Diverse strains of Actinobacillus lignieresii isolated from clinically affected cattle in a geographically restricted area.

OBJECTIVE

To investigate whether an outbreak of Actinobacillus lignieresii was caused by one or multiple strains.

METHODS

Nine isolates of A. lignieresii were obtained from the lymph nodes of 15 affected cattle from two farms to determine whether a single strain was involved. An enterobacterial repetitive insertion consensus sequence (ERIC) PCR was used for genotyping, and the repeats-in-toxin genes were analysed by PCR and sequencing.

RESULTS

Isolates from the two farms belonged to two and three genotypes, with a total of four genotypes detected. Genes of the apxICABD operons of some strains had deletions in the apxIA (~697 bp) and in the apxID (~187 bp) genes. The toxin gene deletions and the ERIC PCR patterns suggested the involvement of different A. lignieresii genotypes.

CONCLUSION

There was no evidence that a unique genotype was associated with actinobacillosis on the two farms, confirming that this disease was associated with other contributing factors.