Managing patients with negative swabs

Published on: 9th November 2022 | Updated on: 16th October 2023

Treating your infection Form – English

Treating your infection Form – Welsh

To: Pharmacists trained to provide the Sore Throat Test and Treat service in BCUHB

Dear All,

There have been some queries regarding how best to manage patients who appear to have a ‘bad’ sore throat, but who have a negative swab, so I am circulating the below advice.

  • The rapid antigen throat swab test we use has Sensitivity 96%, specificity 98%. That means, out of 100 people who have Group A beta-haemolytic streptococcal infections (GABHS), 4 will not get a positive result where this is actually the case (false negative) and 2 will not get a negative result where this is actually the case (false positive).
  •  As tonsillitis is a self-limiting infection, even if it is caused by Strep A, it should resolve in 5-7 days with or without antibiotics. NICE guidance and STTT service guidance is based on the principle that a negative test result should result in treatment of symptoms with the analgesia protocol, even if pus is present on tonsils. Pus is of equal weighting in both Centor and Fever Pain to all other symptoms, therefore its presence is not necessarily more indicative of a bacterial infection.
  • Within current BCUHB Primary Care Antimicrobial Guidelines the use of antibiotics for sore throat should generally be avoided and should normally only be considered to prevent complications of Strep infection
  •  All patients should be given safety net advice of action to be taken if symptoms do not improve or deteriorate. The attached may be of use in supporting this advice.

If you require any further clarification regarding this, please get in touch.

Kind regards


Ffôn Symudol • Mobile (07769) 934 852
e-bost • e-mail

Rhybudd Ebost (2010) – Bwrdd Iechyd Prifysgol Betsi Cadwaladr
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