A Rapid (4-6-hour) Urine-culture System for Direct Identification and Direct Antimicrobial Susceptibility Testing

Abstract

This study evaluates a new direct rapid system for urine cultures, including detection and quantitation of positive specimens by Gram stain, direct identification by 4–6-hour incubation of sediment with reagent strips, and antibiotic susceptibility testing by direct (3-4-hour) diskelution methods. Of 987 routine urine specimens, 121 had significant (≤ 10⁵ colony-forming units/ml) gram-negative bacilluria, of which 89% were detected by the Gram stain. Direct rapid identification was correct in 94%. Results of direct diskelution antimicrobial tests showed overall agreement with results of standard disk diffusion in 93% of tests, and major discrepancies in 4%. For urine specimens with gram-negative bacilluria, this system permitted detection, quantitation, identification, and antimicrobial susceptibility testing in four to six hours with reasonable, though not complete, accuracy.