Comparative evaluation of chromogenic agar medium and conventional culture system for isolation and presumptive identification of uropathogens

Abstract

Objective: Urine is the most frequent specimen received for culture/sensitivity by clinical laboratories. The microbiological performance of HiCrome UTI agar medium was compared with Blood agar and MacConkey agar for isolation and presumptive identification of bacteria from urine culture. Methods: A total of 443 consecutively collected midstream and/or catheter-catch urine samples from patients attending the Islami Bank Medical College Hospital, Rajshahi, Bangladesh during January to December, 2012 were cultured. Urine samples showing pus cells ≥ 5/HPF were inoculated on to Blood agar (BA), MacConkey agar (MAC) and HiCrome UTI agar (CA) media simultaneously and incubated overnight aerobically at 370C. Rate of isolation and presumptive identification of bacterial species were compared for different media. Results: Culture yielded a total of 199 bacterial isolates from 189 (42.67%) positive plates including 179 (40.40%) unimicrobial and 10 (2.26%) polymicrobial (mixed growth of pair of bacteria) growths. Both HiCrome UTI agar and Blood agar media supported 100% growths while 151 (75.88%) growths were observed on MacConkey agar. The rate of presumptive identification was found significantly higher on HiCrome UTI agar (97.49%) than MAC agar (67.34%) (P<0.001) as primary urine culture medium. Of 199 isolates, E. coli was found to be the leading uropathogen isolated from 118 (59.30%) samples with its presumptive identification rate of 95.76%, 93.22% and 5.93% on CA, MAC and BA respectively. All 10 (100%) polymicrobial growths were demonstrated distinctly on CA against only 01(10%) on each BA and MAC. Conclusion: HiCrome UTI agar was found to be more useful as primary urine culture medium in both higher rate of isolation and presumptive identification of uropathogens in comparison to conventional media. Its inherent characteristics in demonstrating polymicrobial growth and ease of rapid identification by distinct colony colour are unique.

In-vitro study of the activity of some medicinal plant leaf extracts on urinary tract infection causing bacterial pathogens isolated from indigenous people of Bolangir district, Odisha, India

“…The CSAS-G was identified as E. coli as it produced pink colour colonies and this is due to the enzyme ß-Dgalactosidase that cleaves the other chromogenic substrate present in the media. This was congruent with the result obtained by Akter et al [13] while studying the antibiotic sensitivity of pathogens causing UTI. CSAS-F was identified as a strain of K. pneumoniae due to the production of blue colonies [14].…”

Prevalence and susceptibility of uropathogens: a recent report from a teaching hospital in Bangladesh

“…Urine samples were inoculated aseptically on chromogenic agar (Hicrome UTI agar), Blood agar and MacConkey agar media by using a calibrated wire loop of 28G with an internal diameter of 3.26 mm holding 0.004 ml of urine and incubated overnight at 37 °C aerobically. Details of culture technique and identification methods have been reported previously [ 11 ]. Mueller–Hinton agar was used for antimicrobial susceptibility testing (AST) following Kirby–Bauer disc diffusion method [ 12 ] against a panel of 11 antibiotics (Oxoid, UK); amoxicillin (10 mcg), nitrofurantoin (300 mcg), cephalexin (30 mcg), cefuroxime (30 mcg), cefaclor (30 mcg), ceftriaxone (30 mcg), ciprofloxacin (10 mcg), gentamicin (10 mcg), nalidixic acid (30 mcg) and co-trimoxazole (25 mcg).…”

Effect of Pulse Electric Field on Water Characteristics as a Disinfection Function in Filtration Unit

“…Therefore, 0.5 Hz was selected as the optimal frequency because the amount of time for which a bacteria cell was exposed increased according to Planck's formula (Eq. 1) [19]. Due to giving high removal efficiency of E. coli and S. aureus.…”