Streptococcal Invasive Disease Group B, 2016

Five hundred forty-four cases of invasive group B streptococcal (GBS) disease (9.9 per 100,000 population), including 27 deaths, were reported in 2016. By age group, annual incidence was highest among infants <1 year of age (49.8 per 100,000 population) and cases aged >70 years (34.2 per 100,000). Fifteen (55%) of the 27 deaths were among cases >65 years. Fifty-two percent of cases were residents of the metropolitan area. Bacteremia without a focus of infection occurred most frequently (35%), followed by cellulitis (22%), septic arthritis (8%), abscess (7%), osteomyelitis (4%), and meningitis (1%). The majority (73%) of cases had GBS isolated from blood; other isolate sites included joint fluid (10%) and bone (2%).

Thirty-eight cases were infants or pregnant women (maternal cases), compared to 42 cases in 2015. Twentyone 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]). Two stillbirth/spontaneous abortions were associated with the 4 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 2016. Overall, 13 of 21 women who delivered GBS-positive infants underwent prenatal screening for GBS. Of these, 4 were positive and 9 negative. Four of the 8 women who did not receive prenatal screening were screened upon admission to the hospital and prior to delivery. Of these, 1 was positive and 3 were negative. Among the 21 women who delivered GBS-positive infants, 14 received intrapartum antimicrobial prophylaxis (IAP). The woman with a positive GBS screen after hospital admission also 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, 2016