A Real Life Saver
This is not the first time Kate Genty has appeared in an issue of F1RST. In the spring, 2018, semester, near the end of her first year at the university, Gentry was one of two Carroll students to donate bone marrow through the Be the Match donor campaign.
Pseudomonas aeruginosa is one such superbug. It’s ubiquitous in the natural world, seems to do quite well in man-made environments and, thanks to our interference, is rapidly selecting for multidrug-resistant strains. In fact, it’s an opportunistic little bug that’s been implicated in hospital-acquired infections and other serious illnesses, according to the Centers for Disease Control and Prevention (CDC). It can attack and infect the lungs of cystic fibrosis patients, in particular, spreading a biofilm across the surface of the lungs that impairs critical lung function. As its resistance to antibiotics grows, so does its danger.
In a research lab in Carroll’s Michael and Mary Jaharis Laboratories building, the war against P. aeruginosa is being fought by biology professor Christine Schneider and Kate Gentry, one of her students.
Specifically, they are hoping to bring new weapons to the fight. Bacteriophages, often simply referred to as phages, are viruses that infect and replicate within bacteria and archaea (a separate, single-celled organism). Their entire existence depends upon a steady supply of bacteria, so they’re found wherever bacteria live. However, unlike traditional antibiotics, which generally target a wide range of bacteria, destroying both good and bad bacteria, phages play favorites.
In this way, phages are of great interest to researchers, noted Schneider. She and her students have been investigating phages for years, first attempting to learn more about their genetic makeup and now trying to establish just what makes them effective as bacteria killers.
Phage therapy itself isn’t new. It’s been employed as a medical treatment in eastern Europe since the middle of the twentieth century, championed by a research institute in Tbilisi, Georgia. Phage therapy has several benefits over traditional antibiotics: phages can target specific infections, are usually harmless to the host organism and are self-dosing—when the host bacteria die off, the phages are unable to continue replicating.
Schneider and her students have their sights on several phages that are known to target P. aeruginosa. “We focused on Pseudomonas aeruginosa because of the clinical problems it causes,” Schneider explained. “The CDC has labeled it one of their bugs of concern.”
Previous Carroll student Eric Graham ’16, who is now a medical student at Penn State, isolated several phages from raw sewage (phages are widely prevalent in bacteria-rich environments like sewage) and had their genomes sequenced in order to identify them. They discovered four phages that fell into the same family as ones already in use in phage therapy applications.
For biology major Gentry, that’s where the fun started. Last summer, Gentry was named a Pioneer Scholar, and engaged in a research project alongside Schneider, slicing up the phages’ genes and trying to determine which ones came loaded and which ones were blanks.
“We want to pick the phage apart and find genes that look promising to us,” said Gentry.
“We know only such a small piece of the phage world,” added Schneider. “We know they kill the bacteria but not clearly how that happens. Essentially, the phage hijacks the bacteria’s life processes and we are trying to tease out which genes help it do that.”
Step one was sequencing the phage’s genetic code. In her work, Gentry has moved on to the next stage, systematically reproducing individual phage genes to see if they can kill Escherichia coli.
E. coli is another strain of bacteria. It normally resides in the guts of warm-blooded organisms. It’s camped in your intestinal tract right now and is mostly harmless, though it can contaminate food and cause food poisoning. “E. coli is the workhorse of any microbiology lab,” noted Schneider. It’s easy to manipulate and cheap to grow in a lab.