Biron improves diagnostic procedure for strep throat with its molecular test
January 9th, 2019
Dr Nicolas Tétreault, PhD, CSPQ, FCACB
Clinical Biochemist - Scientific Director
Always at the forefront of new technologies, Biron Health Group launched, earlier in 2019, an innovative molecular test that has replacedt he traditional throat culture in the screening of streptococcal pharyngitis, or strep throat. With undeniable benefits for health care professionals and their patients, especially children, the molecular test reduces wait times in the event of a negative result in the rapid strep test (strepto direct).
What is pharyngitis?
Pharyngitis is a well-known throat inflammation. Most of the time, it is caused by a virus. However, it can also be caused by a bacterium: group A streptococcus (GAS). This infection is responsible for 20%-30% of strep throat cases in children and 5%-15% of cases in adults.
The incidence of strep throat increases during winter and can continue until early spring.
During the peak season, 35% to 40% of strep throat cases in children and adolescents are caused by GAS.
Children aged 3 to 15 are particularly at risk.
In children over the age of 3, GAS typically causes an abrupt onset of symptoms.
A group A streptococcal infection is the most common cause of bacterial pharyngitis for which antibiotic therapy exists.
An untreated GAS infection can lead to scarlet fever (an inflammatory disease that affects several organs) or lead to complications such as rheumatic fever or post-streptococcal kidney disease (glomerulonephritis).
The molecular test used at Biron also detects group C and G streptococci, which can also cause bacterial pharyngitis.
Symptoms of pharyngitis caused by group A streptococcus may include the following:
Fever higher than 38 0C
Sore throat (rapid onset)
Nausea or vomiting
Tonsillitis (may have pus deposits)
Red spots on the palate
Swelling of the cervical lymph nodes
Conventional method of confirming negatives: The throat culture
No single sign or symptom reliably identifies pharyngitis caused by group A streptococcus. If your health care professional suspects this type of infection, additional tests can confirm it. Available at Biron, the rapid strep test (also called “strepto direct”) that detects group A streptococcal antigens is commonly used. The quick result allows you to check whether bacteria are present, but has certain limitations.
A negative result does not necessarily indicate the absence of bacteria. Therefore, it is typically necessary to perform a throat culture to validate the result. This sample will be analyzed in the laboratory where a negative result will be confirmed if no bacterial growth is observed after 48 hours. In children, this step is essential, as it is very important not to treat the condition with antibiotics if no bacteria are present.
Modern method of confirming negatives: Molecular diagnostics
Biron uses molecular testing that allows unequivocal results to be obtained much more rapidly than a throat culture in the event of a negative result in the strepto direct test. This test searchs for the molecular signature (DNA) of the bacterium, thereby avoiding the waiting time caused by the process of growing a bacterium in a culture. While it can take up to 48 hours to get the results of the culture, the molecular test can be performed in just a few minutes. In most cases, patients can view their results at MyBiron or receive them by email the same day, and their attending physician is also quickly informed. There may be a wait of 24 hours depending on the time of the patient’s appointment. The result of this test is as reliable as that from a culture.
It should be noted that the doctor may make the decision to prescribe antibiotics if the patient has signs or symptoms that are considered sufficient to treat without waiting for the final result to confirm the negatives.
The avantages of molecular testing
Avoids having to wait up to 48 hours in case of a negative result with the culture method. The result can be obtained in less than 24 hours.
Avoids the taking of unnecessary antibiotics, which can have harmful effects, especially on children.
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