Strep Throat - Diagnosis
How was your strep throat diagnosed?
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How is strep throat diagnosed?
Throat culture
During the doctor's physical examination, a throat culture might be taken by touching a soft cotton swab (similar to a Q-tip) to the throat and tonsil areas. The swab is then sent to the laboratory for evaluation of strep or other bacteria. After 24-48 hours, the rapidly-growing strep bacteria can be identified if present in the sample. A throat culture is the gold standard in diagnosing strep throat infection.
A culture for strep throat should not be done as a screening test in an individual who is experiencing no symptoms suggestive of strep throat. This is because bacteria may be present without causing an infection. A person may be a carrier of the bacteria but not infected.
Rapid strep test
Rapid strep tests (also called the Rapid Antigen Detection Test or RADT) are available that can give results in minutes. A sample from the back of the throat or tonsils is taken using a swab similar to the sample for culture. Using a RADT kit, the doctor can determine within a few minutes if strep is the likely cause of sore throat. This test is less precise than throat cultures.
Most RADT tests are approximately 95% accurate in diagnosing strep throat. This implies a "false negative" rate of 5%. In such circumstances the more definitive throat culture should be obtained. If your health care professional has a high suspicion for strep throat, both tests (RADT and throat culture) may be performed, and treatment should be started as soon as possible even if the rapid test is negative for strep while waiting for the definitive culture results. If the throat culture is negative for strep infection, then antibiotics should be stopped.
Taking any "self prescribed" antibiotic prior to seeing the doctor should be avoided because even a single dose of antibiotic can interfere with the culture results and the health care practitioner's ability to correctly diagnose and treat the infection.
Blood test for strep throat infection
Streptococcus infection can be detected by measuring the antibodies produced by the body against the bacteria. Two blood tests are most commonly used: (a) ASO titer (anti streptolysin O) and (b) anti DN-ase B titer. These antibodies may not be present in the blood for a few weeks after an infection, and therefore their measurement may not be accurate to detect an active or acute infection. ASO and anti-DN-ase B titers also may not be detectable if the person had been appropriately treated with antibiotics.
These tests may be useful in detecting prior infections and evaluating a person with complications of strep throat infection such as rheumatic fever or glomerulonephritis (see below).
See what others are saying
As a child, I would get a lot of strep throat, even through my adult years. When I was 30 (I'm now 35), I developed strep again, but this time around it was the most aggressive strep I've ever had. It started on a Monday. I was given medicine and by Thursday the pain was worse and my tonsils swelled so bad that it restricted my airway. I was rushed to the emergency room with a 105-degree fever and a rash all over my body. The ER doctor said my tonsils were the biggest tonsils he's ever seen. I had them removed that evening. Knock on wood, it's been five years since I've had strep.
I became aware on Sunday evening of a headache I had not experienced before, very painful. Went to bed but was unable to sleep well. The next day I awoke with fever and vomiting. Spent most of the day on sofa feeling very ill. Tuesday my husband drove me to our doctor surgery where bloods were taken and antibiotics, painkillers were prescribed. I spent days sleeping on and off, body aching, fever, night sweats, very difficult few days. Thursday my doctor phoned and confirmed strep throat. It's now Sunday a week later I am beginning to feel better, I get fatigued at times but not lying down as much. This has been a very difficult week for me as I am a working mum of two teenagers who is very active and very rarely sits down. Good luck to you if you're reading this and you have strep throat, I wouldn't wish it on anyone.
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