Antimicrobial resistance mechanism of Enterobacter cloacae to carbapenems

Abstract:

Objective To study the molecular epidemiological characteristics of carbapenem-resistant Enterobacter cloacae (CREC) and mechanism of carbapenem resistance, provide basis for clinical empirical antimicrobial use as well as prevention and control of healthcare-associated infection. Methods CREC isolated from a hospital between April and September 2019 were identified and performed antimicrobial susceptibility analysis, carbapenemase was screened by modified carbapenem inactivation method (mCIM) and EDTA-modified carbapenem inactivation method (eCIM), carbapenem-resistant genes were detected by polymerase chain reaction (PCR), molecular epidemiological characteristics were analyzed by multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). Results Among 8 strains of CREC, 5 were from intensive care unit (ICU) and were highly resistant to cephalosporins and enzyme inhibitors commonly used in clinical practice. All strains carried metallo-β-lactamases, 7 strains carried bla_NDM-1 and 1 strain carried bla_IPM-4. MLST molecular typing and PFGE homology analysis showed 6 ST sequence types and 6 clone groups. ST596 (3 strains), ST121 (1 strain), ST993 (1 strain), ST91 (1 strain), ST794 (1 strain) B and ST88 (1 strain) belonged to groups A, C, F, E, B and D respectively. Conclusion CREC in this hospital mainly comes from ICU, producing of metalloenzyme bla_NDM-1 β-lactamase is the main resistance mechanism. ST596 group A Enterobacter cloacae has local epidemic in ICU for a short time, prevention and control measures of HAI should be strengthened to curb the outbreak.