Emergence and dissemination of multidrug-resistant Escherichia coli ST8346 coharboring bla and bla in Southern Taiwan, 2017-2021.

BACKGROUND

Enterobacterales carrying bla represent an emerging challenge in treating infectious diseases. In this study, we aimed to investigate the characteristics of bla-producing Enterobacterales from three hospitals in southern Taiwan.

METHODS

Enterobacterales strains that were nonsusceptible to more than one carbapenem (ertapenem, meropenem, imipenem, or doripenem) were collected from hospitalized patients. Molecular typing for New Delhi metallo-β-lactamase (NDM) and antibiotic susceptibility tests were performed, followed by multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), and plasmid analysis by PCR-based replicon typing.

RESULTS

A total of 1311 carbapenem-nonsusceptible Enterobacterales were isolated from 2017 to 2021. bla-encoding genes were detected in 108 isolates, with 53 (49.1%) harboring bla and 55 (50.9%) harboring bla. The rate of bla detection among isolates decreased to 2% in 2021. However, the rate of E. coli harboring bla increased from 1% to 12% of total isolates during the study period. Of 47 NDM-5-positive E. coli isolates, 44 (93.6%) were ST8346 with high genetic relatedness. E. coli ST8346 isolates showed high-level resistance to both carbapenems and aminoglycosides. Most (38 out of 47, 80.9%) bla-harboring E. coli isolates co-harbored bla. We analyzed the regions harboring bla in E. coli ST8346 via PCR amplification. bla and bla were located on two separate plasmids, IncF and IncX3, respectively.

CONCLUSION

The dissemination of E. coli ST8346 caused an increase in bla and bla co-harboring Enterobacterales in southern Taiwan, which show high-level resistance to both carbapenems and aminoglycosides. We identified a distinct IncF plasmid encoding bla that has the potential for rapid spread and needs further surveillance.