The prevalence of colistin-resistant Gram-negative bacteria isolated from hospitalized patients with bacteremia

Abstract

This study sought to investigate the prevalence of colistin-resistant Gram-negative bacteria (CoR-GNB) among Pseudomonas aeruginosa, Acinetobacter baumannii, Escherichia coli, and Klebsiella pneumoniae isolated from patients with bacteremia and to identify other antimicrobials as a potential therapy for CoR-GNB infections. We retrospectively reviewed the data of non-repeated clinical bacterial isolates from patients admitted to Phramongkutklao Hospital during May 2017–April 2018. We obtained the minimum inhibitory concentrations (MICs) of the studied isolates and interpreted the MIC values followed by the Clinical and Laboratory Standards Institute (CLSI) criteria. Out of 623 bacterial isolates, the prevalence of E. coli was predominantly high (349), followed by K. pneumoniae (150), P. aeruginosa (64), and A. baumannii (60). The CoR-GNB rates among E. coli, K. pneumoniae, A. baumannii, and P. aeruginosa were 2.9%, 17.3%, 5.0%, and 1.6%, respectively. Seven out of 26 colistin-resistant K. pneumoniae isolates and seven out of 10 colistin-resistant E. coli isolates were still susceptible to carbapenems (the MICs for imipenem and meropenem were ≤1 μg/ml). Tigecycline and aminoglycosides might be the best therapeutic choices against CoR-GNB. In conclusion, our findings confirmed a CoR-GNB prevalence of approximately 1.6%–17.3%, depending on the bacterial species. Certain available antimicrobials remain effective against CoR-GNB.