Corynebacterium lactis: Antimicrobial Resistance and Impact on Invertebrate Model Systems

Corynebacterium lactis was isolated from the skin abscess of a companion dog and from raw milk of a cow with unspecific mastitis. As information about the species was scarce and a zoonotic potential could not be excluded, we started a basic characterization of C. lactis strain RW3-42 with respect to antibiotic susceptibility and the response of invertebrate animal model systems to infection. C. lactis showed a number of antimicrobial resistances and is able to colonize Caenorhabditis elegans. In contrast, Galleria mellonella larvae were not impaired by C. lactis. Genome analyses of strain RW2-5 revealed the absence of toxin-encoding genes, and only a rather small number of other virulence factors were found, i.e., SpaA- and SpaH-type pili and the non-fimbrial adhesins DIP0733, DIP1281, DIP1621 and EmbC in addition to a homologue of Salmonella RhuM involved in killing of C. elegans. The results obtained indicate a limited pathogenic potential of the species.