Emergent Escherichia coli of the highly virulent B2-ST1193 clone producing KPC-2 carbapenemase in ready-to-eat vegetables

Objectives

Critical priority carbapenem-resistant pathogens constitute a worldwide public health problem. Escherichia coli (E. coli) ST1193 is an emerging high-risk clone that demonstrates prolonged gut persistence, and association with community-onset urinary and bloodstream infections. The purpose of this study is to report microbiological and genomic data on the emergence of KPC-2-producing E. coli ST1193 in ready-to-eat (RTE) vegetables.

Methods

RTE vegetables were purchased from markets in southeastern Brazil. Epiphytic and endophytic Gram-negative bacteria displaying resistance to broad-spectrum beta-lactams were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry. Whole-genome sequence was conducted using the Illumina NextSeq platform. Antimicrobial susceptibility, conjugation, and acid tolerance assays were performed. Virulence behaviour was evaluated using the Galleria mellonella (G. mellonella) infection model.

Results

Epiphytic KPC-2-producing E. coli belonging to pandemic ST1193 was identified in RTE arugula. Genomic analysis predicted clinically relevant genes conferring resistance to β-lactams, fluoroquinolones, hazardous heavy metals, pesticides, disinfectants, and chlorine sanitizer. The bla_KPC-2 gene was carried by a conjugative IncF plasmid. Acid tolerance of E. coli KPC-2/ST1193 during exposure to pH 2.0 was confirmed, being associated with gadWX and ibaG pH tolerance genes, supporting survival to stomach acid prior to reaching the small intestine, and potential for a dietary mode of host colonization. Virulent behaviour was supported by wide virulome of the highly virulent phylogroup B2, whereas single nucleotide polymorphisms of core genes (cgSNP)-based phylogenomics revealed clonal relationship with healthcare-associated lineages circulating in the United States, China, Mexico, France, and Brazil.

Conclusions

We report the occurrence of KPC-2-producing E. coli of the highly virulent B2-ST1193 clone in RTE vegetables, highlighting a possible route of dissemination of the World Health Organization (WHO) priority pathogens to humans. © 2024 The Author(s). Published by Elsevier Ltd on behalf of International Society for Antimicrobial Chemotherapy.