Vet Res Commun. 2026 Jan 15;50(2):105. doi: 10.1007/s11259-025-11044-9.
ABSTRACT
BACKGROUND: Burkholderia pseudomallei, the causative agent of melioidosis in humans and animals, has been implicated in acute infections with high mortality rates in animal hosts and in mastitis in dairy cattle. It has intrinsic resistance to a wide range of antibiotics and is also known to possess a multitude of virulence determinants. This study provides baseline data on the occurrence of this pathogen in bovine milk samples in Osogbo, Southwestern Nigeria.
METHODS: A total of 371 milk samples collected from dairy cows with clinical and subclinical mastitis were assessed for the presence of B. pseudomallei using phenotypic microbiological techniques, confirmed by molecular methods. Selected resistance (folA, folP, Omp38, bpeE and bpeF) and virulence (bsaU, pili/fimbriae, bimA, tssA and wbiE) genes were screened for using self-designed specific primers, while antibiotic susceptibility testing against clinically relevant antibiotics was via the Kirby-Bauer disc diffusion technique.
RESULTS: Molecular identification confirmed 16 isolates (4.31%) as B. pseudomallei. Resistance to amoxicillin-clavulanic acid, imipenem, tetracycline and ceftazidime was absolute (100.0%), trailed by trimethoprim-sulfamethoxazole (SXT) at 93.8%. Meropenem exhibited the highest activity in vitro, as 93.8% of isolates were susceptible to it. All isolates (100.0%) were classified as extremely drug-resistant (XDR), with multiple antibiotic resistance indices ≥ 0.2. All isolates (100.0%) also harboured both resistance and virulence determinants, with 68.8% having ≥ 6 genes – 93.75% had the folP gene. The predominant virulence gene was BsaU, detected in 87.5% of isolates. No isolates had the wbiE gene.
CONCLUSION: The presence of XDR strains and carriage of multiple resistance and virulence genes in B. pseudomallei strains portend serious implications in affected dairy cattle. This study recommends prudent antibiotic use in dairy cattle and the proper processing of milk before consumption to limit the risk of zoonotic transmission.
PMID:41538090 | DOI:10.1007/s11259-025-11044-9
