SUSCEPTIBILITY OF DIFFERENT REPRESENTATIVES OF THE GENUS CANDIDA TO ANTIMYCOTICS
Authors: Ananyeva M.M. 
Published: April 2019

Representatives of Candida.spp. demonstrate different susceptibility to azole compounds, which are widely used in the treatment of candidiasis. Due to the resistance to these compounds, C. glabrata remains in the body and, moreover, is able to multiply and increase its population. It quite often causes the development of nosocomial infections.

The purpose of this study was to investigate the susceptibility of clinical strains of C. albicans and C. glabrata isolated from surgical patients to antifungal drugs.

Materials and methods. We studied 5 clinical strains of C. albicans and 5 clinical strains of C. glabrata, taken from the patients of Thoracic and Vascular Surgery Units, V.M. Sklifosovskiy Poltava Regional Clinical Hospital.

In order to assess the susceptibility of the studied clinical isolates to antimycotics, the method of two-fold serial dilutions (macrodilution) in liquid nutrient medium was used as the standard procedure according to the order of the Ministry of Public Health of Ukraine No. 167 dated April 05, 2007, on Approval of Guidelines “Assessment of Microbial Susceptibility to Antibacterial Drugs”. MIC was determined by the lowest concentration of the antifungal drug, which was able to suppress the visible growth of the studied microorganism culture. The presence of growth was assessed by inspecting the tubes in transmitted light compared to the “negative” control.

To control the quality of evaluating susceptibility of microorganisms to antifungals, we used the reference strain Candida albicans CCM 885 taken from the Museum of Living Cultures of the Department of Microbiology, Virology and Immunology, UMSA. Testing of the control strain was carried out in accordance with the method described above in parallel with the study of clinical isolates. The findings obtained by evaluating the susceptibility (MIC) of the control strain were compared with the relevant parameters of its passport characteristics. If they match, the conditions of the experiment were considered as standard, and the results of evaluating sensitivity of clinical isolates obtained under these conditions were considered as reliable.

To identify susceptibility of the genus Candida spp., natural anti-fungal agents of the polyene series (amphotericin B) and synthetic drugs of the azoles group (fluconazole, itraconazole) and pyrimidine derivatives (flucytosine) were used.

Statistical analysis of the findings obtained was carried out using the standard software package "Microsoft Excel 2010". The presence of differences between the studied parameters was assessed by Student's t-test.

Results and discussion. The study has demonstrated that the synthetic antifungal, flucytosine, has a low fungistatic effect on Candida spp. The presence of flucytosine inhibits the reproduction of the reference C. albicans strain at a concentration of 2 μg / ml. Along with it, clinical strains of yeast-like fungi of this genus were equally sensitive to flucytosine with a MIC of 3.2 ± 0.96 μ / ml. This indicates a low efficacy of this antimycotic for Candida spp.