among patients with enterococcal bacteraemia.

METHODS

Retrospective cohort study including adults aged >16 years with enterococcal bacteraemia, treated with β-lactam antibiotics active against Enterococcus spp. or vancomycin. Treatment classification was based on the first antibiotic used for >4 days in the 7 days after blood culture collection. Subgroup analyses for patients with penicillin-susceptible enterococcal bacteraemia and patients with monomicrobial penicillin-susceptible enterococcal bacteraemia were performed. The dependent variable was 30-day all-cause mortality. The propensity score (PS) for vancomycin treatment was calculated. Univariate and multi-variate analyses adjusted for PS were performed.

RESULTS

In total, 516 patients with enterococcal bacteraemia were included. Mortality was similar for patients treated with β-lactams (123/315, 39%) and vancomycin (82/201, 40.8%). Independent factors significantly associated with mortality included healthcare-associated or hospital-acquired infection, age, female sex, Charlson Comorbidity Index, dialysis, SOFA score and low albumin. After adjustment for these factors and PS, the odds ratio (OR) for death in patients treated with vancomycin was 0.95 [95% confidence interval (CI) 0.56-1.59]. Results were similar among patients with penicillin-susceptible enterococcal bacteraemia and patients with monomicrobial penicillin-susceptible enterococcal bacteraemia (n=237, adjusted OR 0.59, 95% CI 0.25-1.43).

CONCLUSION

No difference in mortality was observed following treatment with a β-lactam or vancomycin among patients with enterococcal bacteraemia. Vancomycin is not recommended for the treatment of penicillin-susceptible enterococcal infections; however, when needed, it is not inferior to β-lactams and the addition of a β-lactam is not necessary.