PREVALENCE AND DETERMINANTS OF MRSA AMONG THE UNDERGRADUATE MEDICAL STUDENTS

Abstract

Introduction: Methicillin resistant Staphylococcus aureus (MRSA) is no longer just a simple healthcare issue as it has insidiously made its way into communities all around the globe. Needless to say, it is important to keep track of the prevalence rate of this hospital-acquired microbe and take measures to curb its growing presence in the community. This study reports the current prevalence of MRSA in undergraduate clinical and preclinical medical students of a tertiary educational institution in tropical, equatorial Malaysia and analyses the determinants that contribute towards the spread of this virulent, drug resistant bacterium. Methodology: A cross-sectional study was conducted in a tertiary educational institution amongst undergraduate medical students enrolled at the time of data collection. An administered questionnaire was used to obtain information regarding determinants of MRSA colonisation. Nasal swabs obtained from students were pre-enriched in Mannitol Salt Broth prior to culture onto Mannitol Salt Agar (MSA) and Mannitol Salt Agar containing the antibiotic Cefoxitin (MSA-Cef). Culture plates were incubated at 37°C for isolation of Methicillin-Sensitive Staphylococcus aureus (MSSA) and at 32°C for isolation of Methicillin Resistant Staphylococcus aureus (MRSA). Presumptive identification of S.aureus was made by examination of colonial morphology on MSA / MSA-Cef plates i.e. characteristically yellow colonies with yellow discolouration of medium. Five randomly selected isolates per culture plate were subcultured for subsequent analyses which included Gram staining and the coagulase tube test for confirmation of S.aureus. Putative MRSA colonies from MSA-Cef plates were confirmed as such using the latex agglutination test. Results: 75% of the study population were pre-clinical students whilst 25% were clinical phase students. The overall prevalence of S.aureus in the study population was 45.8% and MRSA, 5%. The prevalence of MRSA amongst pre-clinical and clinical students was 4.3% and 7.1% respectively. A history of antibiotic use in the 6 months prior to sampling was a significant risk factor for acquiring MRSA carriage. Swimming was significantly associated with MRSA colonisation but did not remain significant in multivariate analysis. All other determinants tested i.e. race, history of flu-like illness, history of hospitalisation, history of soft skin injury / infection, having household members younger than 7 years, having companion animals, smoking, partaking in sports, gymnasium training, swimming and working in a hospital environment, were not significantly associated with MRSA carriage. Conclusion: The overall prevalence of MRSA obtained in this study was found to be higher than that obtained in other similar studies conducted in Malaysia, possibly reflecting the fact that medical students, particularly clinical – phase medical students, fall in the high-risk category for acquiring MRSA carriage. The latter premise is echoed in this study by the fact that the prevalence of MRSA amongst clinical students, who are constantly exposed to the hospital environment, was higher as compared to that of pre-clinical students.