On September 22, 2026, researchers published a study in the Proceedings of the National Academy of Sciences revealing that broader-spectrum bacteriophages share specific structural variations in their tail fibers, a discovery that could expand phage therapy options against antibiotic-resistant infections.
Structural Diversity in Tail Fibers Controls Phage Host Range
Bacteriophages are viruses that infect and kill bacteria, but most target only a single bacterial strain. To uncover why some phages attack multiple strains, researchers analyzed genetic data from more than 1,300 unique Pseudomonas aeruginosa strains. They found 53 distinct variants of pili—long, hair-like fibers that bacteria shoot out to attach to surfaces like catheters and contact lenses. Phages use these pili to hitch a ride to the bacterial surface. The McMaster University research team compared AI-generated models of phage tail fibers and discovered that broader-spectrum phages featured tail fibers that varied significantly at the point of contact with the pili, whereas narrow-acting phages had similar tail fibers.
Did you know? Phages were identified over 100 years ago and were used to treat bacterial infections before antibiotics were discovered.
Clinical Implications for Drug-Resistant Pathogens
Antibiotic resistance kills millions of people worldwide each year, driving researchers to look for alternatives such as phage therapy. “We are starting to encounter bacterial pathogens that are not killed by any of our current antibiotics, and one of the ways we can treat those essentially untreatable infections is by using phages, which are natural predators of bacteria,” said senior author Lori L. Burrows, PhD, professor emeritus of biochemistry and biomedical sciences at McMaster University, in an interview with Medscape News Canada. Burrows noted that phages operate on a lock-and-key mechanism, making them much more selective than conventional antibiotics.
First author Ikram Qaderi, a PhD candidate at McMaster University, told Medscape News Canada that the physical shape of a phage’s tail fibers may serve as a useful predictor of its activity. “If we can understand what determines which bacteria a phage can recognize, we may eventually be able to predict which phages are most likely to work against a particular infection and reduce the time it takes to identify an effective treatment,” Qaderi said.
Expert Perspectives on Expanded Phage Utility
Isaac Bogoch, MD, an infectious diseases specialist at the Toronto General Hospital, University of Toronto who was not involved in the research, told Medscape News Canada that identifying broader-acting phages could make treatments faster and more accessible. “We know how difficult it is to find a specific bacteriophage, and when we do find those phages, there are issues with specificity; they only target a single pathogen,” Bogoch said. “This study shows that it might be easier and faster to identify phages that have slightly broader targets, which might be helpful in combating several different infections.”
Frequently Asked Questions About Bacteriophage Research
What is a bacteriophage?
A bacteriophage, or phage, is a virus that specifically targets, infects, and kills bacterial cells.
Why are broader-spectrum phages difficult to find?
Phages typically act like a lock-and-key, requiring precise alignment with specific bacterial host structures such as pili, which makes finding effective matches a time-consuming process.
How did researchers identify tail fiber differences?
Researchers used AI-generated models to compare the tail fiber structures of narrow-acting phages against those of broader-spectrum phages that tolerate variations in bacterial pili.
Who funded the study?
The research was supported by Canadian Institutes of Health Research Project grants.
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