Isolation of virulent Rhodococcus equi from Arabian horses in Sanliurfa, Turkey

The purposes of this study were to investigate plasmid profiles of the isolated virulent (VapA positive) agents by RFLP and to determine the quantitative aspects of Rhodococcus equi in the feces of adult horses and foals, as well as in soil. The frequency of detection of R. equi and virulent R. equi in fecal samples and soil was studied from 20 farms in the Sanliurfa region. A total of 315 samples were examined. Nasal swabs from 25 foals with pneumonia were also analyzed. R. equi was isolated and identified from 263 (83.4%) samples originating from 15 out of 20 farms. From 105 samples each of soil and equine and foal feces, R. equi was isolated in 91 (86.6%), 94 (89.5%), and 78 (74.2%) samples, respectively. A total of 789 colonies isolated and identified as R. equi were examined by PCR for the VapA gene. As a result of PCR, 32 (4.0%) agents were identified as virulent R. equi. All virulent R. equi isolates contained 85 kb type-I plasmid. Additionally, R. equi could not be isolated from nasal swabs in foals with pneumonia. Because of the existence of virulent R. equi in the environment, preventive measures should be taken against the risk of infection.