Susceptibility of Corynebacterium pseudotuberculosis to selected antimicrobial agents

Caseous lymphadenitis is a chronic disease that affects small ruminant farms worldwide and causes economic losses to breeders. The disease is caused by the bacterium Corynebacterium pseudotuberculosis, which penetrates the lymph nodes of the host and induces the formation of abscesses. This bacterium is able to form a biofilm to protect itself against adverse environmental conditions, disinfectants and antibiotics. In this study, 33 field isolates of the bacterium Corynebacterium pseudotuberculosis obtained from nine sheep and goat farms in the Czech Republic were examined. The susceptibility of these isolates to eight antibiotics, which were chosen according to the European Committee on Antimicrobial Susceptibility. Testing (EUCAST) breakpoints for Corynebacterium spp. and according to the spectrum of antibiotics used in individual farms, was investigated. The analyses were also supplemented with tests of the biofilm formation ability of individual isolates and with tests of the sensitivity of these biofilms to a disinfectant based on active chlorine.