Why does a negative rapid strep test result need to be confirmed by a throat culture?
A chief contention is whether negative tests result from a rapid analysis of a throat swab, done in a doctor’s office, should be confirmed through a follow-up laboratory culture. The rapid test detects certain antigens, one of the body’s efforts to fight off strep bacteria.
How common is a false negative rapid strep test?
The clinical issue is that rapid strep tests have very high specificity – in the range of 98 percent to 99 percent – so there are very few false positives. However, the sensitivity of most current rapid strep tests ranges from 90 percent to 95 percent, so there is a greater chance of false negatives.
How could the rapid strep test give a false positive result?
This means that 98 of 100 positive tests correctly indicate the presence specifically of Group A Streptococcus bacteria; 2 of 100 positive results are “false positives,” meaning that the patient is either carrying the strep bacteria in their tonsils but does not have an active infection from it, or the test detected a …
Can you still have strep if rapid test is negative?
The rapid strep test can give false-negative results even when strep bacteria are present. When the results of a rapid strep test are negative, many doctors recommend doing a throat culture to make sure that strep throat is not present. Neisseria meningitidis.
Can you test negative for strep but still have it?
If you test negative for group A Streptococcus, but still have a sore throat, your doctor may look at other possible causes, including infections from other bacteria or viruses. If a strep infection is left untreated, it can lead to more serious medical conditions, including: streptococcal pneumonia. ear infections.
Can you test positive for strep but have something else?
Someone who tests positive for strep throat but has no symptoms (called a “carrier”) usually does not need antibiotics. They are less likely to spread the bacteria to others and very unlikely to get complications. If a carrier gets a sore throat illness caused by a virus, the rapid strep test can be positive.
Are strep tests ever wrong?
Keep in mind, though, that up to a third of negative rapid strep test results are false (meaning someone actually has a strep throat infection even though the rapid strep results were negative). A throat culture may then be done to ensure accuracy.
What shows up on a throat culture?
A throat culture or strep test is performed by using a throat swab to detect the presence of group A streptococcus bacteria, the most common cause of strep throat. These bacteria also can cause other infections, including scarlet fever, abscesses, and pneumonia.
Which is more accurate a rapid strep test or a throat culture?
With a rapid strep test, results are ready in 10 minutes instead of 1 to 2 days with a throat culture. If the rapid strep test results are positive, antibiotics can be started immediately. A throat culture is more accurate than the rapid strep test. The rapid strep test can give false-negative results even when strep bacteria are present.
When is the rapid strep test is negative?
In this study, researchers retrospectively reviewed 11 years’ worth of laboratory records from two clinical microbiology laboratories in Seattle on >21,000 adolescents and adults with negative rapid strep antigen tests who then had pharyngeal swabs submitted for culture. For 1023 patients (4.8%), throat cultures grew group A strep.
When to start antibiotics after a throat culture?
If strep throat is likely, a test called a rapid strep test (or quick strep) may be done before a throat culture. With a rapid strep test, results are ready in 10 minutes instead of 1 to 2 days with a throat culture. If the rapid strep test results are positive, antibiotics can be started right away.
How long does it take for a strep test to come back?
The traditional test for a strep throat has been a throat culture. The major drawback of a throat culture is that the results take two to three days due to the time necessary to allow enough GAS bacteria to grow to enable accurate identification. Just about any painful sore throat is caused by strep. See Answer What is a rapid strep test?