Human-associated NDM-5-producing multidrug-resistant Escherichia coli detected in retail beef and pork in Hungary, 2021

Background: Carbapenem-resistant Enterobacterales pose a significant public health threat, particularly when detected in food-producing animals and retail meat. Although carbapenems are not used in European Union animal production, sporadic cases of carbapenemase-producing Escherichia coli have emerged across multiple European countries since 2019. The detection of human-associated carbapenemase genes in meat raises concerns about potential transmission to humans through the food chain.

Methods: In this study, we characterize three multidrug-resistant (MDR) E. coli isolates harboring bla_NDM-5 recovered from retail beef and pork in Hungary in 2021. E. coli isolates were subjected to phenotypic antimicrobial susceptibility testing using broth microdilution, conjugation experiments, and genotypic characterization through whole-genome sequencing using Illumina and Oxford Nanopore platforms. Hybrid assemblies enabled comprehensive comparative genomic and plasmid analyses.

Results: All three isolates belonged to the human-associated uropathogenic clone ST405 (O102:H6) and were clonally related with a maximum of two single nucleotide polymorphisms. They exhibited identical genomic profiles conferring resistance to carbapenems, cephalosporins, fluoroquinolones, tetracycline, and azithromycin. Comparative genomic analysis revealed close genetic relationships with human clinical isolates from Australia and the United Kingdom, suggesting international dissemination. The bla_NDM-5 gene was located on conjugative IncFII-IncFIB hybrid plasmids (approximately 132 kb) closely related to clinical plasmids from human isolates in the United States, differing only by the absence of a bla_CTX-M-15-ISEcp1 transposition unit.

Conclusion: The detection of human-associated bla_NDM-5-carrying E. coli ST405 in retail meat represents a serious food safety concern, highlighting potential transmission routes to humans and emphasizing the need for enhanced surveillance and epidemiological investigations.