[Automated direct antimicrobial susceptibility testing of urine specimens]

Two microscopical screening methods have been used to assay the suitability of urine samples for automated direct antimicrobial susceptibility testing by the means of a "MS-2 Microbiology System" apparatus. Gram stained smears showed if specimens were monomicrobic and fresh-mount bacterioscopy gave information about presumptive counts to establish inoculum size. The results obtained by the automated method have been compared with those of the direct disk diffusion method and the classical Stokes method on a single isolated colony. The three systems were reliable and only 7% of specimens gave major discrepancies and 15% minor errors. The influence of each antibiotic drug and of each bacterial species on the discrepancies has been discussed. Direct susceptibility testing by MS-2 seems to be accurate and in the same time so fast (5-6 h vs. 18-24 h) to appear very useful in the rational guide of chemotherapy in the more severe UTI.