Hospital epidemiology and antimicrobial susceptibility of isolated methicillin-resistant Staphylococcus aureus: a one-year retrospective study at a tertiary care center in Thailand
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Background: Increased rates of Staphylococcus aureus resistance and its morbidity and mortality have raised concern about the strategy of antibiotic use.
Objectives: This study aimed to determine the prevalence of methicillin-resistant S. aureus (MRSA) and vancomycin-resistant S. aureus (VRSA) isolates among Thai patients with S. aureus infection and to identify risk factors and appropriate antibiotics for these resistant strains.
Methods: Data of culture-proven S. aureus isolates from clinical specimens during 2017 in King Chulalongkorn Memorial Hospital, Thailand, were retrospectively collected and classified as methicillin-sensitive S. aureus or MRSA by cefoxitin screening and oxacillin minimum inhibitory concentration by the Vitek 2 system. Each isolate was also tested for susceptibility to teicoplanin, erythromycin, clindamycin, linezolid, trimethoprim/sulfamethoxazole, ciprofloxacin, moxifloxacin, tetracycline, doxycycline, and vancomycin by Vitek 2. Demographic information and comorbidities from medical records were reviewed to identify risk factors for S. aureus infection.
Results: MRSA isolates were identified in 147 (17%) of 890 patients with no different ratio in adults or children. A higher proportion of MRSA in hospital-acquired settings was observed (27% vs. 12%; p < 0.001). Comorbidities significantly associated with MRSA were chronic lung, cardiovascular, and neurological diseases. Atrial fibrillation, dementia, and benign prostatic hyperplasia were independently associated with MRSA isolation. Vancomycin was still susceptible to all kinds of infection. One VRSA isolate was from colonization.
Conclusion: The prevalence of MRSA in our facility seemed to be comparatively low. Vancomycin is still an appropriate option for MRSA coverage since all S. aureus isolates in our center were sensitive to vancomycin. However, careful attention is warranted since one colonization isolate was VRSA.