ACOG, AAP Update Guidance on Group B Strep in Infants

Family Physician Experts Weigh In

July 24, 2019 02:54 pm Chris Crawford

The American College of Obstetricians and Gynecologists(www.acog.org) and the American Academy of Pediatrics(pediatrics.aappublications.org) have coordinated to update their respective guidance on preventing/managing infection caused by group B Streptococcus in infants.

[woman holding newborn]

These separate but aligned publications replace the CDC's 2010 perinatal GBS infection prevention guidelines.(www.cdc.gov)

"ACOG is excited to release its revised guidance, which includes an updated recommendation to now perform routine screening for group B Streptococcus between 36-0/7 and 37-6/7 weeks of gestation," said ACOG President Ted Anderson, M.D., Ph.D., in a news release.(www.aap.org)  

"ACOG Committee Opinion: Prevention of Early-Onset Group B Streptococcal Disease in Newborns" was published early online June 25 and appears in the July 2019 issue of Obstetrics & Gynecology. The AAP's clinical report, "Management of Infants at Risk for Group B Streptococcal Disease," was published early online July 8 for the August issue of Pediatrics.

Story Highlights
  • The American College of Obstetricians and Gynecologists and American Academy of Pediatrics recently coordinated to update their respective guidance on preventing/managing infection caused by group B Streptococcus in infants.
  • Both groups agreed in supporting universal maternal screening and, when appropriate, administration of antibiotics to prevent transmission of GBS bacteria from mother to infant before or during delivery.
  • The newly released guidance replaces the CDC's 2010 perinatal GBS infection prevention guidelines.

"AAP is pleased to support maternal policies and procedures that help safeguard infants from this disease, which can have severe -- and sometimes fatal -- consequences," said the report's lead author and AAP Committee on Fetus and Newborn member, Karen Puopolo, M.D., Ph.D., in the release. "We know that by taking preventive steps during prenatal care, and by treating the mother with antibiotics during labor, we can prevent infection in babies. This is especially important for preterm babies who face higher risks."

Both groups agreed in supporting universal maternal screening and, when appropriate, antibiotic administration to prevent transmission of GBS bacteria from mother to infant before or during delivery.

Since GBS prevention recommendations were first introduced in 1990, the national incidence of early-onset GBS disease has declined from 1.8 cases per 1,000 live births to 0.23 cases per 1,000 live births in 2015, the release noted.

Updated Recommendations/Conclusions

The groups' updated GBS recommendations/conclusions are wide-ranging and include the following:

  • Targeted intravenous intrapartum antibiotic prophylaxis has demonstrated efficacy in preventing GBS early-onset disease in neonates born to women with positive antepartum GBS cultures and those who have other risk factors for intrapartum GBS colonization.
  • In evaluating the risk for GBS infection in newborns, separate consideration should be given to infants born at 35-0/7 weeks' or older gestation and those born at 34-6/7 weeks' or younger gestation. Infants born at 34-6/7 weeks' gestation are preterm and at highest risk for early-onset sepsis, including GBS disease.
  • Regardless of planned mode of birth, all pregnant women should undergo antepartum screening for GBS at 36-0/7 to 37-6/7 weeks of gestation unless intrapartum antibiotic prophylaxis for GBS is indicated because of GBS bacteriuria during pregnancy or based on a history of a previous GBS-infected newborn. This new recommended timing for screening provides a five-week window for valid culture results that includes births that occur up to a gestational age of at least 41-0/7 weeks.
  • Early-onset GBS infection should be diagnosed by blood or cerebrospinal fluid culture.
  • Evaluation for late-onset GBS disease, which is associated with preterm birth, should be based on clinical signs of illness.
  • In updated dosing recommendations for treatment of neonatal and infant GBS disease, the preferred antibiotic for confirmed GBS disease in infants is penicillin G, followed by ampicillin.

About 20% to 30% of pregnant women in the United States carry the GBS bacteria in their gastrointestinal or genital tract, which can result in transmission to the infant shortly before or during delivery. About half of infants born to women with GBS bacteria who have not been treated with antibiotics will pick up the bacteria, which leads to an invasive infection in about 1% to 2% of them.

According to the release, experts acknowledge that questions remain about the longer-term health impacts of antibiotics when administered during birth because the treatment impacts the newborn's gut microbiota, which develops and diversifies through early childhood.

"We hope to identify more ways to prevent these infections, such as a vaccine that could be used worldwide," Puopolo said in the release. "These guidelines are the most effective tool we have right now to protect infants and save lives."

Family Physician Experts' Perspectives

Sarah Coles, M.D., of Phoenix, a member of the AAFP's Commission on the Health of the Public and Science, peer-reviewed the updated GBS recommendations in April.

She told AAFP News that the CDC's 2010 recommendations originally called for universal screening of women for GBS between 35 and 37 weeks' gestation. The new ACOG-recommended screening window allows physicians to have valid culture results up to 41-0/7 weeks' gestation.

"This will reduce the number of times a patient will need to be rescreened," Coles said. "As in the prior guidelines, women who have GBS bacteriuria at any point in the pregnancy will need intrapartum prophylaxis and do not need to be rescreened."

Another big change in these ACOG recommendations, she said, is that women who present in labor with unknown GBS status but who had known GBS colonization during a previous pregnancy are now candidates for GBS intrapartum prophylaxis.

"This is in direct opposition to the 2010 CDC guidelines," said Coles. "The rationale for this change was that women who were GBS-colonized during a previous pregnancy have a 50% chance of GBS carriage in the current pregnancy.

"However, specific patient-oriented evidence of reduced GBS early-onset disease is lacking in this guidance. It is reasonable to conduct shared decision-making with these women when considering intrapartum antibiotic prophylaxis."

Coles added that there are specific criteria that need to be met for women with unknown GBS status to require intrapartum GBS prophylaxis, including

  • birth at less than 37-0/7 weeks of gestation,
  • rupture of membranes for 18 hours or more at term,
  • intrapartum fever (100.4°F or higher) and
  • positive results of intrapartum nucleic acid amplification testing for GBS.

Colleen K. Cagno, M.D., of Tucson, Ariz., who wrote about preventing GBS disease in the July 1, 2012, issue of American Family Physician, told AAFP News it's important that family physicians note a patient's penicillin allergy status in lab requisitions for GBS culture and, if the patient is allergic, request that the specimen be tested for clindamycin susceptibility.

"When determining an antibiotic prophylaxis regimen, consider penicillin allergy skin testing if the woman is at low risk or unknown risk of an anaphylactic reaction," Cagno said.

Coles agreed: "I think this is a very important point. Up to 10% of adults report a penicillin allergy, but approximately 90% are not truly allergic. This could be that they have lost sensitization to penicillin over time or the original reaction was not due to penicillin."

Furthermore, Coles said physicians should evaluate patients who report penicillin allergies for high-risk reactions, such as anaphylaxis, angioedema and respiratory distress. Low-risk reactions for penicillin allergy can be skin-tested, or first-generation cephalosporins (e.g., cefazolin) can be used.

"Histories concerning for high risk of anaphylaxis should receive clindamycin for intrapartum prophylaxis," she said. "However, physicians must remember to request susceptibility testing of the GBS culture to clindamycin. Clindamycin resistance rates are greater than 20%. If the isolate is not sensitive to clindamycin, vancomycin is used."

Cagno said a shorter duration of recommended intrapartum antibiotics is less effective than four or more hours of prophylaxis.

"However, two hours of antibiotics exposure has been shown to reduce GBS vaginal colony counts and decrease the frequency of a clinical neonatal sepsis diagnosis," she added. "Therefore, obstetric interventions, when necessary, should not be delayed solely to provide four hours of antibiotic administration before birth."

Cagno said when screening for GBS infection, it's crucial that the specimen is collected correctly.

"A vaginal-rectal specimen is recommended," she said. "The most common error by clinicians when screening for GBS is collection of a vaginal culture only without concomitant rectal sampling. Per the CDC, the swab should be inserted two centimeters into the vagina and the same swab inserted one centimeter into the anus when screening for GBS."

It should be noted that the CDC's mobile app on this topic(www.cdc.gov) has yet to be updated with these latest recommendations, but the agency said this is in the works.

Cagno concluded that "counseling for women who are currently pregnant about the timing of GBS screening and the decision regarding intrapartum antibiotics when the GBS culture results are unknown will be important to start now."

Related AAFP News Coverage
AAFP Collaborates With CDC on App to Prevent Group B Streptococcus Disease
(3/5/2014)

More From AAFP
Clinical Practice Guideline: Group B Strep

Familydoctor.org: Group B Strep Infection(familydoctor.org)