Streptococcal Invasive Disease Group B, 2017

Five hundred seventy-six cases of invasive group B streptococcal (GBS) disease (10.4 per 100,000 population), including 32 deaths, were reported in 2017. By age group, annual incidence was highest among infants <1 year of age (50.0 per 100,000 population) and cases aged ≥70 years (40.5 per 100,000). Eighteen (35%) of the 32 deaths were among cases ≥65 years. Fifty percent of cases were residents of the metropolitan area. Bacteremia without a focus of infection occurred most frequently (32%), followed by cellulitis (20%), septic arthritis (7%), abscess (6%), osteomyelitis (5%), pneumonia (5%) and meningitis (1%). The majority (80%) of cases had GBS isolated from blood; other isolate sites included joint fluid (10%) and bone (1%).

Forty-two cases were infants or pregnant women (maternal cases), compared to 38 cases in 2016. Twenty infants developed early-onset disease (occurred within 6 days of birth [0.3 cases per 1,000 live births]), and 13 infants developed late-onset disease (occurred at 7 to 89 days [0.2 cases per 1,000 live births]). Six stillbirth/spontaneous abortions were associated with the 9 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 2017. Overall, 12 of 20 women who delivered GBS-positive infants underwent prenatal screening for GBS. Of these, 1 was positive and 11 negative. One of the 8 women who did not receive prenatal screening was screened upon admission to the hospital and prior to delivery, and was positive. Among the 20 women who delivered GBS- positive infants, 9 received intrapartum antimicrobial prophylaxis (IAP) including the woman with a positive GBS screened after hospital admission.

• For up to date information see: Group B Streptococcus (GBS)
• Full issue>> Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2017