Genomic Characterization and Antimicrobial Resistance of ESBL-Producing, Escherichia coli Isolates in Suzhou, China.

BACKGROUND

The prevalence of third-generation cephalosporin-resistant and extended-spectrum beta-lactamases (ESBL) producing Escherichia coli poses a significant global public health concern due to their resistance to multiple antibiotics; however, their prevalence and epidemiological patterns in China are not very well investigated.

OBJECTIVE

This study aimed to investigate the molecular epidemiology, and antimicrobial susceptibility of ESBL-producing E. coli among clinical isolates in China.

METHODS

Phenotypic ESBL-producing E. coli isolates were collected from in-patients at a non-tertiary hospital in Suzhou from 2018.06.01 -2019.11.30. All isolates were identified and analyzed by conventional microbiological methods, and antimicrobial susceptibility testing was determined. Genes associated with resistance to β-lactamases, fluoroquinolone, aminoglycosides, sulfonamides, sequence types (STs), and genetic relationship were characterized through whole-genome sequencing (WGS) data.

RESULTS

Eighty-six isolates were collected and sequenced, and genomic analysis identified twenty-five different sequence types (STs). The most prevalent STs were ST131 (n=22, 25.6%), ST1193 (n=16, 18.6%), ST38 (n=9, 10.5%) and ST167 (n=6, 7.0%). blaCTX-M genotypes were the most dominant, comprising a variety of subtypes (eg, blaCTX-M-14, blaCTX-M-15, blaCTX-M-27, blaCTX-M-55) and blaTEM-type among ESBL-producing E. coli in our study. All cases of co-carriage of β-lactamase genes showed a strong link to amoxicillin/sulbactam resistance, while the co-carriage of blaCTX-M-15/TEM-1B or blaCTX-M-15/OXA-1 were strongly linked to resistance against cefepime, ceftazidime, and aztreonam. In addition, genes associated with resistance to fluoroquinolone, aminoglycosides, and sulfonamides were also detected.

CONCLUSION

Our findings highlighted the prevalence of globally circulating ESBL-producing E. coli clones, such as ST131 and ST1193, in Suzhou, China. These clones and sublineages are also resistant to quinolones. No predominant blaCTX-M subtypes were detected, while the coexistence of different ESBL types was strongly linked to resistance to amoxicillin/sulbactam, cefepime, ceftazidime, and aztreonam, suggesting the widespread circulation of diverse blaCTX-M genes within the Suzhou community. In clinical cases of ESBL resistance, carbapenem therapy is recommended as most (>90%) isolates were susceptible.