Clinical Impact of Vancomycin Treatment in Ampicillin-Susceptible Enterococci Bloodstream Infections

Enterococci are major causes of bacteremia. Although the mortality rate of ampicillin- susceptible enterococci (ASE) bloodstream infections (BSI) is lower, compared with that of ampicillin-resistant enterococci BSI, the role of treatment regimens in ASE BSI remains to be determined. This retrospective study aimed to evaluate the treatment outcomes and factors associated with mortality among patients with ASE BSI. The charts of 145 enrolled patients with ASE BSI between January 2013 and April 2022 at Phramongkutklao Hospital were reviewed. The 30-day and in-hospital mortality rates were 28.8 and 41.9%, respectively. The 30-day mortality rate was higher in the vancomycin treatment group than in the beta-lactam treatment group (61.5 vs. 26%; p = 0.02). Pitt bacteremia score (OR 1.44, 95% CI 1.20-1.71); age-adjusted Charlson Comorbidity Index (OR 1.34, 95% CI 1.14-1.58); and vancomycin treatment (OR 4.07, 95% CI 1.02-16.22) were independent factors associated with 30-day mortality. The severity of illness, comorbidity and definitive therapy with vancomycin increased the mortality rate of patients with ASE BSI. Anti-enterococcal beta-lactams remain the first line antibiotics for ASE bacteremia.