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What Does Faint Positive Rapid Strep Test Result Indicate?
Question: Hello, My 2 year old son has had symptoms of vomiting, diarrhea, and today had a red and swollen throat. Rapid strep test gave a "faint positive line" so the doctor also cultured it and prescribed antibiotic . Does a faint positive line mean positive? or negative? I am just afraid if I start him on an unnecessary antibiotic (because he really has a stomach virus) it will make his symptoms worse...
Brief Answer:
If the clinical signs are consistent then antibiotic is justified
Detailed Answer:
Hello
Thanks for the query
Streptococcal infection is one of the most common causes of red swollen throat in this age.Fever,vomiting,pain abdomen,swallowing difficulty with enlarged red tonsils and lymph nodes,sometimes associated with rashes are characteristic of streptococcal sore throat.Strep infection should be treated with antibiotic.
The other common cause is viral infection which does not need any antibiotic treatment.
In the presence of symptoms suggestive of streptococcal infection and faint line I would like to repeat the test.The faint line can be due to inadequate sample,overpouring of sample,sample near the cutoff value or some other technical issues.
Rapid antigen test has adequate sensitivity and specificity.So if it comes clearly positive there is no need of sending the culture.As the test was inconclusive(faint line) in your case culture has been sent.We will get the culture report after 48 hours.We can not wait for the culture report to start the antibiotic as the condition can worsen.
So in the present condition in which the test showed a faint line and repeat test has not been done,I would like to start the antibiotic and will wait for the culture report.The further decision to continue or discontinue the antibiotic will depend on the culture report.
I hope this helps.
I shall be glad to answer if you have any more query.
Regards
If the clinical signs are consistent then antibiotic is justified
Detailed Answer:
Hello
Thanks for the query
Streptococcal infection is one of the most common causes of red swollen throat in this age.Fever,vomiting,pain abdomen,swallowing difficulty with enlarged red tonsils and lymph nodes,sometimes associated with rashes are characteristic of streptococcal sore throat.Strep infection should be treated with antibiotic.
The other common cause is viral infection which does not need any antibiotic treatment.
In the presence of symptoms suggestive of streptococcal infection and faint line I would like to repeat the test.The faint line can be due to inadequate sample,overpouring of sample,sample near the cutoff value or some other technical issues.
Rapid antigen test has adequate sensitivity and specificity.So if it comes clearly positive there is no need of sending the culture.As the test was inconclusive(faint line) in your case culture has been sent.We will get the culture report after 48 hours.We can not wait for the culture report to start the antibiotic as the condition can worsen.
So in the present condition in which the test showed a faint line and repeat test has not been done,I would like to start the antibiotic and will wait for the culture report.The further decision to continue or discontinue the antibiotic will depend on the culture report.
I hope this helps.
I shall be glad to answer if you have any more query.
Regards
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Above answer was peer-reviewed by :
Dr. Chakravarthy Mazumdar
Answered by
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