The use of bacterial DNA from saliva for the detection of GAS pharyngitis

Abstract

Background Acute tonsillitis is a very common medical condition. Despite different methods of detection, all tests are based on GAS sampling using a throat swab. However, obtaining the swab can elicit vomiting and is often accompanied by fear and apprehension in children. The aim of this study was to find a non-invasive method for the detection of GAS pharyngitis. Methods A classic throat swab was obtained for culture, and a saliva sample was taken from 100 subjects recruited from Meuhedet Health Care Organization clinic. Real time PCR was performed to detect GAS dnaseB specific gene in the saliva samples. Results 56% of the throat cultures and 48% of the PCR samples were positive for GAS. The overall sensitivity and specificity of the saliva PCR method was 79% and 91% respectively; NPV and PPV were 77% and 92% respectively. When excluding patients who presented on the first day of fever, sensitivity and specificity increased to 90% and 100% respectively. No other anamnestic or clinical findings increased the yield of the test. Conclusion Saliva-based PCR amplification of GAS DNA method is effective in detection of GAS pharyngitis. Further studies are needed to achieve detection rates to replace the traditional throat swab-based approach.

Keywords

• streptococcus group a
• pharyngitis
• tonsillitis
• throat swab
• pcr
• saliva