An assessment of Chromogenic Agar Medium and Conventional Culture System for the Isolation of Uropathogens

Abstract

Original Research ArticleIntroduction: Urinary tract infections (UTI) account for significant health burden among all age groups. Isolation and identification of the uropathogens by bacterial culture and selection of appropriate antimicrobial drugs through susceptibility testing is the mainstay in management of UTI cases. Material & Methods: This was a cross-sectional study which was carried out in the Department of Microbiology, Rajshahi Medical College (RMC) to evaluate the performance of a Chromogenic agar medium (commercially named as HiCrome UTI agar) and conventional culture system like Blood agar (BA) and MacConkey (MAC) agar for isolation and presumptive identification of the uropathogens. Results: Slightly higher bacterial growth was noted among female (29.33%) than male (17.00%) patients as a whole and 15-45 years was the leading age group with higher number of culture positive cases. Out of 300 urine samples cultured, a total of 139 (46.33%) yielded bacterial growth and 161 (53.67%) were negative for bacterial growth. Bacterial isolates included E. coli 91(62.75%), Klebsiella spp. 18(12.41%), Enterococcus spp. 16(11.03%), Pseudomonas spp. 09(06.28%), Staph. saprophyticus 05(3.44%), Enterobactor spp. 04(2.75%) and Proteus spp. 02(1.37%). It is evident from the present study that both HiCrome UTI agar and BA media supported growth of all 145 bacteria, while MAC agar yielded 133(91.72%) bacterial growths. The rate of presumptive identification of the isolates was found significantly higher (97.24%) on HiCrome UTI agar when compared with the MacConkey agar (80.68%) and Blood agar (27.58%) media. In antimicrobial susceptibility testing, majority of the isolates showed very high (78% -100%) sensitivity to Imipenem. Ceftazidime and Cefuroxime were also found efficacious against E. coli and Staph. saprophyticus, while Klebsella spp., Enterococcus spp., Pseudomonas spp., Enterobacter spp. and Proteus spp. showed variable sensitivity to these drugs. Further, most of the isolates showed moderate to poor sensitivity to Ciprofloxacin, Nalidixic acid, Cephalexin, Amoxicillin and Cotrimoxazole. (Minimize that red mark) Conclusion: HiCrome UTI agar can be recommended as primary urine culture medium to be used by the clinical microbiology laboratories.

Evaluation of Chromogenic Agar Media for Isolation, Identification and Direct Antibiotic Susceptibility Testing of Uropathogens

“…A total of 58 (37.42%) of the 155 urine samples examined produced bacterial growth, whereas 97 (62.58%) showed no growth at all. This outcome is consistent with other related investigations conducted by Gul Nahar et al [13] and Sharmin [14], who discovered bacterial growth to be around 46.33% and 42.5%, respectively. 54 (36%) of the culture-positive cases showed significant development of only one organism, whereas the remaining 2 (1.42%) showed mixed growth in two organisms.…”

“…In the present study E. coli was the most common 39(67.24%), followed by Enterobacter aeruginosa 06(10.34%), Klebsiella pneumoniae 04(6.89%), Pseudomonas aeruginosa 04(06.89%), Staphylococcus aureus 02(03.44%), Proteus vulgaris 02(03.44). Other researchers [13,14] also noted the same trend with gram-negative being the predominant agent. Similar investigations carried out in Israel and the USA also revealed a high prevalence of E. coli isolation from urine cultures [18].…”

“…54 (36%) of the culture-positive cases showed significant development of only one organism, whereas the remaining 2 (1.42%) showed mixed growth in two organisms. Studies by Gul Nahar et al [13] revealed 44.33% single growth and 2.00% polymicrobial growth. Similar results were reported from two other studies carried out by Sharmin et al [14] and Fatema et al [15].…”

“…Except for a little change in the zone diameter, the direct antibiotic sensitivity test provided results that were identical to those of the conventional antibiotic sensitivity test. Direct antibiotic sensitivity testing has been the subject of numerous investigations, all of which have shown it to be more effective than traditional antibiotic sensitivity testing [2,13,14]. The standardization of urochrome for AST is a potential issue as the CLSI zone sizes are interpreted with Muller Hinton Agar (MHA).…”