PROPOSED MIC QUALITY-CONTROL GUIDELINES FOR NATIONAL COMMITTEE FOR CLINICAL LABORATORY STANDARDS SUSCEPTIBILITY TESTS USING 7 VETERINARY ANTIMICROBIAL AGENTS - CEFTIOFUR, ENROFLOXACIN, FLORFENICOL, PENICILLIN G-NOVOBIOCIN, PIRLIMYCIN, PREMAFLOXACIN, AND SPECTINOMYCIN

The present multicenter study proposes broth microdilution quality con trol (QC) ranges for the antimicrobial agents ceftiofur, enrofloxacin, florfenicol, penicillin G-novobiocin, pirlimycin, premafloxacin, and spectinomycin, which are used in veterinary practice. Six separate lab oratories tested replicates of National Committee for Clinical Laborat ory Standards (NCCLS)-recommended QC organisms (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 2 9213, and Enterococcus faecalis ATCC 29212) on medium rots both common and unique to all laboratories. The proposed ranges were within 3 or 4 log(2) dilution steps of the modal MICs for all organism-antimicrobi al agent pairs, depending on their MIC distributions. With greater tha n or equal to 94.7% of all MIC results being within the proposed QC ra nges, all combinations tested comply with NCCLS guidelines and all hav e been accepted by the NCCLS subcommittee developing susceptibility te sting procedures for veterinary laboratories.