Corynebacterium ulcerans from diseased wild boars

Abstract

Two Corynebacterium strains were isolated from lymph nodes of wild boars showing severe alterations caused by caseous lymphadenitis. The wild boars came from different districts in southern Germany; one was found dead, the other had been shot. The two Corynebacterium strains obtained were both positive for phospholipase D. Further analysis of biochemical profiles did not allow unambiguous differentiation between Corynebacterium ulcerans and Corynebacterium pseudotuberculosis. Fourier-transformed infrared spectroscopy as well as partial sequencing of the genes for 16S rRNA and RNA polymerase beta subunit (rpoB) clearly identified both strains as Corynebacterium ulcerans. The tox gene for diphtheria toxin (DT) could be detected in both porcine isolates by PCR. Partial DNA sequencing of this tox gene showed significant differences from sequences described for other Corynebacterium ulcerans strains and a higher degree of similarity to that of Corynebacterium diphtheria. Production of diphtheria toxin could not be detected. These results indicate that wild game could be a reservoir for zoonotic Corynebacterium ulcerans.