Comparing the Outcomes of Adults with Enterobacteriaceae Bacteremia Receiving Short-Course Versus Prolonged-Course Antibiotic Therapy in a Multicenter, Propensity Score-Matched Cohort

Background The recommended duration of antibiotic treatment for Enterobacteriaceae bloodstream infections is 7-14 days. We compared the outcomes of patients receiving short-course (6-10 days) vs prolonged-course (11-16 days) antibiotic therapy for Enterobacteriaceae bacteremia. Methods A retrospective cohort study was conducted at 3 medical centers and included patients with monomicrobial Enterobacteriaceae bacteremia treated with in vitro active therapy in the range of 6-16 days between 2008 and 2014. 1:1 nearest neighbor propensity score matching without replacement was performed prior to regression analysis to estimate the risk of all-cause mortality within 30 days after the end of antibiotic treatment comparing patients in the 2 treatment groups. Secondary outcomes included recurrent bloodstream infections, Clostridium difficile infections (CDI), and the emergence of multidrug-resistant gram-negative (MDRGN) bacteria, all within 30 days after the end of antibiotic therapy. Results There were 385 well-balanced matched pairs. The median duration of therapy in the short-course group and prolonged-course group was 8 days (interquartile range [IQR], 7-9 days) and 15 days (IQR, 13-15 days), respectively. No difference in mortality between the treatment groups was observed (adjusted hazard ratio [aHR], 1.00; 95% confidence interval [CI],.62-1.63). The odds of recurrent bloodstream infections and CDI were also similar. There was a trend toward a protective effect of short-course antibiotic therapy on the emergence of MDRGN bacteria (odds ratio, 0.59; 95% CI,.32-1.09; P =.09). Conclusions Short courses of antibiotic therapy yield similar clinical outcomes as prolonged courses of antibiotic therapy for Enterobacteriaceae bacteremia, and may protect against subsequent MDRGN bacteria.