Higher nasal carriage rate of methicillin-resistant Staphylococcus aureus among dental students who have clinical experience

Background. Methicillin-resistant Staphylococcus aureus (MRSA) has been isolated from dental clinical surfaces, dental patients, and dental health care professionals. The authors conducted a study to determine the prevalence rate of nasal MRSA colonization among dental school students and to identify the characteristics of the isolated strains. Methods. The authors collected nasal samples from 159 dental students. The authors performed mecA gene detection, staphylococcal cassette chromosome mec (SCCmec) typing, and antimicrobial susceptibility tests on each sample. The authors compared the results of 2 groups (students who had clinical experience and students who did not have clinical experience). Results. Five (3.1%) dental students had MRSA colonization, as confirmed by the presence of the mecA gene in the nasal cavity. Prior clinical experience was associated significantly with nasal MRSA carriage (P <.05). Four of the strains were SCCmec type IV, and 1 strain was SCCmec type I. All isolates were resistant to amoxicillin and clavulanic acid, imipenem, and oxacillin, but were susceptible to several antimicrobial agents including mupirocin, trimethoprim and sulfamethoxazole, and rifampin. The nasal MRSA colonization was eradicated with the use of mupirocin ointment. Conclusions. Nasal MRSA colonization occurs in some dental students, especially those who have clinical experience. Practical Implications. Education about MRSA colonization and transmission, as well as infection prevention and control measures is necessary for dental students, especially when they participate in clinical practice.