Prevention of early-onset group B streptococcal infection in newborns

　　In October 2013, the Society of Obstetrician and Gynaecologists of Canada (SOGC) published a revised guideline for the prevention of early-onset group B Streptococcus (GBS) infection in newborns. Drawing on a retrospective analysis of relevant evidence from the literature, the guideline outlines intrapartum management strategies to prevent early-onset GBS infection. The key updates include prophylactic antibiotic administration, antimicrobial susceptibility testing, and the management of premature rupture of membranes.

　　The evidence in this guideline was sourced from MEDLINE, CINAHL, and The Cochrane Library, covering relevant literature published between January 1980 and July 2012. Controlled vocabulary terms and keywords included: Group B Streptococcus, antibiotic therapy, infection, and prevention. Study types encompassed systematic reviews, randomized controlled trials or clinical controlled trials, and observational studies. No restrictions were imposed on publication date or language. Additionally, unpublished literature was identified through searches of websites of health technology assessment agencies and related organizations, clinical practice guidelines, clinical trial registries, and international medical professional societies. Search results were updated regularly and incorporated into the guideline. Outcomes for mothers and infants were assessed, including maternal complications associated with antenatal and intrapartum antibiotic use, as well as the incidence of early-onset GBS infection in newborns.

　　The recommendations in this guideline are intended to help clinicians identify and manage pregnancy-related risk factors for neonatal GBS infection, with the aim of improving maternal and infant outcomes; however, no cost-effectiveness analysis was conducted. The recommendations are as follows.

1.　 All pregnant women should be screened for GBS colonization in the vagina and rectum between 35 and 37 weeks of gestation (II-1A). Pregnant women scheduled for cesarean delivery are at risk of premature rupture of membranes or preterm labor and should also undergo screening (II-2B).

2. 　Because GBS colonization is strongly associated with early-onset GBS infection in newborns, pregnant women who meet any of the following criteria should receive prophylactic intravenous antibiotics at the onset of labor or in the event of premature rupture of membranes: a positive GBS culture from a vaginal or rectal swab obtained between 35 and 37 weeks’ gestation (II‑2B); a history of GBS infection in a previous infant born to the same mother (II‑3B); or GBS bacteriuria during the current pregnancy (regardless of the colony-forming unit count) (II‑2A).

3. 　All pregnant women who deliver before 37 weeks’ gestation or experience premature rupture of membranes should receive prophylactic intravenous antibiotics for at least 48 hours. However, this does not apply to those whose vaginal or rectal swab cultures or rapid nucleic acid tests for Group B Streptococcus (GBS) are negative within 5 weeks (II-3A).

4. 　Pregnant women with intrapartum fever and signs of chorioamnionitis should receive intravenous broad-spectrum antibiotics covering GBS, regardless of GBS colonization status or gestational age (II-2A).

5. 　Pregnant women with a positive urine GBS test and those with a positive GBS culture from a vaginal or rectal swab should undergo antibiotic susceptibility testing if they are allergic to penicillin (II-1A).

6. 　For pregnant women with premature rupture of membranes at or beyond 37 weeks’ gestation, prophylactic intravenous antibiotics are indicated if a vaginal or rectal swab culture is positive for Group B Streptococcus (GBS), if GBS bacteriuria is present during the current pregnancy, or if a previous infant delivered by this woman had a history of GBS infection. It is recommended to promptly initiate obstetric management, such as labor induction, to terminate the pregnancy (II-2B).

7. 　For pregnant women at or beyond 37 weeks’ gestation who have had premature rupture of membranes for more than 18 hours, if the Group B Streptococcus (GBS) colonization status remains unclear and no GBS screening was performed between 35 and 37 weeks’ gestation, or if the screening result is unknown, prophylactic intravenous antibiotics should be administered (II-2B).

8. 　Pregnant women with premature rupture of membranes before 37 weeks’ gestation, who are awaiting labor onset or require termination of pregnancy based on obstetric indications, should receive prophylactic intravenous antibiotics for at least 48 hours if the Group B Streptococcus (GBS) culture result is either unknown or positive. (Money D, Allen VM, Society of Obstetrician and Gynaecologists of Canada. The prevention of early-onset neonatal group B streptococcal disease[J]. J Obstet Gynaecol Can, 2013, 35: 939-951.)

(Contributed by Li Xing, Department of Obstetrics and Gynecology, Peking University First Hospital)