Antimicrobial Resistance Patterns in Methicillin-Resistant Staphylococcus aureus from Patients Hospitalized during 2015-2017 in Hospitals in Poland.

OBJECTIVE: The aim of this study was to determine antimicrobial resistance profiles of methicillin-resistant Staphylococcus aureus (MRSA) isolates from clinical samples from patients hospitalized during 2015-2017 in hospitals of -Masovian district in Poland. MATERIALS AND METHODS: Antimicrobial resistance of 112 MRSA isolates was tested with a disc diffusion method. Isolates were examined for methicillin resistance using a 30 µg cefoxitin disk. Resistance was confirmed by PCR detection of the mecA gene. PCR was also used to determine spa gene polymorphism in X-region. RESULTS: A large number of MRSA isolates showed resistance to levofloxacin (83.9%), ciprofloxacin (83%), erythromycin (77.7%) and clindamycin (72.3%). A lower number of MRSA isolates showed resistance to tetracycline (10.7%), amikacin (14.2%), gentamicin and trimethoprim with sulfamethoxazole (8.0%). None of the MRSA isolates were resistant to linezolid and teicoplanin. Among MRSA isolates, 92.9% were multidrug-resistant (MDR). Resistance to erythromycin, clindamycin, ciprofloxacin and levofloxacin was the most common resistance pattern among MDR MRSA isolates. The highest number of isolates was resistant to 4 groups of antimicrobials (53.8%). The number of drugs to which MRSA isolates were resistant in 2017 was significantly higher than that in 2016 (p = 0.002). The size polymorphism analysis of X fragment of the spa gene revealed high genetic diversity of the investigated group MRSA isolates. CONCLUSION: This study demonstrates that in the hospital environment, MRSA isolates can quickly acquire new antimicrobial resistance determinants and that knowledge of current resistance patterns is important for the effective treatment of infections caused by MDR MRSA.