Analysis of antibiotic sensitivity of clinical strains of microorganisms with the Russian Mueller–Hinton broth

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Introduction. One of the reasons for spreading antibiotic-resistant microorganisms is the uncontrolled use and inadequate empirical prescription of antibiotics which is not based on the results of the pathogen sensitivity testing. The broth dilution method and one of its implementation options, the reference microdilution method, in contrast to the disk diffusion method, allows testing virtually all pathogen-antibiotic combinations. To realize the method, a production technology of Russian Mueller–Hinton broth (MHB-Obolensk) has been developed under the import substitution program. The aim. To evaluate the quality of the developed domestic Mueller–Hinton broth in comparative tests with its imported analog BD BBL (MHB-BD) in testing clinical strains of microorganisms, including microorganism–antibiotic combinations pairs which cannot be reliably investigated by the disc diffusion method. Materials and methods. The study investigated the sensitivity of 47 clinical strains of Gram-positive and Gram-negative bacteria to antibiotics of various functional groups using the broth microdilution method with MHB-Obolensk and MHB-BD. Results. The MICs values of antibiotics for clinical strains obtained with the developed and control media did not practically differ from each other or differed by +/– one dilution. The difference by two two-fold dilutions was noted when testing Enterococcus faecium–ampicillin, Klebsiella pneumoniae–meropenem, Pseudomonas aeruginosa–levofloxacin and Staphylococcus aureus–ciprofloxacin combinations. For the first two combinations, the MIC values were lower in MHB-Obolensk, and for the last two, they were higher than in MHB-BD. The differences obtained did not affect the clinical categories of sensitivity. Conclusion. The antibiograms of clinical strains in developed Russian Mueller–Hinton broth was obtained, which did not differ from those for the comparison medium. MHB-Obolensk complies with the requirements of national and international standards and can be used to reliably test, among other things, current combinations of microorganism–antibiotic pairs that cannot be studied using the disk diffusion method.