Sore throat may be due to viruses or bacteria. Signs that point toward the cause include:
Viral: associated with cough/runny nose
Bacterial: no cold symptoms, sometimes headache or stomach ache
Typical symptoms of strep include fever, sore throat, enlarged lymph nodes, headache and stomachache. While vomiting is not typically a symptom of strep, we have been seeing more of this presentation this spring.
When NOT to test:
Cough is a sign making it unlikely that it is caused by strep throat and testing is discouraged if cough is a presenting symptom. This is because in those cases, a virus is most likely the cause of the sore throat. Up to 20% of school age kids may be carrying strep at any given time, and testing in cases of apparent viral infections (as in cases without fever or in the presence of cough) will lead to increased detection of benign ‘ carrier ‘ strep and the unnecessary use of antibiotics.
Strep also rarely infects children under age 3 years, and when it does it does not lead to rheumatic heart disease, known as acute rheumatic fever , the primary reason we treat strep as in most cases it will resolve on its own. With some exceptions, we do not test children under 3 years of age for strep.
There are different strains of strep. Group A strep is the variant that we test for as it is the strain with the potential to lead to complications. Other strains of strep such as group G and group C are considered normal flora (routinely found in the body) and in most cases do not need to be treated.
How do we test?
Molecular rapid: this test is similar to a PCR and is considered to be highly accurate as a standalone test as the standard of care. It does not need to be backed up by a culture. Most of our patients will receive this test and have a result within 10-15 minutes.
Rapid antigen: this test takes about 5 minutes but is less accurate than a molecular rapid test. Therefore it must be backed up by a culture which can take 3-5 days to return. We use this test for patients whose insurances do not cover the molecular test.
Guidelines for treatment of strep from the Infectious Disease Society of America can be found here: https://www.aafp.org/pubs/afp/issues/2013/0901/p338.html