EVALUATION OF CHROMAGARTM ORIENTATION CHROMOGENIC MEDIUM FOR ISOLATION AND DIFFERENTIATION OF PATHOGENIC URINARY TRACT MICROORGANISMS

Aim. To evaluate CHROMagar™ Orientation Chromogenic Medium for isolation and differentiation of pathogenic urinary tract microorganisms. Materials and methods. A prospective study was conducted, which included 147 consecutive urine samples from patients with clinically suspected UTIs of Karaganda city (Republic of Kazakhstan) in 2019. The presumptive microorganisms’ identification was carried out at CHROMagar™ Orientation in accordance with morphology, colony color on the characteristics recommended by the manufacturer. The final identification of isolates to species was performed by matrix-associated laser desorption/ionization – time-of-flight mass spectrometry (MALDI-TOF MS) using the Microflex LT system and the MALDI Biotyper Compass v.4.1.80 software (Bruker Daltonics, Germany). The recommended values of Score ≥2.0 were used as a criterion for reliable species identification. Results and discussion. 55 (37.4%) of 147 urine cultures gave a positive growth of bacteria, 86 (58.5%) did not give a growth, 6 samples were regarded as contaminated material. Comparative results of using CHROMagar™ Orientation for identification of the claimed microorganisms reached 100% sensitivity and specificity compared to mass-spectrometry. Excellent species identification was for E. coli – colonies were stained in dark pink, but there are some limitations for the rest microorganisms – Klebsiella, Enterobacter, Citrobacter, Serratia , respectively, in such cases, further species identification with additional tests is necessary. Conclusions. The results of the study showed that the chromogenic environment of CHROMagar™ Orientation can be used to isolate and differentiate urinary tract microorganisms. This is a reliable identification of relevant uropathogens, cultures differentiation, saving time and research costs.