Genomic characterization of <i>mcr-1.1</i>-positive <i>Salmonella</i> Kentucky ST198 from a captive Asian houbara bustard reveals links to broiler poultry in the United Arab Emirates

The Asian houbara bustard (<i>Chlamydotis macqueenii</i>) is a vulnerable species supported by conservation breeding programs internationally, as well as in the United Arab Emirates (UAE). Infectious diseases caused by antimicrobial-resistant pathogens represent an emerging threat to captive populations. This study aimed to characterize the genomic features, antimicrobial resistance (AMR) determinants, and phylogenomic relatedness of an <i>mcr-1.1</i>-positive multidrug-resistant <i>Salmonella</i> Kentucky ST198 isolate recovered from a captive Asian houbara bustard in the United Arab Emirates. Post-mortem bacteriological culture of yolk sac samples yielded <i>S</i>. Kentucky isolate FAZ18016, which underwent antimicrobial susceptibility testing and long-read whole-genome sequencing. The isolate exhibited phenotypic multidrug resistance to 17 antimicrobials, supported by 21 resistance genomic determinants including <i>bla</i> _{TEM - 1}, <i>mph(A), tet(A), floR, sul1/sul3</i>, and <i>mcr</i>-1.1. The colistin minimum inhibitory concentration was 8 mg/L. The <i>mcr</i>-1.1 gene was located on an IncHI2 plasmid co-harboring <i>tet(A), terC</i>, and multiple insertion sequences, sharing >99% nucleotide identity with plasmids described in <i>Klebsiella pneumoniae</i> and <i>Escherichia coli</i>. A total of 156 virulence-associated genes were identified, including complete Salmonella Pathogenicity Island 1 and 2, type III secretion systems and type VI secretion system components. Core-genome single-nucleotide polymorphism analysis assigned FAZ18016 to sequence type (ST) 198 and revealed 31-166 Single nucleotide polymorphism (SNP) differences from previously characterized UAE broiler isolates, with the closest related strains differing by 31-33 SNPs, consistent with relatively recent common ancestry. These findings indicate potential spillover of a high-risk, <i>mcr</i>-1.1-carrying <i>S</i>. Kentucky ST198 clone from poultry into captive wildlife and highlight the need for integrated genomic AMR surveillance and strengthened biosecurity at the wildlife-poultry interface within a One Health framework.