Peculiarities of antibiotic resistance of Staphylococcus aureus strains isolated from nosocomial infections

Aim. To study of the antibiotic resistance of S. aureus strains isolated from nosocomial infections (pneumonia, surgical site infections and sepsis) in a multidisciplinary surgical clinic. Methods. Microbiological testing of sputum in 41 patients with pneumonia, of samples (wound, abscess, drainage) obtained from 40 patients with surgical site infections (SSI) and of blood from 46 patients with signs of sepsis was performed. The obtaining cultures were identified by conventional methods (including morphological, cultural, biochemical features, etc.). Disc diffusion method was used to detect methicillin-resistant S. aureus (MRSA) strains. Inducible clindamycin resistance (ICR) of S. aureus strains was determined by double disk approximation test (D-test). Results. Methicillin-resistant S. aureus was found in 14.3% (2 of 14) of the patients with surgical site infections, in the sputum 27.3% (3 of 11) of the patients with pneumonia, and in the blood 50.0% (7 of 14) of the patients with sepsis (p >0.05). The rate of inducible clindamycin resistance of isolated S. aureus strains in patients with surgical site infections (2 of 14 cases, 14.3%) and with pneumonia (2 of 11 cases, 18.2%) did not statistically significant difference with the rate of methicillin resistance (p >0.05). However the rate was significantly lower septic infections — 7.1% and 50.0% respectively (p=0.0328). Conclusion. Among S. aureus strains isolated from nosocomial infections, the rate of methicillin-resistant S. aureus had not depended on the type of nosocomial infection; the rate of inducible clindamycin resistance in septic infections was lower than resistance to methicillin.