Genomic characterization of extended-spectrum β-lactamase-producing Enterobacterales isolated from abdominal surgical...

Rectal swabs of 104 patients who underwent abdominal surgery were screened for ESBL producers. Sequence types (STs) and resistance genes were identified by whole-genome sequencing of 46 isolates from 17 patients. All but seven isolates were assigned to recognized STs. While 18 ESBL-producing E. coli (EPEC) strains were of unique STs, ESBL-producing K. pneumoniae (EPKP) strains were mainly ST14 or ST15. Eight patients harboured strains of the same ST before and after abdominal surgery. The most prevalent resistant genes in E. coli were bla_EC (69.57%), bla_CTX-M (65.22%), and bla_TEM (36.95%), while bla_SHV was present in only K. pneumoniae (41.30%). Overall, genes encoding β-lactamases of classes A (bla_CTX-M, bla_TEM, bla_Z), C (bla_SHV, bla_MIR, and bla_DHA), and D (bla_OXA) were identified, the most prevalent variants being bla_CTX-M-15, bla_TEM-1B, bla_SHV-28, and bla_OXA-1. Interestingly, bla_CMY-2, the most common pAmpC β-lactamase genes reported worldwide, and mobile colistin resistance genes, mcr-10-1, were also identified. The presence of bla_CMY-2 and mcr-10-1 is concerning as they may constitute a potentially high risk of pan-resistant post-surgical infections. It is imperative that healthcare professionals monitor intra-abdominal surgical site infections rigorously to prevent transmission of faecal ESBL carriage in high-risk patients.