Infections caused by clonal spread of metallo-beta-lactamase-producing Enterobacter cloacae complex isolates in southern Taiwan

Carbapenem-resistant Enterobacter cloacae complex (CR-ECC) became a clinically important pathogen with increased incidence worldwide in recent years. In Taiwan, IMP-8 accounted for most carbapenemase produced by ECC in earlier studies. The study characterized the infection types, species identification, sequence typing, antimicrobial susceptibilities, and beta-lactamase-producing genes among CR-ECC isolates at a medical center in southern Taiwan. Clinical ECC isolates resistant to ertapenem, imipenem, and meropenem in the study hospital between 2014 and 2022 were collected and their clinical information was obtained from electrical medical record. The isolates were subjected to multilocus sequence typing, species identification by hsp60 sequencing, polymerase chain reaction detection of beta-lactamases genes, and antimicrobial susceptibility tests. Fifty-four ECC isolates causing infections were included. Bloodstream (20 episodes, 37.0%) and lower respiratory tract infections (14, 25.9%) were the common infection types. The crude in-hospital mortality was 51.8%. Carbapenemase genes were detected among 90.7% of the isolates and blaIMP-8 remained to be the most common gene. blaNDM-1 harboring E. hormaechei subsp. xiangfangensis ST171 and blaVIM-1 harboring E. hormaechei subsp. hoffmannii ST78, which have not been reported in Taiwan, were responsible for the increased incidence of CR-ECC since 2019. The amikacin and colistin resistance rates were lower than 20%, while other agents were less active in vitro. CR-ECC infection heralds a poor prognosis and has limited treatment options. The increased CR-ECC infections in southern Taiwan can be attributed to the emergence of NDM-1-producing E. hormaechei subsp. xiangfangensis ST171 and VIM-1-producing E. hormaechei subsp. hoffmannii ST78.