Abstract
Even though Escherichia coli are common bacteria of the bovine vaginal microbiota, they represent an important pathogen that causes diseases in the reproductive tract and subfertility. However, the actual endometrial virulence profile of E. coli is poorly understood. The present study aims to characterize the phylogenetic structure and virulence potential of native vaginal populations of E. coli from healthy heifers (H), and cows with postpartum uterine diseases (PUD), such as metritis/endometritis (MT) or repeat breeder cows (RB). To this end, the virulence repertoire of 97 E. coli isolates was genotypically and phenotypically assessed. Most of them were assigned to phylogenetic group A (74%), followed by B1 (17%) and D (9%); RB strains were significantly (p < 0.05) more represented by B1. Seven of the 15 evaluated virulence genes (VFG) were detected and the most prevalent were fimH (87%), agn43 (41%) and csgA (35%); while traT (27%), fyuA (11%), hlyA (5%) and kpsMT II (5%) were observed in a lower proportion. Particularly, fyuA was significantly higher (p < 0.05) in MT cows whereas csgA showed the same behavior in PUD animals (p < 0.05). When comparing H and PUD strains, these last ones were associated to positive expression of biofilm, fimbriae curli/cellulose and motility; yet RB strains did not show motility. Vaginal B1 E. coli populations, that possess VFG (fyuA and csgA) as well as the expression of motility, curli fimbriae/cellulose and biofilm, may represent risk factors for endometrial disorders; specifically, those that also, have kpsMT II may have a pathogenic potential for causing the RB syndrome. Future research focusing on the detection of these strains in the vaginal microbiota of cows with postpartum uterine diseases should be done since the control of their presence in vagina could reduce the risk that they access the uterus during the postpartum period.
Highlights
Ascending infection from the bovine vagina after parturition frequently leads to disease of the upper female genital tract [1,2]
Our findings showed for the first time, a significant association among repeat breeder (RB) cows with E. coli from phylogenetic group B1, with the presence of fyuA, csgA, and kpsMT II, as well as a higher potential for curli fimbriae/cellulose expression and biofilm formation
It can be concluded that vaginal E. coli from animals with metritis or endometritis or repeat breeders possess Virulence factor gene (VFG) that could confer ability to colonize the bovine genitalia
Summary
Ascending infection from the bovine vagina after parturition frequently leads to disease of the upper female genital tract [1,2]. Postpartum uterine disease (puerperal metritis, clinical and subclinical endometritis) have a significant impact in dairy farms productivity because they perturb reproductive performance and contribute to cow discomfort, reduce milk production, increase treatment costs, antibiotic therapies and culling rates [3,4,5,6,7]. A repeat breeder (RB) is usually defined as a cow with apparently healthy genitalia that cannot conceive after three or more artificial inseminations or natural mating but exhibits normal estrous cycles [9]. This syndrome is one of the most important reproductive disorders in dairy cows that have the subclinical endometritis as one of its main causes [8]. Bacterial infection can modify the uterine environment producing inflammation, denudation of the mucosa and changes in its secretion with subsequent embryonic death [8], which results in an increase of days open and number of services per conception, as well as in early culling [5, 10, 11]
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