Guidelines for Preventing Perinatal Group B Streptococcal Disease

The CDC recommends that pregnant women undergo vaginal and rectal screening for GBS colonization at 35 to 37 weeks to help prevent GBS in infants.

Although much has changed in the updated CDC guidelines for the prevention of perinatal group B streptococcal (GBS) disease, the foundation of prevention remains unchanged from GBS guidelines the agency issued eight years ago.

According to Julie Wood, MD, who served as the American Academy of Family Physicians (AAFP) representative to the CDC's working group on GBS, pregnant women still should undergo vaginal and rectal screening for GBS colonization at 35 to 37 weeks. Intrapartum antibiotic prophylaxis, or IAP, is recommended for women in the following groups:

  • those who delivered a previous infant with GBS disease;
  • those with GBS bacteriuria during the current pregnancy;
  • those with a GBS-positive screening result in the current pregnancy; and
  • those with unknown GBS status who deliver at less than 37 weeks' gestation, have an intrapartum temperature of 100.4 or greater, or have rupture of membranes for 18 hours or longer.

Penicillin G remains the preferred agent for IAP, although ampicillin is an acceptable alternative.

For women who are allergic to penicillin, erthyromycin was removed as an option for IAP because of increasing resistance, said Wood, who is associate director of the Research Family Medicine Residency Program in Kansas City, MO, in an AAFP statement. Cefazolin remains the antibiotic recommended for penicillin-allergic patients at low risk of anaphylaxis.

Incidence of GBS has declined from 1.7 cases per 1,000 live births in the early 1990s to 0.34 to 0.37 cases per 1,000 live births in 2008, according to the CDC. However, GBS disease remains the leading infectious cause of morbidity and mortality among U.S. newborns.

"We have made a significant impact in preventing group B streptococcal infection in newborns since the introduction of the original CDC guidelines in 1996 and with the 2002 revision," Wood said. "With this recent evidence review and update in the guidelines, family physicians and those who care for pregnant women and newborns have the opportunity to further improve morbidity and mortality of newborns due to illness caused by group B strep."

Other key changes to the updated guidelines include the following:

  • expanded recommendations on laboratory detection of GBS;
  • clarification of the colony-count threshold required for reporting GBS detected in the urine of pregnant women;
  • revised algorithms for GBS screening and intrapartum chemoprophylaxis for women with preterm labor or preterm premature rupture of membranes;
  • a change in the recommended dose of penicillin G for chemoprophylaxis to 5.0 million units intravenously, followed by 2.5 million to 3.0 million units intravenously every four hours; and
  • a revised algorithm for management of newborns with respect to risk for early-onset GBS disease.

The CDC has developed Web pages about the GBS guidelines with recommendations, algorithms, question-and-answer features and other information that is specific to obstetric care providers, neonatal care providers, and laboratory personnel.

For more:

  • Prevention of Perinatal Group B Streptococcal Disease: Revised Guidelines from CDC
  • AAFP Endorsement of Evidence-based Clinical Practice Guidelines Developed by External Organizations