OUTBREAK OF EARLY-ONSET GROUP-B STREPTOCOCCAL SEPSIS

During January and August, 1990, 23 cases of early onset Group B Strep tococcus (GBS) disease occurred in a Kansas City, MO, hospital with an attack rate of 14/1000 live births, compared with an annual rate of 1 .2 cases/1000 live births for 1988 through 1989. Case infants were com pared with controls matched by birth weight, race, maternal age and da y of delivery and to a second group of infants of mothers colonized wi th GBS to identify risk factors and consider intervention strategies d uring the outbreak. The presence of multiple serotypes among the invas ive strains suggested that the outbreak was not caused by a common sou rce. Case mothers were more likely than control mothers to have chorio amnionitis, intrapartum fever or rupture of membranes >12 hours, and p remature case infants were more likely to have a history of rupture of membranes before onset of labor. Multiparous mothers of case infants were more likely to have a history of spontaneous abortion (odds ratio , 6.7; 95% confidence interval, 1.0 to 45.9). No single factor could e xplain the increase in GBS disease. If intrapartum antibiotic prophyla xis had been used for selected GBS carriers based on presence of eithe r rupture of membranes >12 hours, intrapartum maternal fever or preter m labor, 7.4% of all deliveries would have received antibiotics and 73 % of cases could potentially have been prevented. We conclude that ide ntification of colonized mothers with perinatal risk factors and use o f intrapartum antibiotics could be expected to prevent substantial dis ease during an outbreak of early onset GBS disease.