Development of in vitro susceptibility testing criteria and quality control parameters

It is well recognized that the susceptibility interpretive values published by NCCLS play an important role in the clinical use of any given antimicrobial agent. The major objective is to provide meaningful breakpoints that allow prediction of clinical efficacy and quality-control values that truly reflect the quality of susceptibility test results generated in a clinical laboratory. To reach these goals, the NCCLS subcommittee requires manufacturers to present data ranging from pharmacokinetics in healthy subjects and patients to clinical verification of proposed breakpoints. It is obvious that this complex area cannot exist without some unpredicted problems. The NCCLS Subcommittee has an ongoing review process to respond to questions from the field on older drugs. These questions are encouraged, as it is often the only way the Subcommittee can know of a particular problem. The Subcommittee attempts to generate semiannual supplemts of its reference tables to reflect the addition of new antimicrobial agents and to correct data for older drugs. The guiding principle is to produce meaningful and usable breakpoints and quality control values.