Empiric combination therapy for gram-negative bacteremia

BACKGROUND: Empirical combination antibiotic regimens consisting of a b-lactam and an aminoglycoside are frequently employed in the pediatric population. Data to demonstrate the comparative benefit of empirical b-lactam combination therapy relative to monotherapy for culture-proven Gramnegative bacteremia are lacking in the pediatric population. METHODS: We conducted a retrospective cohort study of children treated for Gram-negative bacteremia at The Johns Hopkins Hospital from 2004 through 2012. We compared the estimated odds of 10-day mortality and the relative duration of bacteremia for children receiving empirical combination therapy versus empirical monotherapy using 1:1 nearest-neighbor propensity-score matching without replacement, before performing regression analysis. RESULTS: We identified 226 matched pairs of patients well balanced on baseline covariates. Ten-day mortality was similar between the groups (odds ratio, 0.84; 95% confidence interval [CI], 0.28 to 1.71). Use of empirical combination therapy was not associated with a decrease in the duration of bacteremia (20.51 days; 95% CI, 22.22 to 1.48 days). There was no survival benefit when evaluating 10-day mortality for the severely ill (pediatric risk of mortality III score ≥15) or profoundly neutropenic patients (absolute neutrophil count ≤100 cells/mL) receiving combination therapy. However, a survival benefit was observed when empirical combination therapy was prescribed for children growing multidrug-resistant Gram-negative organisms from the bloodstream (odds ratio, 0.70; 95% CI, 0.51 to 0.84). CONCLUSIONS: Although there appears to be no advantage to the routine addition of an aminoglycoside to a b-lactam as empirical therapy for children who have Gram-negative bacteremia, children who have risk factors for MDRGN organisms appear to benefit from this practice.