Forecasting how step A may affect patients – and healthcare providers – this respiratory season.
September 2023- The Journal of Healthcare Contracting
Here are three things to know about Strep A diagnostics during this year’s back-to-school season. First, although group A strep infections can occur any time of year, they are more common in the United States in winter and spring. Second, while it’s true anyone can contract a GAS infection, children between the ages of 5 and 15 years are most susceptible. And third, based on preliminary 2022–2023 data from the Centers for Disease Control and Prevention, less severe group A strep infections in children have returned to levels similar to or higher than those seen in pre-pandemic years.
A common bacterium
Group A streptococcus (GAS), also referred to as strep A, is a common bacterium. Many of us carry it in our throats and on our skin and it doesn’t always result in illness, according to the UK Health Security Agency. However, GAS does cause several infections, some mild and some more serious. Milder infections include scarlet fever, impetigo (red sores around the nose and mouth), cellulitis and pharyngitis (sore throat). These can be easily treated with antibiotics. The more serious – but rarer – infections linked to GAS come from invasive group A strep, known as iGAS. These infections are caused by the bacteria getting into parts of the body where it is not normally found, such as the lungs or bloodstream. In rare cases an iGAS infection can be fatal.
GAS is spread by close contact with an infected person and can be passed on through coughs and sneezes or from a wound. Some people can have the bacteria present in their body without feeling unwell or showing any symptoms of infections, and while they can pass it on, the risk of spread is much greater when a person is unwell.
The CDC doesn’t track non-invasive group A strep, but estimates that pharyngitis causes an estimated 5.2 million outpatient visits and 2.8 million antibiotic prescriptions annually among U.S. persons aged 0–64 years. Globally, the burden from GAS infections is even greater. The World Health Organization estimates 111 million children in the developing world have impetigo and 470,000 new cases of acute rheumatic fever (a potential outgrowth of GAS) occur each year.
Currently, GAS is not resistant to penicillin and amoxicillin, first-line antibiotics for strep throat, sa7s CDC.
“Many viral syndromes can present similar to strep, however, clinicians and pediatricians look for specific signs (e.g., sore throat without cough, palatial petechiae, sandpaper rash), which help determine which diagnosis scores higher on differentials,” says Aparna Ahuja, M.D., divisional vice president of medical, clinical and scientific affairs for Abbott’s rapid diagnostics business. “There is some overlap of symptoms, including fever, sore throat, nausea and vomiting, but absence of cough is one of the key distinguishers for strep compared to viral infections like COVID and flu. In the eventuality of a misdiagnosis and not prescribing the right treatment for strep pharyngitis cases, further spread of infection along with worsening of symptoms/progression is a possibility.”
The usage of rapid point-of-care (POC) tests is increasing, says Dr. Ahuja, adding that she is speaking about strep A pharyngitis and scarlet fever but not severe strep infections such as streptococcal toxic shock syndrome (TSS) or necrotizing fasciitis, which are not diagnosed with a rapid test or managed on an outpatient basis. “Most physicians prefer rapid tests, as results are known quickly and decision on further course of treatment can be made immediately, while the patient is still available to the doctor. For patients – in this case, often children – there’s a desire to understand the cause of the illness and get appropriate treatment to enable quick recovery.”
Rapid molecular tests help to provide high-quality actionable results at the point of care, she says. During one visit, the cause of illness can be identified and targeted therapy initiated, which leads to a better patient outcome. “Additionally, having rapid results can help provide timely information so patients can isolate appropriately, which helps avoid spreading strep A infections to family members and the larger community. It leads to fewer missed days of school or work for individuals and their families, and helps reduce antibiotic use in subjects who explicitly ask for a prescription.”
Because of molecular technology and performance, tests such as Abbott’s CLIA-waived ID NOW™ Strep A 2 test do not require any follow-up culture to confirm negative results, enabling clinicians to treat confidently at the point of care with early positive detection and often during a patient visit, says Dr. Ahuja. “This efficiency supports antimicrobial stewardship. Inappropriate prescription of antibiotics results in ineffective treatment, and may contribute to antimicrobial resistance, which is an increasing public health concern.”
Invasive group A strep
The Centers for Disease Control and Prevention is looking into an increase in invasive group A strep (iGAS) infections among children in the United States.
These infections are caused by the bacteria getting into parts of the body where it is not normally found, such as the lungs or bloodstream. Not to be confused with routine strep throat, iGAS infections include necrotizing fasciitis (a serious bacterial infection that destroys tissue under the skin), streptococcal toxic shock syndrome (a rare but serious bacterial infection which can develop quickly into low blood pressure, multiple organ failure and death), cellulitis with blood infection, and pneumonia.
CDC estimates that in the most recent five years, approximately 14,000 to 25,000 cases of invasive group A strep disease have occurred each year in the United States. Between 1,500 and 2,300 people die annually due to invasive group A strep disease.
While iGAS infections are still uncommon, the number of cases rose in 2022, particularly among children under 10, reports the UK Health Security Agency. It isn’t possible to say for certain what is causing higher case numbers, but it is likely a combination of factors, including increased social mixing compared to the previous years as well as increases in other respiratory viruses.
Per the U. S. Centers for Disease Control and Prevention, preliminary 2023 data indicate iGAS infections have remained high in children in some areas of the country even after respiratory viruses decreased in those areas. This is occurring during the time when group A strep infections are normally highest (December through April). Additionally, some areas of the country have also seen an increase in iGAS infections in adults, particularly those aged 65 years or older.