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Published on: September 25, 2014
Rapid strep testing in children with recently treated streptococcal pharyngitis
Amin J Barakat1, Coni Evans2, Monica Gill3
1Georgetown University Medical Center Washington DC USA.
Insights
Rapid antigen-detection tests (RADTs) show a higher false positive rate in children recently treated for group A Streptococcus (GAS) pharyngitis. Throat cultures are recommended for these children to avoid antibiotic overuse.
Area of Science:
- Pediatric infectious diseases
- Diagnostic test accuracy
Background:
- Rapid antigen-detection tests (RADTs) are standard for diagnosing group A Streptococcus (GAS) pharyngitis.
- Concerns exist regarding increased false positives in recently treated GAS patients, potentially leading to antibiotic overuse.
Purpose of the Study:
- To investigate if RADTs exhibit an elevated false positive rate in children recently treated for GAS pharyngitis.
Main Methods:
- A prospective study compared 300 children recently treated for GAS pharyngitis (study group) with 306 untreated children (control group).
- Both RADT and throat cultures were performed on all participants presenting with acute pharyngitis symptoms.
- False positive and false negative rates were calculated and compared between the groups.
Main Results:
- The study group showed a significantly higher false positive rate of 11.5% compared to 0% in the control group.
- False positives were more prevalent in younger children within the study group.
Conclusions:
- RADTs are generally reliable but can lead to overtreatment in children recently treated for GAS.
- For children treated for GAS within 28 days, throat cultures are essential for confirming active infection.
- Positive RADT results should guide treatment decisions primarily in children not recently treated for GAS.
Importance:
The use of the rapid antigen-detection test (RADT) has become the standard of care in the early diagnosis of group A beta-hemolytic Streptococcus (GAS) pharyngitis. Concern has been expressed over increased false positives when the child had been treated recently for GAS pharyngitis, resulting in over use of antibiotics.
Objective:
To determine if the false positive rate for RADT is increased in children recently treated for GAS pharyngitis.
Methods:
We conducted a prospective study to evaluate 300 children from a private practice with acute pharyngitis who were treated for GAS pharyngitis within the preceding 28 days (study group) compared to 306 children of comparable age who had not been previously treated (control group). RADT and throat culture were performed on all children presenting with signs and symptoms of acute pharyngitis. The false positive and false negative rates were determined and compared in both groups.
Results:
The false positive rate of 11.5% (23/200) in the study group was significantly higher than the false positive rate of 0 in the control group. False positives were more likely to occur in younger children.
Interpretation:
These data would indicate that while RADT is reliable in most children, it can lead to over treatment in children who have been recently treated for GAS. In children treated in the preceding 28 days for GAS pharyngitis, the presence of infection should be determined with a throat culture only. Treatment based on a positive RADT should be reserved for children not recently treated for GAS pharyngitis.
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