Antibiogram of Methicillin-Resistant Staphylococcus aureus Isolates From MRSA Colonized Patients in Two Tertiary Hospital Emergency Departments

Background: Methicillin-Resistant Staphylococcus aureus (MRSA) colonized patients are at increased risk of developing MRSA infections. Objectives: This study was undertaken to evaluate the minimum inhibitory concentration (MIC) of anti-MRSA antibiotics for MRSA isolates from MRSA colonized patients. Patients and Methods: From November 2009 to March 2011, a prospective study was performed in two emergency departments. Patients at high risk for MRSA colonization were identified, and MRSA surveillance cultures obtained. The MIC for anti-MRSA antibiotics in cultures from each patient was evaluated. Results: A total of 276 patients were assessed. Of these, 23.6% (65/276) were MRSA culture positive. The MIC 50 and MIC 90 for vancomycin with these MRSA isolates by E-test were both 2 µg/mL. The MIC 50 and MIC 90 for teicoplanin were 2 µg/mL and 3 µg/mL, respectively, among MRSA isolates. Nearly all (62/65, 95.4%) MRSA isolates were sensitive to trimethoprim /sulfamethoxazole. Of all patients, 47.7% (31/65) of the MRSA isolates were sensitive to gentamicin, 40% (26/65) to minocycline, 13.8% (9/65) to clindamycin, 6.2% (4/65) to erythromycin, and 1.5% (1/65) to levofloxacin. Conclusions: The average value of the vancomycin MIC for isolates from MRSA colonized patients was 2 µg/ml. trimethoprim / sulfamethoxazole was the second most effective anti-MRSA oral antibiotic in vitro.