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To screen a pregnant woman for the presence of group B streptococcus (GBS) in her vagina or rectum to determine the risk that she will pass the bacteria on to her newborn during labor and delivery, possibly resulting in a serious infection in her newborn called early-onset GBS
When a woman is between 35 and 37 weeks of pregnancy or has preterm labor or preterm premature rupture of membranes
A swab obtained from the vagina and rectum of a pregnant woman; a urine sample collected anytime during pregnancy may be used to detect significant numbers of GBS.
Group B strep (GBS) is the common name for the bacterium Streptococcus agalactiae that can be present (colonizing) in the digestive tract and genital tract. It rarely causes symptoms or problems in healthy adults but can cause infections and serious illness in newborns who become infected before or during labor and delivery. GBS screening identifies the presence of the bacteria in the vaginal/rectal area of a pregnant woman.
GBS can cause early-onset GBS disease that occurs within the first week after birth. Signs and symptoms in newborns include fever, difficulty with feeding and breathing, irritability or lethargy, and a blue tint to the skin. GBS can cause serious infections such as pneumonia, sepsis, and meningitis. According to the Centers for Disease Control and Prevention, it is the most common cause of life-threatening infections in newborns.
Approximately 25% of pregnant women carry group B strep in their rectum or vagina. However, the number of infants with GBS disease has decreased significantly in recent years because of a concerted effort by healthcare practitioners to screen pregnant women for GBS late in their pregnancy and, when they are positive for GBS, to treat them with intravenous antibiotics (usually penicillin or ampicillin) during labor. This prevents or greatly decreases the risk of passing the bacteria to the newborn. Nevertheless, GBS disease remains the primary cause of early-onset sepsis, a serious and life-threatening infection in newborns.
Currently there is no vaccine available to prevent GBS, and treating all pregnant women with antibiotics is not practical. Screening for GBS and appropriate treatment continues to be the best means for preventing GBS disease in newborns.
For screening pregnant women, a swab is typically obtained from the vagina and rectum. Urine collected during pregnancy may be cultured for significant numbers of GBS.
No test preparation is needed.
A prenatal screening test for group B strep (GBS) is used to detect the presence of this bacteria in the vagina or rectum of pregnant women. About 25% of pregnant women are colonized by GBS. Screening is used to determine the risk that they will pass the bacteria to their newborns during birth, possibly causing a serious infection called early-onset GBS.
The Centers for Disease Control and Prevention (CDC) recommend:
Healthcare practitioners check newborns soon after birth for signs and symptoms of GBS and sepsis, and if present, perform additional testing (e.g., culture of the infant's blood or spinal fluid) and treating newborns promptly if necessary.
GBS testing may include the following:
Group B strep screening is usually ordered when a woman is 35 to 37 weeks pregnant. A woman can be positive for GBS at one time during her pregnancy and negative at another. That is why it is important to screen a woman late in her pregnancy, closer to the time when she will deliver and could potentially pass the bacteria to her newborn.
Testing should also be performed when a woman goes into labor prior to 35 weeks of pregnancy to determine her GBS status.
A positive test for GBS in a healthy pregnant woman means that the bacteria are currently present in her vagina and/or rectum and she is at risk of passing the bacteria to her infant. She should be given antibiotics intravenously during labor to prevent spreading the bacteria to her baby. This treatment is known as intrapartum prophylaxis.
Pregnant women who have a urine culture positive for significant numbers of GBS any time during their pregnancy should receive appropriate intrapartum prophylaxis to prevent disease in their infants.
A negative result means that the woman is not likely to have GBS in the areas tested. No intrapartum prophylaxis is recommended unless she has other risk factors.
Every pregnant woman should know her GBS status before she delivers and discuss with her healthcare practitioner what antibiotic treatment will be given during her labor if she is positive for GBS.
CDC recommendations represent contributions from and a consensus amongst a large number of national health organizations, including the American College of Obstetricians and Gynecologists, the American Academy of Pediatrics, the American College of Nurse-Midwives, the American Academy of Family Physicians, and the American Society for Microbiology.
Administering antibiotics during labor to those who are colonized with GBS has greatly decreased the incidence of babies born with early-onset GBS infection. A GBS vaccine is not currently available.
No. It is a common bacterium that colonizes both men and women and is not considered an STD.
No. Since about 75% of pregnant women are not colonized by GBS at the time of delivery, it makes the most sense to treat the 25% who are. The numbers of GBS present can vary throughout a woman's pregnancy, so treatment earlier during a pregnancy does not ensure that GBS is not present at the time of delivery.
Infants can also contract late-onset GBS infection from 7 days to several months after birth. Late-onset disease is not preventable by administering antibiotics during labor since the bacteria are not acquired during pregnancy or during the birth process.
Group A streptococcus (GAS) and group B streptococcus (GBS) are similar types of bacteria, but they cause different types of infections. Group A strep is not usually part of the normal bacterial flora. It is the bacteria that causes "strep throat" that is detected using a rapid strep test or a throat culture. Group A strep may also cause severe skin and wound infections. Group B strep can be part of the normal bacteria found in the throat, vaginal tract, and digestive tract. GBS causes infections in newborns and in adults with weakened immune systems.
Yes. Although GBS usually does not cause illness in healthy adults, it may cause infections of the lining of the uterus (endometritis) in women who have given birth (postpartum) or who have undergone other obstetric or gynecological procedures. GBS also causes wound infections and serious blood and central nervous system infections in adults, especially in those who have diabetes.
GBS can also cause skin infections, pneumonia, septicemia and urinary tract infections (UTI) in the elderly and those with underlying health conditions and/or weakened immune systems, congestive heart failure, vascular disease, liver disease, heart disease, AIDS, or cancer.
General screening of asymptomatic people, as it is discussed in this article, is not performed in these populations. Cultures of the affected areas of the body are done only if signs and symptoms of infection are present.
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