Comparison of disk diffusion and agar dilution methods for erythromycin, ciprofloxacin, and tetracycline susceptibility testing of Campylobacter coli and for tetracycline susceptibility testing of Campylobacter jejuni subsp. jejuni.

With disk diffusion, the following zone diameters are suggested to be resistant and susceptible breakpoints, respectively: for susceptibility testing of Campylobacter coli, no inhibition zone and 15 mm or more for erythromycin, and 20 mm or less and 25 mm or more for ciprofloxacin, in the absence or presence of an inhibition zone around the nalidixic acid disk; and for susceptibility testing of C. coli and Campylobacter jejuni, 20 mm or less and 26 mm or more for tetracycline.