Racial Disparities in Invasive Methicillin-resistant Staphylococcus Aureus Infections, 2005-2014

Background: Despite substantial attention to the individual topics, little is known about the relationship between racial disparities and antimicrobial-resistant and/or healthcare-associated infection trends, such as for methicillin-resistant Staphylococcus aureus (MRSA).

Methods: We analyzed Emerging Infections Program 2005-2014 surveillance data (9 US states) to determine whether reductions in invasive MRSA incidence (isolated from normally sterile body sites) affected racial disparities in rates. Case classification included hospital-onset (HO, culture >3 days after admission), healthcare-associated community onset (HACO, culture ≤3 days after admission and dialysis, hospitalization, surgery, or long-term care residence within 1 year prior), or community-associated (CA, all others). Negative binomial regression models were used to evaluate the adjusted rate ratio (aRR) of MRSA in black patients (vs in white patients) controlling for age, sex, and temporal trends.

Results: During 2005-2014, invasive HO and HACO (but not CA) MRSA rates decreased. Despite this, blacks had higher rates for HO (aRR, 3.20; 95% confidence interval [CI], 2.35-4.35), HACO (aRR, 3.84; 95% CI, 2.94-5.01), and CA (aRR, 2.78; 95% CI, 2.30-3.37) MRSA. Limiting the analysis to chronic dialysis patients reduced, but did not eliminate, the higher HACO MRSA rates among blacks (aRR, 1.83; 95% CI, 1.72-1.96), even though invasive MRSA rates among dialysis patients decreased during 2005-2014. These racial differences did not change over time.

Conclusions: Previous reductions in healthcare-associated MRSA infections have not affected racial disparities in MRSA rates. Improved understanding of the underlying causes of these differences is needed to develop effective prevention interventions that reduce racial disparities in MRSA infections.