Development of a rapid PCR assay specific for Staphylococcus saprophyticusand application to direct detection from urine samples

Staphylococcus saprophyticus is one of the most frequently encountered micr oorganisms associated with acute urinary tract infections (UTIs) in young, sexually active female outpatients. Conventional identification methods bas ed on biochemical characteristics can efficiently identify S. saprophyticus , but the rapidities of these methods need to be improved. Rapid and direct identification of this bacterium from urine samples would be useful to imp rove time required for the diagnosis of S. saprophyticus infections in the clinical microbiology laboratory, We have developed a PCR-based assay for t he specific detection of S. saprophyticus. An arbitrarily primed PCR amplif ication product of 380 bp specific for S. saprophyticus was sequenced and u sed to design a set of S. saprophyticus-specific PCR amplification primers. The PCR assay was specific for S. saprophyticus when tested with DNA from 49 gram-positive and 31 gram-negative bacterial species. This assay was als o able to amplify efficiently DNA from all 60 strains of S. saprophyticus f rom various origins tested. This assay was adapted for direct detection fro m urine samples. The sensitivity levels achieved with urine samples was 19 CFU with 30 cycles of amplification and 0.5 CFU with 40 cycles of amplifica tion. This PCR assay fur the specific detection of S. saprophyticus is simp le and rapid (approximately 90 min, including the time for urine specimen p reparation).