Streptococcal Invasive Disease Group B, 2013

Five hundred ninety-five cases of invasive group B streptococcal (GBS) disease (11.1 per 100,000 population), including 22 deaths, were reported in 2013. This was the largest number of GBS cases reported since surveillance was initiated in 1995 as part of EIP; the second largest was 564 cases, reported in 2012.

By age group, annual incidence was highest among infants <1 year of age (44.4 per 100,000 population), and persons ≥70 years of age (37.9 per 100,000). Thirteen (59%) of the 22 deaths were among persons ≥65 years of age. Fifty-nine percent of cases were residents of the metropolitan area. Bacteremia without a focus of infection occurred most frequently (30% of infections), followed by cellulitis (23%), osteomyelitis (18%), septic arthritis (9%), pneumonia (5%), and meningitis (1%). The majority (61%) of cases had GBS isolated from blood; other isolate sites included bone (20%), and joint fluid (12%).

Twenty-nine cases were infants or pregnant women (maternal cases), compared to 32 cases in 2012. Seventeen infants developed early-onset disease (occurring within 6 days of birth [0.2 cases per 1,000 live births]), and 12 infants developed late-onset disease (occurring at 7 to 89 days of age [0.2 cases per 1,000 live births]). Ten stillbirth/spontaneous abortions were associated with the 12 maternal GBS infections.

Since 2002, there has been a recommendation for universal prenatal screening of all pregnant women at 35 to 37 weeks gestation. In light of this, we reviewed the maternal charts for all early-onset cases reported in 2013. Overall, 11 of the 17 women who delivered GBS-positive infants underwent prenatal screening for GBS. Of these, 2 tested positive, and 9 negative. One of the six women who did not receive prenatal screening was screened upon admission to the hospital and prior to delivery. Among the 17 women who delivered GBS-infected infants, six received intrapartum antimicrobial prophylaxis (IAP). One of the two women with a positive GBS screen received IAP.

• For up to date information see: Group B Streptococcus (GBS)
• Full issue>> Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2013