Group B streptococcal infection secondary prevention

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Rim Halaby, M.D. [2]

Overview

Currently available GBS prevention strategies will not prevent all cases of early-onset disease. Rapid detection of neonatal infections and initiation of appropriate treatment is needed to minimize morbidity and mortality among the cases that continue to occur. Any newborn with signs of sepsis should receive a full diagnostic evaluation and receive antibiotic therapy pending the results of the evaluation, regardless of maternal colonization status. Well-appearing newborns whose mothers had suspected chorioamnionitis should undergo a limited evaluation and receive antibiotic therapy pending culture results. Well-appearing infants whose mothers had no chorioamnionitis and no indication for GBS prophylaxis should be managed according to routine clinical care. Well-appearing infants of any gestational age whose mother received adequate intrapartum GBS prophylaxis (≥4 hours of penicillin, ampicillin, or cefazolin before delivery) should be observed for ≥48 hours, and no routine diagnostic testing is recommended. For well-appearing infants born to mothers who had an indication for GBS prophylaxis but received no or inadequate prophylaxis, if the infant is well-appearing and ≥37 weeks and 0 days' gestational age and the duration of membrane rupture before delivery was <18 hours, then the infant should be observed for ≥48 hours, and no routine diagnostic testing is recommended. If the infant is well-appearing and either <37 weeks and 0 days' gestational age or the duration of membrane rupture before delivery was ≥18 hours, then the infant should undergo a limited evaluation and observation for ≥48 hours.

Secondary Prevention of Early-Onset GBS Among Infants

Secondary Prevention Algorithm

Shown below is an algorithm summarizing the indications for secondary prevention of early-onset GBS among infants.

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Infants with Signs of Sepsis

Any newborn with signs of sepsis should receive a full diagnostic evaluation and receive antibiotic therapy pending the results of the evaluation, regardless of maternal colonization status. Therapy for the infant should include antimicrobial agents active against GBS (including intravenous ampicillin) as well as other organisms that might cause neonatal sepsis, such as E. coli (AII).

Although maternal GBS colonization might increase clinical suspicion for early-onset GBS disease in an infant, in the era of universal screening, >60% of early-onset GBS cases have occurred among infants born to women who had a negative prenatal GBS culture screen. False-negative cases are not unexpected because culture at 35--37 weeks' gestation will fail to detect some women with intrapartum GBS colonization. As effective prevention strategies are increasingly implemented, a growing proportion of the remaining relatively low burden of disease will reflect inherent limitations in the strategies. Signs of sepsis in any newborn can be an indication of early-onset GBS disease, regardless of maternal colonization status.

Infants Born to Women with Chorioamnionitis

Well-appearing newborns whose mothers had suspected chorioamnionitis should undergo a limited evaluation and receive antibiotic therapy pending culture results (AII). The evaluation should include a blood culture and a CBC including white blood cell differential and platelet count; no chest radiograph or lumbar puncture is needed. Consultation with obstetric providers to assess whether chorioamnionitis was suspected is important to determine neonatal management (CIII).

Chorioamnionitis is an important risk factor for early-onset GBS disease in women with GBS colonization and can reflect an intrauterine onset of infection in the neonate . Intrapartum fever, one sign of chorioamnionitis in parturient women, has been associated with failure of intrapartum antibiotics to prevent GBS disease in the newborn. Intrapartum treatment of chorioamnionitis can prevent neonatal sepsis. The diagnosis of chorioamnionitis usually is made clinically on the basis of signs and symptoms such as fever (which might be low-grade), uterine tenderness, fetal tachycardia, maternal tachycardia, and foul-smelling or purulent amniotic fluid. In an effort to avert neonatal infections, maternal fever alone in labor may be used as a sign of chorioamnionitis and hence indication for antibiotic treatment, particularly among women with a significant risk factor for chorioamnionitis (e.g., prolonged labor or prolonged rupture of membranes).

Well-Appearing Infants Exposed to Inadequate Intrapartum Antibiotics

Well-appearing infants whose mothers had no chorioamnionitis and no indication for GBS prophylaxis should be managed according to routine clinical care (CIII).

Well-appearing infants of any gestational age whose mother received adequate intrapartum GBS prophylaxis (≥4 hours of penicillin, ampicillin, or cefazolin before delivery) should be observed for ≥48 hours, and no routine diagnostic testing is recommended (BIII). Such infants can be discharged home as early as 24 hours after delivery, assuming that other discharge criteria have been met, ready access to medical care exists, and that a person able to comply fully with instructions for home observation will be present (CIII).

For well-appearing infants born to mothers who had an indication for GBS prophylaxis but received no or inadequate prophylaxis, if the infant is well-appearing and ≥37 weeks and 0 days' gestational age and the duration of membrane rupture before delivery was <18 hours, then the infant should be observed for ≥48 hours, and no routine diagnostic testing is recommended (BIII). If the infant is well-appearing and either <37 weeks and 0 days' gestational age or the duration of membrane rupture before delivery was ≥18 hours, then the infant should undergo a limited evaluation and observation for ≥48 hours (BIII).

The management of well-appearing infants whose mothers received inadequate intrapartum antibiotic prophylaxis (because of either a short duration of exposure before delivery or use of an agent with limited efficacy data) can be challenging. Previous GBS prevention guidelines have recommended that infants whose mothers received inadequate intrapartum antibiotic prophylaxis and those <35 weeks' gestational age exposed to intrapartum antibiotics be evaluated with a blood culture and complete blood count (CBC) with differential (13,15). There are limitations to this diagnostic approach. The sensitivity of blood culture can be low among newborns exposed to intrapartum antibiotics (217,218). Available data on the performance of the CBC as a screening test for neonatal sepsis suggest that although the negative predictive value is high, the positive predictive value is low, particularly among healthy-appearing term infants (219--221). The sensitivity of the CBC is lowest immediately after birth, and its performance as a screen for sepsis can be improved by obtaining the blood specimen between 6--12 hours of life (220,222,223). Clinical signs of sepsis have been found to be a more sensitive indicator of neonatal sepsis than hematologic tests (201).

Certain centers provide intramuscular penicillin to asymptomatic infants within 1 hour of birth; this practice is based on results of observational studies demonstrating declines in early-onset GBS disease coincident with a policy of universal administration of intramuscular penicillin to newborns (224--226). However, because the studies used historic control groups and were conducted at a single center that does not screen pregnant women routinely for antenatal GBS colonization, the findings are not generalizable to other settings.

References

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