Invasive group B streptococcal disease in Maryland nursing home residents

Between 1991 and 1995, among 999 nonpregnant adult Maryland residents with group B Streptococcus (GBS) isolated from a normally sterile site, 84 resided in nursing homes (NHs). The age- adjusted annual incidence of GBS infection (per 100,000 population) among those greater than or equal to 65 years old was 72.3 for NH residents and 17.5 for community residents (relative risk, 4.1; P < .001). Thirty-four case patients resided in 11 NHs with <greater than or equal to>2 cases; 1 NH had 8 case patients within 22 months. Six of 8 case patients from 3 NHs had serotype V GBS. Molecular subtyping of several isolates identified 2 case patients in 1 NH with identical subtype patterns. NH residents have a markedly higher incidence of invasive GBS than do community residents greater than or equal to 65 years old and may serve as a target group for immunization when GBS vaccines become available. Further evaluation of intra-NH transmission of GBS is warranted.