Abstract

Background: Nasal carriage of methicillin resistant Staphylococcus aureus (MRSA) is a major factor for its
transmission especially from the health workers and medical students to their patients. There are a number of
published data on the prevalence of MRSA among health workers but data on nasal colonization of medical students
by MRSA are sparse in Nigeria. The objectives of this study are to determine the prevalence of nasal carriage of MRSA
among medical students of the Ben Carson School of Medicine, Babcock University, Ilishan-Remo, Ogun State, Nigeria,
and identify risk factors associated with this nasal carriage.
Methodology: A case control study involving 100 clinical (study group) and 100 pre- clinical (control group) medical
students was undertaken between March 2018 and October 2019. Structured questionnaire was administered to
obtain socio-demographic information and potential risk factors. Nasal swab was collected from each student and
cultured for isolation of S. aureus by standard microbiology techniques. Phenotypic MRSA was detected by the
cefoxitin 30µg disk diffusion method according to the guideline of Clinical and Laboratory Standards Institute. The
mecA gene was detected by conventional polymerase chain reaction (PCR) assay.
Results: The prevalence of S. aureus nasal carriage among the study group was 14% (14/100) while the prevalence
among the control group was 6% (6/100) (p=0.097). The prevalence of phenotypic MRSA among the study group
was 4% (4/100) and 1% (1/100) among the control group (p=0.3687) while mecA gene was detected in 3 of the 4
(75%) phenotypic MRSA positive study participants and in the only (100%) phenotypic MRSA positive (1%) control
group. Antibiotics usage without prescription, antibiotic treatment of common cold, and use of antibiotics in the
previous one year, were significantly associated with MRSA carriage among the study group.
Conclusion: Although the prevalence of nasal carriage of S. aureus and MRSA among clinical and pre-clinical medical
students was not statistically significant, the risk factors identified with carriage of MRSA among the study group
indicates the need for antimicrobial stewardship program to reduce carriage and transmission of MRSA by medical
students.