IDENTIFICATION AND EPIDEMIOLOGIC RELATIONSHIP OF RHODOCOCCUS-EQUI ISOLATED FROM CASES OF LYMPHADENITIS IN CATTLE

The present study was designed to comparatively investigate 10 Rhodoco ccus equi isolates from cases of lymphadenitis in cattle. The isolates could be identified by cultural and biochemical properties. By seroty ping the R. equi isolates 9 and 1, cultures could be classified as Nak azawa's serotypes 15 and 8, respectively. The isolates did not aggluti nate rabbit erythrocytes, were uniformly susceptible to most of the an tibiotics tested, did not contain plasmids nor expressed virulence-ass ociated proteins and yielded identical patterns in protein fingerprint ing. To further analyze the epidemiological relationships, the isolate s were additionally subjected to DNA fingerprinting. This was performe d by pulsed-field gel electrophoresis (PFGE) after digestion of the ch romosomal DNA with the endonuclease AsnI. PFGE analysis of the chromos omal DNA revealed 4 DNA restriction groups with DNA pattern I with 7 i solates as predominant group and DNA pattern II to IV with one isolate , respectively. The present results indicate that a single R. equi clo ne belonging to Nakazawa's serotype 15 and according to PFGE to DNA re striction pattern I of the present investigation seems to be responsib le for most of the cases of lymphadenitis of cattle described in this study.