Genotyping of Leptospira directly in urine samples of cattle demonstrates a diversity of species and strains in Brazil

Abstract

The aim of this study was to identify Leptospira in urine samples of cattle by direct sequencing of the secY gene. The validity of this approach was assessed using ten Leptospira strains obtained from cattle in Brazil and 77 DNA samples previously extracted from cattle urine, that were positive by PCR for the genus-specific lipL32 gene of Leptospira. Direct sequencing identified 24 (31·1%) interpretable secY sequences and these were identical to those obtained from direct DNA sequencing of the urine samples from which they were recovered. Phylogenetic analyses identified four species: L. interrogans, L. borgpetersenii, L. noguchii, and L. santarosai with the most prevalent genotypes being associated with L. borgpetersenii. While direct sequencing cannot, as yet, replace culturing of leptospires, it is a valid additional tool for epidemiological studies. An unexpected finding from this study was the genetic diversity of Leptospira infecting Brazilian cattle.