The return of phage therapy to combat disease


EXCERPT: . . . Under pressure from this assault, bacterial populations did what they’d done for aeons: evolve or die. Those strains that could survive antibiotics are now winning the evolutionary race, and we are progressively running out of cures.

[...] In a 2000 essay in Science magazine, he [Joshua Lederberg] argued that humans needed to work with nature rather than against it; we needed to take ‘the germs’-eye view of infection’. Modern medicine tends to adopt a somewhat mechanistic approach: fix the flaw, repair the malfunction, extricate and eradicate the invading entity. But the human body and illness do not follow such linear paths; they are influenced by ecological and evolutionary processes, which new treatments might try to manage in a more holistic way

[...] Phage therapy is not so much a cutting-edge new treatment as a revival and updating of an old one. ‘Phage’ derives from the Ancient Greek phágos, for ‘glutton’, and phageîn, ‘to eat’. In a biological context, it’s short for ‘bacteriophage’: a category of viruses, each of which targets a specific species or strain of bacteria. You can find them anywhere and everywhere. Chan goes ‘bioprospecting’ for phages in sewage, ponds and drains – basically ‘wherever the bacteria are,’ he told me. ‘It’s pretty gross.’

Phages were discovered before modern antibiotics, more than a century ago, when physicians had few options for curing infectious diseases. [...] But phages were soon eclipsed by other treatments. [...] Throughout the first half of the 20th century, research into phage therapy continued. But it soon became obvious that antibiotics enjoyed several advantages. [...]

Just as bacteria can evolve resistance to antibiotics, they can develop resistance to bacteriophages. [...] the phage exerted selective evolutionary pressure on the bacterium, so that it could survive the virus only by losing its antibiotic resistance. These sorts of effects had been observed decades ago, before phages slid out of Western medicine. If better understood, could this phenomenon be used to our advantage? Could evolution be used as a tool?

This is what Chan and Turner have been trying to do for the past five years. Their strategy is to find phages that can do more than simply kill offending bacteria, the way antibiotics do; they want phages that can push the right evolutionary buttons, rendering the patient’s bacteria more vulnerable to antibiotics, less virulent, or even harmless. Chan and Turner call this wizardry ‘evolutionary engineering’.


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