Egyptian Journal of Medical Microbiology Volume 24 / No. 2 / April 2015 29-34 Egyptian Journal of Medical Microbiology 29 ORIGINAL ARTICLE Evaluation of the Chromogenic Medium (CPS) in the Isolation and Identification of Urinary Tract Pathogens Reham Raafat, Reham Dwedar* and Eman El-Seidi Medical Microbiology & Immunology Department, Faculty of Medicine, Cairo University ABSTRACT Key words: Urinary tract infection, Chromogenic media Background: Urine cultures constitute the majority of the workload for a microbiology laboratory with only 20%-30% of urine sample resulting in significant growth. Chromogenic media (CM) are available for urine specimens to enable rapid identification of common pathogens and also has been reported to increase mixed culture detection, reducing unnecessary workup. Chromogenic media offers the potential to lower costs by providing decreased work time, storage space and identification costs. Objectives: The present study focused on evaluation of the chromogenic medium (CPS) for the diagnosis of UTI in comparison with CLED as a conventional medium. Methodology: Over the period of January to July 2014, fifty urine samples with ≥100 pus cells /HPF were examined. CPS and CLED media were used for direct inoculation in addition to conventional biochemical reactions and/or API as needed. Results: In comparison with CLED, CPS showed a sensitivity of 93.5%, specificity of 100%, positive predictive value of 100%, negative predictive value of 57.1% and total agreement of 94%. The sensitivity of CPS for E. coli was 95%, for KESC was 75%, for Proteeae was 100% and for Enterococcus was 100%. The specificity of CPS for detection of E. coli was 100%, for KESC was 100%, for Proteeae was 97.9% and for Enterococcus was 100%. Conclusion: CPS proved to be a rapid, cost-effective diagnostic method for urinary tract infections. Therefore, CPS can replace the standard primary plating media used in routine diagnosis of urinary tract infection. INTRODUCTION Urinary tract infections (UTI) constitutes one of the most common infectious diseases for which patients seek medical attention, and although many of these infections are treated empirically, urine cultures account for a significant portion of every clinical microbiology laboratory’s daily workload 1,2 . Because only 20 to 30% of urine samples result in significant growth, a considerable amount of time is spent in evaluating samples that do not have clinical utility 3. Therefore any new method or medium with the ability to streamline urine culture processing in a meaningful way should be welcomed. Urine cultures have conventionally been performed using sheep blood agar (BA),as a nonselective medium, and a selective medium such as MacConkey (MAC) agar, cysteine lactose electrolyte- deficient (CLED) agar, or eosin methylene blue (EMB) agar 4 . *Corresponding Author: Reham Ali Dwedar, Medical Microbiology & Immunology Department, Faculty of Medicine, Cairo University E-mail: rehamdwedar@gmail.com; Tel: 01222744624 Chromogenic media applicable to urine culture processing and reporting had been commercially available for more than 20 years and are intended to perfectly identify more frequently occurring bacteria and yeasts on primary culture with no further testing or a minimum number of confirmatory tests. Substrates present in chromogenic media target specific classes of enzymes produced by certain bacteria and yeasts [5] . Target enzymes hydrolyze chromogenic substrates forming colored products which allow for easy identification of specific organisms 5,6 . The use of these media also allow for substantial upgrading of biochemical identification procedures without a significant rise in total costs 7 . Chromogenic media may facilitate improved sensitivity of identification and may promote more uniform interpretation of urine culture plates by less experienced bench technologists 8 , also may provide clinicians with relevant information regarding their choice of empiric antimicrobial therapy 9, 10 . The current study aimed to evaluate the chromogenic medium (CPS) [bioMérieux, Marcy l’Etoile, France]) for routine diagnosis of bacteriuria in comparison with CLED (cysteine-, lactose-, electrolyte- deficient) as a conventional standard media.