Abstract

CRUZ-SOTO, Alejandro Sergio et al. Genetic relationships, biofilm formation, motility and virulence of Escherichia coli isolated from bovine mastitis. Rev. mex. de cienc. pecuarias [online]. 2020, vol.11, n.1, pp.167-182.  Epub June 11, 2020. ISSN 2448-6698.  https://doi.org/10.22319/rmcp.v11i1.4998.

Escherichia coli is an environmental bacterium frequently implicated in bovine mammary infections. Although specific virulence factors are unknown, biofilm-forming bacteria are associated with persistent infections, and motile bacteria exhibit increased virulence. An analysis was done of the genetic relationship, biofilm formation capacity and motility of bovine mastitis-associated E. coli, as well as the in vivo virulence of representative bacterial isolates. Of the 34 isolates, 67.7 % belonged to phylogenetic group A, 17.6 % to group B1 and 14.7 % to group D. Genetic relationship analysis done with (GTG)5-PCR indicated that the analyzed bacteria are diverse, with only two isolates exhibiting 100 % similarity, and the remaining 32 being grouped into seven main clusters with more than 70 % similarity. Biofilm formation capacity ranged from strong to moderate and weak in 76.5 % of the isolates. The csgA and fimA genes were detected in 52.9 % of the biofilm-forming isolates. Most (70.6 %) of the isolates were motile. In vivo infection assays using Galleria mellonella showed the biofilm-forming bacteria to be more pathogenic than the non-biofilm-forming ones. The studied bovine mastitis-associated E. coli were genetically diverse. Biofilm formation capacity and motility were variable among the isolates, but the biofilm-forming bacteria were more pathogenic than the non-biofilm-forming ones.

Keywords : E. coli; Bovine mastitis; Diversity; Biofilm; Virulence.