Assess for Centor criteria:
- Absence of cough
- Anterior cervical adenitis
- Tonsillar exudate.
How many criteria are present?
Two types of tests are available at the point-of-care for group A strep:
- Nucleic Acid Amplification Testing
- Commercially available NAAT has demonstrated sensitivities of 95% to 100%, compared with 76% to 90% for most RADT
- POC NAAT typically costs 3 to 4 times more than traditional RADT, although NAAT provides a cost savings in cases where the ordering of a backup throat culture is avoided.
- Rapid Antigen Detection Testing/Throat Culture
- In settings where NAAT is not available, laboratory determination of GABHS is primarily done with RADT or a throat culture, with throat culture serving as the gold standard. A properly performed throat culture (swabbing the posterior pharynx and tonsils, avoiding the tongue and lips) is 90% to 95% sensitive.
- Original RADT used the latex agglutination technique, but newer RADT uses enzyme immunoassay techniques and optical immunoassay technology, which are more sensitive.
Zero or 1 Centor Criteria
2 or 3 Centor Criteria
4 or more Centor Criteria