| Congresso Brasileiro de Microbiologia 2023 | Resumo: 712-1 | ||||
Resumo:Leptospirosis plays a major role in bovine reproductive diseases. Recently, Bovine Genital Leptospirosis (BGL) was described as a reproductive syndrome, characterized by genital colonization by leptospires. BGL leads to reproductive failures such as abortions and embryonic death, impairing the profitability of a herd. It is known that bulls can be infected by Leptospira spp. and shed the bacteria in their semen, and sexual transmission from male to female has been suggested. Since an infected bull could spread the leptospires to multiple cows, its treatment is crucial to prevent leptospirosis in a herd. An efficient streptomycin protocol for the treatment of genital carriers of leptospires was developed but only tested in experimentally infected ewes under controlled conditions. The aim of this case study was to evaluate the protocol of a three-dose of streptomycin protocol in naturally infected bulls in field conditions. Semen of six asymptomatic bulls of a beef herd, which has a history of cows with BGL, were collected by electroejaculation and sent for diagnosis to the Laboratory of Veterinary Bacteriology. The DNA of the semen was extracted using the Wizard SV Genomic DNA Purification System® (Promega), according to the manufacturer's protocol. Conventional PCR targeted the lipL32 gene, exclusive of pathogenic and intermediate strains. The positive samples in lipL32-PCR were submitted to a nested PCR of the secY gene and intended for BigDye sequencing. Sequences were edited and compared to the sequences already deposited in GenBank. The PCR-positive bulls were treated with streptomycin (Streptomax®, Ourofino) 25mg/kg, intramuscularly, daily for three consecutive days (three doses). After seven days of treatment, a new sampling was performed, and the semen was analyzed again by lipL32-PCR. Of the six bulls, two (2/6, 33.3%) were PCR-positive. Two sequences, one of each bull, were obtained and characterized as Leptospira interrogans serogroup Sejroe, most probably serovar (sv) Hardjoprajitno, with 99-100% homology with strain UF24. The two infected bulls received the three-dose streptomycin treatment and were both negative in the post-treatment PCR. The presence of infected bulls transmitting leptospires in semen, particularly in a herd with cows with confirmed uterine infection, reinforces the sexual transmission via of BGL hypothesis. It was not surprising the identification of genital colonization by L. interrogans sv Hardjoprajitno, since it is the main agent of BGL and has been frequently identified in the reproductive tract of cows. Streptomycin treatment has been used in a single dose to treat renal infection by leptospires, however, an experimental study showed that three doses are necessary to achieve genital clearance. Herein, the three-dose streptomycin protocol was efficient to perform the genital clearance of the naturally infected bulls, reproducing the results obtained in ewes in experimental conditions. This study reinforces the role of bulls in the sexual transmission of bovine leptospirosis and demonstrates an efficient treatment protocol for genital clearance in males Palavras-chave: bovine, PCR, lipL32, genital, Sejroe Agência de fomento:Fundação Carlos Chagas de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) e Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) | |||||