A decade-long study of around 35 million Americans in 10 states has found that group A streptococcus infections have more than doubled by 2022. What's more, "strep" – which also causes a bizarre flesh-eating disease – had become shockingly resistant to common antibiotics.
Group A streptococcus (GAS) – which may be best known by one of its manifestations, "strep throat" – is caused by the Streptococcus pyogenes bacterium and can have more serious outcomes than, for example, pharyngitis. Also known as "invasive strep," this bug can cause necrotizing fasciitis, a flesh-eating disease, as well as toxic shock syndrome, a sepsis-like infection that can trigger organ failure.
The comprehensive report out of the US Centers for Disease Control and Prevention (CDC) highlights the value of long-term research into the epidemiology of infectious illnesses that had, up to a certain point, remained rare and stable.
"Invasive GAS cases from January 1, 2013, through December 31, 2022, were identified through active surveillance for invasive bacterial pathogens in 10 US states, covering 34 ,991,238 persons," researchers detailed of the data gathered from California, Colorado, Georgia, Maryland, Oregon, New York, New Mexico Tennessee, Connecticut and Minnesota.
Prior to 2013, infections had remained relatively low and stable for 17 years. Overall, strep's prevalence more than doubled, from 3.6 per 100,000 people to 28.2 per 100,000 people. While this doesn't seem like a lot, certain demographics are disproportionately impacted by both cases and fatalities, especially those who are socially and medically vulnerable. In total, annual cases rose from 1,082 in 2013 to 2,759 in 2022.
For the entire period, 21,312 strep cases were identified, with 1,981 deaths – nearly 10% of those who fell ill. However, people in long-term care such as aged-care had almost twice the risk of dying from their infection (17.7% of cases).
Based on the 10-state sample, the researchers believe they'd find far more overall cases and fatalities if it had been a nation-wide study.
What's more, the rise in cases appears to be related to bacterium diversity: Over the 10-year period, there was a significant uptick in rarer strains causing infection, from 0.3% to 26.9%, including a rise in the types triggering flesh-eating infections. at the same time, antimicrobial resistance jumped, particularly in response to clindamycin and macrolide (from 12.7% to 33.1%) and tetracycline (16.2% to 45.1%). Fortunately, all strains of the bug are still vulnerable to treatment with β-lactams like penicillin and ampicillin.
Digging into the numbers, the scientists found that there was a sharp rise in cases in people who had underlying medical conditions – some which made them particularly vulnerable to skin infections, including those with diabetes and obesity. There was also an increase among people who inject drugs. And, for the sections of the community experiencing homelessness, infections rose almost tenfold in the decade, to 807 cases per 100,000 people.
Ultimately, this report shows an urgent need for both public awareness of avoiding infection – and for more diverse therapeutic interventions. The CDC has called for better access to wound care, more education for the vulnerable members of society who are most at risk, and more attentive monitoring and epidemiological modeling to track antimicrobial resistance. Research into a vaccine is also currently lacking.
"The increasing invasive GAS burden, particularly among groups that have been economically and socially marginalized, requires urgent attention," the researchers noted. "Ongoing surveillance to monitor disease burden, strain distribution, and antimicrobial resistance is essential. Improved understanding of drivers of GAS transmission and increasing disease incidence could guide prevention and control efforts prior to availability of a licensed vaccine.
"Efforts to reduce risk factors, including underlying skin breakdown and infections, particularly for groups with the highest disease incidence, will be critical to change the trajectory of invasive GAS infections in the US," they added.
Invasive strep is highly contagious, spreading via airborne droplets of an infected person when they cough, sneeze or talk – much like COVID-19's virus. You can also contract it by touching an infected surface – from doorknobs to skin lesions – and then having your fingers come into contact with your nose or mouth. While food handling is a very rare source of transmission, sharing plates, cups and utensils with an infected person holds a far greater risk.
For strep throat, symptoms usually appear two to five days following exposure. But given the severity and breadth of the infection, it's important to seek medical help as soon as possible. Broader CDC estimates suggest around 5.2 million Americans seek medical treatment for the throat infection each year.
This research was published in the Journal of the American Medical Association.
Source: Centers for Disease Control and Protection via EurekAlert!
