Contribution of the Uriselect4® and the CPS ID3® chromogenic media to the isolation and identification of urinary tract infections bacteria

Abstract

Rapid and accurate identification of pathogens involved in urinary tract infections helps to guide antimicrobial therapy. Chromogenic agars provide presumptive identification directly from primary isolation media. They have been intended to make the bacterial isolation and identification process easier and faster. Our study aimed to compare the performance and the cost of the CPS ID3® and the Uriselect4® chromogenic agars with the conventional method for the isolation and identification of urinary tract infections bacteria.We included 301 urinary samples in a prospective study conducted in May 2018 in the clinical laboratory of the National institute of nutrition and food technology of Tunis. Isolates from routine media were identified using API® system while isolates from chromogenic media were directly identified by colony color with reference to the manufacturer's recommendations. Chromogenic media yielded more pure positive cultures and allowed better isolation of Escherichia coli, Klebsiella pneumoniae, Citrobacter koseri, Morganella morganii and Streptococcus agalactiae. Sensitivity and specificity of the presumptive identification of most commonly isolated uropathogens were higher with the Uriselect4® medium than with the CPS ID3® medium. Chromogenic media yielded the identification of pathogenic organisms 24 hours sooner than the conventional method in approximately 63 % of cases with the CPS ID3® medium and in 77.7% of cases with the Uriselect4® medium. Chromogenic media allowed a much better isolation of bacteria commonly involved in urinary tract infections with a quick, easy and accurate presumptive identification especially with the Uriselect4® medium.