Nasal carriage and antimicrobial susceptibility of Staphylococcus aureus among medical students at the HRH Princess Maha Chakri Sirindhorn Medical Center, Thailand: A cross sectional study

Summary: Objective: To determine the epidemiology of the nasal carriage of Staphylococcus aureus and its susceptibility pattern among preclinical medical students at the HRH Princess Maha Chakri Sirindhorn Medical Center, Srinakharinwirot University. Methods: Nasal swabs were taken from 128 preclinical medical students prior to working at the hospital. Susceptibility testing of S. aureus was performed using Kirby Bauer's disc diffusion method. Results: Of the 128 participants, 38/128 (29.7%; 95% confidence interval [CI] = 21.8%, 37.6%) were carriers of S. aureus. No methicillin-resistant S. aureus was detected by the cefoxitin disk diffusion test. Resistance of S. aureus to erythromycin, clindamycin, tetracycline, chloramphenicol and fusidic acid was observed at the following rates: 63.2% (95% CI; 47.8%, 78.5%), 63.2% (95% CI; 47.8%, 78.5%), 34.2% (95% CI; 19.1%, 49.3%), 2.6% (95% CI; −2.5%, 7.7%) and 2.6% (95% CI; −2.5%, 7.7%), respectively. There was no statistically significant correlation between nasal carriage of S. aureus and possible risk factors. Conclusions: The prevalence of asymptomatic nasal carriage of S. aureus was higher than reported by previous literature in Thailand, and S. aureus isolates exhibited relatively high resistance to erythromycin and clindamycin. Keywords: Staphylococcus aureus, Medical students, Nasal carriage, Antimicrobial susceptibility