Reinventing the fight against bacteria, one phage at a time.

Penicillin and the Eclipse of Phage Therapy in Western Medicine (1928–1950) Abstract: The period between the late 1920s and the mid-20th century witnessed a fundamental transformation in antimicrobial therapeutics. Bacteriophage therapy, once a promising solution to bacterial infections, saw increasing use in European clinics during the interwar years. However, the discovery and mass production of penicillin during World War II radically shifted clinical priorities. This article examines the rise of penicillin and the scientific, clinical, and industrial dynamics that led to the displacement of phage therapy in Western medical practice by 1950. Introduction: A Divided Therapeutic Landscape In the interwar period, Western medicine faced a crisis of infectious disease without a universal remedy. While chemical antiseptics and arsenical compounds like Salvarsan were used for certain infections, many remained untreatable. Bacteriophage therapy emerged as a candidate solution, particula...

Understanding Bacteriophage Life Cycles: The Lytic and Lysogenic Pathways Bacteriophages, or phages for short, are viruses that infect and replicate within bacteria. They are the most abundant biological entities on Earth, with an estimated 10³¹ particles—more than all the stars in the universe. But despite their microscopic size, phages have a massive influence on microbial ecosystems, human health, and the future of medicine. At the core of how phages function are two distinct reproductive strategies: the lytic cycle and the lysogenic cycle . Understanding these two pathways is essential for grasping how phage therapy works, how bacterial populations are controlled in nature, and how genetic material can be transferred between microorganisms. The Lytic Cycle: Destruction for Reproduction In the lytic cycle, a phage takes over a bacterium with the sole purpose of producing as many new phage particles as possible. The process is swift and lethal to the host cell. Stages of the ly...

The Viruses That Kill Bacteria: An Introduction to Bacteriophages When people hear the word "virus," they often think of disease, danger, and global pandemics. But not all viruses are harmful to humans. In fact, some viruses exclusively target bacteria—and they may hold the key to solving one of the greatest medical challenges of our time: antibiotic resistance. These viruses are called bacteriophages. What Are Bacteriophages? Bacteriophages, or simply phages, are viruses that infect and destroy bacteria. The term comes from the Greek words "bacteria" and "phagein," meaning "to devour." True to their name, phages invade bacterial cells, hijack their machinery to reproduce, and eventually destroy them from within. Discovered over a century ago, phages are the most abundant biological entities on the planet. It is estimated that there are more than 10³¹ phages on Earth—far more than all other organisms combined. They are found wherever bacteria...

Revolutionizing Phage Therapy: High-Throughput Platforms for Personalized Bacterial Targeting Artistic View As multidrug-resistant bacterial infections continue to challenge global health systems, the urgency for precise, rapid, and adaptable therapeutic alternatives has never been greater. Among the most promising solutions is the revival of bacteriophage (phage) therapy, now significantly enhanced by innovative high-throughput screening technologies that tailor treatment to each patient's infection profile. The Problem: Precision in an Age of Resistance One of the longstanding challenges in phage therapy has been its host specificity : phages that kill one bacterial strain may have no effect on another, even within the same species. Traditional phage matching relies on slow culturing methods and empirical testing, delaying critical treatment and limiting phage therapy’s clinical viability. In an age of rapid-onset sepsis and pan-resistant infections, such limitations are una...

CRISPR-Engineered Phages in Clinical Trials: A Precision Strike Against Antibiotic-Resistant UTIs Artistic view In the face of mounting antibiotic resistance, a new generation of antimicrobial therapy is emerging—not from a chemistry lab, but from the convergence of bacteriophage biology and CRISPR gene editing . Among the pioneers in this field is Locus Biosciences , a North Carolina-based biotech company that has launched the world’s first clinical trial using CRISPR-enhanced phages to treat urinary tract infections (UTIs) caused by Escherichia coli . This innovation represents a fundamental leap forward in the application of precision medicine to bacterial infections. The Clinical Challenge: E. coli and the UTI Burden Urinary tract infections affect more than 150 million people worldwide each year. In the United States alone, they account for over 8 million doctor visits annually , with E. coli responsible for up to 80–90% of all cases. While most UTIs are treatable with sta...

Phage Therapy in European Clinics: Targeting Staphylococcal and Streptococcal Infections in the 1930s Illustration of Félix d'Hérelle with patients infected and cured by phages in Europe (artist's view) During the late 1920s and early 1930s, long before antibiotics revolutionized medicine, European clinics were overwhelmed by bacterial infections that resisted conventional treatments. Among the most feared were those caused by Staphylococcus aureus and Streptococcus pyogenes , which plagued maternity wards, surgical theaters, and military hospitals. These pathogens, responsible for postpartum sepsis, wound infections, and hospital-acquired abscesses, often led to fatal outcomes. It was in this bleak landscape that Félix d’Hérelle’s phage therapy emerged as a compelling and controversial alternative. A Novel Approach in Clinical Medicine Félix d’Hérelle, a French-Canadian microbiologist and co-discoverer of bacteriophages, began promoting the therapeutic use of these bacteri...

Félix d’Hérelle’s Phage Therapy Trials in Tunisia: A Forgotten Milestone in Medical Experimentation Illustration of Félix d'Hérelle with patients in Tunisia (artist's impression) In the early 1920s, the arid hospital wards of French Tunisia became the site of one of the earliest large-scale clinical applications of bacteriophage therapy in human patients. Led by Félix d’Hérelle—microbiologist, iconoclast, and self-styled bacteriophage evangelist—this episode stands as a largely overlooked but pivotal moment in the history of therapeutic microbiology. At a time when the mechanisms of bacterial disease were only partially understood and antibiotics had yet to transform modern medicine, d’Hérelle’s ambition was radical: to cure deadly infections using living viruses that specifically target and destroy bacterial pathogens. His experiments in North Africa were not preliminary lab trials, but structured medical interventions on infected patients in real clinical settings. The Set...

A New Era for Precision Antimicrobials: AI-Guided Phage Therapy Targets Resistant Infections In a landmark achievement for the field of precision medicine, a consortium of French researchers has unveiled a novel artificial intelligence model capable of matching bacteriophages—viruses that infect bacteria—with specific pathogenic bacterial strains based solely on their genomic profiles. The study, published in Nature Microbiology on October 31, 2024, marks a major step toward making phage therapy scalable, predictable, and clinically viable against multidrug-resistant bacterial infections. Artist's impression of Aude Berkheim working in her laboratory This breakthrough arrives at a critical moment. As antibiotic resistance accelerates into a global public health crisis, alternatives are urgently needed. Phage therapy, first developed over a century ago by Félix d’Hérelle, is now being reimagined through the lens of artificial intelligence and genomic medicine. The Problem: Resis...

A New Kind of Cure: The First Large-Scale Human Trial of Phage Therapy in India, 1927 Félix d'Hérelle healing an Indian cholera infected folk. (Artistic view) In 1927, amid the humid wards of cholera hospitals in British India, a quiet but radical shift in medical treatment was underway. It did not involve chemical drugs or surgical intervention, but rather the introduction of a living biological agent—bacteriophages—into the human body to combat infection. This was the world’s first large-scale clinical trial of phage therapy in humans. The architect of the trial was Félix d’Hérelle, the French-Canadian microbiologist who, a decade earlier, had discovered that invisible viral agents were capable of destroying bacterial cultures. He called them bacteriophages —“bacteria eaters”—and envisioned a future in which these viruses could serve as precision tools in medicine. With the help of the Haffkine Institute in Bombay, one of the premier bacteriological research centers of the time...

The First Trial: Félix d’Hérelle’s Pioneering Phage Therapy in Poultry and the Birth of Precision Antimicrobials Félix d'Hérelle saving chickens (artistic view) In the summer of 1919, in the modest aviaries of the Institut Pasteur in Paris, one of the most quietly revolutionary experiments in modern medicine took place—not in humans, but in chickens. The scientist behind it, Félix d’Hérelle, had already made waves two years earlier when he announced to the French Academy of Sciences the discovery of an “invisible microbe” that preyed on bacteria—a virus he would name the bacteriophage (literally, “bacteria eater”). While others debated whether this enigmatic agent was truly viral, d’Hérelle was less concerned with nomenclature and more with utility. Could this microbial predator be used not merely to study bacteria, but to destroy them—in the body of a living organism? The Scientific Landscape: Bacteria Without Boundaries At the time, the world had just emerged from the devast...

Bacteriophages: Ancient Predators and the Next Frontier in Medicine In the animated documentary The Deadliest Being on Planet Earth , the Kurzgesagt team delves into the world of bacteriophages—viruses that prey exclusively on bacteria. With vibrant visuals and precise narration, the video introduces viewers to an invisible ecosystem where microscopic hunters orchestrate life-and-death dramas that shape the biosphere. These entities, though virtually unknown to the general public, may soon become central to the future of medicine. At the heart of the video lies a paradox: bacteriophages (or "phages") are among the most abundant biological entities on Earth—outnumbering all other organisms combined—yet their therapeutic potential has been largely sidelined in the antibiotic era. The video outlines the historical trajectory of phage research, spotlighting Félix d’Hérelle’s early 20th-century work and the rise of phage therapy, only to show how it was later eclipsed by the dis...

From Discovery to Remedy: The Early Therapeutic Applications of Phage Therapy by Félix d’Hérelle Félix d'Hérelle, grasshopper and phages (artist view) Félix d’Hérelle's 1917 identification of bacteriophages marked a conceptual breakthrough — but it was in the immediate years that followed that his work took on an audacious, revolutionary dimension: the deliberate use of phages to treat bacterial infections in animals and humans. Long before the advent of antibiotics, d’Hérelle believed he had uncovered a natural, precise, and replicable antiviral weapon against bacteria — and he wasted no time proving it. From Observation to Experiment: Animal Trials After returning to Paris from his work in Tunisia, d’Hérelle turned his full attention to bacteriophages. He believed that these invisible bacterial parasites could be cultivated and administered as therapeutic agents. His first challenge: to prove their efficacy in living organisms. One of his earliest controlled experiments was c...

Félix d’Hérelle: The Forgotten Father of Phage Therapy Picture of Félix d'Hérelle (Pasteur Institute) A Visionary in the Shadows of History In the annals of microbiology, certain names are carved into stone — Pasteur, Koch, Fleming. But among them, one figure remains unjustly obscured: Félix d’Hérelle, a self-taught microbiologist who, in 1917, discovered the existence of bacteriophages — viruses that infect and destroy bacteria. Through meticulous experimentation and bold clinical application, d’Hérelle not only identified a new biological entity, but pioneered one of the most promising alternatives to antibiotics: phage therapy. A Self-Made Scientist Born in 1873 in Montreal, d’Hérelle had no formal degree in science. Instead, he was an intellectual adventurer — multilingual, well-read, and ferociously curious. After working in Guatemala and Mexico on fermentation and agricultural microbiology, he returned to France where he joined the Pasteur Institute in Paris as an unpaid ...