Group B Screen by Culture Information Sheet

‌Overview

MDL Test Name

Group B Screen by Culture

MDL Test Code

GBS

Ask at Order Questions

• Does the patient have a penicillin allergy?

• Is the patient >34 weeks gestation?

  Specimen Source

  Rectovaginal

  
  

  ‌Specimen Requirements

  Container/Tube

  ESwab

  Specimen Volume (minimum)

• N/A (swab specimen)

• Must have swab present in container

  Sample Stability Time

  48 hours

  Transport/Storage Conditions

• Refrigerated (2 – 8°C)

• Ambient (20 – 25°C)

  Patient Preparation / Collection Instructions

• Remove swab from the packaging, careful not to contaminate it. Collect both a vaginal AND rectal specimen, using a single swab. Swab the lower vagina (vaginal introitus), followed by the rectum (swab should be inserted through the anal sphincter) preferably using the same swab. Move the swab from side to side, or rotate the swab at the collection site, allowing several seconds for absorption of organisms by the swab. Place the swab into transport tube and label it appropriately.

• NOTE: Cervical, perianal, perirectal, or perineal specimens have been shown to be less sensitive than co-collection of vaginal and rectal specimens and are NOT acceptable.

• Refer to the WSU MDL ESwab Collection Guide

  
  

  ‌Performance

  Days Performed

  Daily; Monday – Sunday

  Report Available (TAT) – (Once received at MDL)

  3 – 4 Days

  Specimen Retention Time

  7 days

  Method Description

• Conventional aerobic bacterial culture technique with selective and non-selective media.

• Identification methods (when appropriate) may include any of the following: conventional biochemical testing, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, commercial identification panels.

  Reference Values

  No growth of Group B Strep (Streptococcus agalactiae)

  Cautions

• This test is for perinatal screening to detect GBS colonization. For diagnosis of GBS disease in nonpregnant adults and in neonates, routine culture of the symptomatic body site should be ordered.

• Detects only the presence or absence of Group B Streptococcus.

• NOTE: Susceptibility testing is not routinely performed for Group B Screen by culture. Susceptibility testing is only performed when ‘Ask at order question’, Penicillin allergy? Is answered ‘yes’ or if an ‘add-on’ request/order is submitted within 7 days of the ‘final date’ of the report.