N9. MRSA, MSSA and other gram positive pathogens
Oral Abstract Submission
Catherine Sutcliffe, PhD, SCM
Disclosure: Bristol Meyer Squibb: Research Grant or Support
Novavax: Research Grant or Support
Pfizer Inc.: Research Grant or Support
Roche Molecular Systems: Research Grant or Support
Robert Weatherholtz, BS
Disclosure: GSK: Grant/Research Support
Merck: Grant/Research Support
Novavax: Grant/Research Support
Pfizer Inc.: Grant/Research Support
Background : Native Americans in the southwestern United States (US) have a higher risk of many infectious diseases than the general US population. The objective of this study was to determine the burden of invasive Staphylococcus aureus disease among Native Americans on the White Mountain Apache (WMA) Tribal lands.
Methods : Prospective population and laboratory-based surveillance for invasive S. aureus infections was conducted from May 2016 through April 2018. A case was defined as a Native American individual living on or around the WMA Tribal lands with S. aureus isolated from a normally sterile site. Incidence rates were calculated using the Indian Health Service User Population as the denominator. Age-standardized incidence rates were calculated by direct standardization methods using US Census data from 2015 as the reference.
Results : 53 cases were identified (Year 1: 24; Year 2: 29). Most cases were adults (90.6%; median age: 47.4 years) and had ≥1 underlying medical condition (86.8%), of which the most common were obesity (50.0%) and diabetes (50.0%). 26.4% of cases were categorized as community acquired. Most infections were methicillin-resistant (MRSA; 75.5%). 88.7% of cases were hospitalized, 7.5% required amputation, and 7.7% died within 30 days of the initial culture. The overall incidence of invasive S. aureus was 156.3 per 100,000 persons (95% confidence interval [CI]: 119.4, 204.5) with no significant difference in the incidence by year (Year 1: 141.5; Year 2: 171.1; incidence rate ratio: 1.21; 95% CI: 0.70, 2.08). The overall incidence of invasive MRSA was 118.0 per 100,000 persons (95% CI: 86.5, 160.8) with no significant difference by year (Year 1: 106.1; Year 2: 129.8; incidence rate ratio: 1.22; 95% CI: 0.66, 2.28). The incidence of invasive S. aureus and MRSA increased with age and was highest among individuals 50-64 years of age. The overall age-adjusted incidence of invasive MRSA was 138.2 per 100,000 persons (Year 1: 125.2; Year 2: 150.9, for comparison US 2015 general population: 18.8 per 100,000 persons).
Conclusion : The WMA community has one of the highest reported incidence rates globally of invasive MRSA. Interventions are urgently needed in this community to reduce the morbidity and mortality associated with these infections.