Extra-renal bovine leptospirosis: Molecular characterization of the Leptospira interrogans Sejroe serogroup on the uterus of non-pregnant cows.

Bovine genital leptospirosis is a chronic disease that causes reproductive disorders such as abortions, stillbirths, and estrus repetition, as well as economic losses. Despite clinical signs related to reproductive failure, the majority of studies have focused on the detection of Leptospira spp. in the urine, while few have considered the reproductive tract. Consequently, the aim of the present study was to investigate the uterus as an important extra-renal site of leptospiral infection in cows. A total of 42 non-pregnant cows were studied at a slaughterhouse. Blood samples and uterine fragments were collected for serology and molecular analysis, respectively. Concerning serologic results, 20.5 % presented as reactive, all of them against the Sejroe serogroup. Regarding lipL32 PCR, 26.2 % (11/42) of samples were positive for pathogenic Leptospira sp. Sequencing the secY gene short region enabled nine strains to be characterized, all of which were L. interrogans, with high identity (98.8 %-99.8 %) with serovar Hardjo. The use of molecular tools substantially improved the sensitivity of Leptospira sp. detection at species level and demonstrated that the uterus is an important site of bovine leptospiral infection. The findings of the present study reinforce our understanding that leptospiral uterine infection are associated to members of the Sejroe serogroup.