Genomic Characteristics of Extended Spectrum β-Lactamase Producing Escherichia coli Isolates Recovered from a District Hospital in China.

PURPOSE: The isolation rate of extended spectrum β-lactamase (ESBL)-producing Escherichia coli is increasing, posing a challenge to clinical anti-infective therapy. This study aims to provide new insight into the genomic characteristics and antimicrobial resistance mechanisms of extended spectrum β-lactamase producing E. coli isolates recovered from a district hospital in China.

METHODS

A total of 36 ESBL-producing E. coli isolates were collected from body fluid samples from a Chinese district hospital. All isolates were subjected to whole genome sequencing to identify their antimicrobial resistance genes, virulence genes, serotypes, sequence types, and phylogenetic relationships by BacWGSTdb 2.0 webserver.

RESULTS

Among these isolates, all were resistant to cefazolin, cefotaxime, ceftriaxone, ampicillin, 24 (66.7%) were resistant to aztreonam, 16 (44.4%) were resistant to cefepime, and 15 were resistant (41.7%) to ceftazidime. The blaCTX-M gene was detected in all ESBL-producing E. coli isolates. Two isolates carrying two different types of blaCTX-M genes simultaneously. The carbapenem resistance gene blaKPC-2 was detected in one (2.8%) isolate. A total of 17 sequence types (STs) were found, with ST131 accounting for the majority (n =13; 36.1%). The most common serotype was O16:H5 associated with seven ST131 strains, followed by O25:H4/ST131 (n = 5) and O75:H5/ST1193 (n = 5). Evaluation of clonal relatedness revealed that all blaCTX-M gene-carrying E. coli had a difference of SNPs range from 7 to 79,198, which could be divided into four clusters. Only 7 SNPs could be found between EC266 and EC622, indicating that they are variants of the same clonal lineage.

CONCLUSION

This study investigated the genomic characteristics of ESBL-producing E. coli isolates recovered from a district hospital in China. Continuous surveillance of ESBL-producing E. coli infections is imperative to create efficient strategies for controlling the transmission of these multi-drug resistant bacteria in clinical and community settings.