Throat Swabs

From culture to molecular testing

Culture has been the mainstay for the detection of throat pathogens like Group A beta-haemolytic Streptococcus (GAS), Streptococcus pyogenes, for many decades, with other options like antigen testing lacking sensitivity. In recent years, molecular tests for GAS have become available but, in all cases, have lacked the ability to handle large volumes of specimens or been too expensive.

Over the past year r-biopharm (AusDiagnostics) have developed a molecular test to detect GAS in throat swabs, that together we have worked to validate. The test successfully detects GAS in throat swabs, is more sensitive than culture, can handle large specimen volumes, and has the potential to reduce turnaround times. Pathlab will be changing over to this new methodology at the beginning of April.

What you need to know:

  • The throat swab to collect remains unchanged, a white cap liquid Amies e-Swab.
  • The standard throat swab test will be a molecular test for GAS.
  • The result will be for the molecular detection of GAS, so you will see a change in the report.
  • If a GAS is detected and the laboratory form indicates the patient has a penicillin allergy, reflex culture will be performed so antibiotic susceptibilities are available.
  • Culture for yeast and Neisseria gonorrhoeae will still be performed but it is essential you provide clear clinical information indicating that this testing is required.

Please note that we will no longer be reporting Group C/G beta-haemolytic streptococci from throat swabs. Although there is some evidence that these organisms can cause sore throat when present in high numbers, they are not associated with post-infectious sequelae such as Rheumatic fever or Glomerulonephritis. Pharyngeal infections caused by Group C/G streptococci are self-limiting and antibiotics are generally not recommended.

We are excited about this change to throat swab testing and the potential improvements it will offer to patient management. Please come back to us if you have any questions.