Clinical Laboratory Use of Differential Light Scattering. I. Antibiotic Susceptibility Testing

Abstract

Abstract Differential light scattering (DLS) provides a quantitative representation of bacterial cells in much greater scope and detail than that provided by microscopy and turbidimetry. The information content of the DLS pattern may prove sufficient to provide a basis for most of the tests performed in the clinical bacteriological laboratory. The first application that we have implemented is an automated system with laser illumination, "Differential III," for rapidly determining susceptibility of bacteria to antibiotics. Its high sensitivity detects physiological changes in the generation of cells that metabolize the drugs. Thus the test can be performed in a relatively short time (1.5 h) and at a rate of about 15 specimens per hour. Extensive laboratory testing has been done and hospital evaluation is under way. Data showing the degree of correlation of the Differential III results with other methods are presented. Other applications of DLS in the clinical laboratory are discussed.