- Ogbue Itohan Joan1,2; Adewuyi Gbolagade Morufu1,2; Samuel Olowo Sunday1,2; Ogbue Idubor Ambrose3,4
- DOI: 10.5281/zenodo.20629450
- GAS Journal of Clinical Medicine and Medical Research (GASJCMMR)
Background: The mecA gene, encoding Penicillin-Binding Protein
2a (PBP2a), is the principal molecular determinant of methicillin resistance in
Staphylococcus aureus. Characterising
the pattern of mecA carriage, including its prevalence, anatomical
distribution, co-carriage with Staphylococcal Cassette Chromosome mec (SCCmec)
types, and clinical determinants, among people living with HIV/AIDS (PLWH) is
essential for understanding MRSA molecular epidemiology in this population. No
such data exist from Edo State, Nigeria.
Methods: Polymerase Chain Reaction based detection of mecA
was performed on 230 MRSA isolates from 176 PLWH at ISTH using validated
primers (amplicon: 147 bp). Co-carriage with SCCmec types II and V and LUK-PVL
was simultaneously characterised. Chi-square, phi coefficient (φ), Spearman
rank correlation (for continuous variables only), Mann-Whitney U, and binary
logistic regression identified determinants of mecA positivity.
Results: mecA was detected in 123/230 isolates (53.5%),
uniformly distributed across nasal (54.9%), axillary (53.8%), and groin (52.1%)
sites (χ²=0.133, p=0.936). Of 123 mecA-positive isolates, 76.4% co-carried
SCCmec type II and 77.2% co-carried SCCmec type V; 67.5% carried all three.
Gene combination patterns were bimodal: 38.3% carried no resistance genes and
36.1% carried all three simultaneously, together accounting for 74.4% of
isolates. Inter-gene concordance was strong (φ 0.642–0.668, all p<0.001). In
multivariable logistic regression, absence of underlying comorbid disease
(aOR=0.40, p=0.007) and hand covering while sneezing (aOR=2.32, p=0.010) were
the only independent predictors. CD4+ count was non-predictive (p=0.505).
Conclusion: mecA carriage is present in 53.5% of MRSA isolates from PLWH at ISTH and is anatomically uniform. The near-binary co-carriage architecture with SCCmec types II and V implies a co-selected resistance cassette complex. Healthcare engagement behaviour and comorbidity status, not immune function, independently predict mecA carriage.
