*¹Okunbor, H. N., ¹,²Otaigbe, I. I., ¹,²Oluwole, T. O., ¹,²Elikwu, C. J., and 3Bhola, A. K.
¹Department of Medical Microbiology, Babcock University Teaching Hospital, Ilishan-Remo, Ogun State, Nigeria
²Department of Medical Microbiology and Parasitology, Babcock University, Ilishan-Remo, Ogun State, Nigeria
³ISID-BMGF Research Capacity Building Mentor
*Correspondence to: okunborh@babcock.edu.ng; Tel: +2348059834262; ORCID: 0009-0001-2016-6310
Abstract:
Background: Antimicrobial resistance (AMR) among Staphylococcus aureus, particularly methicillin-resistant S. aureus (MRSA) and vancomycin-resistant S. aureus (VRSA), poses a major global public health challenge. Data on the molecular epidemiology of resistance genes in Nigeria remain limited. The objectives of this study are to determine the prevalence of mecA, vanA, and vanB genes among nasal S. aureus isolates, assess antimicrobial susceptibility profiles, and explore associations of prevalence with demographic and clinical characteristics of hospitalized patients in Babcock University Teaching Hospital (BUTH), Ilishan-Remo, Nigeria.
Methodology: This descriptive cross-sectional study was conducted among 400 inpatients admitted to BUTH, Ilishan-Remo, Nigeria for various medical conditions, between June 2023 and June 2024. Sociodemographic and clinical data were obtained through interviewer-administered questionnaires and structured data extraction tools. Nasal swabs were collected from consenting participants who has been hospitalized for at least 48–72 hours. S. aureus isolates were identified using standard microbiological methods. Antimicrobial susceptibility testing was performed using the Kirby–Bauer disk diffusion method following CLSI 2023 guidelines. Polymerase chain reaction (PCR) was used to detect mecA, vanA, and vanB genes. Data were analysed using SPSS version 25.0. Associations between categorical variables were tested using Chi-square test and p value < 0.05 was considered statistically significant.
Results: S. aureus isolates were recovered from 27 (6.8%) of the 400 participants. mecA gene was detected in 25 of the 27 isolates (92.6%), representing 6.3% MRSA prevalence among the study participants, while vanA was identified in 7 of the 27 isolates (25.9%), representing 1.8% VRSA prevalence among the participants. No isolate carried vanB gene. Ward type showed a significant association with mecA carriage (χ²=15.336, p=0.032), while demographic characteristics and prior antibiotic use were not significantly associated with resistance gene carriage. All isolates were susceptible to linezolid, tedizolid, ceftaroline, and quinupristin–dalfopristin. High resistance rates were observed for levofloxacin (63.0%), erythromycin (44.4%), and gentamicin (37.0%).
Conclusion: This study reports a high prevalence of methicillin (mecA) and vancomycin (vanA) resistance genes carriage among S. aureus isolates colonizing the nostrils of hospitalized patients in BUTH, Ilishan-Remo, Ogun State, Nigeria. Strengthened infection prevention measures, antimicrobial stewardship, and confirmatory molecular sequencing are urgently needed.
Keywords: Staphylococcus aureus, mecA, vanA, nasal colonization, antimicrobial resistance, Nigeria
Download this Article in PDF format below