Isolation and Characterization of Carbapenem-Resistant Escherichia coli Carrying bla_NDM and mcr-1 from Recurrent...

The emergence of carbapenem-resistant E. coli (CRECO), leading to few antibacterial drugs available for CRECO infection. In this study, we report three carbapenem-resistant Escherichia coli (E. coli) isolates coproducing bla_NDM and mcr-1 from patients with recurrent urinary tract infection (RUTI). Carbapenem-resistant E. coli strains, E55, E84, and E85, were isolated from the urine sample of RUTI patients.

Antimicrobial susceptibility testing (AST) was conducted with VITEK-2 compact system and Kirby-Bauer (K-B) disk diffusion method. The ESBL test was detected by the disk diffusion method. The EDTA-modified carbapenem inactivation method (eCIM) and modified carbapenem inactivation method (mCIM) were performed for screening the carbapenemase. Multilocus sequence typing (MLST) was performed for molecular typing of the strains. The resistance genes were detected by PCR.

The three isolates were all susceptible to tigecycline and nitrofurantoin. The bla_NDM-1, bla_CMY-6, bla_TEM-1 and bla_CTX-M-1, mcr-1, and porin loss expression of outer membrane protein F (OmpF) were detected in E55, which was assigned to ST2. The E84 and E85 were identified as ST471 carrying bla_NDM-5, bla_CTX-M55, and bla_TEM-1 and the quinsolone-resistant genes aac(6')-Ib-cr and mcr-1.

To our knowledge, our study is the first to report carbapenem-resistant E. coli strains carrying bla_NDM and mcr-1 from urine of the recurrent urinary tract infection patients. These E. coli strains carrying bla_NDM and mcr-1 should be closely monitored.