Rapid processing of urine specimens by urine screening and the AutoMicrobic system

A total of 1,500 clean-voided urine specimens were analyzed for the presence of bacteria by urine screening with the Autobac 1 system. The specimens found positive by this method were further processed on the same day for identification and for antimicrobial susceptibility testing on the AutoMicrobic system with the Enterobacteriaceae-plus Card and the General Susceptibility Card, respectively. The inocula for these tests were prepared from the centrifuged and washed growth in the eugonic broth aspirated from the Autobac cuvette chambers. Of 1,500 specimens that were analyzed, 183 contained single isolates of gram-negative bacilli. The results of these rapid procedures were compared with results for the same organisms isolated from urine specimens cultured by the conventional method. The data showed 92.3% agreement for identification and a correlation of 93.6% for antibiotic susceptibility between the two procedures. It is concluded that gram-negative bacilli can be rapidly identified and tested for antimicrobial susceptibility with a high degree of accuracy from the centrifuged eugonic broth after urine screening. These findings also suggest that the AutoMicrobic system provides a rapid and convenient method for same-day processing of positive urine cultures when combined with the urine screening procedure.