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Beta strep test


Strep B Test: MedlinePlus Medical Test

What is a group B strep test?

Strep B, also known as group B strep (GBS), is a type of bacteria commonly found in the digestive tract, urinary tract, and genital area. It rarely causes symptoms or problems in adults but can be deadly to newborns.

In women, GBS is mostly found in the vagina and rectum. So a pregnant woman who is infected can pass the bacteria to her baby during labor and delivery. GBS can cause pneumonia, meningitis, and other serious illnesses in a baby. GBS infections are the leading cause of death and disability in newborns.

A group B strep test checks for GBS bacteria. If the test shows that a pregnant woman has GBS, she can take antibiotics during labor to protect her baby from infection.

Other names: group B streptococcus, group B beta-hemolytic streptococcus, streptococcus agalactiae, beta-hemolytic strep culture

What is it used for?

A group B strep test is most often used to look for GBS bacteria in pregnant women. Most pregnant women are tested as part of routine prenatal screening. It may also be used to test infants who show signs of infection.

Why do I need a group B strep test?

You may need a strep B test if you are pregnant. The American College of Obstetricians and Gynecologists recommends GBS testing for all pregnant women. Testing is usually done in the 36th or 37th week of pregnancy. If you go into labor earlier than 36 weeks, you may be tested at that time.

A baby may need a group B strep test if he or she has symptoms of infection. These include:

  • High fever
  • Trouble with feeding
  • Trouble breathing
  • Lack of energy (hard to wake up)

What happens during a group B strep test?

If you are pregnant, your health care provider may order a swab test or a urine test.

For a swab test, you will lie on your back on an exam table. Your health care provider will use a small cotton swab to take a sample of cells and fluids from your vagina and rectum.

For a urine test, you will most likely be told to use the "clean catch method" to ensure your sample is sterile. It includes the following steps.

  • Wash your hands.
  • Clean your genital area with a cleansing pad given to you by your provider. To clean, open your labia and wipe from front to back.
  • Start to urinate into the toilet.
  • Move the collection container under your urine stream.
  • Collect at least an ounce or two of urine into the container, which should have markings to indicate the amounts.
  • Finish urinating into the toilet.
  • Return the sample container as instructed by your health care provider.

If your baby needs testing, a provider may do a blood test or a spinal tap.

For a blood test, a health care professional will use a small needle to take a blood sample from your baby's heel. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. Your baby may feel a little sting when the needle goes in or out.

A spinal tap, also known as a lumbar puncture, is a test that collects and looks at spinal fluid, the clear liquid that surrounds the brain and spinal cord. During the procedure:

  • A nurse or other health care provider will hold your baby in a curled-up position.
  • A health care provider will clean your baby's back and inject an anesthetic into the skin, so your baby won't feel pain during the procedure. The provider may put a numbing cream on your baby's back before this injection.
  • The provider may also give your baby a sedative and/or pain reliever to help him or her better tolerate the procedure.
  • Once the area on the back is completely numb, your provider will insert a thin, hollow needle between two vertebrae in the lower spine. Vertebrae are the small backbones that make up the spine.
  • The provider will withdraw a small amount of cerebrospinal fluid for testing. This will take about five minutes.

Will I need to do anything to prepare for the test?

You don't any special preparations for group B strep tests.

Are there any risks to the test?

There is no risk to you from a swab or urine test. Your baby may have slight pain or bruising after a blood test, but that should go away quickly. Your baby will likely feel some pain after a spinal tap, but that shouldn't last too long. There is also a small risk of infection or bleeding after a spinal tap.

What do the results mean?

If you are pregnant and results show you have GBS bacteria, you will be given antibiotics intravenously (directly to your veins) during labor, at least four hours before delivery. This will prevent you from passing the bacteria to your baby. Taking antibiotics earlier in your pregnancy is not effective, because the bacteria can grow back very quickly. It's also more effective to take antibiotics through your vein, rather than by mouth.

You may not need antibiotics if you are having a planned delivery by Cesarean section (C-section). During a C-section, a baby is delivered through the mother's abdomen rather than vaginally. But you still should be tested during pregnancy because you may go into labor before your scheduled C-section.

If your baby's results show a GBS infection, he or she will be treated with antibiotics. If your provider suspects a GBS infection, he or she may treat your baby before test results are available. This is because GBS can cause serious illness or death.

If you have questions about your results or your baby's results, talk to your health care provider.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about a group B strep test?

Strep B is one type of strep bacteria. Other forms of strep cause different types of infections. These include strep A, which causes strep throat, and streptococcus pneumoniae, which causes the most common type of pneumonia. Streptococcus pneumonia bacteria can also cause infections of the ear, sinuses, and bloodstream.

References

  1. ACOG: The American College of Obstetricians and Gynecologists [Internet]. Washington D.C.: American College of Obstetricians and Gynecologists; c2019. Group B Strep and Pregnancy; 2019 Jul [cited 2019 Nov 15]; [about 3 screens]. Available from: https://www.acog.org/Patients/FAQs/Group-B-Strep-and-Pregnancy
  2. Centers for Disease Control and Prevention [Internet]. Atlanta: U.S. Department of Health and Human Services; Group B Strep (GBS): Prevention; [cited 2019 Nov 15]; [about 4 screens]. Available from: https://www.cdc.gov/groupbstrep/about/prevention.html
  3. Centers for Disease Control and Prevention [Internet]. Atlanta: U.S. Department of Health and Human Services; Group B Strep (GBS): Signs and Symptoms; [cited 2019 Nov 15]; [about 4 screens]. Available from: https://www.cdc.gov/groupbstrep/about/symptoms.html
  4. Centers for Disease Control and Prevention [Internet]. Atlanta: U.S. Department of Health and Human Services; Streptococcus Laboratory: Streptococcus pneumoniae; [cited 2019 Nov 15]; [about 3 screens]. Available from: https://www.cdc.gov/streplab/pneumococcus/index.html
  5. Centers for Disease Control and Prevention [Internet]. Atlanta: U.S. Department of Health and Human Services; Travelers' Health: Pneumococcal Disease; [updated 2014 Aug 5; cited 2019 Nov 15]; [about 3 screens]. Available from: https://wwwnc.cdc.gov/travel/diseases/pneumococcal-disease-streptococcus-pneumoniae
  6. Intermountain Healthcare: Primary Children's Hospital [Internet]. Salt Lake City: Intermountain Healthcare; c2019. Lumbar Puncture in a Newborn; [cited 2019 Nov 15]; [about 4 screens]. Available from: https://intermountainhealthcare.org/ext/Dcmnt?ncid=520190573
  7. Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2019. Blood Culture; [updated 2019 Sep 23; cited 2019 Nov 15]; [about 2 screens]. Available from: https://labtestsonline. org/tests/blood-culture
  8. Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2019. Prenatal Group B Strep (GBS) Screening; [updated 2019 May 6; cited 2019 Nov 15]; [about 2 screens]. Available from: https://labtestsonline.org/tests/prenatal-group-b-strep-gbs-screening
  9. Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2019. Urine Culture; [updated 2019 Sep 18; cited 2019 Nov 15]; [about 2 screens]. Available from: https://labtestsonline.org/tests/urine-culture
  10. Michigan Medicine: University of Michigan [Internet]. Ann Arbor (MI): Regents of the University of Michigan; c1995–2021. Group B Streptococcal Infections in Newborns[cited 2021 Aug 6]; [about 3 screens]. Available from: https://www.uofmhealth.org/health-library/zp3014spec
  11. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2019. Health Encyclopedia: Group B Streptococcus Infection in Babies; [cited 2019 Nov 15]; [about 2 screens]. Available from: https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=90&contentid=P02363
  12. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2019. Health Encyclopedia: Pneumonia; [cited 2019 Nov 15]; [about 2 screens]. Available from: https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=85&contentid=P01321
  13. WHO Guidelines on Drawing Blood: Best Practices in Phlebotomy [Internet]. Geneva (SUI): World Health Organization; c2010. 6. Paediatric and neonatal blood sampling; [cited 2019 Nov 15]; [about 3 screens]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK138647

Group B strep disease - Symptoms and causes

Overview

Group B strep (streptococcus) is a common bacterium often carried in the intestines or lower genital tract. The bacterium is usually harmless in healthy adults. In newborns, however, it can cause a serious illness known as group B strep disease.

Group B strep can also cause dangerous infections in adults with certain chronic medical conditions, such as diabetes or liver disease. Older adults are at increased risk of illness due to group B strep, too.

If you're a healthy adult, there's nothing you need to do about group B strep. If you're pregnant, get a group B strep screening test during your third trimester. If you have group B strep, antibiotic treatment during labor can protect your baby.

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Symptoms

Infants

Most babies born to women carrying group B strep are healthy. But the few who are infected by group B strep during labor can become critically ill.

In infants, illness caused by group B strep can be within six hours of birth (early onset) — or weeks or months after birth (late onset).

Signs and symptoms might include:

  • Fever
  • Low body temperature
  • Difficulty feeding
  • Sluggishness, limpness or weak muscle tone
  • Difficulty breathing
  • Irritability
  • Jitteriness
  • Seizures
  • Rash
  • Jaundice

Adults

Many adults carry group B strep in their bodies — usually in the bowel, vagina, rectum, bladder or throat — and have no signs or symptoms.

In some cases, however, group B strep can cause a urinary tract infection or other more-serious infections. Signs and symptoms of infections that may be caused by group B strep include the following.

Urinary tract infection

  • A strong, persistent urge to urinate
  • A burning sensation or pain when urinating
  • Passing frequent, small amounts of urine
  • Urine that appears red, bright pink or cola colored — a sign of blood in the urine
  • Pelvic pain

Blood infection (bacteremia)

  • Fever
  • Chills
  • Confusion or lack of alertness

Pneumonia

  • Fever
  • Chills
  • Cough
  • Shortness of breath
  • Chest pain when you breathe or cough

Skin or soft-tissue infection

  • Swelling, warmth or redness in the area of the infection
  • Pain in the area of the infection
  • Lesions with pus or drainage

Bone or joint infection

  • Fever
  • Chills
  • Swelling, warmth or redness over the area of the infection
  • Pain in the area of the infection
  • Stiffness or inability to use a limb or joint

When to see a doctor

If you have signs or symptoms of group B strep infection — particularly if you're pregnant, you have a chronic medical condition or you're older than 65 — contact your doctor right away.

If you notice your infant has signs or symptoms of group B strep disease, contact your baby's doctor immediately.

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Causes

Many healthy people carry group B strep bacteria in their bodies. You might carry the bacteria in your body for a short time — it can come and go — or you might always have it. Group B strep bacteria aren't sexually transmitted, and they're not spread through food or water. How the bacteria are spread to anyone other than newborns isn't known.

Group B strep can spread to a baby during a vaginal delivery if the baby is exposed to — or swallows — fluids containing group B strep.

Risk factors

Infants

An infant is at increased risk of developing group B strep disease if:

  • The mother carries group B strep in her body
  • The baby is born prematurely (earlier than 37 weeks)
  • The mother's water breaks 18 hours or more before delivery
  • The mother has an infection of the placental tissues and amniotic fluid (chorioamnionitis)
  • The mother has a urinary tract infection during the pregnancy
  • The mother's temperature is greater than 100. 4 F (38 C) during labor
  • The mother previously delivered an infant with group B strep disease

Adults

Adults age 65 and older are at increased risk of group B strep. You're also at increased risk of if you have a condition that impairs your immune system or other serious diseases, including the following:

  • Diabetes
  • HIV infection
  • Liver disease
  • Heart disease
  • Cancer or history of cancer

Complications

Group B strep infection can lead to life-threatening disease in infants, including:

  • Pneumonia
  • Inflammation of the membranes and fluid surrounding the brain and spinal cord (meningitis)
  • Infection in the bloodstream (bacteremia)

If you're pregnant, group B strep can cause the following:

  • Urinary tract infection
  • Infection of the placenta and amniotic fluid (chorioamnionitis)
  • Infection of the membrane lining the uterus (endometritis)
  • Bacteremia

If you're an older adult or you have a chronic health condition, group B strep bacteria can lead to any of the following conditions:

  • Skin infection
  • Bacteremia
  • Urinary tract infection
  • Pneumonia
  • Bone and joint infections
  • Infection of the heart valves (endocarditis)
  • Meningitis

Prevention

If you're pregnant, the American College of Obstetricians and Gynecologists recommends a group B strep screening during weeks 36 to 37 of pregnancy. Your doctor will take swab samples from your vagina and rectum and send them to a lab for testing.

A positive test indicates that you carry group B strep. It doesn't mean that you're ill or that your baby will be affected, but that you're at increased risk of passing the bacteria to your baby.

To prevent group B bacteria from spreading to your baby during labor or delivery, your doctor can give you an IV antibiotic — usually penicillin or a related drug — when labor begins.

If you're allergic to penicillin or related drugs, you might receive clindamycin or vancomycin as an alternative. Because the effectiveness of these alternatives is not well understood, your baby will be monitored for up to 48 hours.

Taking oral antibiotics ahead of time won't help because the bacteria can return before labor begins.

Antibiotic treatment during labor is also recommended if you:

  • Have a urinary tract infection
  • Delivered a previous baby with group B strep disease
  • Develop a fever during labor
  • Haven't delivered your baby within 18 hours of your water breaking
  • Go into labor before 37 weeks and haven't been tested for group B strep

Vaccine in development

Although it's not available yet, researchers are working on a group B strep vaccine that could help prevent group B strep infections in the future.

By Mayo Clinic Staff

Related

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Culture for group B beta-hemolytic streptococcus (Streptococcus group B, S. agalactiae)

Method of determination The study is carried out by the method of sowing on dense nutrient media. The identification of microorganisms is carried out by mass spectrometry using a Microflex Brucker Daltonik MALDI Biotyper, BRUKER, Germany.

Test material A swab from the entrance to the vagina or anorectal area; vaginal discharge, cervical discharge

Home visit available

Synonyms: Streptococcus group B (S. agalactiae) Culture.

Brief description of the study "Culture for group B beta-hemolytic streptococcus (Streptococcus group B, S. agalactiae)"

Group B streptococcus (GBS, Streptococcus agalactiae) causes severe illness in newborns and is dangerous for certain patients other age groups.

In the vast majority of cases, newborns become infected with GBS during maternal deliveries, with a higher incidence during vaginal delivery. GBS causes early neonatal infections such as sepsis, meningitis, pneumonia, osteomyelitis, arthritis, and pyelonephritis, with rates ranging from 0.2 to 5 or more per 1,000 live births in different countries. In obstetric practice, group B streptococcus is associated with bacteremia, urinary tract infections, chorioamnionitis, premature rupture of amniotic fluid, preterm labor, postpartum endometritis, etc.

GBS in the human body can colonize the oropharynx, anal area of ​​the rectum, vagina (usually vestibule), urogenital tract, skin.

It has been established that GBS in 5-35% of women can be detected in the vagina and often in the urethra of their sexual partners A significant association of carriage of GBS in the vagina has been shown not only with early septicemia of newborns, but also with spontaneous miscarriages, premature birth, premature rupture of amniotic fluid , urinary infection in pregnant women, the birth of children with low body weight, the development of chorioamnionitis in childbirth, endometritis and sepsis in puerperas. The highest level of colonization in women of reproductive age and pregnant women. In pregnant women, GBS is isolated from the listed areas in 7-30% of cases (more often in young people who have high sexual activity or use intrauterine contraceptives). Of these, 60-75% remain GBS carriers until the end of pregnancy.

Vaginal-rectal swabs are collected to detect colonization of the vagina of pregnant women with group B streptococcus. In all other cases, the biomaterial is taken only if there are clinical signs of infection.

GBS has a natural sensitivity to beta-lactam antibiotics, including penicillins. Determination of sensitivity is necessary in cases where the patient has an individual intolerance to drugs of this group.

Isolateable microorganisms and pathogens:

  • Streptococcus agalactiae.

What is the purpose of culture for group B beta-hemolytic streptococcus (Streptococcus group B, S. agalactiae)? in order to identify bacteriocarrier and determine the need for antibiotic prophylaxis during childbirth, to prevent neonatal complications (septicemia, pneumonia and neonatal meningitis).

What can affect the result of the test "Culture for beta-hemolytic streptococcus group B (Streptococcus group B, S. agalactiae)"

Failure to follow the rules for preparing for the study may affect the result of the test.

Rapid strep throat tests

EnglishUkr/Rus

Guziy A.V.

  • Editorial staff of the Ukrainian Medical Journal

Summary. Medical Technology Instructions for Use published


In acute viral or bacterial tonsillitis, patients usually notice an improvement in their condition within a week and do not need medical intervention. In the case when pharmacological treatment is still necessary, according to the recommendations of NICE (National Institute for Health and Care Excellence - National Institute for Health Excellence), UK, patients with a bacterial infection should first be identified using the FeverPAIN or Centor rating scale. Their results, together with the data of the clinical study, serve as a criterion for refusing antibiotic therapy, or prescribing a reserve group agent, or immediately starting antibiotic therapy.

Rapid tests

In May 2018, NICE published a medical technology guide for 11 rapid tests for group A β-hemolytic streptococcus in throat infection, which are complementary to current clinical assessment methods. Compared to the laboratory study of the culture of swabs of the mucous membrane of the throat, the innovative aspect of rapid tests, due to the time savings, makes it possible to use the latter in primary health care. The initial cost of testing may be reimbursable if it improves antimicrobial treatment, reduces antibiotic resistance, and improves patient satisfaction. The compilers of the instructions took into account all currently identified rapid testing methods, in accordance with the inclusion criteria. However, various revisions and additions are possible in the future.

Most (9 out of 11) are rapid antigen detection tests, 8 of which are based on immunochromatographic assay. To perform it, it is necessary to place a sample of a swab from the throat on the absorbent area of ​​the test strip. In the presence of group A streptococcus, the sample should cause a line to appear as it moves along the test strip containing the corresponding antigen. The result is evaluated either visually or with the help of a reading analyzer. One of the remaining tests for determining the antigen uses a turbodimetric analysis method based on a change in optical properties in the presence of an antigen-antibody complex. In the other two, either a nucleic acid amplification method, or a polymerase chain reaction, or an isothermal amplification of a nucleic acid in a certain segment of the streptococcus genome. During the polymerase chain reaction, fluorescent probes label DNA molecules, producing a glow that is determined by the reading analyzer. The test is considered positive when a certain fluorescence threshold is reached within a set time (usually up to 15 minutes).

Reasonable use

A FeverPAIN score of 4 or 5 (Centor score of 3 or 4) indicates a high likelihood of streptococcal infection and is a criterion for prescribing antibiotic therapy.

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