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Group A Streptococcus Screen-Provincial

Discipline

Microbiology

Overview

Description

Streptococcus pyogenes (Group A Streptococcus) is the most frequent cause of bacterial pharyngitis. Culture via selective media can be used to grow S. pyogenes that may be associated with infection.

Ordering Recommendations

  • Specimens may be collected from patients with signs and symptoms of pharyngitis.

Alias

  • GASS

Specimen Information

Specimen types accepted

  • Throat swab

Specimen collection container

  • E-swab collection system (preferred) or M-40 Transystem swabs

Collection procedure

  • Depress tongue gently with a tongue depressor. Sample the posterior pharynx, tonsils, and inflamed areas with swab. Avoid touching the oral mucosa or tongue with the swab.

  • NOTE: Repeat specimens received within a 24-hour period are not processed.

Required volume

  • 1 Throat swab

Transport and stability

  • Transport at room temperature, as soon as possible. If delay is anticipated, keep specimen at 4°C.

Testing Information

Relevant clinical history

  • Patient History
    • Symptoms, duration of symptoms and history of past/current antimicrobial therapy

Performance

Methodology

  • Specimen is cultured on chromogenic media for Streptococcus pyogenes (Group A Streptococcus, GAS).

Days/times performed

  • Specimens will be cultured at RUH, RGH, Victoria Hospital, or Battlefords Union Hospital.

Maximum laboratory time

  • Reports of no/non-significant growth are sent at 24 and 48 hours, if applicable.

  • Susceptibility testing is not routinely performed as organism is universally susceptible to first line treatment with beta-lactam antibiotics. If susceptibility testing is required, please clearly indicate on requisition or contact Microbiology Laboratory

Specimen retention time

  • Specimens retained for 3-7 days after culturing.

Last Updated: November 19, 2025