Identification and characterization of a Trueperella pyogenes deficient in proteolytic activity isolated from bovine mastitis: a case report

In the present study, we identified and characterized a single Trueperella (T) pyogenes strain 754B isolated from dairy milk using several phenotypical methods, MALDI-TOF MS fingerprinting and by various genotypic techniques investigating the molecular target genes 16S rRNA, ISR, sodA and gap. The genotypic techniques also included the amplification of the putative virulence factor encoding genes plo, cbpA, nanH, nanP, fimA, fimC, fimE and tet(W) specific for T pyogenes. Screening of the presence of the putative virulence genes showed that the T pyogenes 754B possess genes plo, fimA, fimC, fimE and tet(W). Meanwhile, the investigated isolate was negative for the presence of gene cbpA and both neuraminidases encoding genes nanH and nanP. However, it was of interest that T pyogenes 754B was lacking any extracellular proteolytic activity which is generally typical for T. pyogenes and is widely used for phenotypic identification of this species. We consider this study as the first observation of T pyogenes with a total lack of proteolytic activity.