Role of NCCLS in antimicrobial susceptibility testing and monitoring.

The role of NCCLS (formerly known as the National Committee for Clinical Laboratory Standards) in establishing guidelines for antimicrobial susceptibility testing, NCCLS's consensus-building process, and new interpretive criteria for antimicrobial susceptibility testing for 2002 are described. When revising and developing new guidelines, NCCLS uses an extensive process to reach consensus, while considering the clinical relevance, cost, and other practical implications of the proposed guidelines. NCCLS groups antimicrobials for susceptibility testing and reporting on the basis of their clinical efficacy, known patterns of microbial resistance, strategies to minimize the emergence of resistance, consensus recommendations, and cost to avoid unnecessary testing. NCCLS guidelines address quality control issues and current methodologies, such as conventional disk diffusion and microbroth dilution tests. In addition, new testing methods for the detection and confirmation of special resistance mechanisms (e.g., extended-spectrum beta-lactamase production) are recommended. In 2002, the minimum inhibitory concentration breakpoints for resistance and susceptibility of Streptococcus pneumoniae to cefotaxime and ceftriaxone in nonmeningitis infection were increased to more accurately predict clinical outcomes. Implementation of new NCCLS guidelines requires the education and collaboration of the laboratory, pharmacy, and medical staff. The NCCLS consensus-building process provides clinicians with clinically relevant and cost-effective strategies for antimicrobial susceptibility testing and reporting, guidelines and criteria for interpreting susceptibility test results, and guidelines for detecting emerging antimicrobial resistance. The use of specialized testing methods for detecting and confirming unusual or difficult-to-identify resistance mechanisms can improve the accuracy of reporting of resistance and avoid therapeutic failures. The implementation of new NCCLS guidelines requires collaboration and education of members of various institutional departments.