Biochemical and serological characteristics of Rhodococcus equi isolates from animals and humans

In the present study, 17 Rhodococcus equi isolates from animals and 13 R. equi isolates from humans were correctly identified by the use of the API Coryne-test system. The biochemical characteristics revealed no significant differences between isolates from animals and humans. Heat extractions at acid pH or autoclave extractions of the bacteria and the use of monospecific antisera against type antigens 1-7 allowed the serotyping of the bacteria. The majority of the R. equi isolates reacted with serotype 1 and serotype 2-specific antisera, extracts of two human isolates reacted with serotype 5 and serotype 6-specific antisera, respectively. The determination of biochemical and serological properties of R. equi might help to characterize individual cultures of this species. This might be useful in epidemiological studies.