GBS FACTS: Frequently Asked Questions
How
common is GBS disease?
Does
everyone who has GBS get sick?
How
does GBS affect newborns?
How
is GBS disease diagnosed and treated?
Can
pregnant women be checked for GBS?
Can
GBS disease among newborns be prevented?
What
research is being done on prevention of GBS disease?
Who
is at higher risk for GBS disease?
Group B streptococcus (GBS) is a type of bacterium that causes illness in newborn babies, pregnant women, the elderly, and adults with other illnesses, such as diabetes or liver disease. GBS is the most common cause of life-threatening infections in newborns.
How
common is GBS disease?
GBS is the most common cause of sepsis (blood infection) and meningitis
(infection of the fluid and lining surrounding the brain) in newborns.
GBS is a frequent cause of newborn pneumonia and is more common
than other, better known, newborn problems such as rubella, congenital
syphilis, and spina bifida.
Before prevention methods were widely used, approximately 8,000
babies in the United States would get GBS disease each year. One
of every 20 babies with GBS disease dies from infection. Babies
that survive, particularly those who have meningitis, may have
long-term problems, such as hearing or vision loss or learning
disabilities.
In pregnant women, GBS can cause bladder infections, womb infections
(amnionitis, endometritis), and stillbirth. Among men and among
women who are not pregnant, the most common diseases caused by
GBS are blood infections, skin or soft tissue infections, and
pneumonia.
Approximately 20% of men and nonpregnant women with GBS disease
die of the disease.
Does
everyone who has GBS get sick?
Many people carry GBS in their bodies but do not become ill. These
people are considered to be "carriers." Adults can carry
GBS in the bowel, vagina, bladder, or throat. One of every four
or five pregnant women carries GBS in the rectum or vagina. A
fetus may come in contact with GBS before or during birth if the
mother carries GBS in the rectum or vagina. People who carry GBS
typically do so temporarily -- that is, they do not become lifelong
carriers of the bacteria.
How
does GBS disease affect newborns?
Approximately one of every 100 to 200 babies whose mothers carry
GBS develop signs and symptoms of GBS disease. Three-fourths of
the cases of GBS disease among newborns occur in the first week
of life ("early-onset disease"), and most of these cases
are apparent a few hours after birth. Sepsis, pneumonia, and meningitis
are the most common problems. Premature babies are more susceptible
to GBS infection than full-term babies, but most (75%) babies
who get GBS disease are full term.
GBS disease may also develop in infants 1 week to several months
after birth ("late-onset disease"). Meningitis is more
common with late-onset GBS disease. Only about half of late-onset
GBS disease among newborns comes from a mother who is a GBS carrier;
the source of infection for others with late-onset GBS disease
is unknown. Late-onset disease is very rare.
How
is GBS disease diagnosed and treated?
GBS disease is diagnosed when the bacterium is grown from cultures
of sterile body fluids, such as blood or spinal fluid. Cultures
take a few days to complete. GBS infections in both newborns and
adults are usually treated with antibiotics (e.g., penicillin
or ampicillin) given through a vein.
Can
pregnant women be checked for GBS?
GBS carriage can be detected during pregnancy by taking a swab
of both the vagina and rectum for special culture. Physicians
who culture for GBS carriage during prenatal visits should do
so late in pregnancy (35-37 weeks’ gestation); cultures collected
earlier do not accurately predict whether a mother will have GBS
at delivery.
A positive culture result means that the mother carries GBS --
not that she or her baby will definitely become ill. Women who
carry GBS should not be given oral antibiotics before labor because
antibiotic treatment at this time does not prevent GBS disease
in newborns. An exception to this is when GBS is identified in
urine during pregnancy. GBS in the urine should be treated at
the time it is diagnosed. Carriage of GBS, in either the vagina
or rectum, becomes important at the time of labor and delivery
-- when antibiotics are effective in preventing the spread of
GBS from mother to baby.
Can
GBS disease among newborns be prevented?
Most GBS disease in newborns can be prevented by giving certain
pregnant women antibiotics through the vein during labor. Any
pregnant woman who previously had a baby with GBS disease or who
has a urinary tract infection caused by GBS should receive antibiotics
during labor.
Pregnant women who carry GBS should be offered antibiotics at
the time of labor or membrane rupture. GBS carriers at highest
risk are those with any of the following conditions:
- fever during labor
- rupture of membranes (water breaking) 18 hours or more before delivery
- labor or rupture of membranes before 37 weeks
Because women who carry GBS but do not develop any of these three complications have a relatively low risk of delivering an infant with GBS disease, the decision to take antibiotics during labor should balance risks and benefits. Penicillin is very effective at preventing GBS disease in the newborn and is generally safe. A GBS carrier with none of the conditions above has the following risks:
- 1 in 200 chance of delivering a baby with GBS disease if antibiotics are not given
- 1 in 4000 chance of delivering a baby with GBS disease if antibiotics are given
- 1 in 10 chance, or lower, of experiencing a mild allergic reaction to penicillin (such as rash)
- 1 in 10, 000 chance of developing a severe allergic reaction--anaphylaxis--to penicillin. Anaphylaxis requires emergency treatment and can be life-threatening.
If a prenatal culture for GBS was not done or the results are not available, physicians may give antibiotics to women with one or more of the risk conditions listed above.
What
research is being done on prevention of GBS disease?
In spite of testing and antibiotic treatment, some babies still
get GBS disease. Vaccines to prevent GBS disease are being developed.
In the future, women who are vaccinated may make antibodies that
cross the placenta and protect the baby during birth and early
infancy.
Who
is at higher risk for GBS disease?
Pregnant women with the following conditions are at higher risk
of having a baby with GBS disease:
- previous baby with GBS disease
- urinary tract infection due to GBS
- GBS carriage late in pregnancy
- fever during labor
- rupture of membranes 18 hours or more before delivery
- labor or rupture of membranes before 37 weeks
Reproduced from the Centers for Disease Control.
