Introduction:
Acute tonsillitis is one of the most common medical conditions for which children and young adults seek medical advice.
Laboratory diagnosis of GAS infections rely on culturing the bacteria from clinical specimens. Other methods of GAS detection include the “rapid antigen test” (RADT) and PCR amplification based.
Despite the different methods of detection, all tests are based of GAS sampling using a throat swab. Indeed obtaining the swab might 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 detection of GAS pharyngitis.
Methods:
This prospective study was performed at Hadassah medical center and Meuhedet Health Maintenance Organization clinic (HMO). For each eligible subject, a throat swab was obtained for culture and a saliva sample was taken by voluntary spitting. Real time PCR (RT-PCR) was performed for detection of GAS dnaseB specific gene in the saliva samples. Throat swab were sent for bacterial culture.
Results:
A total of 100 subjects were enrolled to the study. 56% of the throat cultures were positive for GAS and 48% of the PCR samples were positive. Overall sensitivity and specificity of the saliva PCR method was 79% and 91% respectively, NPV and PPV were 77% and 92% respectively.
Interestingly when excluding the patients who presented on the first day of fever sensitivity and specificity increased to 90% and 100% respectively.
No other Anamnestic or clinical findings on examination were found to increase the yield of the test.
Conclusion:
Saliva based PCR amplification of GAS DNA method is effective in detection of GAS pharyngitis, however further study is needed in order to achieve detection rates that will enable to replace the traditionally throat swab based approach.
