Tightly clustered outbreak of group A streptococcal disease at a long-term care facility

Abstract

Objective: To describe investigation of a tightly clustered outbreak of invasive group A streptococcal (GAS) disease associated with a high mortality rate in a long-term care facility (LTCF).

Design: Cross-sectional carriage survey and epidemiologic investigation of LTCF resident and employee cohorts.

Setting: A 104-bed community LTCF between March 1 and April 7, 2004.

Patients: A cohort of LTCF residents with assigned beds at the time of the outbreak.

Interventions: Reinforcement of standard infection control measures and receipt of chemoprophylaxis by GAS carriers.

Results: Four confirmed and 2 probable GAS cases occurred between March 16 and April 1, 2004. Four case patients died. The final case occurred during the investigation, before the patient was determined to be a GAS carrier. No case occurred during the 6 months after the intervention. Disease was caused by type emm3 GAS; 16.5% of residents and 2.4% of employees carried the outbreak strain. Disease was clustered in 1 quadrant of the LTCF and associated with nonintact skin. GAS disease or carriage was associated with having frequent personal visitors.

Conclusions: Widespread carriage of a virulent GAS strain likely resulted from inadequate infection control measures. Enhanced infection control and targeted prophylaxis for GAS carriers appeared to end the outbreak. In addition to employees, regular visitors to LTCFs should be trained in hand hygiene and infection control because of the potential for extended relationships over time, leading to interaction with multiple residents, and disease transmission in such residential settings. Specific attention to prevention of skin breaks and proper wound care may prevent disease. The occurrence of a sixth case during the investigation suggests urgency in addressing severe, large, or tightly clustered outbreaks of GAS infection in LTCFs.