Evolving Bacteria

Antibiotic resistance is a growing problem. This shouldn’t be a surprise though, because if you exert pressure on a population, it will evolve. What we are seeing today is the evolution of bacteria from our overuse of antibiotics, from farms to hospitals to personal use. We don’t have any clear answers at the moment, but phage therapy looks quite promising.

phage therapy
A 3D printed phage

Using Phages

Phages or bacteriophages are viruses that target bacteria. You can find phages on the table, on you, in ponds, etc. Delivery of isolated phages (via injection or inhalation) to the site of infection is what phage therapy is all about! These viruses attack the bacteria causing the infection, lyse them, but leave your cells alone. What’s the difference between you and bacteria? Well, your cells are eukaryotes and bacteria are prokaryotes. We differ in the expressed surface proteins (among other things); because viruses are picky about what they bind, this difference keeps our cells safe from phage invasions.

Phage Mechanism

To dock on the bacteria cell, phages attach to efflux pumps. These active transport pumps remove toxic substances (for the bacteria), like antibiotics, for example. Resistant bacteria display more pumps, which makes phage-docking easier. The coolest thing about phage therapy is that the phage attacks drive the bacteria to evolve. This evolution down regulates the pumps expressed which (drum roll) re-sensitizes the bacteria to antibiotics again. Win-win for all! Except the bacteria.

Why Isn’t This More Common?

Phage therapy seems like a novel concept, but it’s actually been around for over 100 years. Georgia (the country) is known for having a phage library and I’m sure you’ve seen the articles about people going there after running out of options in the US. Unfortunately, phages are cheap and easy to obtain, so it’s not a good incentive for drug companies to jump onboard. But one promising aspect is that phages can make obsolete antibiotics useful again. As of right now, phages can only be used in the US for end-of-life, emergency treatment, but who knows, maybe it will eventually become standard care. Or, knowing the scientific community, we’ll continue to explore other types of therapy (such as quorum sensing or nanoparticle drug delivery) alongside of phage research.