Dynamics of resistance to antibiotics in nosocomial staphylococci from multidisciplinary hospital

Abstract

Background. Staphylococci are still the leading causative agents of infections associated with healthcare, and the study of their antibiotic resistance is still relevant.
 Aim. The research is aimed at study of antibiotic resistance of hospital strains of staphylococci in dynamics.
 Materials and methods. Susceptibility to 16 antimicrobial agents was studied in 554 Staphylococcus strains, isolated from patients in a multidisciplinary medical centre. The method of serial microdilutions was used.
 Results. Antibiotic-resistant strains prevailed (85.4%). Methicillin-resistance and multy-resistance were found to be more typical for coagulase-negative strains 75.2% and 74.1% respectively, than for Staphylococcus aureus 14.2% and 15.4% respectively. Methicillin-resistance and poly-resistance in S. aureus was found to decrease it was 11.1% and 12.8% in 20152016 (17.1% and 17.9% respectively in 20112012). On the contrary, methicillin-resistance in coagulase-negative staphylococci strains during the same period increased 1.5 times. Totally, methicillin-resistant strains composed a half of the isolates 48.7%. The studied Staphylococcus strains were susceptible to vancomycin, daptomycin, tigecycline. Resistance to linezolid and amikacin was 2.2% and 2.7% respectively. S. aureus strains were all susceptible to linezolid, fusidic acid, rifampicin, trimethoprim-sulfamethoxazole. Minimum inhibitory concentrations (MIC) of antibiotics for staphylococci varied in wide ranges from 0.06 to 128 mg/l. For S. aureus and S. epidermidis, the MIC50 and MIC90 of only five drugs (benzylpenicillin, tigecycline, vancomycin, linezolid, and daptomycin) were the same, while the MIC50 and MIC90 of most of the other studied drugs against S. epidermidis were significantly higher compared to S. aureus.
 Conclusion. The variability of resistance of staphylococci to antimicrobial drugs in a multidisciplinary hospital confirms the need for continuous monitoring of their antibiotic resistance.