Management of the infants at increased risk for early onset sepsis from group B streptococcal infection

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Management of the infants at increased risk for
early onset sepsis from group B streptococcal
infection

• Martin Skidmore
• University of Toronto

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Group B Streptococcus (GBS)

• Most GBS early onset sepsis (EOS) caused by types
  Ia, Ib, II, III V
• Type III more commonly associated with late onset
  sepsis/meningitis
• 20-30 of American women are colonised (may be
  as high as 60)
• 50 of infants born to colonised mothers become,
  themselves, colonised
• 1-2 of colonised infants will develop invasive
  GBS

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• GBS bacteriuria at anytime during the pregnancy
• Previous child with invasive GBS disease

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BACKGROUND

• 1996 consensus guidelines from The Centers for
  Disease Control and Prevention recommended
  intrapartum antibiotic prophylaxis (IAP) to women
  at risk for delivering an infant with EOS, GBS
  infection
• 2002 CDC conducted a large, retrospective cohort
  study which demonstrated positive impact and
  issued universal screening guidelines

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Impact

• Incidence of EOS from GBS
• 1993 1.7 cases/1000 live births
• 2003-5 0.34 cases/1000 live births
• a reduction of 80
• Incidence of EOS from non GBS unchanged

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Recommendations

• Screen ALL mothers with rectovaginal cultures at
  35-37 weeks for GBS
• Treat those with positive cultures with
  penicillin in labour

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Cost

• As many as 22 of all mothers will receive IAP to
  prevent disease in 0.2 of infants and prevent
  mortality in 0.01 of infants

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Strategies (A)

• Well-appearing infant of GBS positive mother, who
  received IAP more than 4 hours prior to delivery
• N/B requires no therapy
• stay in hospital 24 hours
• Insufficient evidence regarding efficacy of
  alternative antibiotics treat as incomplete
  IAP

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Strategies (B)

• Well-appearing infant of GBS positive mother, who
  received IAP less than 4 hours prior to delivery
  (or not at all)
• Risk approximately 1
• ¼ are asymptomatic
• Is empiric treatment therefore justified?
• 95 who develop EOS will present with clinical
  signs lt 24 hours
• 4 between 24 and 48 hours
• 1 gt 48 hours
• Therefore to detect each case of EOS 2000
  infants would require 48 hours hospitalization
• Therefore case for careful assessment and
  discharge at 24 hours

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Use of the CBC

• Positive predictive value is low in the newborn
• One study abnormal CBC
• WBC 5.0 x109/L or lower
• WBC 30 x109/L or greater
• Immature/mature ratio gt 0.2
• 1665 well appearing term infants at risk for EOS
• PPV of 1.5 of abnormal CBC in identifying the
  development of clinical sepsis
• None developed positive blood culture
• Ottolini et al 2003

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Use of the CBC cont.

• Various scoring systems for analyzing CBCs
• best individual finding with highest PPV is a low
  total WBC (5.0 x109/L)
• LR between 10 and 20
• ? justifies treatment even if well appearing
  infants
• (only 22-44 of infants with sepsis will have
  such a low WBC)
• Fowlie, Schmidt 1998

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Strategies (C)

• Well appearing infant of a GBS-negative mother
  with risk factors at delivery
• eg.
• ROM 18 hours
• Pyrexia 38C
• premature labour at lt 36 weeks
• GBS bacteriuria
• Previous child with invasive GBS disease
• Present in 22 and only identified 50 who
  eventually developed invasive GBS disease
• Schrag et al, 2002
• Towers et al, 1999
• Limited evaluation CBC 24 hours of
  observation

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Strategies (D)

• Well appearing infant of mother with unknown GBS
  status
• Managed as per risk factors
• Absence of risk factors no intervention
  required
• Risk factors present
• IAP gt 4 hours routine care
• IAP lt 4 hours limited evaluation
• (applies to late preterm infant as GBS screening
  results may not be available)

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Chorioamnionitis

• pyrexia may occur with epidural and/or
  dehydration
• possible chorioamnionitis
• fever only
• definite chorioamnionitis
• fever
• left shift in mat CBC
• lower uterine tenderness

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Chorioamnionitis

• Chorioamnionitis but infant well at birth
• OR for sepsis 0.26 (95 C1 0.11to 0.63)
• Invasive infection lt 2
• Jackson et al, 2004
• Therefore limited evaluation only?
• requirement for resuscitation at birth
• otherwise, treat only if CBC is suggestive of
  infection (ie low WBC)

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How should an infant be monitored, investigated
and treated given the

• Presence of clinical signs of sepsis
• GBS culture status of the mother
• Treatment status of the mother
• Presence / absence of maternal risk factors for
  neonatal sepsis?

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