Frequency of occurrence and antimicrobial susceptibility of bacteria isolated from patients hospitalized with bloodstream infections in United States medical centers (2015–2017)

Abstract

The frequency and antimicrobial susceptibility of organisms causing bloodstream infections in the United States were evaluated by consecutively collecting (1/patient) 9210 bacterial isolates from 33 US medical centers in 2015–2017. Isolates were susceptibility tested by reference broth microdilution methods. Whole genome sequencing was performed on carbapenem-resistant Enterobacteriaceae (CRE). The most common organisms were Staphylococcus aureus (24.3%), Escherichia coli (20.8%), and Klebsiella pneumoniae (9.1%). Overall, 50.0% of isolates were gram-negative bacilli and 41.4% were Enterobacteriaceae. The most active agents against Enterobacteriaceae were ceftazidime–avibactam (99.9% susceptible), amikacin (99.7% susceptible), and the carbapenems meropenem and doripenem (99.1% susceptible). Among 28 CRE isolates (0.7% of Enterobacteriaceae), 21 produced a KPC-like carbapenemase, 2 an NMD-like, and 1 a KPC-17 and an NDM-1. Colistin (100.0% susceptible), ceftolozane–tazobactam (98.7% susceptible), ceftazidime–avibactam (98.2% susceptible), amikacin (97.9% susceptible), and tobramycin (95.6% susceptible) were very active against Pseudomonas aeruginosa. Among S. aureus isolates, 57.8% were oxacillin-susceptible.