Use of Chromogenic Agar Media for Identification of Uropathogen

Abstract

Chromogenic agar media are increasingly being used as versatile tools in early differentiation and identification of Gram positive and Gram negative isolates from clinical specimens. We have evaluated the chromogenic medium as it’s use reduces the burden of biochemical characterization and reduces the workload for identification of bacteria. This study included 400 consecutively collected midstream and/or catheter-catch urine samples obtained from patients attending the hospital out patient department (OPD) and also from patients admitted in BSMMU hospital. They were inoculated on blood agar, MacConkey agar, cystine lactose, electrolyte deficient media and chromogenic agar plate for isolation of uropathogen. Out of 400 urine samples tested, 154 (38.5%) yielded significant growth of single organism and 16 (4%) yielded mixed growth. No growth was observed in 230 (57.5%) cases. The chromogenic agar media allowed the growth and primary identification in 171 (92.5%) strains out of 186 strains. The predominant uropathogens were Escherichia coli, Klebsiella spp. Enterococcus spp. and Eneterobacter spp. (KES group). The different coloured colonies produced by the breakdown of the chromogenic substrate by the specific enzymes of the bacteria were very useful in the presumptive identification of these organisms even from polymicrobial cultures by the color differences of the colonies. The medium also supported growth and differentiation of Gram positive organisms like Staphylococcus and Enterococci. Chromogenic agar media can be used as primary culture medium for isolation and identification of predominant uropathogens like E.coli, KES group and Enterococci. It is an easy to use primary screening medium that considerably reduces the daily workload and thus minimizes or limits the use of identification tests. Key words: Chromogenic agar medium, KES, CLED media, UTI DOI: http://dx.doi.org/10.3329/bjmm.v4i1.8464 BJMM 2011; 4(1): 18-23

CHROMagar Orientation Medium Reduces Urine Culture Workload

“…1). A similar finding was reported by Sharmin et al (15), who performed medium comparison studies on 400 urine samples and plated to BA and MAC agar, CLED agar, and a chromogenic medium. They concluded that the chromogenic medium considerably reduced workload and minimized the use of conventional identification tests.…”

“…Chromogenic media have been reported to be an acceptable alternative to traditional media for the isolation of urinary pathogens (1,9,10,11,12,13,14). Chromogenic media may facilitate improved sensitivity of identification of some Grampositive cocci (e.g., enterococci) in mixed cultures with Enterobacteriaceae and may promote more uniform interpretation of urine culture plates by less experienced bench technologists (1,10,13,15). 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.…”

Drug Resistance Pattern of the Isolated Organisms While Treating UTIs

“…Rahman et al [31] and Ahmed and Rashid [32] in their studies in Bangladesh also reported E. coli as being the commonest pathogen responsible for bacteriuria which is consistent with the findings of this study. The findings of E. coli are also in agreement with the study done by Sharmin [33] in Bangladesh. Another study done by Hasan et al [34] in a tertiary hospital in Indian study showed 50.7% incidence of UTI caused by E. coli, which was nearer to our study.…”

Comparative evaluation of different culture media for the isolation and identification of common urinary pathogens

“…Our findings correlate with the study done by Manjusree BS and Sharmin et al 11,12 Out of 199 pure growths, 126 were gram negative bacilli and 56 were gram positive cocci and 17 were Candida species. In the present study, gram negative bacilli outnumbering gram positive cocci.…”