A potential new victory in the war against antibiotic-resistant "superbugs" lies in the discovery of specific viruses that eat bacteria - called bacteriophages. Researchers in the UK have isolated certain phages, which have been shown to target the infectious hospital bug Clostridium difficile.
C. diff, as the superbug is known, is responsible for 250,000 infections in the US each year and results in 14,000 deaths, the researchers say.
Causing excess medical costs of $1 billion each year, finding a solution to this problem is one of both medical and economic importance.
Dr. Martha Clokie, from the University of Leicester's Department of Infection, Immunity and Infection, has been studying how naturally occurring bacteriophages - which means "eaters of bacteria" - could serve as an alternative to antibiotics.
A dead, burst open cell is pictured here with phages escaping. These phages can then repeat the process on other cells. Credit: Samples from Dr. Martha Clokie taken by Stefan Hyman, School of Biological Sciences, University of Leicester.
Though Dr. Clokie gives credit to the important role antibiotics have played in saving lives, she says new treatments are needed:
"Less than a century following their discovery, the future impact of antibiotics is dwindling at a pace that no one anticipated, with more and more bacteria out-smarting and 'out-evolving' these miracle drugs. This has re-energized the search for new treatments."
Unlike antibiotics, Dr. Clokie says phages "are specific in what they kill," noting that they usually infect only one specific species or strain of bacteria.
By injecting their DNA into the bacterium, she notes that phages then replicate and cause the bacterial cell to "burst open." Once the dead bacterium is opened, the phages can then repeat the process on other host cells.
Maintaining gut bacteria balance
What is so remarkable about the research team's finding is that they were able to isolate and characterize 26 distinct phages - the biggest set of C. diff phages that are currently known.
These phages infect strains of C. diff that are "clinically relevant," and they have been proven to be effective against 90% of the strains currently seen in the UK.
Dr. Clokie says:
"C. diff bacteria primarily affect our digestive system. Whilst relatively innocuous in individuals with a healthy gut flora, they pose a serious threat when our natural digestive environment is disrupted or depleted, such as after chronic antibiotic use."
She notes that the ability of phages to only infect and kill a specific type of bacteria is "particularly important" when dealing with C. diff infections, because keeping the balance of gut bacteria "greatly reduces the chance of relapse."
Clinical trials soon
Dr. Clokie's phages have been licensed by a US biopharmaceutical company called AmpliPhi Biosciences Corporation, and together, they aim to have a mixture of C. diff phages ready for phase I and II clinical trials in the near future.
The company, which has developed phage-based therapeutics, is funding further development and testing of these phages.
Dr. Clokie and colleagues from the University of Leicester will work with scientists from the University of Glasgow in Scotland to analyze the efficacy of the phages in treating infections.
The work has been predominantly funded by the Medical Research Council (MRC), and Dr. Des Walsh, head of Infections and Immunity at the MRC, says that Dr. Clokie "has established an impressive collection of phage viruses and has developed strong partnerships to translate her research into potential new treatments for Clostridium difficile infection."
"Ultimately," says Dr. Clokie, "I hope this will pave the way for a greater use of bacteriophages in the wider, global fight against antibiotic-resistant bacteria."
When asked how long until patients might begin to see benefits from her research, Dr. Clokie told Medical News Today:
"We are now funded for a year to be able to develop an optimal C. diff phage product. We know our viruses work individually and we need to establish how they behave in a mixture and to select the viruses with the best combined killing spectrum on C. diff."
"If all goes well," she added, "we could see a product in 5-10 years."
Medical News Today recently reported that scientists have printed microscopic 3D cages to study bacteria.