Though the human body contains trillions of bacteria and (usually) remains healthy, many bacteria continue to evolve to outsmart current antibiotic medications.
Tom Frieden, director of the U.S. Centers for Disease and Control and Prevention (CDC), warns that we’re buying time on the biological clock and that current medications soon will not be able to cure people of life-threatening infections.
“Many people see antimicrobial resistance as a threat to someone else,” he said during a press conference last month. “Without more action now, more patients will be thrust back to ... a post-antibacterial era.”
Two newly published papers show that the next generation of bacteria-killers is on the horizon, including a treatment for deadly bacteria affecting military personnel in the Middle East and the highly infectious hospital superbug Clostridium difficile (C. diff).
PPMOs: A New Approach to Fighting Bacteria
Researchers at Oregon State University and other institutions say bacteria’s new worst enemy may be a peptide-conjugated phosphorodiamidate morpholino oligomer, or PPMO. These lab-synthesized forms of DNA or RNA can silence specific genetic targets, and researchers say they function better than a standard antibiotic without the risk of bacteria becoming resistant to them.
Researchers tested PPMOs against infections in animals caused by two strains of Acinetobacter, which is affecting overseas troops. Researchers say the PPMOs performed better than broad-spectrum antibiotics against A. baumannii, which can cause respiratory infections and sepsis and can be deadly to people with a weakened immune system.
Unlike antibiotics, which attack a bacteria cell’s function and can cause other side effects, PPMOs disrupt the bacteria’s genes. Issues of toxicity need to be addressed in further testing before PPMOs can be used in humans, the researchers said.
“The mechanism that PPMOs use to kill bacteria is revolutionary,” lead author Bruce Geller, a microbiology professor at Oregon State, said in a statement. “Molecular medicine is the way of the future.”
C. diff is one of the natural microbes found in your gut, but chronic antibiotic use can make it go haywire. It’s also one of the many superbugs turning up at hospitals. It caused 14,000 deaths and 250,000 hospitalizations between 2005 and 2011, according to the CDC.
Specialists at the University of Leicester and AmpliPhi Biosciences Corporation have found phages, viruses that eat bacteria, to specifically target C. diff. They work by attaching to bacteria as a host, injecting their DNA—which replicates—and causing the bacterial cell to burst open.
Researchers say these phages are effective against 90 percent of the most clinically relevant C. diff strains in the United Kingdom.
“The key advantage of using phages over antibiotics lies in their specificity. A phage will infect and kill only a specific strain or species of bacteria. This is particularly important when treating conditions like C. diff infections, where maintenance of the natural balance of gut bacteria greatly reduces the chance of relapse,” Dr. Martha Clokie, from the University of Leicester's Department of Infection, Immunity and Inflammation, said in a statement.
AmpliPhi is funding the development of these C. diff phages and hopes to have a mixture ready for clinical trials soon.