Characterization of Corynebacterium diphtheriae, C. confusum and C. amycolatum isolated from sows with genitourinary infection

Porcine Corynebacterium infection is still poorly studied, even though the pig has been described as an asymptomatic carrier of Corynebacterium species, including the zoonotic species C. ulcerans, C. confusum and C. amycolatum. Here we present the identification, molecular and antimicrobial susceptibility characterization of coryneform bacteria isolated from sows with urinary tract infection. C. diphtheriae, C. confusum and C. amycolatum were isolated from sows with urinary infection and metritis. Corynebacterium species were identified by MALDI-TOF MS and confirmed by 16S rRNA and rpoB sequencing. All porcine C. diphtheriae strains were further characterized as non-toxigenic (tox−). SE-AFLP genotyping was also performed and enabled not only Corynebacterium species differentiation but also the assessment of C. amycolatum genetic heterogeneity. All studied porcine Corynebacterium strains presented alarming resistance profiles with high MIC values for macrolides/lincosamide, tetracyclines and quinolones, which can be related with high usage in both veterinary and human medicine. Isolation of zoonotic Corynebacterium species from commercial swine is important for assessing the potential zoonotic risk for farmers and further implication for both human and animal treatment.