Standardizing antimicrobial susceptibility testing of Campylobacter species.

We concur with the conclusion of Hakanen et al. (A. Hakanen, P. Huovinen, P. Kotilainen, A. Siitunen, and H. Jousimies-Somer, Letter, J. Clin. Microbiol. 40:2705–2706, 2002) in that a global surveillance of Campylobacter spp. would be enhanced by the acceptance of a standardized antimicrobial susceptibility testing method including the identification of an appropriate quality control (QC) organism. In June 2002, we presented to the National Committee for Clinical Laboratory Standards (NCCLS) subcommittees on Antimicrobial Susceptibility Testing (AST) and Veterinary Antimicrobial Susceptibility Testing (VAST) a recommended testing method and QC organism for the in vitro susceptibility testing of bacteria belonging to the genus Campylobacter. These data were generated from an international multilaboratory study in which seven test sites were involved. The recommended testing method was agar dilution, and the QC organism was Campylobacter jejuni isolate ATCC 33560. We also recommended QC ranges for five antimicrobial agents: ciprofloxacin, doxycycline, gentamicin, meropenem, and tetracycline. This testing method was validated by including human clinical isolates of C. jejuni, C. coli, C. doylei, C. fetus, and C. lari. Both subcommittees accepted our recommendations for the testing method, the QC organism, and the QC ranges for the five antimicrobial agents. The testing method is available in the NCCLS documents M31-A2 (testing method and tentative QC ranges) and M7-A6 with corresponding M100-S13 Supplemental Tables (available in January 2003).