Invasive Group A Streptococcal Infections Among Residents at a Skilled Nursing Facility — Pennsylvania, 2009–2010

Background:

Group A Streptococcus (GAS) causes approximately 11,500 invasive infections and 1,900 deaths annually in the United States. Risk factors for GAS infection among skilled nursing facility (SNF) residents are not well-defined. In September 2010, the Pennsylvania Department of Health investigated a prolonged outbreak of invasive GAS infections among residents of an SNF specializing in neurological and pulmonary care.

Objective:

To characterize the outbreak, interrupt transmission, and identify modifiable risk factors specific to SNFs.

Methods:

A case was defined as symptomatic, culture-confirmed GAS infection in a resident during January 2009–September 2010. Cases were categorized as invasive (GAS cultured from a normally sterile site) or noninvasive. A 1:3 matched case-control study was performed; control subjects were selected randomly after matching by SNF residence on the positive culture date. All 297 residents and 139 staff were cultured to identify asymptomatic GAS carriers; available GAS isolates from patients and all isolates from carriers were emm-typed at the Centers for Disease Control and Prevention. Infection prevention practices were evaluated.

Results:

We identified 23 cases, including 13 invasive (all bloodstream infections, including 2 deaths) and 10 noninvasive, during October 12, 2009–September 22, 2010. Five carriers (1 resident, 2 nurses, and 2 housekeepers) were identified. On multivariable analysis, presence of >2 wounds was associated with infection (adjusted odds ratio: 4.5; 95% confidence interval: 1.1–18). Isolates from all 5 carriers and 3 patients with onsets in September 2010 were emm-typed. Two of the 3 patient isolates were emm 11. The third patient isolate and 3 carrier isolates (1 resident and 2 nurses) were emm 89; the remaining carrier isolates were emm 3.6 and emm 2. Multiple infection prevention deficiencies were noted, including inadequate hand hygiene and sharing of wound care supplies. Interventions included antibiotics for carriers, infection prevention education and audits, and ongoing active surveillance.

Conclusions:

This extended outbreak likely started with introduction of multiple GAS strains into a vulnerable population; suboptimal infection prevention practices likely facilitated transmission. Adherence to infection prevention guidelines, particularly during wound care, is critical in preventing GAS outbreaks among SNF residents. Because residents in skilled nursing facilities require complex medical care, facilities should allocate resources, including a full-time infection preventionist, to ensure a strong infection prevention program.