Evaluation of frequency, antimicrobial resistance and multidrug resistance patterns of methicillin-resistant Staphylococcus aureus isolates at a university hospital in Northern Cyprus, 2016 to 2020.

Objective: Staphylococcus aureus is a major human pathogen which is responsible for a wide variety of clinical manifestations both in nosocomial and community settings. The presence of methicillinresistant Staphylococcus aureus (MRSA) limits treatment options. There are major gaps in literature regarding the epidemiological and antimicrobial resistance characteristics of S. aureus in Northern Cyprus. This study aims to define the frequency of MRSA in a major hospital in Northern Cyprus and determine MRSA susceptibility to currently available antimicrobials in order to define the most effective regimen for the treatment of S. aureus infections. Methods: Four hundred and forty-nine clinical samples collected between January 2016 to December 2020 were retrospectively included in the study. Samples were cultured on Eosin-Methylene Blue (EMB) and 5% sheep blood agar and were incubated at 35°C for 24-48 h. Laboratory identification of isolates and antimicrobial susceptibility testing have been performed by Vitek-2 (bioMérieux, France) automated identification and susceptibility testing system. Antibiotic susceptibility was assessed according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. Multi-drug resistance (MDR4) was determined by analyses of beta-lactam resistance plus nonsusceptibility to three additional classes of antimicrobial drugs. Data analysis was performed using SPSS Statistics Software version 23. A p value <0.05 was considered as statistically significant. Results: Of the 449 S. aureus isolates, 40.5% (n=182) were MRSA. In the inpatients group, MRSA infection rate was statistically higher (p=0.001) compared to outpatients. A significant correlation was observed between older age and MRSA infection. MRSA isolates exhibited higher resistance to erythromycin (85.4%), clindamycin (52.9%), ciprofloxacin (23.8%), levofloxacin (19.8%), tetracycline (68.0%), fosfomycin (13.0%), rifampicin (12.0%) and tobramycin (11.1%) compared to MSSA isolates (p<0.05). MDR was detected in 30.8% of the isolates. All isolates, MRSA and MSSA, showed high susceptibility to daptomycin, linezolid, vancomycin, fusidic acid, teicoplanin and gentamicin. The rate of MDR MRSA was observed to decrease statistically in the post-pandemic period compared to pre-pandemic period (p=0.0001). Conclusion: Over the five-year period, of the study, MRSA isolates have shown an increased resistance to several antibiotics. Therefore, the Infection Control Committee should work actively and inappropriate antibiotic use should be limited in order to prevent the spread of MDR pathogens. [ABSTRACT FROM AUTHOR]