Streptococcal Invasive Disease Group B, 2008

Four hundred eighteen cases of invasive group B streptococcal disease (8.0 per 100,000 population), including 24 deaths, were reported in 2008. These cases were those in which group B Streptococcus (GBS) was isolated from a normally sterile site. This represents the largest number of GBS cases reported since surveillance was initiated in 1995.

By age group, annual incidence was highest among case-patients <1 year of age (64.5 per 100,000 population) and those 70 years of age or older (31.2 per 100,000). Fifty-seven percent of case-patients were residents of the metropolitan area. Bacteremia without focus of infection was the most common type (41%) of infection associated with invasive GBS disease followed by cellulitis (13%), osteomyelitis (12%), pneumonia (8%), septic arthritis (6%), abscesses (4%) and meningitis (1%). The majority (70%) of case-patients had GBS isolated from blood only. Other common isolation sites included joint fluid (11%) and bone (11%).

Forty-five case-patients were infants or pregnant women (maternal case), compared to 46 case-patients in 2007. Twenty-three infants developed early-onset (within 6 days of birth) disease (0.31 cases per 1,000 live births), and 20 infants developed late-onset (7 to 89 days of age) disease. One stillbirth/spontaneous abortion was associated with two maternal GBS infections.

The Prevention of Perinatal Group B Streptococcal Disease, Revised Guidelines published by CDC in August 2002 included the recommendation for universal prenatal screening of all pregnant women at 35 to 37 weeks gestation and updated prophylaxis regimens for women with penicillin allergies. In light of these guidelines, MDH reviewed the maternal charts for all 23 early-onset case-patients reported during 2008. Overall, 12 (52%) of 23 women who delivered GBS-positive infants underwent prenatal screening for GBS. Of these, 5 (42%) were positive, 6 (50%) negative, and 1 (8%) had an unknown result. Among the eight women who did not receive prenatal screening, two (25%) were screened upon admission to the hospital and prior to delivery. Among the 23 women who delivered GBS-positive infants, 13 (57%) received intrapartum antimicrobial prophylaxis (IAP). All five women with a positive GBS screen received IAP. MDH continues to follow the incidence of GBS disease among infants, screening for GBS among pregnant women, and the use of IAP for GBS-positive women during labor and delivery.

• For up to date information see: Group B Streptococcus (GBS)
• Full issue>> Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2008