Isolation of virulent and intermediately virulent Rhodococcus equi from soil and sand on parks and yards in Japan.

Rhodococcus equi is an emerging opportunistic pathogen of human immunodeficiency virus-infected patients. However, little is known about the distribution of virulent and intermediately virulent R. equi in human environment. In the present study, R. equi was isolated from 173 of 234 (73.9%) samples collected from soil and sand on 115 parks and 49 yards in Japan. The numbers of R. equi from soil and sand ranged from 2.5 x 10(1) to 1.2 x 10(5) per gram of sample. None of 1,294 isolates from those samples showed virulence-associated 15- to 17-kDa antigens and a 20-kDa antigen. These results suggest that avirulent R. equi is widespread in parks and yards, but the human environment has not been contaminated with virulent and intermediately virulent R. equi strains yet.