Clinical Review

Preventing early-onset group B streptococcal disease in newborns

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7 patient questions about GBS answered


 

References

In 1992, the American College of Obstetricians and Gynecologists (ACOG) and the American Academy of Pediatrics (AAP) published their first joint guidelines on the prevention of early-onset neonatal group B streptococcal (GBS) infection.1 In this initial statement, the organizations recommended universal culturing of obstetric patients at 28 weeks’ gestation and treatment of colonized women during labor if they had a recognized risk factor for neonatal GBS infection.

In 1996, the Centers for Disease Control and Prevention (CDC) published its first set of official guidelines on the topic and suggested that both universal screening and a risk-factor–based approach were reasonable options.2 The 2002 update of the CDC guidelines strongly recommended universal screening of all pregnant women at 35 to 37 weeks’ gestation and intrapartum prophylaxis for all colonized women regardless of risk factors.3

The third set of CDC guidelines was published in 2010.4 The key features of this version were the elimination of erythromycin as an alternative to penicillin in patients who are allergic to beta-lactam antibiotics and the establishment of 4 hours as the critical interval for administration of prophylaxis prior to delivery. The 2010 publication was the last such report from the CDC. Since then ACOG and AAP have been tasked with providing updated practice guidelines. To that end, ACOG recently issued a new Committee Opinion on “Prevention of Group B Streptococcal Early-Onset Disease in Newborns.”5 Here we will highlight the key features of our current strategy for preventing neonatal GBS infection.

CASE Pregnant patient presents with many questions about GBS

A 26-year-old primigravid woman presents for her first prenatal appointment at 9 weeks’ gestation. Her older sister recently delivered a term infant that died in the first week of life from GBS sepsis. Understandably, she has many questions.

1. Your patient first wants to know, “What is this streptococcal organism and how likely am I to have this infection?”

Streptococcus agalactiae, also known as GBS, is a gram-positive encapsulated bacterium that produces beta hemolysis when grown on blood agar. Approximately 25% of pregnant women harbor this organism in the lower genital tract and/or rectum.6

GBS is one of the most important causes of neonatal infection, particularly in preterm infants. The frequency of infection is now 0.23 per 1,000 live births in the US.5

Neonatal infection can be divided into early-onset infection (occurring within the first 7 days of life) and late-onset infection (occurring from after the first week until the third month of life). Approximately 80% to 85% of cases of neonatal GBS infections are early in onset. Virtually all of the early-onset infections result from vertical transmission during delivery from a colonized mother to her infant.5-7

2. “How dangerous is this infection to my baby and me? Are there certain factors that increase the risk of my baby becoming infected?”

GBS is responsible for approximately 2% to 3% of cases of either asymptomatic bacteriuria or acute cystitis. Women with urinary tract infections caused by GBS are at increased risk for preterm premature rupture of membranes and preterm delivery. Genital tract colonization also increases a woman’s risk for chorioamnionitis and endometritis, particularly after cesarean delivery (CD). In addition, GBS can be part of the polymicrobial flora in women who have a wound (incisional site) infection following CD.6,7

Continue to: In colonized women, several risk factors...

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