Can a Strep Test Be Wrong?

At Kidswood Pediatrics, your child’s health is our top priority. When your child comes to us with a sore throat, fever, or swollen glands—common symptoms of strep throat—we often use a rapid strep test to quickly check for group A Streptococcus bacteria. This test involves gently swabbing the back of your child’s throat, and it can provide results within minutes right here in our office.

While rapid strep tests are convenient and can help us start treatment quickly when positive, no test is perfect. Occasionally, a rapid strep test may produce a false negative—meaning the test says your child does not have strep throat when, in fact, they do. This can happen if the bacteria level is too low to be detected or if the throat swab didn’t collect enough bacteria. Rapid strep tests are not quite as sensitive as traditional throat cultures, which is why they sometimes miss cases of strep.

Because your child’s well-being matters to us at Kidswood Pediatrics, if your child’s rapid strep test is negative but they still have symptoms that strongly suggest strep throat, our pediatric providers may recommend a follow-up throat culture. A throat culture is more accurate, though it takes a bit longer to get results. This two-step approach helps us ensure your child receives the best and most accurate care.

At Kidswood Pediatrics, we know that a sore throat can be stressful for both children and parents. One of the common tests we perform to check for strep throat is the rapid strep test, also known as a Rapid Antigen Detection Test (RADT). These tests are popular in pediatric clinics like ours because they give results in just a few minutes, helping us quickly determine the best treatment for your child.

It’s important for our families to know that while rapid strep tests are highly specific (about 95% to 98%), false positives can still occur. This means the test might sometimes indicate strep throat when your child doesn’t actually have a strep infection. False positives can happen for a few reasons, such as:

● The presence of non-group A streptococci (other harmless bacteria) in the throat that the test misidentifies as the strep bacteria.

● Technical errors during the test process.

● Another key point for parents at Kidswood Pediatrics: Some children are “carriers” of group A Streptococcus—they have the bacteria in their throats but don’t feel sick. If your child is a carrier and develops a sore throat from a virus (which is very common), a strep test may come back positive even though strep isn’t causing the symptoms. Studies show that 10% to 20% of school-aged children can be asymptomatic carriers, which can make interpreting test results more challenging.

● Throat cultures, which we sometimes use for confirmation, are slightly more accurate but can also show false positives in carrier children.

At Kidswood Pediatrics, our pediatricians always consider your child’s symptoms, medical history, and the local rate of strep infections, along with test results to make the best diagnosis. If you ever have questions about testing or results, our team is here to help explain what they mean for your child’s care.

At Kidswood Pediatrics, we know that a sore throat in your child can be concerning, especially when you’re worried about strep throat. Our team uses strep tests to detect the presence of Streptococcus bacteria in the throat. However, parents need to understand that these tests are not always accurate, especially in children.

One common reason for inaccurate results is improper sample collection. Sometimes, if the swab does not adequately touch the infected area of your child’s throat or tonsils, it may not pick up enough bacteria, leading to a false negative result. This is why our pediatric nurses and doctors are trained to collect samples carefully and make your child as comfortable as possible during the process.

Timing can also affect the accuracy of the test. Testing too early in the course of illness, before the bacteria have multiplied enough, might result in a negative test even if strep is present. We take your child’s symptoms and the timeline of their illness into account when deciding when to test.

Recent antibiotic use is another important factor. If your child has started antibiotics before the test is performed, the bacteria may be suppressed or partially cleared, which can also cause a false negative result. Additionally, some children can be carriers of Streptococcus bacteria without having an active infection, which can make interpreting the results more challenging.

If your child receives a false negative result on a strep test, it’s natural to feel concerned—especially if symptoms of strep throat persist or worsen. At Kidswood Pediatrics, Dr. Zully Ambroise, MD, typically recommends considering a repeat strep test 24 to 48 hours after the initial negative result, particularly if your child continues to show classic signs of strep throat, such as sore throat, fever, headache, or swollen tonsils. Waiting this short period allows any strep bacteria present in low numbers during the first test to multiply, increasing the chances of detection with a follow-up test.

Dr. Zully encourages you to stay in close communication with your Kidswood Pediatrics provider about any ongoing or worsening symptoms. Dr. Zully will use his clinical judgment and knowledge of your child’s overall health when determining whether retesting, a throat culture, or even starting treatment based on clinical suspicion is appropriate. In some cases, if your child’s symptoms are highly suggestive of strep despite a negative rapid test, we may recommend a confirmatory throat culture or discuss next steps together.

Your child’s well-being is always our top priority. Please follow the specific guidance provided by your Kidswood Pediatrics provider regarding testing, retesting, or treatment options for strep throat. For more information, call us or schedule an appointment online. We serve patients from Winter Park FL, Goldenrod FL, Lockhart FL, Maitland FL, Apopka FL, Casselberry FL and Oviedo, FL.