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Test Code LAB4775 GROUP B STREP PCR

Important Note

This test is replacing CULTURE, BETA STREP B SCREEN (LAB4502)

Infectious

Specimen Type

Eswab (liquid Amies)

  • Vaginal/Rectal Specimen

Collection Instructions

Swab both the lower vagina and rectum (through the anal sphincter). Sampling both sites increases detection of colonization substantially compared with sampling the cervix or the vagina without also swabbing the rectum. (May 1, 2025 CDC recommendations) Clinical Guidelines for Group B Strep Disease).

Turnaround Time

24-48 hours

Test Schedule

Daily

Specimen Stability

Room temperature (15-30 °C ) for up to 24 hours

Refrigerated (2-8 °C) for up to 48 hours

Method

Cepheid GeneXpert Real-time PCR assay

Reference Ranges

Group B Strep by PCR: Detected*

Group B Strep by PCR: Not Detected

Group B Strep by PCR: Indeterminant*

 

*Pencillin-allergic patients that are positive for Group B Strep will automatically reflex to Group B Strep culture for susceptibility testing. Indeterminant results will also reflex to culture.

 

 

Synonyms

GBS PCR; Group B Strep; Strep Screen: Beta-Hemolytic Streptococcus; Streptococcus Group B; GBS; Culture, Beta Strep B Screen; Strep B; Strep B Screen

Test Components

Streptococcus, group B, amplified probe technique

CPT Codes

87150

Interfering Substances

Potentially interfering endogenous and exogenous substances include human amniotic fluid, urine, human blood, vaginal antifungal medications, anti- diarrheal medications, laxatives, stool softeners, topical hemorrhoid ointments, and deodorant sprays.

Specimen Rejection Criteria

  • Incorrect or expired transport medium
  • Any specimen that has leaked
  • Improper storage conditions during transport
  • Improper sample collection

Limitations

  • Culture test results may be affected by concurrent antibiotic therapy. GBS DNA may continue to be detected following antimicrobial therapy.
  • A positive result does not necessarily indicate the presence of viable organisms.
  • Mutations or polymorphisms in primer or probe binding regions may affect detection of new or unknown variants and may result in a false negative result.