Nasal carriage rate and molecular epidemiology of methicillin-resistant Staphylococcus aureus among medical students at a Taiwanese university

Objective: To investigate whether clinical exposure in the hospital affects nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) among medical students. Methods: A total of 322 medical students, both pre-clinical (n= 167) and clinical (n= 155), were recruited. Specimens were obtained from the nares of the subjects for the detection of S. aureus. A questionnaire was completed for each subject. All the MRSA isolates were further molecularly characterized. Results: The overall S. aureus carriage rate was 19.3%, with a rate of 16.8% for pre-clinical students and 21.9% for clinical students (p= 0.26). The carriage rate of MRSA was 2.2%, with a rate of 2.4% for pre-clinical students and 1.9% for clinical students (p= 0.54). There was no significant difference between the pre-clinical and clinical students in terms of nasal carriage of S. aureus and MRSA. All seven MRSA isolates were categorized as community strains in Taiwan. The risk factors for acquisition of S. aureus included male gender, age ≥23 years, and not taking antibiotics in the past year. Conclusions: As in the general population, less than 5% of medical students in northern Taiwan harbored MRSA, categorized as community strains, in their nares. The carriage of MRSA was not affected by clinical exposure in the hospital for 1-2 years.