Genomic characterisation, detection of genes encoding virulence factors and evaluation of antibiotic resistance of Trueperella pyogenes isolated from cattle with clinical metritis.

Trueperella pyogenes is one of the most important microorganisms causing metritis in post-partum cattle. Co-infection with other bacterial species such as Escherichia coli or Fusobacterium necrofurom increases the severity of the disease and the persistence of bacteria in utero. The aim of this study was to investigate the frequency of T. pyogenes strains, and their virulence and antimicrobial resistant profiles in metritis cases. The study was carried out on 200 samples obtained from metritis discharges of postpartum cattle on 18 farms around Tehran, Iran. Sixty-five T. pyogenes isolates (32.5%) were identified, of which 16 isolates were detected as pure cultures and the other 49 isolates from cultures most commonly mixed with E. coli or F. necrofurom. In terms of diversity in biochemical characteristic of T. pyogenes strains, 8 different biotypes were identified among the isolates. Single or multi antimicrobial resistance was observed in 48 isolates (73.9%), which was mostly against trimethoprim sulfamethoxazole, azithromycin, erythromycin and streptomycin. The tetracycline resistance gene tetW and macrolide resistance genes ermB and ermX were detected in 30, 18 and 25 isolates, respectively. In the screening of genes encoding virulence factors, fimA and plo genes were identified in all tested isolates. Genes encoding nanP, nanH, fimC, fimG, fimE and cbpA were detected in 50, 54, 45, 40, 50 and 37 of isolates, respectively. Thirteen different genotypes were observed in these T. pyogenes isolates. A significant association between clonal types and virulence factor genes, biochemical profile, CAMP test result, severity of the disease and sampling time was detected.