Identification and differentiation of avirulent and virulent Rhodococcus equi using selective media and colony blotting DNA hybridization to determine their concentrations in the environment

Abstract

Selective agar media have been used for many years to facilitate the isolation of Rhodococcus equi from environmental and clinical samples. However, characterisation of R. equi still requires the use of immunochemical or polymerase chain reaction (PCR) analysis to differentiate between virulent and avirulent isolates. Here, we describe a novel method to detect and differentiate between R. equi isolates using colony blotting and DNA hybridization. Radiolabelled PCR product derived from the R. equi rrnA gene and specific hybridization conditions enabled differentiation of colonies of R. equi from environmental species, whilst radiolabelled PCR product derived from the R. equi vapA gene, under ..