Genomic Characterization of Multidrug-Resistant Enterobacter hormaechei from Bovine Raw Milk: Implications for Food Safety and Public Health.

Antimicrobial resistance in foodborne bacteria poses a growing threat to public health. In this study, multidrug-resistant Enterobacter hormaechei (E. hormaechei), a member of the Enterobacter cloacae complex (ECC), was isolated from bovine raw milk in Gujarat, India, and examined for its prevalence, antimicrobial resistance, and genomic characteristics. A total of 21 presumptive E. hormaechei isolates were recovered from 190 raw milk samples (11.05%) based on morphological and biochemical characteristics and further confirmed using a species-specific PCR assay. Based on their phenotypic antimicrobial resistance profiles, eight multidrug-resistant (MDR) isolates were selected for whole-genome sequencing and downstream genomic analyses. Whole-genome sequencing of the MDR isolates revealed distinct sequence types, with ST350 and ST68 clustered closely. The sequenced isolates harbored a diverse repertoire of antimicrobial resistance genes, including blaACT, qnrS1/qnrB7, fosA, oqxA/B, mph(A), and aminoglycoside-modifying enzymes, consistent with their multidrug-resistant phenotypes. Virulence profiling identified genes associated with iron acquisition, adhesion, stress response, and type VI secretion systems, suggesting the presence of virulence-associated genetic determinants. Plasmid replicons (IncFII and Col-type) and the insertion sequence IS26 were identified among the sequenced isolates. This study provides a genomic characterization of MDR E. hormaechei isolates from raw milk in Gujarat, India, and emphasizes the importance of continuous AMR surveillance to monitor the spread of Enterobacter lineages with relevance to food safety and public health.