Automation of antimicrobial susceptibility testing

Laboratory services lag significantly behind the time demands of the clinician in determining the appropriate antimicrobic drug to treat a bacterial infection. The authors discuss several new automated optical systems that promise to shorten the time lag for results, as well as lead to improved precision and standardization. The advantages of expressing antimicrobic susceptibility results as Minimum Inhibitory Concentration (MIC) over the three classifications of sensitive, intermediate, or resistant commonly determined by the Kirby-Bauer disc diffusion method are discussed. Computerization is a central feature of emerging instrumentation for antimicrobic susceptibility testin, and it will be potentially useful in providing interpretive data relating the MIC to specific dose-site combinations. The paper is concluded by short descriptions of nonoptical techniques that investigators have used to measure bacterial growth.