Not all sore throats are "strep throats" and not all strep infections cause sore throats. It's difficult to make the diagnosis of strep throat based on the patient's symptoms or what the doctor finds on examination. Some studies have found that even experienced clinicians are right only half the time when making the diagnosis based solely on clinical findings.
The "throat culture" is considered the best way to make a definitive diagnosis of strep throat. The process involves using a long cotton tipped stick to wipe the back of the child's throat - a process that's usually difficult. The secretions are then put on a special plate and incubated. Two days later the lab reports if streptococcus bacteria are present. If so, then the child is started on an antibiotic.
When the rapid strep tests first became available, doctors could run the test in the office and know the results in 20-30 minutes. Many doctors felt comfortable that a negative test was truly negative meaning the patient didn't have a strep throat. However, some doctors don't believe a positive rapid test result. They will hold off treatment until they get the results of the throat culture back from the lab. This delay in treatment may prolong the symptoms and the number of days the child spreads the strep bacteria.
A recent study looked at the results of rapid strep tests and throat cultures of 450 people with sore throats. All had both a rapid strep test and a throat culture. The results of the rapid strep test were just as accurate as the throat cultures. The authors conclude that the rapid strep test results are accurate and treatment decisions should be made based on them. They feel there is no need for a confirmatory throat culture.
Journal of the American Board of Family Practice, 7/02, pp. 261-5.
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