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

Abstract

Urinary tract infections (UTIs) are one of the most commonly occurring infections in outpatient settings and hospital admissions globally. No single medium is capable of supporting the growth and identification of all uropathogens. Recently, in order to improve isolation and presumptive identification in urine samples, chromogenic agar media are being used more and more frequently as versatile primary culture tools. Direct susceptibility testing by disc diffusion on clinical samples offers a rapid and inexpensive means of obtaining information to guide antimicrobial therapy. The objective was to evaluate and compare the effectiveness of conventional culture systems and chromogenic agar medium for the isolation, identification, and direct testing of uropathogen's antibiotic susceptibility. The study comprised 155 clinically suspected UTI patients. Uncentrifuged urine samples underwent wet mount analysis and centrifuged samples for Gram staining before the culture. All urine samples that were received in the lab underwent Direct Susceptibility Testing (DST) right away. A total of 155 urine samples were cultured on all three media (HiChrome UTI Agar, Sheep Blood Agar, and MacConkey Agar). 58 (37.32%) showed significant bacterial growth, while 97 (62.58%) showed no growth. A single organism was isolated in 54 (36% of the samples), and two (1.42%) samples yielded mixed growths of two species. We conclude that the Hichrome agar medium can be a desirable, simple primary isolation and identification medium that significantly lessens the daily workload associated with urine culture in microbiology labs.