Strep b testing

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.

Products & Services

Book: Mayo Clinic Family Health Book, 5th Edition
Newsletter: Mayo Clinic Health Letter — Digital Edition

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.

Request an Appointment at Mayo Clinic

From Mayo Clinic to your inbox

Sign up for free, and stay up to date on research advancements, health tips and current health topics, like COVID-19, plus expertise on managing health.

To provide you with the most relevant and helpful information, and understand which information is beneficial, we may combine your email and website usage information with other information we have about you. If you are a Mayo Clinic patient, this could include protected health information. If we combine this information with your protected health information, we will treat all of that information as protected health information and will only use or disclose that information as set forth in our notice of privacy practices. You may opt-out of email communications at any time by clicking on the unsubscribe link in the e-mail.

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

Products & Services

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

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
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
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
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
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
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
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
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
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
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
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
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
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

Blood test for streptococcus in the laboratory

Serogroup B streptococci (GBS) have long been known to cause mastitis in cattle and small cattle and have been named Streptococcus agalactiae . Previously, until 1937 inclusive, this microorganism was considered as a commensal of the human body. Since the 60s, this species, as a human pathogen, has occasionally begun to be isolated in a variety of nosological forms of infection: endocarditis, pyelonephritis, meningitis, pneumonia, abscess, peritonitis, generic sepsis, neonatal sepsis, pharyngitis, etc. Within 1970s–1980s GBS is becoming one of the most common causative agents of purulent-septic infections in newborns and mothers in the United States and Western Europe. In the early 90s, the first publications about the role of this type of streptococcus in the pathology of pregnancy and pyoinflammatory diseases of newborns also appeared in our country. To date, official registration of diseases caused by this microorganism in the Russian Federation has not been carried out.

Streptococci of this species, according to the modern nomenclature according to the Bergay determinant, are included in the genus Streptococcus family Sreptococcaeae species S.agalactiae . The modern classification of streptococci is based on the division into serological groups according to the Lensfield classification. S.agalactiae are assigned to serogroup B and are its only representatives. GBS is a heterogeneous population consisting of a number of serotypes and their combinations. Currently, 9 serotypes have been identified, designated by Roman numerals: I, II, III, IV, V, VI, VII, VIII. Type I is divided into subtypes Ia and Ib.

The habitat of the pathogen is the human body, large and small cattle, the possibility of its transmission from animals to humans and vice versa has not been proven. The localization of GBS in humans is the gastrointestinal tract (colon), vagina, urethra, sometimes the microorganism can colonize the pharynx. Pathogenicity factors: the ability to adhere and invade, resistance to phagocytosis, hemolysin, hyaluronidase, peptidase (impairs the chemotaxis of polymorphonuclear leukocytes to the site of GBS infection).

GBS can cause severe infections in people. The most sensitive to them are newborns, pregnant women, diabetics, chronic patients, children with dystrophy, the elderly, people with reduced immunity. Spontaneous abortions, preterm labor, chorioamnionitis, pyelonephritis, urinary tract infections, endocarditis, sepsis, as well as complications after caesarean section, meningitis, mastitis and endometritis in puerperas can be associated with GBS. In neonates, GBS mainly causes sepsis, meningitis, and pneumonia. Transmission of the pathogen to the newborn can occur intranatally and postnatally. According to foreign sources, in recent years there has been a relative increase in the number of diseases caused by GBS in the elderly against the background of a slight decrease in the incidence among newborns. The observed phenomenon is associated, on the one hand, with the active prevention of this infection in maternity hospitals, and, on the other hand, with an increase in the number of elderly patients with reduced immunity. In the latter, GBS usually causes infection of the skin and bones, sepsis without a clear source of its origin, urosepsis, pneumonia, and peritonitis. Often these infections occur repeatedly in such patients.

An important role in the development of GBS infections in newborns is played by factors predisposing to the disease, the so-called “risk factors”, which can be conditionally divided into two groups:

associated with the peculiarities of childbirth or colonization of mothers with GBS;
directly related to newborns.

The first group includes the presence of GBS on the mucous membrane of the cervix in pregnant women, the massiveness of colonization (isolation of the pathogen simultaneously from several examined loci), cases of GBS infections in children in anamnesis in parturient women, premature birth, a long anhydrous period, fever during childbirth, chorioamnionitis , bacteriuria due to GBS.

The second group includes the fact and massive colonization of newborns with GBS, prematurity and low birth weight, birth by caesarean section, intrauterine instrumental examination of the fetus, lasting more than 12 hours.

Penicillin is still the most effective and widely used drug for the treatment of infections caused by streptococci. Along with serogroup A streptococci, GBS retain their sensitivity to this antibiotic, although GBS strains in a small number of cases are resistant to penicillin G. In addition to penicillin, streptococci have been found to be highly sensitive to ampicillin, erythromycin, clindamycin, lincomycin, oxacillin and meroponem. The first three generations of cephalosprins, with the exception of cefoxitin and moxalactam, have a wider spectrum of activity than penicillin. The high sensitivity of GBS to a number of relatively new drugs with a wide spectrum of activity was also noted: thienamycin, mezlocillin, azlocillin and piperacillin. GBS strains have been found to be frequently resistant to aminoglycoses, nalidixic acid, tetracycline, chloramphenicol, bacitracin, trimethoprim, and metromnidazole. Nevertheless, the combined use of aminoglycosides with penicillin or ampicillin in experimental studies on laboratory animals revealed a synergistic effect of such combinations. In recent years, foreign literature reports on the isolation of GBS strains resistant to beta-lactam antibiotics. The nature of this phenomenon is associated with the appearance in the cells of microorganisms of the genes responsible for the synthesis of penicillin-binding proteins (PBPs). According to a number of foreign researchers, the number of GBS strains resistant to erythromycin can range from 5.9up to 32.0% and the number of strains resistant to clindamycin from 6.9 to 14.3%. The use of therapeutic bacteriophages for the prevention and treatment of GBS infection is currently impossible due to the lack of active specific bacteriophages.

Indications for examination. Birth of a child with a history of GBS infection in a woman in labor, GBS bacteriuria during this pregnancy, threatened preterm labor, fever during labor (≥ 38°C), waterless period lasting more than 18 hours.

Material for research. Blood, CSF, sputum, fetal fluid, joint fluid, tissue fragments, oropharyngeal swabs, vaginal swabs/scrapes, rectal swabs.

Etiological diagnosis includes isolation of the pathogen and identification of its DNA.

Comparative characteristics of laboratory diagnostic methods. Isolation of the pathogen in the diagnosis of GBS infections is the "gold standard" and is an important step in a series of diagnostic measures. A standard culture is used using, for example, 5% blood agar. Timely isolation of the pathogen with the determination of sensitivity to antibiotics largely determines the effectiveness of the treatment and prevention of this disease.

If an infection is suspected, a variety of biological material is examined. In the case of determining the carriage of GBS in pregnant women, smears from the mucous membrane of the vagina and rectum are examined for 35–37 weeks. pregnancy. If it is not possible to inoculate immediately, transport media may be used. The time needed to isolate and identify GBS is usually 4 to 5 days.

Identification of a specific DNA fragment S.agalactiae by PCR is carried out in the study of various biological material. Scrapings of epithelial cells from the side walls of the vagina, perianal smears at 34–36 weeks of gestation are examined to detect colonization of the vagina and/or rectum by S.agalactiae; blood, CSF of a newborn - for the diagnosis of septic conditions; swabs from the oropharynx - in newborns with clinical symptoms of pneumonia to confirm the diagnosis. The advantage of this study is that it allows testing within a few hours and thereby accelerates clinical decision-making on the prevention and treatment of the disease. The diagnostic sensitivity of the study is 81%, the diagnostic specificity is 97.6%. Detection of S.agalactiae DNA by PCR can be performed in a qualitative and quantitative format. The quantitative format of the test allows the study to be used to assess the degree of GBS colonization of a selected locus. However, the detection of a specific DNA fragment S.agalactiae by PCR does not allow the detection of viable microorganisms and, accordingly, their sensitivity to antibiotics.

Antigenic latex test for group B streptococcus in the Optimum medical laboratory in Sochi (Adler)

Get test results

Home
Analyzes and prices
Group B streptococcus test

More about the doctor

This study is temporarily not performed by our laboratory

Group B Streptococcus Antigen Latex Test is a laboratory test using the latex agglutination method. Group B streptococci can colonize the distal (lower) digestive tract and vagina of healthy individuals. This group of streptococci is a normal part of the microflora, but can cause infections in immunocompromised people, people with a normally functioning immune system immune to such microorganisms. Most often, pregnant women and newborns suffer from B-streptococcal infections, since their body has a reduced resistance to any infections. Infection of a child during childbirth can lead to serious consequences, including inflammation of the meninges and infection in the cerebrospinal fluid, septic complications.

The child can become infected through the penetration of microorganisms from the vagina into the uterus and fetal bladder through a violation of the integrity of the membranes. The newborn swallows contaminated amniotic fluid, sometimes they are aspirated into the respiratory tract.

Diseases associated with infection with group B streptococcus are commonly referred to as BSB ( B-streptococcal disease ). PSB may include manifestation pneumonia , inflammation of the pia mater ( meningitis ). Since the central nervous system is affected, the child may have neurological symptoms: convulsions, weakening or strengthening of reflexes. The newborn may refuse to feed, cry continuously. Body temperature rises.

Streptococci are normally present in the genital tract of women, but before delivery, obstetricians strive to achieve purity of the vagina of the 2nd or 1st degree, because. streptococci are opportunistic pathogens and therefore can cause serious illness in debilitated infants, especially premature ones. Inflammation in the central nervous system is dangerous for further neurological disability.

Diagnosis of streptococcal infection

Standard swab from the oropharynx, nasopharynx, nose (in a dry transport tube).

The study is performed before the patient is treated with antibacterial drugs. Do not pre-rinse the mouth and nose. The material is taken on an empty stomach.

A swab from the throat is taken as follows: pressing the tongue with a spatula, insert a swab between the arches of the tonsils and the uvula, collect material from the posterior surface of the pharynx, tonsils and areas of inflammation or ulceration.

Latex agglutination is an effective method for detecting streptococcal infection. This laboratory method is based on the adhesion (agglutination) of streptococcal antigens in the presence of infection, clots are visible to the naked eye.