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The early diagnosis of canine leptospirosis is still a challenge for clinicians that in most cases only have basic routine tests as diagnostic tools. This study aimed to isolate and characterize leptospires from the blood of dogs with clinical signs suggestive of leptospirosis and to evaluate the results of some laboratory tests in hamsters experimentally infected with these isolates. The blood of 22 animals was submitted to bacteriological culturing, and the isolates recovered were characterized by serogrouping, partial DNA sequencing (secY), and multiple locus variable-number tandem repeat analysis (MLVA). Golden Syrian hamsters were infected with isolated leptospires and submitted to serology using microscopic agglutination test (MAT), polymerase chain reaction (PCR), complete blood counts, and serum biochemistry. Three isolates (13.63%) were obtained, and all were assigned to the serogroup Icterohaemorrhagiae. The DNA sequencing results showed that all the isolates belonged to the species Leptospira interrogans, and the MLVA results evidenced that the profile of the strains was compatible with Copenhageni/Icterohaemorrhagiae serovars. Regarding laboratory tests performed on hamsters infected with these isolated strains, marked leukocytosis by neutrophilia and monocytosis was observed, associated with an accentuated increase in renal and hepatic indicators. In addition, a titer of 800 was detected by MAT for only the serogroup Icterohaemorrhagiae, and blood, liver, kidneys, and lung samples were PCR positive. The presence of these isolates suggests that the dogs were infected with strains carried by rodents, and significant changes were found in routine laboratory tests, which, when correlated, can help veterinarians with early diagnosis. [ABSTRACT FROM AUTHOR]

• A Leptospira strain was recovered from urine of a water buffalo. • The isolate was assigned to the species L. borgpetersenii and the Sejroe serogroup. • This was the first isolation of a strain other than the subgroup Wolffi in Brazil. • The strain was detected in the reproductive tract of experimentally infected hamsters. The isolation of leptospires from buffaloes worldwide is still limited to a few strains. Thus, the aim of this study was to describe the first Leptospira isolate from buffalo urine, assigned to the Sejroe serogroup, which does not belong to the Wolffi subgroup, traditionally isolated in Brazil. A total of 244 urine samples of water buffaloes (Bubalus bubalis) raised in the Brazilian Amazon were subjected to bacteriological culturing and polymerase chain reaction (PCR) for the detection of leptospires. The obtained isolate was characterized by serogrouping using polyclonal antibodies, partial DNA sequencing, Hardjo-Bovis-specific PCR, multiple-locus variable-number tandem repeat analysis (MLVA/VNTR) and experimental infection in hamsters. PCR was performed on the urine samples; 11/244 were positive (4.5 %) for Leptospira , and only one isolate was recovered (0.4 %). Regarding characterization, the isolate was assigned to the Sejroe serogroup with high titers (12,800) for the Saxkoebing and Sejroe serovar antisera. The isolate was negative for Hardjo-Bovis-specific PCR, and the species Leptospira borgpetersenii was identified by DNA sequencing. The MLVA results showed that the VNTR profile of the isolate was 1−2-5, compatible with that of serovars Sejroe/Istrica. In the experimental infection in hamsters, the animals did not develop clinical signs, and no macroscopic lesions were observed on the organs at necropsy; however, the strain was detected in the kidneys, uterus, and testicles of the animals. The isolate described herein highlights infection by Sejroe strains that may be overlooked in buffaloes and that may be different from those normally isolated and used in serological studies. [ABSTRACT FROM AUTHOR]