Group A Streptococcus Outbreak in a Long-Term Care Facility, Virginia, 2011 – 2012

BACKGROUND: From October 2011 to January 2012, the Virginia Department of Health (VDH) received three reports of invasive Group A Streptococcus (GAS) infection in residents of a 180-bed long-term care facility. GAS is a common bacterium, yet invasive disease is rare and may result in serious health outcomes, particularly among residents of congregate care facilities. VDH initiated an investigation to identify potential sources of the outbreak, determine the magnitude of the outbreak, characterize risk factors for illness and make recommendations to control disease transmission. 

METHODS: To institute faster reporting of new invasive and non-invasive GAS cases for the epidemiologic investigation, VDH initiated daily surveillance for signs and symptoms compatible with GAS among residents and staff. A case was defined as an infection with isolation of GAS from a sterile or non-sterile site, one or more related sign or symptom and an onset date between October 2011 and March 2012. Employees and residents were screened to identify GAS carriers and carriers received appropriate chemoprophylaxis. The Division of Consolidated Laboratory Services performed cultures and pulsed-field gel electrophoresis (PFGE) analysis on all samples for molecular characterization. Infection control and environmental practices were assessed through direct observations and review of policies.

RESULTS: Overall, nine (2%) of 380 residents and staff met the outbreak case definition. Onset dates ranged from October 16, 2011 to March 10, 2012. Two individuals with invasive disease died (40% case fatality rate among all invasive cases). Through the carriage study, 20 (5%) additional individuals of the 376 residents and staff tested were GAS carriers, including seven residents and 13 staff. During visits to the facility, staff members were observed practicing inadequate hand hygiene, expressed confusion about when to initiate transmission-based precautions, and did not have adequate supplies of PPE available to them. PFGE analysis revealed two distinct patterns among cases and seven distinct patterns among cases and carriers.

CONCLUSIONS: No conclusive source for the outbreak was identified, but no new cases were observed during the three month surveillance period after carriers received chemoprophylaxis. It is not known whether this measure stopped the spread of disease. It is likely that the simultaneous chemoprophylaxis of carriers, exclusion of employee carriers from work until 24-hours after they began antibiotic treatment and infection control practice improvements stopped disease transmission within the facility. This outbreak and the resulting screening efforts highlight the importance of collaboration between public health agencies, laboratories and long-term care facilities during outbreak investigations.