Genomic diversity and novel sequence types of Pasteurella multocida from diverse animal hosts in Connecticut, United States, 2022-2023.

Pasteurella multocida is a zoonotic pathogen infecting a wide range of domestic and wild animals. Although genomic data are available for several domestic hosts, isolates from wildlife remain underrepresented. Here, we performed whole-genome sequencing of nine P. multocida isolates recovered in Connecticut between 2022 and 2023 from cows, a deer, a rabbit, a cat, and a pheasant to characterize their genetic features and enhance our understanding of the host-associated diversity. All isolates except one feline strain shared a common genotype across multiple host species, being classified as capsular type A and LPS type L3. In contrast, the feline isolate lacked a detected capsule locus and was classified as LPS type L1. Bovine isolates exhibited higher antimicrobial resistance, including the only multidrug-resistant isolate, and exclusively harbored antimicrobial resistance (AMR) genes [aph(3')-Ia, aph(6)-Id, sul2, and tet(H)], whereas non-bovine isolates showed low resistance and no evidence of AMR determinants. Multilocus sequence typing revealed that all bovine isolates belonged to ST1 (Multi-Host scheme) and ST79 (RIRDC scheme), while non-bovine isolates displayed greater genetic diversity, including five novel sequence types. Virulence-associated genes were largely conserved across hosts. Core-genome SNP-based phylogenetic analysis revealed largely host-associated clustering, with bovine isolates grouping with bovine lineages from other countries and non-bovine isolates clustering with genetically diverse international lineages, including avian and human-associated strains. Collectively, these findings highlight host-linked patterns in AMR and genomic diversity of P. multocida and underscore the importance of integrated phenotypic and genomic surveillance across animal hosts.