Genomic features of a highly virulent, ceftiofur-resistant, CTX-M-8-producing Escherichia coli ST224 causing fatal infection in a domestic cat

Abstract

Escherichia coli strains producing extended-spectrum β-lactamases (ESBLs), especially CTX-M-type, have been largely described in companion animals; however, genomic data are lacking to clarify the clinical impact of ESBL-producing isolates in these hosts. The aim of this study was to present the genomic features of a highly virulent, ceftiofur-resistant, CTX-M-8-producing E. coli isolate from a case of pneumonia in a domestic cat with fatal outcome. Genomic DNA was sequenced using an Illumina NextSeq 500 platform and was assembled using CLC Genomic Workbench. Genomic data were analysed using online bioinformatics tools. The genome size was evaluated at 5.1Mb, with 5334 protein-coding sequences. The strain was assigned to sequence type 224 (ST224) and presented genes conferring resistance to β-lactams (blaCTX-M-8), sulphonamides (sul2), tetracycline (tetA) and trimethoprim (dfrA14) as well as chromosomal point mutations in ParC (S80I), GyrA (S83L) and GyrB (D87N). In addition, the presence of the virulence genes cba, gad, ipfA, iroN, iss, mchF and tsh was detected. This draft genome sequence might provide important data for a better understanding of genomic aspects regarding the dissemination of CTX-M-8-producing E. coli in the human-animal-environment interface.