Group B Streptococcus
An overview of risk factors, screening, and treatment
for moms and babies
Erin Burnette, FNP
February 2011
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What is Group B Strep (GBS)?
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A bacteria that is often found in the GI
tract that can colonize the vagina in some
women
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Colonization can be transient.
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Gram positive
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Also known as Streptococcus agalactiae
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GBS and pregnancy
GBS in pregnancy can cause miscarriage,
endometritis, bacteremia, and
chorioamnionitis.
 GBS infection can also affect the baby
leading to still birth, prematurity, or
invasive neonatal disease.
 Because of these potential consequences,
pregnant women are screened prenatally.
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Transmission
Infants can acquire GBS from the mother
through vertical transmission from the
vagina during labor.
 GBS can be transmitted through intact
membranes but this is not common.
 The infant can become sick from GBS, or
become colonized and remain healthy.
 Aspirating GBS into fetal lungs can lead to
bacteremia.
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Universal Screening
Universal culture based screening has
been shown to be more effective than
risk based screening.
 Testing is done between 35-37 weeks
 Vaginal and rectal areas are swabbed
 If a woman had GBS UTI during
pregnancy, culture may not be done as
she automatically would be treated as
GBS +.
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Neonatal Early Onset GBS infection
May cause pneumonia, sepsis, meningitis
 Onset usually within 24 hours (60-70%)
 32% of cases identified between 24-48h.
 <8% of cases identified after 48 hours.
 Rapid clinical decline common
with early onset disease.
 Incidence: 0.4 per every
1000 live births.
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Signs/Symptoms of sepsis
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Usually general,
nonspecific, and
nonlocalizing:
Temperature
instability
Respiratory distress
Lethargy
Feeding problems
Jaundice
Apnea
Some symptoms can
be more severe:
 Purpura
 Seizures

90% of babies show symptoms within 24 hours of life.
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At Risk?
Presence of certain risk factors make
infants at higher risk of GBS infection.
 Gestational age <37 weeks, ROM >18
hours, intraamniotic infection, young
mothers, black race, and previous infant
with invasive disease.
 Low levels of maternal GBS antibody may
also be a risk factor.
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Infants Immature Immune system
Limitations in neutrophil production
 Impaired/immature neutrophils don’t
function properly
 More likely to exhaust marrow reserves if
stressed, such as in sepsis
 Preterm infants have less vernix, which
has been shown to play a role in host
defense
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Labs
CBC drawn early in life may not always be
helpful in determining risk of sepsis.
 Blood cultures can be helpful. Studies
have shown median time for a blood
culture to become positive with GBS: 9.3
hours. Positive with other organisms:
19.8 hours.
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Late Onset GBS infection
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May present between 1-3 months of life.
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Often presents as bacteremia or
meningitis.
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Not seen in the newborn nursery period
due to timing of onset.
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Complications of GBS infection

GBS infection can lead to developmental
delay, blindness, deafness, as well as
other neurological impairments.
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GBS can also lead to death. Risk of death
is generally inversely related to
gestational age and birth weight.
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Maternal Treatment Recommendations
Intrapartum antibiotic treatment given
intravenously can reduce risk of vertical
transmission.
 Goal: Reach adequate circulating levels
of the antibiotic in maternal and fetal
circulation without reaching toxic levels.
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Intrapartum Antibiotic Therapy…
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Moms in labor should get IV antibiotics if:
1. + GBS culture late in gestation.
2. Unknown GBS status delivering
before 37 weeks.
3. ROM >18 hours
4. Previous infant with GBS disease
5. GBS bacturia during pregnancy
6. Maternal temp of 100.4/38 ̊
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…Intrapartum Antibiotic Therapy
GBS is susceptible to Penicillin and
Amoxicillin
 If mom has a mild PCN allergy, may use
Cefazolin
 If mom has a history of anaphylactic type
reaction to PCN, may use Clindamycin or
Vancomycin
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What About??
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C/S prior to labor onset with intact
membranes?
Risk of vertical transmission very low.
Routine screening still indicated in
case ROM or labor starts before c/s.
If no risk factors, intrapartum
antibiotics not necessarily indicated.
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Adequacy of Treatment
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In order to be deemed “adequate
treatment”:
1. IV administration of a beta lactam
antibiotic (such as PCN 5mu) at least 4
hours prior to delivery.
2. Continue maintenance dosing q4
hours until delivery (such as PCN 3mu)
3. Antibiotic given was PCN,
ampicillin, or cefazolin
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What do we do in the nursery?
Suggestions from the new 2010 CDC guidelines
New CDC algorithms, click link for:
Indications for intrapartum antibiotics and Treatment of the infant
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Newborn Nursery GBS Algorithm
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Treatment of the infant: signs of
sepsis present
These infants need a full diagnostic
workup (CBC & blood culture, and a CXR
if respiratory distress is significant, and LP
if condition warrants).
 Antibiotics should be started and
continued until results of evaluation are
complete.
 IV ampicillin and gram – coverage, often
gentamicin.
 These infants most often go to NICU.
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Treatment of the Infant: maternal
diagnosis of chorioamnionitis:
S/Sx of “chorio”: maternal fever, uterine
tenderness, maternal or fetal tachycardia,
foul/purulent amniotic fluid.
 These infants should undergo a limited
diagnostic evaluation (CBC and blood
culture).
 Give antibiotics pending results of the
culture.
 Observe for 48 hours.
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Treatment of the Infant: well
appearing w/ inadequate maternal abx
It can be appropriate to monitor the
infant clinically for signs of sepsis.
 Well appearing infant >37 weeks with
ROM <18 hours: monitor for 48 hours.
 Well appearing infant <37 weeks &/or
ROM >18 hours: limited evaluation and
monitor for 48 hours.
 Use clinical judgment!
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Treatment of the Infant: Well appearing
infant (any GA) w/ adequate maternal abx
Observe clinically for 24-48 hours
 Usually do not need a workup
 If ALL discharge criteria are met at 24
hours, can consider discharge.
 Be sure to educate family on home
observation and ensure adequate medical
follow up.
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Treatment of the Infant: Maternal
GBS status unknown
GBS status can be unknown due to lack of
prenatal care, lack of prenatal records,
premature delivery, etc.
 Obstetrically, these moms should be
managed according to risk factors
(gestational age, length of ROM, etc) and
treated as appropriate.
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When GBS is negative
GBS negative means LOW risk but not NO
risk. Why?
 False negative rates have been reported
from 4-8%. Why?
 Transient nature of GBS, errors in
specimen collection/lab processing.
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FYI: 60% of infants with GBS disease were
born to GBS negative mothers.
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Other bugs causing neonatal sepsis
While GBS is the most common organism
causing early onset sepsis, it isn’t the only
one.
 Others include E. Coli, H. influenzae, and
coagulase negative staphyloccus.
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Future Research
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Maternal Vaccine against GBS!
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This has been difficult due to ethical issues
with pregnant women in clinical trials.
Also, EOS GBS is not extremely common, so
it can be a difficult outcome to measure.
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References
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Centers for Disease Control and Prevention. (2010). Prevention of
Perinatal Group B Streptococcal Disease MMWR. CDC.
Illuzzi, J., & Bracken, M. (2006). Duration of Intrapartum
Prophylaxis for Neonatal Group B Streptococcal Disease. Obstetrics
and Gynecology , 108 (5), 1254-1267.
Jardine, L., Davies, M., & Faoagali, J. (2006). Incubation Time
Required for Neonatal Blood Cultures to Become Positive. Journal
of Paediatrics and Child Health , 797-802.
Koenig, J., & Keenan, W. (2009). Group B Streptococcus and EarlyOnset Sepsis in the Era of Maternal Prophylaxis. Pediatric Clinics of
North America , 56 (3).
Merenstein, G., & Gardner, S. (2002). Handbook of Neonatal
Intensive Care (Fifth ed.). St. Louis: Mosby.
Verani, J., & Schrag, S. (2010). Group B Streptococcal Disease in
Infants: Progress in Prevention and Continued Challenges. Clinics in
Perinatology , 37, 375-392.
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