Evaluation of the Chromogenic medium ChromID CPS for Isolation & Identification of Urinary Tract Pathogens

Abstract

Urinary tract infections are one of the most common causes of hospital admissions and clinic visits globally, making urine, the most frequent sample received for culture. Only 20 to 30% of urine samples result in significant growth, a considerable amount of time is expended evaluating samples that do not have clinical utility. Therefore, any new medium or method with the ability to streamline urine culture processing in a meaningful way, such as reducing technologist workload, improving results, or reducing laboratory costs, would be welcomed and has the potential to have considerable laboratory impact. In most of the clinical laboratories of the developing world, a combination of blood agar and MacConkey's agar is traditionally used for urine culture. Although, use of Cysteine Lactose Electrolyte Deficient (CLED) agar is a better option for the detection of uropathogens instead of combination of two media. Currently a number of chromogenic media are available commercially for the detection of uropathogens such as CPS ID2 Agar, Chromagar Orientation, Uriselect and Rainbow UTI.3 Chromogenic UTI medium (CUM) (Oxoid, United Kingdom) is one of the recently marketed nonselective media which contains essential ingredients to support growth of all common bacterial uropathogens and also provides their presumptive identification. Chromogenic media have been reported to be an acceptable alternative to traditional media for the isolation of urinary pathogens and facilitate improved sensitivity of identification of some microorganisms and may promote more uniform interpretation of urine culture plates by less experienced bench technologists. Chromogenic media may also promote more rapid identification of the etiological agent(s) of infection and may provide clinicians with relevant information regarding their choice of empirical antimicrobial therapy for their patients. Consequently, this may decrease inappropriate use of antibacterial and antifungal agents. Our study focused on evaluation of chromogenic media Chrom ID CPS [bioMérieux, France] in comparison to traditional media such as blood, MacConkey and CLED agar for isolation and identification of common urinary tract pathogens. Urine samples collected from inpatients from Ain Shams University Hospitals Mid stream urine sample or from catheter from patient suspected to have UTI and only samples with significant bacteruria included in our study. E.coli was the most common causative organism (48.3%) followed by klebsiella (10.0%).