Group B streptococcus

Alternative names 
Streptococcus agalactiae; Sepsis of the newborn; Lancefield group B streptococcus; Group B streptococcal septicemia of the newborn

This is a severe, systemic infection affecting newborn infants, caused by group B streptococcus.

Causes, incidence, and risk factors

This form of infection is caused by group B streptococcus Streptococcus agalactiae, a bacterium which is commonly found in the human gastrointestinal (GI) and genitourinary tracts.

Early onset of the disease occurs from birth to 6 days of life, generally in the first 24 hours. Late onset of the disease is generally seen in newborns from 7 days to 3 months of age, with most cases occurring in babies around 1 month old.

Group B streptococcus was formerly responsible for about three-fourths of sepsis (overwhelming infection of the blood and organs) cases in infants. However, this has decreased since the institution of screening and treatment of pregnant women at risk.

Risk factors include a mother who is known to have group B streptococcus in her GI or genitourinary tracts, rupture of membranes more than 18 hours prior to delivery, prematurity (less than 37 weeks), and maternal fever during labor.

Group B streptococcus may infect the fetus by traveling from the mother’s bloodstream through the placenta or through ruptured membranes as the infant passes through the birth canal. The infant may also become infected after delivery, but this produces a later appearance of illness.


  • unstable temperature (low or high)  
  • poor feeding  
  • appears unwell, stressed, or anxious  
  • breathing difficulties       o grunting       o flaring of the nostrils       o rapid breathing (tachypnea)       o short periods without breathing (apneic episodes - see apnea)       o blue appearance (cyanosis)  
  • rapid heart rate (tachycardia) or extremely slow heart rate (bradycardia)  
  • irregular heartbeat (arrhythmia)  
  • lethargy  
  • coma  
  • shock

Signs and tests

  • blood culture (grows group B strep)  
  • CSF culture (cerebrospinal fluid - from a spinal tap)  
  • urine culture (see Urine collection - infants)  
  • CBC (complete blood count)  
  • chest X-ray (pneumonitis, pleural effusions)  
  • blood gases  
  • coagulation studies (see PT and PTT)

The health care provider is likely to administer one or more of the following:

  • IV (intravenous) antibiotics  
  • IV fluids and medications to reverse shock  
  • oxygen therapy  
  • correct clotting abnormalities  
  • assisted ventilation  
  • ECMO (Extra Corporeal Membrane Oxygenator) in very severe cases

Expectations (prognosis)
This disease can be fatal without early treatment.

Possible complications include:

  • disseminated intravascular coagulation (DIC)  
  • respiratory arrest  
  • meningitis  
  • hypoglycemia

Calling your health care provider
This disease is usually diagnosed shortly after birth (from birth to seven days), usually while the baby is still in the hospital. However, if you have a newborn at home with severe symptoms suggestive of this disorder, get to the emergency room or call the local emergency number (such as 911) immediately!


The American Academy of Pediatrics, American College of Obstetricians and Gynecologists, and the Centers for Disease Control and Prevention have agreed upon two sets of procedures to be followed to decrease the risk of Group B streptococcus disease in infants.

In the first, pregnant women are tested for group B streptococcus at 35 to 37 weeks of pregnancy. Those who show presence of the organism are given intravenous antibiotics during labor.

In the second protocol, prenatal screening is not done, but women are given antibiotics during labor (if they meet certain risk factors).

Both sets of procedures are currently accepted as standard of care. In all cases, proper hand washing by nursery caretakers, visitors, and parents helps prevent transmission after the infant is born.

A high index of suspicion increases the likelihood of an early diagnosis in infants who “don’t look quite right.” Although early diagnosis is not preventative, it can help decrease the risk of some complications.

Johns Hopkins patient information

Last revised: December 7, 2012
by Mamikon Bozoyan, M.D.

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