Genomic Characteristics of an Extensive-Drug-Resistant Clinical Escherichia coli O99 H30 ST38 Recovered from Wound

Antibiotic-resistant Escherichia coli is one of the major opportunistic pathogens that cause hospital-acquired infections worldwide. These infections include catheter-associated urinary tract infections (UTIs), ventilator-associated pneumonia, surgical wound infections, and bacteraemia. Objectives: To understand the mechanisms of resistance and prevent its spread, we studied E. coli C91 (ST38), a clinical outbreak strain that was extensively drug-resistant. The strain was isolated from an intensive care unit (ICU) in one of Kuwait's largest hospitals from a patient with UTI.

This isolate has a diverse portfolio of antimicrobial resistance and virulence genes and belongs to ST38 O99 H30, posing a serious challenge to treating infected patients in clinical settings.

This study used whole-genome sequencing (Illumina, MiSeq) to identify the strain's multi-locus sequence type, resistance genes (ResFinder), and virulence factors. This study also measured the minimum inhibitory concentrations (MIC) of a panel of antibiotics against this isolate.

The analysis showed that E. coli C-91 was identified as O99 H30 ST38 and was resistant to all antibiotics tested, including colistin (MIC > 32 mg/L). It also showed intermediate resistance to imipenem and meropenem (MIC = 8 mg/L). Genome analysis revealed various acquired resistance genes, including mcr-1, bla CTX-M-14, bla CTX-M-15, and bla OXA1. However, we did not detect bla NDM or bla VIM. There were also several point mutations resulting in amino acid changes in chromosomal genes: gyrA, parC, pmrB, and ampC promoter. Additionally, we detected several multidrug efflux pumps, including the multidrug efflux pump mdf(A). Eleven prophage regions were identified, and PHAGE_Entero_SfI_NC was detected to contain ISEc46 and ethidium multidrug resistance protein E (emrE), a small multidrug resistance (SMR) protein family. Finally, there was an abundance of virulence factors in this isolate, including fimbriae, biofilm, and capsule formation genes. Conclusions: This isolate has a diverse portfolio of antimicrobial resistance and virulence genes and belongs to ST38 O99 H30, posing a serious challenge to treating infected patients in clinical settings.