Streptococcal Invasive Disease Group B, 2012

Five hundred sixty-four cases of invasive group B streptococcal disease (10.6 per 100,000 population), including 35 deaths, were reported in 2012. 2012 had the largest number of GBS cases reported since surveillance was initiated in 1995, the second largest was 535, reported in 2011.

By age group, annual incidence was highest among infants <1 year of age (39.5 per 100,000 population) and cases aged 70 years or older (37.6 per 100,000). Seventeen (49%) of the 35 deaths were among cases age 65 years and older. Fifty-three percent of cases were residents of the metropolitan area. Bacteremia without a focus of infection occurred most frequently (25% of infections), followed by cellulitis (22%), osteomyelitis (13%), septic arthritis (8%), pneumonia (5%), and meningitis (1%). The majority (67%) of cases had GBS isolated from blood; other isolate sites included bone (17%) and joint fluid (12%).

Thirty-two cases were infants or pregnant women (maternal cases), compared to 35 cases in 2011. Ten infants developed early-onset disease (occurred within 6 days of birth [0.1 cases per 1,000 live births]), and 13 infants developed late-onset disease (occurred at 7 to 89 days of age [0.2 cases per 1,000 live births]). Nine 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 2012. Overall, 8 of 10 women who delivered GBS-positive infants underwent prenatal screening for GBS. Of these, 1 was positive, and 7 negative. One of the two women who did not receive prenatal screening was screened upon admission to the hospital and prior to delivery. Among the 10 women who delivered GBS-positive infants, 3 received intrapartum antimicrobial prophylaxis (IAP). The one woman 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, 2012