Prevalence of Multidrug-Resistant and Methicillin-Resistant Staphylococcus aureus Nasal Carriage Among Asymptomatic Individuals in a Tertiary Institution.

Abstract:

Introduction: Nasal carriage of Staphylococcus aureus plays a major role in its spread to other parts of the body or to other individuals, which usually results in hospital and community-associated diseases. This study was aimed at investigating the prevalence of multidrug-resistant and methicillin-resistant strains of Staphylococcus aureus in asymptomatic individuals. Methods: This cross-sectional study investigated the prevalence of nasal carriage of multidrug-resistant and methicillin-resistant Staphylococcus aureus among asymptomatic university students. In this study, samples were collected from the nasal cavity of 250 asymptomatic individuals after seeking and obtaining their individual verbal and signed written consent. The swabs were streaked on selective agar, and bacterial colonies were subjected to biochemical tests. Antibiograms of the isolates were determined using multi-disc antibiotics and agar dilution methods, and the Multiple Antibiotic Resistance index (MARindex) of each isolate was calculated. Results: From the study, 152(60.8%) out of the 250 samples collected were identified as Staphylococcus aureus. Seventy-two (72, 47.37%) isolates were identified as multidrug-resistant S. aureus. Eighty-five (55.9%) isolates were resistant to cloxacillin, while 94 (61.8%) and 100 (65.8%) isolates demonstrated resistance to oxacillin at concentrations of 2 µg/mL and 4 µg/mL, respectively, indicating a high prevalence of phenotypically methicillin-resistant Staphylococcus aureus. The MARindex showed that 51.3% of the isolates had MARindex ≤0.2, while 48.7% of the isolates had MARindex >0.2. Conclusion: The high prevalence of multidrug-resistant and phenotypically methicillin-resistant Staphylococcus aureus among asymptomatic individuals highlights the potential role of healthy carriers as reservoirs of antimicrobial-resistant bacteria within the community. Enhanced surveillance and antimicrobial stewardship measures are recommended.