Inefficiency of the Leptospira transport medium (LTM) in the isolation of Leptospira spp. from urine of livestock in the Caatinga biome, Brazil

ABSTRACT: Leptospirosis is a zoonotic infection caused by bacteria of the genus Leptospira spp. of global importance, and in recent years efforts to isolate leptospires have intensified due to the importance of using these isolated strains to elucidate the phylogenetic behavior of the genus. In this survey, the efficiency of Leptospira transport medium (LTM) for leptospire isolation was evaluated by using 139 urine samples collected from bovine, goat, sheep and swine slaughtered in the Caatinga biome, Brazil. Leptospira spp. DNA was found in 41/139 (29.5%) of the urine cultures from pigs, cattle, sheep and goats, being 20/31 (64.5%) from pigs, 0/36 (0%) from cattle, 13/36 (36.1%) from sheep and 8/36 (22.2%) from goats. There was statistical difference in the proportions of PCR-positivity between pigs and cattle (P < 0.001), sheep (P = 0.038) and goats (P = 0.001). Sequencing of a urine sample from pig revealed 100% identity with L. borgpetersenii. There was no leptospire growth in any sample, and most culture samples presented high contamination. LTM was ineffective in recovering leptospires in urine cultures from livestock in the Caatinga biome despite PCR positivity, which suggests a further in-depth evaluation of this transport method to identify possible factors that may influence its performance, since the isolation of autochthonous leptospires is essential to elucidate epidemiological aspects of Leptospira spp. infection in semiarid conditions.