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Agreement between rapid antigen detection test and culture for group A streptococcus in patients recently treated for pharyngotonsillitis - a prospective observational study in primary care

Rystedt, Karin ; Hedin, Katarina LU ; Tyrstrup, Mia LU ; Skoog-Ståhlgren, Gunilla ; Edlund, Charlotta ; Giske, Christian G. ; Gunnarsson, Ronny and Sundvall, Pär Daniel (2023) In Scandinavian Journal of Primary Health Care 41(1). p.91-97
Abstract

Objective: The aim was to compare rapid antigen detection test (RADT) and throat culture for group A streptococci (GAS) among patients recently treated with penicillin V for GAS pharyngotonsillitis. Design and setting: The study was a secondary analysis within a randomized controlled trial comparing 5 versus 10 days of penicillin V for GAS pharyngotonsillitis. Patients were recruited at 17 primary health care centres in Sweden. Subjects: We included 316 patients ≥ 6 years of age, having 3–4 Centor criteria, a positive RADT and a positive throat culture for GAS at inclusion, and also having a RADT and throat culture for GAS taken at a follow-up visit within 21 days. Main outcome measures: RADT and conventional throat culture for GAS.... (More)

Objective: The aim was to compare rapid antigen detection test (RADT) and throat culture for group A streptococci (GAS) among patients recently treated with penicillin V for GAS pharyngotonsillitis. Design and setting: The study was a secondary analysis within a randomized controlled trial comparing 5 versus 10 days of penicillin V for GAS pharyngotonsillitis. Patients were recruited at 17 primary health care centres in Sweden. Subjects: We included 316 patients ≥ 6 years of age, having 3–4 Centor criteria, a positive RADT and a positive throat culture for GAS at inclusion, and also having a RADT and throat culture for GAS taken at a follow-up visit within 21 days. Main outcome measures: RADT and conventional throat culture for GAS. Results: This prospective study showed 91% agreement between RADT and culture at follow-up within 21 days. Only 3/316 participants had negative RADT with a positive throat culture for GAS at follow-up, and 27/316 patients with positive RADT had a negative culture for GAS. Log rank test did not reveal any difference in the decline over time of positive tests between RADT and throat culture (p = 0.24). Agreement between RADT and throat culture for GAS at the follow-up was not associated with treatment duration, number of days from inclusion until follow-up, throat symptoms at follow-up, gender, or age. Conclusion: RADT and culture for GAS agreed to a high extent also after recent penicillin V treatment. RADT for GAS means a low risk for missing the presence of GAS.KEY POINTS Testing for group A streptococci (GAS) before antibiotic treatment can reduce antibiotic prescription for pharyngotonsillitis. It has been proposed that rapid antigen detection tests (RADT) for group A streptococci after recent penicillin V treatment may be falsely positive due to possible persisting antigens from non-viable bacteria. The decline of the presence of GAS was similar between RADT and conventional throat culture in patients who had recently completed penicillin V treatment for GAS pharyngotonsillitis RADT for GAS is useful in identifying the presence of GAS after recent penicillin V treatment.

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; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
primary care, rapid antigen detection test, Streptococcal pharyngotonsillitis
in
Scandinavian Journal of Primary Health Care
volume
41
issue
1
pages
7 pages
publisher
Taylor & Francis
external identifiers
  • pmid:36880344
  • scopus:85150433599
ISSN
0281-3432
DOI
10.1080/02813432.2023.2182631
language
English
LU publication?
yes
id
13c7f019-70a6-48d0-bf26-91aa95d0070c
date added to LUP
2023-08-08 14:55:54
date last changed
2025-01-26 04:19:53
@article{13c7f019-70a6-48d0-bf26-91aa95d0070c,
  abstract     = {{<p>Objective: The aim was to compare rapid antigen detection test (RADT) and throat culture for group A streptococci (GAS) among patients recently treated with penicillin V for GAS pharyngotonsillitis. Design and setting: The study was a secondary analysis within a randomized controlled trial comparing 5 versus 10 days of penicillin V for GAS pharyngotonsillitis. Patients were recruited at 17 primary health care centres in Sweden. Subjects: We included 316 patients ≥ 6 years of age, having 3–4 Centor criteria, a positive RADT and a positive throat culture for GAS at inclusion, and also having a RADT and throat culture for GAS taken at a follow-up visit within 21 days. Main outcome measures: RADT and conventional throat culture for GAS. Results: This prospective study showed 91% agreement between RADT and culture at follow-up within 21 days. Only 3/316 participants had negative RADT with a positive throat culture for GAS at follow-up, and 27/316 patients with positive RADT had a negative culture for GAS. Log rank test did not reveal any difference in the decline over time of positive tests between RADT and throat culture (p = 0.24). Agreement between RADT and throat culture for GAS at the follow-up was not associated with treatment duration, number of days from inclusion until follow-up, throat symptoms at follow-up, gender, or age. Conclusion: RADT and culture for GAS agreed to a high extent also after recent penicillin V treatment. RADT for GAS means a low risk for missing the presence of GAS.KEY POINTS Testing for group A streptococci (GAS) before antibiotic treatment can reduce antibiotic prescription for pharyngotonsillitis. It has been proposed that rapid antigen detection tests (RADT) for group A streptococci after recent penicillin V treatment may be falsely positive due to possible persisting antigens from non-viable bacteria. The decline of the presence of GAS was similar between RADT and conventional throat culture in patients who had recently completed penicillin V treatment for GAS pharyngotonsillitis RADT for GAS is useful in identifying the presence of GAS after recent penicillin V treatment.</p>}},
  author       = {{Rystedt, Karin and Hedin, Katarina and Tyrstrup, Mia and Skoog-Ståhlgren, Gunilla and Edlund, Charlotta and Giske, Christian G. and Gunnarsson, Ronny and Sundvall, Pär Daniel}},
  issn         = {{0281-3432}},
  keywords     = {{primary care; rapid antigen detection test; Streptococcal pharyngotonsillitis}},
  language     = {{eng}},
  number       = {{1}},
  pages        = {{91--97}},
  publisher    = {{Taylor & Francis}},
  series       = {{Scandinavian Journal of Primary Health Care}},
  title        = {{Agreement between rapid antigen detection test and culture for group A streptococcus in patients recently treated for pharyngotonsillitis - a prospective observational study in primary care}},
  url          = {{http://dx.doi.org/10.1080/02813432.2023.2182631}},
  doi          = {{10.1080/02813432.2023.2182631}},
  volume       = {{41}},
  year         = {{2023}},
}