Study of the sensitivity of methicillin-resistant Staphylococcus aureus to antibiotics and bacteriophage preparations

Objective. To evaluate the sensitivity of methicillin-resistant Staphylococcus aureus strains to antibiotics and therapeutic and prophylactic preparations of bacteriophages. Materials and methods. The antibiotic sensitivity of strains of methicillin-resistant S.aureus was studied by the disco-diffusion method, the determination of the minimum inhibitory concentrations of vancomycin and linezolid by broth microdilution method, and ceftaroline by E-tests. The sensitivity of methicillin-resistant S.aureus to bacteriophage preparations was studied. Results. It has been established that linezolid and vancomycin are quite active drugs against methicillin-resistant S.aureus (MRSA), however, resistance to them begins to develop. MRSA resistance to fluoroquinolones and cefoxitin was the highest of all antibiotics tested; the results obtained with cefoxitin can be interpreted for other cephalosporins (except ceftaroline) and all penicillins. Only 67.9% of MRSA strains retained sensitivity to ceftaroline, but ceftaroline-resistant strains had low levels of minimal inhibitory concentration. The preparations of the bacteriophages “Sextaphage” and “Piobacteriophage Phagio” showed their lytic activity only in relation to 35.8% and 18.9% of MRSA isolates, respectively. Conclusion. Monitoring the development of antibiotic resistance in methicillin-resistant S.aureus is an important part of the strategy of rational antibiotic therapy for staphylococcal infections. Only taking into account the preliminary step-by-step determination of the phage sensitivity of the causative agent of the disease, bacteriophage preparations can be considered as a completely possible alternative to antibiotics for the treatment of purulent inflammatory diseases caused by MRSA.