What is GAS pharyngitis and why is it sometimes hard to detect?
Dr Ellen Jo Baron: ‘Pharyngitis’ means inflammation of the throat, but most people know it as a simple sore throat. Several types of bacteria and viruses can infect the lining of the back of the throat and cause a reaction – pus cells, redness and pain. GAS stands for ‘group A Streptococcus’ and is the major bacterial cause of a sore throat. It is important to detect and treat it with penicillin or a similar antibiotic. If untreated, patients can develop illnesses like rheumatic fever. It’s not hard to detect GAS using a good culture in the laboratory, but right now many clinics use rapid antigen tests that, while fast, are not very sensitive.
What are the technical advantages of Xpert Xpress Strep A over other GAS diagnostics solutions currently on the market?
It is easy to perform – only a few simple steps are needed – and results are available in around 20 minutes. It’s also one of the most sensitive commercially available tests around. The instrument used is small and portable, so it can be performed in several outpatient settings. It can be connected to the laboratory or hospital computer system, or deliver results directly to a cloud information system. This allows them to be quickly sent back to caregivers. The sample – a swab of the back of the throat – is placed into a tube of liquid that can be used for other tests later if necessary, such as to culture for other bacteria that might have caused someone’s sore throat if the Xpert Xpress Strep A test is negative.
How do these advantages translate for hospital staff?
One problem with antigen tests is that, if the staff don’t go back to check the result in time, they have to do it again. With our test, it doesn’t matter if you didn’t get back in time as the answer has already been determined and it’s on the computer screen. At the same time, because our tests are highly accurate, doctors can make reliable care decisions for patients immediately.
What are the benefits for patients?
Because Xpert Xpress Strep A is so accurate, clinicians can diagnose patients immediately. This saves patients time, avoiding unnecessary trips to the drug store. Our tests also cut back on using unnecessary antibiotics that lead to all kinds of problems. One of the more common reasons that children come into healthcare is adverse effects associated with taking antibiotics. Our test is able to cut back on these because children will only get antibiotics when they need them. It also helps with a patient’s state of mind.
What plans do you have to improve your assays in future?
We are always working to improve our assays, including making them faster and more sensitive. Our Xpert Xpress product line is the latest development from Cepheid, offering tests with no compromise in quality and ease of use, and even faster results that patients and healthcare providers can truly benefit from. We also have been able to multiplex many of our assays for broader organism coverage.
