| Summary: | This study aimed to investigate the presence and distribution of virulence determinants and their antimicrobial susceptibilities of
44 Pseudomonas aeruginosa isolates obtained from clinical bovine mastitis cases. In addition, selected 6 P. aeruginosa isolates were further
characterized using whole-genome sequencing (WGS). Based on the presence of T3SS-related genes, 25% of the isolates were found to carry
exoU and/or exoS genes belonging to invasive (exoU-/exoS+, 18.2%) and cytotoxic (exoU+/exoS-, 6.8%) strains. But, none of the isolates
carried both exoU and exoS genes. In terms of other virulence genes examined, various virulence gene profiles were observed among the
isolates. The majority of the isolates (72.7%) were susceptible to all tested antimicrobials. Resistance rates to ciprofloxacin and carbapenems
(imipenem and meropenem) were determined as 25% and 4.5%, respectively. WGS analysis indicated the presence of different resistome,
but fosA genes in all isolates, and different combinations of mutations in gyrA, parC, oprD, efflux pump, and genes playing a role in the
regulation of ampC gene expression. Different sequence types (STs) and serotypes were found in representative isolates with the occurrence
of the O11-ST235 clone, which is a worldwide multidrug-resistant high-risk clone representing a serious public health threat. The findings
of this study provide valuable information on P. aeruginosa isolated from clinical bovine mastitis cases and current antimicrobial resistance
levels and virulence determinants.
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