Putative virulence factors of extra-intestinal Escherichia coli isolated from bovine mastitis with different clinical scores.

We investigated the genes kpsMTII, iucD, sfaDE, afaBC, papA and papC, (proposed to be involved in extra-intestinal pathogenic Escherichia coliExPEC), phylogroup classification and the invitro swimming and swarming motility in 50 E.coli isolated from bovine mastitis with different clinical severity scores (mild, moderate and severe). The aforementioned genes were detected in 12 (n=12/50; 240%) isolates. kpsMTII and iucD were the most frequent genes identified in six (n=6/50; 120%) and four (n=4/50; 80%) of the isolates, respectively. In only one (n=1/50; 20%) isolate, more than one gene was simultaneously identified: iucD and kpsMTll were detected whereas sfaDE and afaBC were not detected. Mild, moderate and severe clinical signs were observed in 400% (n=20/50), 280% (n=14/50) and 320% (n=16/50) of the cases. Commensal phylogroups B1 (n=19/50; 380%) and A (n=19/50; 380%) were prevalent; whereas pathogenic phylogroups B2 and D were observed in only 100% (n=5/50). Swarming and swimming motilities were observed in 900% (n=45/50) and 680% (n=34/50) of the isolates, respectively; and there was a significant association (P=00036) between swarming motility and severe clinical cases (score 3). To the best of our knowledge, this is the first study where clinical severity of bovine mastitis cases and the genes proposed to classify ExPEC were assessed in relation to swarming and swimming motility.