Ronny Gunnarsson, Institute of Medicine, Sahlgrenska Academy at the University of Gothenburg.
Photo Credit: Pernilla Häyhänen
Scientific Frontline: Extended "At a Glance" Summary: Antibiotic Efficacy in Preventing Invasive Streptococcal Infections
The Core Concept: Prescribing antibiotics for uncomplicated, acute sore throats has a negligible effect on preventing the population-level spread of potentially life-threatening invasive Group A streptococcus (iGAS) infections.
Key Distinction/Mechanism: While antibiotics are routinely debated as a preventive measure against iGAS, the infection's transmission dynamics render this approach highly ineffective. Most patients seek care after their peak contagious window, and up to 25% of iGAS cases are transmitted by asymptomatic carriers who would not trigger clinical intervention.
Major Frameworks/Components:
- Statistical Inefficacy: Even under an extreme theoretical model where every sore throat patient is tested and treated, only 6.7% of iGAS cases in children and 2.8% in adults could be prevented.
- Guideline Limitations: When adhering strictly to targeted diagnostic symptom guidelines (such as the Centor criteria), the maximum preventive effect drops to 1.6% in children and 1.2% in adults.
- Resource Burden: Preventing a single case of iGAS requires conducting between 45,000 and 110,000 throat swabs and dispensing up to 110,000 antibiotic prescriptions, which creates severe strain on primary care infrastructure and elevates the risk of widespread antibiotic side effects.
Branch of Science: Epidemiology, Infectious Disease Medicine, Public Health, Microbiology.
Future Application: Clinical protocols must pivot away from broad antibiotic dispensation for simple throat infections. Future medical strategies should focus on rapid diagnostic triage to identify early warning signs of systemic infection, alongside the continued development of a targeted, effective streptococcal vaccine.
Why It Matters: This research scientifically dismantles a primary justification for the widespread use of antibiotics in minor respiratory infections. It redirects clinical focus toward genuine early-warning diagnostics and supports global public health efforts to curtail antibiotic resistance.
Antibiotics for sore throats have a negligible preventive effect against serious streptococcal infections in the population, according to a study from the University of Gothenburg. Instead, healthcare professionals must quickly recognize the warning signs of a serious infection.
Group A Streptococcus (GAS) is a common bacterium that can cause invasive GAS infection (iGAS) if the bacteria enter the blood or lungs, for example. The condition is potentially life-threatening and relatively uncommon, but its incidence has increased in several countries in recent years.
Because uncomplicated sore throats can sometimes develop into iGAS or infect others in the community, early antibiotic treatment is often debated as a preventive measure.
However, the researchers behind the current study show that prescribing antibiotics for uncomplicated acute sore throats to prevent iGAS has a very limited effect at the population level.
"The intention to prevent iGAS infections should no longer be used as an argument for treating common throat infections with antibiotics; that strategy is greatly overrated," says Ronny Gunnarsson, lead author of the study, family physician, and professor emeritus at the University of Gothenburg.
Minimal Preventive Effect
By combining scientific evidence with epidemiological data for the entire Swedish population in 2024, the researchers calculated how different strategies affect the incidence of iGAS.
The results show that even in an extreme scenario—where all patients seeking care for a sore throat are tested and treated if they carry the bacteria—at most 6.7 percent of iGAS cases could be prevented in children and 2.8 percent in adults.
If current Swedish guidelines are followed instead, wherein testing is performed only if the patient presents with three to four specific symptoms according to the Centor criteria, the preventive effect is a maximum of 1.6 percent in children and 1.2 percent in adults.
"The proportion of iGAS cases that can actually be prevented with antibiotics is much smaller than one might think. Our calculations show that throat swabs must be taken from between 45,000 and 110,000 patients, and up to 110,000 antibiotic prescriptions must be written, just to prevent a single case of iGAS," says Gunnarsson.
Contagious Before the Healthcare Visit
The researchers pointed to several reasons why antibiotics are ineffective against iGAS at the population level. Most people who develop a sore throat never contact a healthcare center. Those who do typically seek care on the third day of illness or later, when they have already passed their most contagious period.
In addition, 15 to 25 percent of iGAS patients are infected by asymptomatic carriers—people who feel completely healthy and therefore should not receive antibiotics. The study concludes that a lowered threshold for testing and treating sore throats would lead to major negative consequences for primary care.
"Broadening the criteria for sampling and antibiotic treatment would mean an enormous burden for primary care and crowd out other patient groups, not to mention the risk of side effects from antibiotics," says Gunnarsson. He continues, "Instead of prescribing antibiotics for uncomplicated sore throats, healthcare providers should focus on quickly recognizing early warning signs of serious infection and, in the long term, await a safe and effective vaccine against streptococci."
Published in journal: Journal of Infectious Diseases
Authors: Ronny Gunnarsson, Erik Wiezell, Carl Wikberg, Pär-Daniel Sundvall, and Karin Rystedt
Source/Credit: Göteborgs Universitet
Edited by: Scientific Frontline
Reference Number: epi030626_01