Antibiotic susceptibility of Brachyspira hyodysenteriae isolates from Czech swine farms: a 10-year follow-up study

Abstract

Brachyspira hyodysenteriaeis the causative agent of swine dysentery. Loss of clinical efficacy of some antimicrobial agents authorized for treating swine dysentery was observed on certain Czech pig farms. The aim of the present study was to evaluate the antimicrobial sensitivity of six antibiotics using a set of 202 randomly selectedB. hyodysenteriaeisolates obtained from farms in the Czech Republic between years 1997 and 2006. Minimum inhibitory concentration of antibiotics tylosin, lincomycin, tylvalosin, chlortetracyclin, tiamulin and valnemulin were tested, using an agar dilution method. All antibiotics tested showed an increase in minimal inhibitory concentrations. Continual decrease in susceptibility of B. hyodysenteriaeisolates to tiamulin and valnemulin was observed. MultiresistantB. hyodysenteriaewere isolated more frequently in the past years. Only a careful use of antibiotics can ensure their efficacy, especially in case of pleuromutilins, in the strategic therapy of swine dysentery. This rare study demonstrates the minimal inhibitory concentration changes of selected antidysenterics among Czech isolates ofBrachyspira hyodysenteriaeduring a ten-year period.