RCOG Advises GBS Prophylaxis for Women in Preterm Labor

Veronica Hackethal, MD

September 20, 2017

Updated guidelines on prevention of early-onset neonatal group B streptococcal (GBS) infection were released by the Royal College of Obstetricians and Gynaecologists (RCOG). The guidelines were published online September 13 in the British Journal of Obstetrics and Gynecology.

The authors recommend offering intrapartum antibiotics to all women who go into labor before 37 weeks of pregnancy, whether or not their waters have broken. The recommendations are intended to prevent early-onset GBS infection in newborns.

"This guidance provides clear advice to doctors and midwives on which women should be offered antibiotics to avoid passing GBS infection onto their babies," coauthor Peter Brocklehurst, MBChB, professor, University of Birmingham, Edgbaston, United Kingdom, said in a news release.

"The management of women whose babies are at raised risk of developing Group B Strep infection remains a vital part of reducing illness and deaths caused by this infection. Ensuring a consistent approach to care in all maternity units is vital to achieving the best outcomes for both mother and baby," he added.

Recommendations

For prevention of early-onset GBS infection, RCOG recommends offering intrapartum intravenous antibiotics (penicillin G, a cephalosporin for women with penicillin allergies, or vancomycin for women with severe penicillin allergies) in the following scenarios:

  • women in confirmed preterm labor (before 37 weeks' gestation);

  • women with a previous baby with early- or late-onset GBS infection;

  • women who have had GBS in their urine during the current pregnancy;

  • women who have tested positive for GBS during the current pregnancy (includes incidental or intentional testing);

  • women who are carriers of GBS and have term rupture of membranes;

  • women who are GBS carriers and have preterm rupture of membranes, along with induction of labor as soon as reasonably possible; and

  • women with fever (≥38°C) who are in labor, regardless of their GBS carrier status.

Although RCOG recommends against universal GBS screening for all pregnant women, if performed, testing should occur at 35 to 37 weeks of pregnancy. In particular, this may apply to women who have had GBS in a previous pregnancy, because results may guide decision-making about the need for intrapartum antibiotics.

Intrapartum antibiotics are not required for GBS carriers who are having a planned cesarean with intact membranes and no labor.

The guidelines also provide recommendations on managing babies at risk for early-onset GBS infection or who have clinical signs of the illness.

"Valuable Resource"

"One of the important aspect[s] of guideline development is that they must be adapted to the needs of the local setting and resources. The British guidelines serve as a valuable resource as US guidelines are updated and modified and vice versa," Andi Shane, MD, Marcus Professor of Hospital Epidemiology and Infection Control, Children's Healthcare of Atlanta, Georgia, told Medscape Medical News. Dr Shane is also an associate professor, Division of Infectious Disease, Department of Pediatrics, Hubert Department of Global Health, Rollins School of Public Health, Atlanta.

Since 2002, US guidelines have advised universal GBS screening for all pregnant women at 35 to 37 weeks' gestation, or for women in preterm labor before this time, the authors explain. Women found to be carriers should be offered antibiotics (usually intravenous benzylpenicillin or ampicillin) during delivery to protect against GBS infection in the newborn.

Stressing prenatal care for all pregnant women and the importance of following guideline recommendations for diagnostic testing, Dr Shane added: "[I]ntrapartum prophylaxis should be administered when indicated, and in situations when diagnostic testing results are not available and clinical criteria are met. While these guidelines are extremely helpful, they do not replace the clinical judgement of the physician."

Standardized Approach for the United Kingdom

In recent years, the United Kingdom has witnessed a significant increase in the incidence of GBS infection in newborns. The guidelines were first published in 2003 and updated in 2012, in part as a response to this increase.

Research conducted by the RCOG in 2015 showed UK practices vary widely in efforts to prevent early-onset GBS infection, Janice Rymer, MD, vice president of education, RCOG, said in the news release.

"This revised guideline will provide standardised treatment of pregnant women with GBS and reduce the risk of their babies developing the infection," she explained.

Another goal is to raise awareness about GBS. To that end, all pregnant women should be provided with appropriate information about GBS, to support decision making, according to the guidelines. The RCOG is currently updating a patient information leaflet for this purpose.

Preterm Birth Major Risk Factor

GBS represents the most common cause of severe early-onset infection in newborns younger than 7 days of age. At the same time, GBS is very common: about 50% of women may naturally harbor the GBS bacteria in their digestive and lower vaginal tracts during pregnancy, the authors say.

Although the bacteria often do not harm the mother, newborns can be infected during birth. In most cases, infected newborns who receive prompt treatment do not develop serious illness and fully recover. However, a small number develop serious disease, which can result in disability and, rarely, death.

Preterm labor represents a major risk factor for early-onset GBS. About 22% of early-onset GBS infection in the United Kingdom and Ireland in 2015 occurred in preterm babies. Preterm babies are also at higher risk for death from GBS infection. Mortality from GBS infection in term infants is only about 2% to 3%, but can rise as high as 20% to 30% in preterm babies.

Other risk factors for early-onset GBS infection include having a previous baby affected by GBS, testing positive for GBS during pregnancy, prolonged rupture of membranes, and maternal fever during labor.

Intrapartum antibiotics are not without risks, the authors write. Rarely, mothers may have an allergic reaction or go into anaphylaxis. Giving antibiotics may change the mother's gut flora, which may have long-term effects. Although the jury is still out on the issue, research suggests antibiotics may also have adverse effects on the neonatal microbiome, which has been linked to later problems such as allergy, obesity, and diabetes.

In addition, overuse of antibiotics can have an effect on a population-wide scale.

"Frequent antibiotic exposure may predispose bacteria to the development of resistance, making treatment more challenging in the future," Dr Shane concluded.

BJOG. Published online on September 13 2017. Full text

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