Clonal Distribution and Its Association With the Carbapenem Resistance Mechanisms of Carbapenem-Non-Susceptible Isolates From Korean Hospitals.

BACKGROUND

Carbapenem resistance in is a serious global health problem. We investigated the clonal distribution and its association with the carbapenem resistance mechanisms of carbapenem-non-susceptible isolates from three Korean hospitals.

METHODS

A total of 155 carbapenem-non-susceptible isolates collected between 2011 and 2019 were analyzed for sequence types (STs), antimicrobial susceptibility, and carbapenem resistance mechanisms, including carbapenemase production, the presence of resistance genes, OprD mutations, and the hyperproduction of AmpC β-lactamase.

RESULTS

Sixty STs were identified in carbapenem-non-susceptible isolates. Two high-risk clones, ST235 (N=41) and ST111 (N=20), were predominant; however, sporadic STs were more prevalent than high-risk clones. The resistance rate to amikacin was the lowest (49.7%), whereas that to piperacillin was the highest (92.3%). Of the 155 carbapenem-non-susceptible isolates, 43 (27.7%) produced carbapenemases. Three metallo-β-lactamase (MBL) genes, (N=38), (N=3), and (N=2), were detected. was detected in clonal complex 235 isolates. Two ST773 isolates carried and . Frameshift mutations in were identified in all isolates tested, regardless of the presence of MBL genes. Hyperproduction of AmpC was detected in MBL gene-negative isolates.

CONCLUSIONS

Frameshift mutations in combined with MBL production or hyperproduction of AmpC are responsible for carbapenem resistance in . Further attention is required to curb the emergence and spread of new carbapenem-resistant clones.