Association between prior hospitalization and nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) in community-dwelling U.S. adults: Evidence from NHANES

While institution-based studies have established an association between prior hospitalization and methicillin-resistant Staphylococcus aureus (MRSA) nasal carriage, this relationship remains unevaluated in community-dwelling adults explicitly excluded from institutionalized populations. The objective of this study was to investigate the potential relationship between prior hospitalization and MRSA nasal carriage in adults residing in non-institutionalized community settings. This cross-sectional analysis included 9512 community-dwelling U.S. adults from the National Health and Nutrition Examination Survey, 2001 to 2004, defining prior hospitalization as self-reported overnight admission within the past 12 months to classify participants into hospitalized and non-hospitalized groups. Logistic regression and inverse probability of treatment weighting using the propensity score analyses were utilized to examine the association between prior hospitalization and MRSA nasal carriage. The mean age of participants was 49.65 ± 19.23 years, with 4966 being female. MRSA nasal carriage was identified in 3.13% (38 out of 1214) of participants in the hospitalized group, compared to 1.10% (91 out of 8298) in the non-hospitalized group. After adjusting for multiple covariates, prior hospitalization was associated with a significantly higher odds of MRSA nasal carriage (odds ratio: 2.03, 95% confidence intervals: 1.35-3.05, P < .001). Propensity score analyses corroborated these findings, yielding an odds ratio of 2.06 (95% confidence intervals: 1.37-3.10, P < .001). These results were consistent across multiple sensitivity analyses. Our study found that prior hospitalization within the past 12 months was associated with an increased risk of MRSA nasal carriage in community-dwelling U.S. adults. However, a limitation of this study is the unavailability of nasal culture data before hospital admission, which precludes determining whether MRSA carriage preceded hospitalization. Further studies are needed to confirm this association.