Bacteria often go dormant to avoid being wiped out by antibiotics or other threats, which makes treatment difficult. Now scientists have discovered a virus that can attack these sleeping bugs, clearing out infections effectively when paired with drugs.
In hostile environments – such as when they’re exposed to antibiotics – bacteria can go into a form of hibernation, where they stop growing and dividing until things calm down. This makes it difficult to fully wipe them out and contributes to the growing problem of antibiotic resistance, which threatens to eventually make even basic infections deadly.
Another form of treatment uses bacteria-hunting viruses called phages to clear out infections, but this has faced efficacy problems too – again, largely thanks to bacteria’s ability to hibernate until the danger passes.
Scientists at ETH Zurich hypothesized that there must be some phage species that can attack bacteria in this dormant state. Now, after years of searching, they’ve identified just such a phage, which they’ve named Paride. The team found that Paride was able to infect the bacteria species Pseudomonas aeruginosa, which is responsible for a range of common infections like pneumonia and UTIs, and is increasingly becoming drug-resistant.
Importantly, the phage can do this even when the bacteria is dormant, although the scientists aren’t yet sure exactly how it does so. For now, they suspect that it first uses a molecular “key” to wake them up, then reproduces by hijacking the bacteria’s mechanism for multiplying.
The team tested Paride’s anti-bacterial action against lab dish cultures of P. aeruginosa. Alone, the phage was able to wipe out 99% of the bacteria, even when dormant. That may sound effective, but the remaining 1% can regroup and cause problems. However, when the phage therapy was paired up with an antibiotic called meropenem, the combo was able to clear out the whole bacteria population.
Meropenem alone has no effect on dormant bacteria at all, but is effective at attacking active bugs. It may be that Paride is waking them all up and killing most, while the antibiotic mops up the rest.
In follow-up tests, the researchers administered the phage, the antibiotic or both to mice with chronic infections. Neither treatment did particularly well on its own, but together they had significant action against the bacteria.
“This shows that our discovery is not just a laboratory artefact, but could also be clinically relevant,” said Enea Maffei, an author of the study. “This is the first phage described in the literature that has been shown to attack bacteria in a dormant state.”
The team says that more work needs to be done to investigate exactly how Paride takes down its sleeping victims, but it’s a promising step towards improving the efficacy of both phage therapy and tackling the superbug scourge.
The research was published in the journal Nature Communications.
Source: ETH Zurich
