Phenotypic characteristics and virulence genotypes of Trueperella (Arcanobacterium) pyogenes strains isolated from European bison (Bison bonasus)

Trueperella (Arcanobacterium) pyogenes is an opportunistic animal pathogen, which in European bison is associated with different suppurative infections mainly of the urogenital tract. Little is known about the virulence of this bacterium and about the pathogenesis of infections. The main objective of this study was to determine phenotypic properties and virulence genotypes of the twenty-five T. pyogenes strains isolated from lesions in various tissues of free-living European bison. Classical bacteriological methods were used for phenotypic characterization. Genes encoding seven known and putative virulence factors of T. pyogenes were detected by PCR technique. Analysis of 16S rDNA partial sequences was performed to establish phylogenetic relationships of the isolated strains. All isolates showed typical morphological features of T. pyogenes and variable biochemical activity. Most of them displayed a strong positive effect in synergistic CAMP test. For all isolates the 16S rRNA gene partial sequence was identical to that of the T. pyogenes reference strain. All isolates carried the plo and fimA genes, while the nanH, nanP, cbpA, fimC and fimG genes were present in 40, 44, 12, 88 and 24% of the isolates, respectively. The T. pyogenes strains isolated from European bison represented various phenotypes and virulence genotypes, but there was no association between the investigated properties of the bacteria and the type of anatomopathological lesions from which they were isolated. These results indicate that the studied virulence factors of T. pyogenes are not significant determinants of the localization and type of infection caused by this bacterium.