Evaluation of a New Chromogenic agar, CHROMagar Orientation, for Detection and Presumptive Identification of Urinary Tract Pathogens

Koh, Eun Ha; Kim, Sunjoo

Abstract

BACKGROUND
Urine samples should be tested in a rapid and cost-effective way, as they represent the largest volume of specimens cultured in the microbiology laboratory. Some bacteria can be presumptively identified with CHROMagar Orientation (CO) according to the specific colors produced on the colonies. In this study, the usefulness of CO agar was evaluated for urine cultures. METHODS: The urine samples from 980 patients from March through April, 2004 were inoculated on blood agar (BAP), MacConkey agar, and CO agar plates, and we compared the detection rates of potential pathogens and the agreement between presumptive identification directly from the CO agar and the confirmative idntification, which was performed using Vitek systems (bioMerieux). RESULTS: The detection rates of urinary tract pathogens on all three media, conventional BAP, MacConkey agar and CO agar were identical (18.9%). All isolates of Escherichia coli (54) and ente-rococci (40) were correctly identified with CO agar. The overall agreement of presumptive identification was 87.4% (187/199). CONCLUSIONS: Use of the CO agar enabled a rapid presumptive identification of E. coli, and ente-rococci, the most common urinary tract pathogens. The CO agar is cost-effective by saving some of the bacterial identification kits that would be required for the conventional BAP and MacConkey agar method.