Invasive group B streptococcal infections in Sweden: incidence, predisposing factors and prognosis.

Objectives: To study the incidence, clinical manifestations, concomitant conditions and case-fatality rate in patients with invasive group B Streptococcus (GBS) infections in the Göteborg area (mean population 582,666) of Sweden during 1981-95.

Design: Patients were identified from the records of the Department of Clinical Bacteriology. Clinical data were obtained from hospital records.

Results: GBS was isolated from blood, cerebrospinal fluid or other sterile body fluids from 211 patients with 215 infectious episodes; 108 in neonates, and 107 in non-neonates. The incidence was 2.4/100,000 per year, with the highest rates in neonates and in persons 65 years old or older. The incidence in neonates was 0.92/1,000 live births. The most common manifestation was septicemia with unknown focus. Of the neonates, 54% were full term and had no underlying conditions. Of the non-neonates, 15% had no underlying conditions. The most common underlying conditions were preterm delivery in neonates, and arteriosclerotic disease and diabetes mellitus in non-neonates. The case-fatality rates were 13% in neonates and 16% in non-neonates.

Conclusions: GBS is an important pathogen in neonates and in adults with concomitant conditions. The morbidity and mortality rates necessitate research to develop GBS vaccines both for women of fertile age and for patients with a wide variety of underlying diseases.