Increase of ciprofloxacin resistance in Campylobacter species in Styria, Austria

Salmonella spp. and thermophilic Campylobacter spp. are the most important diarrhea-causing pathogens in the area investigated in Styria, Austria. The isolation rate of Campylobacter in the more than 62,000 stool specimens investigated in the six-year period between 1988 and 1993 ranged between 1.90% in 1988 and 3.58% in 1991. The testing of susceptibility to nalidixic acid has been an usual characteristic for species identification. Nalidixic acid-resistant strains were rare in 1988-1990, but in the summer of 1991, we found an increasing number of these isolates. At the same time, we learnt about the increasing use of enrofloxacin in veterinary medicine, especially in the poultry industry, and therefore we started routine testing of Campylobacter spp. susceptibility to ciprofloxacin in 1992. In 1992, the resistance rate to ciprofloxacin was already 16.9%, rising to 22.1% in 1993.