Rise of a Silent Invader Pneumococcal Genotype 23B1 Behind Spike in Dangerous Pneumonia Infections in Belgium and Globally
Nikhil Prasad Fact checked by:Thailand Medical News Team Mar 22, 2025 9 hours, 5 minutes ago
Medical News: A new study has revealed alarming insights into the growing threat of a previously underestimated bacterial strain in Belgian children. Researchers from the University of Antwerp, KU Leuven, and the University Hospitals Leuven have identified a genetic variant of the Streptococcus pneumoniae bacterium - called genotype 23B1 - that is not only rapidly spreading among young children but also shows increasing resistance to commonly used antibiotics like penicillin.
Rise of a Silent Invader Pneumococcal Genotype 23B1 Behind Spike in Dangerous Pneumonia
Infections in Belgium and Globally
This
Medical News report dives into the concerning rise of the 23B1 strain, its connection to more frequent infections, and why global health authorities should be paying close attention.
What Is Streptococcus Pneumoniae and Why It Matters
Streptococcus pneumoniae, commonly known as pneumococcus, is a bacterium that can cause a range of illnesses - from sinus and ear infections to severe and life-threatening conditions like pneumonia, meningitis, and blood infections.
Vaccination programs targeting the most dangerous strains have helped reduce serious illness in many countries, including Belgium. However, some strains not included in current vaccines - called non-vaccine types (NVTs) - are becoming more common.
One of these NVTs is serotype 23B. And more specifically, its genetic variant 23B1 has now emerged as a key player in both spreading among healthy children and causing serious disease in the pediatric population.
Uncovering the Spread in Day Care Centers and Hospitals
The research team collected over 6,600 samples from children aged 6 to 30 months attending Belgian day care centers between 2016 and 2022. They found that 16% of children carried serotype 23B. Notably, 69% of these carried the 23B1 variant, which showed much higher resistance to penicillin compared to its sibling 23B0.
What’s more concerning is that during the 2020–2021 winter season - a time also impacted by COVID-19 restrictions - carriage rates of 23B surged to over 21%, mainly driven by the 23B1 variant. This spike in healthy carriers matched an increase in serious infections among hospitalized children under 18, with 90% of the invasive cases in 2021 being caused by 23B1.
Penicillin Resistance Is Rising
The study showed that 23B1 is far more resistant to penicillin than 23B0. Median minimum inhibitory concentrations (MICs) for penicillin - a measure of how much antibiotic is needed to stop the bacteria - were 0.25 mg/L for 23B1 compared to only 0.03 mg/L for 23B0. This means that 23B1 is significantly harder to treat with standard penicillin therapy.
Even more alarming, resistance to another common antibiotic, co-trimoxazole, was closely tied to the presence of 23B1, with researchers observing an almost perfect correlation. While amoxicillin still rema
ins effective, the study warns that the shared resistance mechanism could eventually extend to this antibiotic too.
Genetic Fingerprinting and Evolution of the Superbug
Using advanced whole-genome sequencing, the team confirmed that 23B1 is genetically very distinct from 23B0, with over 11,000 differences in their DNA. The most dominant version of 23B1 was linked to a genetic sequence called ST2372, which was responsible for the largest surge in 23B cases seen in 2021.
This sharp genetic difference means that 23B1 isn’t just a slight variation - it’s practically a new type of pathogen with its own behavior, risks, and resistance profile. Alarmingly, none of the 23B1 and 23B0 strains shared the same genetic lineage, further solidifying their separate evolutionary paths.
The Vaccine Connection and the Role of COVID-19
Belgium’s pneumococcal vaccination policy has switched several times over the past decade. The country moved from a 13-valent (PCV13) vaccine to a 10-valent (PCV10) one in 2015–2016 before reverting to PCV13 in 2019 after a resurgence of another strain, 19A. During the PCV10 years, 23B1 silently grew in prevalence, especially in day care centers.
Then came COVID-19. Even though Belgian day care centers remained open, general social distancing and mask mandates were in effect. These public health measures may have shifted the balance of viral and bacterial infections, possibly giving bacteria like 23B1 more room to spread without competition.
A Global Problem in the Making
Belgium isn’t alone. Countries like the UK, Spain, Norway, and the USA are also reporting rises in 23B and especially 23B1, often linked to drug-resistant infections in children. The common thread? These cases frequently involve the ST2372 version of 23B1 - the same dominant strain found in Belgium.
In fact, the surge in infections caused by this variant is so concerning that serotype 23B is now being considered for inclusion in upcoming next-generation 21-valent pneumococcal vaccines.
Conclusion
The emergence and spread of pneumococcal genotype 23B1 represent a major warning sign. This variant is not only expanding rapidly among young children in day care centers but also causing serious and sometimes life-threatening infections. Its increased resistance to key antibiotics like penicillin makes it especially dangerous, and its genetic distinctiveness suggests it's evolving along a path of its own. Without immediate and focused global surveillance, and possibly vaccine updates, 23B1 could become a dominant and difficult-to-treat pathogen in pediatric populations worldwide.
The study findings were published in the peer reviewed Journal of Clinical Microbiology.
https://journals.asm.org/doi/10.1128/jcm.01696-24
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Medical News.
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