Outbreak of invasive group A streptococcal infections in a nursing home. Lessons on prevention and control.

OBJECTIVE: Nine outbreaks of group A streptococcal (GAS) infections in nursing homes were reported to the Centers for Disease Control (Atlanta, Ga) during the past two winters. We conducted an intensive epidemiologic and laboratory investigation of one of these outbreaks to determine clinical characteristics, risk factors for transmission and infection, and methods of control and prevention. METHODS: Cases were detected using cultures and serologic tests. Matched case-control and retrospective cohort studies were performed to determine risk factors for infection. RESULTS: Between December 13, 1989, and January 31, 1990, 16 (20%) of 80 residents, and three (7%) of 45 staff, were infected with GAS. Eleven of the residents had invasive disease and four died. Isolates were available from four persons; all were serotype M-1, T-1. There was strong spatial clustering of cases within the nursing home; having a roommate with prior infection was the most important risk factor. Residents with preexisting decubiti had a reduced risk of infection, perhaps because of stricter infection control practices in their care. No evidence was found for common-source transmission of infection. No further cases occurred after improvement of infection control practices and administration of prophylactic antimicrobials to all residents and staff. CONCLUSIONS: Invasive GAS disease is increasing nationwide, and is a potentially serious problem in the growing and high-risk setting of nursing homes. These data suggest that, in this outbreak, a virulent GAS strain was introduced, with subsequent person-to-person transmission. Adherence to infection control practices can prevent or control GAS outbreaks. Prophylactic antimicrobials may be an effective adjunct to control severe or ongoing outbreaks.

Commentary: applying hospital quality indicators to clinical practice.

Hospitals use various methods to establish performance benchmarks. This may include cooperative data shared between organizations to allow broad, general comparisons. These can, however, be misinterpreted as representing standards of patient care. In the authors' institution, a more complete examination was made of one of these quality indicators when it appeared quality indicator standards were in conflict with standards of patient care. The authors conclude that quality indicators are valuable when screening a hospital, just as we utilize screening tests to identify patients at potential risk. Neither should we apply broad quality indicators as standards of care without a full understanding of their strengths and weaknesses and the foundation on which they are built.