The development and extent of quinolone-resistance in broiler isolates of campylobacters over a 15-year period was investigated. Minimal inhibitory concentrations of enrofloxacin, ciprofloxacin and nalidixic acid for 567 Campylobacter jejuni and 233 Campylobacter coli strains were determined by the agar dilution method. Of the strains, 180, 420 and 200 were isolated during 1987, 1992 and 2000, respectively. Enrofloxacin or ciprofloxacin resistance was not found in isolates from 1987. The first fluoroquinolone resistance (1.4% to enrofloxacin and 1.2% to ciprofloxacin) appeared in strains isolated in 1992, approximately 2 years after the licensing of enrofloxacin in Turkey. The rate of resistance to nalidixic acid was 5.5% in 1987 and 7.3% in 1992. However, the resistance of campylobacters to quinolones increased dramatically in 2000, with 75.5%, 73% and 94.5% of the strains being resistant to enrofloxacin, ciprofloxacin and nalidixic acid, respectively. Fluoroquinolone resistant strains originated from 7.1% of 28 broiler flocks in 1992, and from 92.9% of 14 flocks in 2000. In total, 18% of C. jejuni and 24% of C. coli strains were resistant to enrofloxacin, and 17.5% of C. jejuni and 22.3% of C. coli strains were resistant to ciprofloxacin. A high level of cross-resistance was observed among enrofloxacin, ciprofloxacin and nalidixic acid. It was concluded that the uncontrolled use of fluoroquinolones in animals in Turkey caused the emergence and spread of high level resistance among poultry strains of campylobacters, which may have serious effects on both animal and human health and may be a serious food safety concern.

The development and extent of quinolone-resistance in broiler isolates of campylobacters over a 15-year period was investigated. Minimal inhibitory concentrations of enrofloxacin, ciprofloxacin and nalidixic acid for 567 Campylobacter jejuni and 233 Campylobacter coli strains were determined by the agar dilution method. Of the strains, 180, 420 and 200 were isolated during 1987, 1992 and 2000, respectively. Enrofloxacin or ciprofloxacin resistance was not found in isolates from 1987. The first fluoroquinolone resistance (1.4% to enrofloxacin and 1.2% to ciprofloxacin) appeared in strains isolated in 1992, approximately 2 years after the licensing of enrofloxacin in Turkey. The rate of resistance to nalidixic acid was 5.5% in 1987 and 7.3% in 1992. However, the resistance of campylobacters to quinolones increased dramatically in 2000, with 75.5%, 73% and 94.5% of the strains being resistant to enrofloxacin, ciprofloxacin and nalidixic acid, respectively. Fluoroquinolone resistant strains originated from 7.1% of 28 broiler flocks in 1992, and from 92.9% of 14 flocks in 2000. In total, 18% of C. jejuni and 24% of C. coli strains were resistant to enrofloxacin, and 17.5% of C. jejuni and 22.3% of C. coli strains were resistant to ciprofloxacin. A high level of cross-resistance was observed among enrofloxacin, ciprofloxacin and nalidixic acid. It was concluded that the uncontrolled use of fluoroquinolones in animals in Turkey caused the emergence and spread of high level resistance among poultry strains of campylobacters, which may have serious effects on both animal and human health and may be a serious food safety concern.