Microbiology Test

Group B Streptococcus

Dr. Nithin Jayan
Medically Reviewed by Dr. Nithin Jayan, MBBS, DNB
Last Updated on Mar 29, 2014
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Test : Group B Streptococcus

Indications : The GBS test is usually done within 35-37 weeks of pregnancy and is ordered for the following reasons -

Monitoring for GBS during late pregnancy
If a person is receiving antibiotic treatment during labor
To reduce infection in the baby of mothers who are carriers

Swabs from the vagina and the rectum are taken and sent to the lab where they will be cultured using appropriate media that will promote the growth of GBS.

No preparation is required prior to the test. Make sure that you tell your doctor regarding any infection that you may have had during an earlier pregnancy.

Physiology : Group B streptococcus (GBS) is a kind of bacteria that is found in intestinal tract of humans. In 10-30% of women it may also be found in the vagina, rectum or in the surrounding areas. In such cases, it is possible for the bacteria to pass on to the baby during child birth. Normally GBS is harmless, but it is also known to be capable of causing stillbirth and infections in newborns. Early-onset GBS disease can cause sepsis (blood infection), pneumonia and, rarely, meningitis in the new born. In the mother it can give rise to pregnancy- related complications.

Although sexual transmission of GBS is possible, it is not a sexually- transmitted infection. GBS is also quite different from the bacteria, Strep A, that causes “strep throat” infection.

GBS test is done to detect the presence of strep A bacteria in body fluids.

Normal Range : Detection of Group B streptococcus

Interpretation :

Normal
When the test result is negative it indicates an absence of GBS.

Abnormal
When the test result is positive, it indicates the presence of GBS in the cultured sample.
If you are pregnant, a positive result means that your baby too could become infected with the bacteria and could face a life-threatening situation. Antibiotic treatment during labor, ideally four hours before delivery, takes care of your infection and also reduces the chances of infection for the baby.

Sample : Cerebrospinal fluid, blood, urine, endocervical, endometrial material, or amniotic fluid

Test Method : Agglutination reaction, Counter immnoelectrophoresis

Related Tests : Group A Streptococcus Screen, Bacterial Antigens.

References : +



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