Appraisal of the domestic kit «MICMICRO » for antimicrobial susceptibility testing by serial microdilution method | CMAC

Appraisal of the domestic kit «MICMICRO » for antimicrobial susceptibility testing by serial microdilution method

Clinical Microbiology and Antimicrobial Chemotherapy. 2020; 22(3):231-236

Type
Original Article

Objective.

To assess efficiency of the “MIC-MICRO” kit developed in the Department of New Technologies of the Saint-Petersburg Pasteur Institute, on reference strains and clinical bacterial isolates.

Materials and Methods.

In order to assess the “MIC-MICRO” kit, several options of its execution were used, including different groups of antibiotics: aztreonam, amikacin, gentamicin, colistin, meropenem, nitrofurantoin, chloramphenicol, cefotaxime, ceftriaxone, ciprofloxacin, erythromycin. In order to determine the range of antibiotic values, the EUCAST-2020 database was used. The quality control of adsorbed antibiotics was carried out using reference strains: Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 29213 and Escherichia coli NCTC 13846 (colistin-resistant). Acceptable and target ranges of MIC values for control strains are evaluated according to “Regular and extended internal quality control for determining MIC and disk diffusion according to EUCAST recommendations” (v10.0). A total of 28 clinical isolates of K. pneumoniae obtained from patients with nosocomial infections in St. Petersburg hospitals in 2018–2019 was used in the study. The coordination of test results was obtained in accordance with GOST R ISO 20776-1-2010. Susceptibility testing results were interpreted in accordance with EUCAST recommendations (v10.0).

Results.

The MIC values in relation to the reference strains obtained using the “MIC-MICRO” kit were determined in the range of recommended values of the EUCAST-2020 standard. The results obtained in relation to clinical isolates of K. pneumoniae showed that the sensitivity categories determined using the developed kit and the serial microdilution method were the same for all the studied strains. The percentage of colistin-resistant isolates (MIC > 2 mg/ml) in the serial microdilution method and determined using the “MIC-MICRO” kit was 35.7%. The percentage of susceptible strains was also similar for two types of methods (64.3%).

Conclusions.

Colistin susceptibility testing of K. pneumoniae strains using the “MIC-MICRO” diagnostic kit and the reference serial microdilution method in a tablet, showed comparable results. Diagnostic efficiency, ease to use and simple interpretation of results make it possible to use the developed “MIC-MICRO” kit in clinical laboratory practice.

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