Method Article

Quantification of Group B Streptococcus Load in the Mouse Vaginal Lumen via Swabbing and Chromogenic Culture

February 26th, 2026

In This Article

Abstract

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Source: Patras, K. A. & Doran, K. S. A Murine Model of Group B Streptococcus Vaginal Colonization. J. Vis. Exp. (2016)

This video demonstrates the quantification of vaginal Group B Streptococcus (GBS) load in a mouse model using swabbing and chromogenic culture. It outlines the steps involved in sample collection, plating, and colony counting to quantify GBS load in the mouse vaginal lumen.

Protocol

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All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.

1. Swabbing the Vaginal Lumen to Quantify GBS Load

  1. Prepare one 1.5 ml micro-centrifuge tube per mouse by adding 100 µl of phosphate-buffered saline (PBS). Just prior to swabbing, pre-wet the swab in PBS.
  2. Restrain the mouse and insert the swab 10 mm into the vaginal lumen. Gently rotate the swab 4 times clockwise and 4 times counter clockwise, applying slight pressure to the vaginal wall.
  3. Transfer the swab to the 1.5 ml microcentrifuge tube with 100 µl of PBS. Prior to plating, vortex the microcentrifuge tube for ~15 sec to release the bacteria from the swab. Serially dilute each sample in PBS and plate 20 µl of dilutions 1:10 through 1:10,000 on differential medium agar plates prepared per the manufacturer's instructions. Incubate the plates at 37 °C for 24 hr. Group B Streptococcus (GBS) colonies will appear either bright pink or mauve in color. Other endogenous flora will be inhibited, or will appear as blue, white, or grey colonies.

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Materials

List of materials used in this article
NameCompanyCatalog NumberComments
Urethro-genital, sterile, calcium alginate swabsPuritan25-801 A 50 
CHROMagar StrepBDRG InternationalSB282 
Dulbecco's Phosphate-Buffered Salt Solution 1xCorning21-031-CV 

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Tags

Vaginal ColonizationMouse ModelSwabbing TechniqueSerial DilutionColony CountingBacterial Load QuantificationPBS BufferMicrocentrifuge Tube

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