Infections in newborn babies are rare in Canada. If a severe bacterial infection does occur in a newborn, the most likely cause is Group B Streptococcus (GBS). This source of infection was first recognized in the 1970s. Out of about 380,000 births in Canada in 1996, there were 567 cases of GBS disease in infants (1.5 cases per 1,000 births). About four per cent of affected babies will die.
GBS is found in the lower intestine and vagina of 15 to 40 per cent of healthy adults. A person who carries GBS is said to be 'colonized' with the bacteria. Healthy people colonized with GBS usually do not get ill. However, those with chronic diseases or lowered immunity can develop a severe, rapidly progressive infection called GBS disease.
Newborn babies are also at risk of GBS disease. They can develop infection of the blood (bacteremia), lung (pneumonia) or fluid around the brain and spinal cord (meningitis). Of those who survive the infection, long term effects can include hearing or vision loss, and seizures. There may also be varying degrees of physical and mental disabilities including cerebral palsy, learning disability and mental retardation.
Babies who are premature (less than 37 weeks) are more at risk of GBS disease and its complications. GBS can also cause disease in pregnant women including infections of the urinary tract or membranes and amniotic fluid (chorioamnionitis).
GBS does sometimes cross the intact membranes and infect a baby in the womb, but this is unusual. Infection usually occurs after the mother’s membranes have ruptured (water breaks) and as the baby passes through the birth canal. A delay between membrane rupture and birth, or a long labour process increase the risk of GBS infection.
About 80 per cent of GBS infections occur within the first seven days of life and are called early onset disease. Symptoms may be present at birth or shortly afterward. These include breathing or feeding problems, poor colour, temperature changes, poor muscle tone, lethargy or seizures.
Late onset disease may occur in infants one week or older and often present as meningitis or pyelonephritis (infection in the upper urinary system). Symptoms include feeding problems, fever, lethargy, irritability, poor weight gain or a generally ill infant.
When infection is suspected, diagnostic tests are done immediately and then antibiotics are started. Testing includes blood tests, chest x-rays and analysis of body fluid samples such as blood, urine or cerebrospinal fluid. Treatment will last for five to 14 days when GBS infection is confirmed.
Women colonized with GBS are up to 30 times more likely to give birth to an infant with GBS disease than women who are not. The best way to test a pregnant woman for GBS is to take a culture swab from the vagina and rectum at 35 - 37 weeks. The results of this swab can be used to predict whether or not the mother is colonized at the time of delivery.
If GBS is present on culture, it does not mean the mother has an infection. It just means the bacteria are there among the many other bacteria on and in her body. There is no benefit in treating the condition before labour begins.
Early treatment does not prevent GBS disease. Instead, the mother receives intravenous penicillin during labour, at least four hours before delivery. Cases of early onset GBS disease are 30 times less with this treatment. Unfortunately, this treatment does not affect late onset disease.
If a woman is allergic to penicillin, other antibiotics such as clindamycin, can be given. The side effects of antibiotics such as allergic reaction must be considered against the possible benefits.
Today’s knowledge about GBS is limited and further study is underway. So far, no prevention plan is 100 per cent effective but some options do exist. The Society of Obstetricians and Gynaecologists of Canada (SOGC) released a policy statement in June 1997 recommending that all pregnant woman be offered a prevention plan.
Intravenous antibiotics should be given to all women in labour who:
• are in preterm labour (before 37 weeks)
• have had a previous pregnancy affected by GBS
• have had a GBS urinary infection during this pregnancy
For the other women, there are two options. One approach includes screening all pregnant women at 35 to 37 weeks and offering intravenous antibiotics during labour to all GBS-colonized women. The other option uses no routine screening but offers intravenous antibiotics.
Even if the mother is GBS colonized, a healthy, full term baby, born after adequate antibiotic treatment will likely require no special tests or treatment.
Many doctors recommend that infants at risk for GBS disease be kept in hospital for a short while after birth so that heart rate, breathing and temperature can be checked regularly. A blood count test may be ordered at about six hours of age, looking for early signs of infection. An individual plan of treatment is needed for a baby who is premature, sick or if the mother did not receive the recommended antibiotics in labour.
Although there is no way to prevent all cases of early onset GBS disease in newborns, evidence does suggest many cases can be prevented. If you are pregnant or plan to be so, discuss GBS with your maternity care provider.