Staphylococcus aureus is a monster.
The bacteria causes skin and wound infections, pneumonia, bloodstream infections, and often death. Every year in America, more than 80,000 people contract staphylococcal infections, and more than 11,000 people die from staph infections, according to the Center for Disease Control.
This summer, senior biology major Wyatt McDonnell combatted the monster, searching for a weak point to attack. Working with two strains of staph—Methicillin-resistant staph, and a similar strain known as MSSA—he found that at a certain stage, simply shining measured amounts of blue and red light on the staph can kill the bacteria.
“We were able to show that it significantly inactivated them,” McDonnell said. “We were shocked and awed. There aren’t a lot of times in science where something works on the first try, much less on the second and the third try and it’s repeatable.”
Physicians usually treat staph infections with antibiotics, but the antibiotics are only effective as long as the strain remains unaltered. The bacteria quickly develops mutations which make the antibiotics obsolete.
The Food and Drug Administration has set a goal of developing 10 new antibiotics by 2020, but McDonnell says that goal is ill-advised. Even if it were possible to quickly develop the antibiotics, clinical trials meant to find treatments suitable for human use should not be a rushed task. Even with a deadline, drugs are often outdated by the time they appear on the market.
“Unfortunately for us, bacteria are starting to get ahead,” McDonnell said. “We can’t churn out antibiotics quick enough. Antibiotics don’t kill every bacteria in an infection: if there are any survivors, and that survivor has picked up the mutation along the way, that’s the start of your next pandemic.”
So McDonnell decided to look for another way.
As a member of the biology department’s LAUREATES program, McDonnell received a stipend to perform six weeks of research in college labs over the summer with Dr. Francis Steiner, his research supervisor. By mid-June, after spending hours in the lab each day, they had results.
“We gave the bacteria a precursor to hemoglobin, they take it up because they think it’s food,” McDonnell said. “But when they go to convert it to heat, the enzyme that does that is very, very slow. So it gets stuck at this compound that is light sensitive. All we had to do after waiting a little while for them to incorporate it was hit them with blue light or red light. It doesn’t even have to be UV, just visible light.”
They had found the monster’s weak point and found a treatment method significantly more comfortable for patients as the therapy treatment does not involve radiation or large doses of antibiotics.
McDonnell stayed on campus an extra week to complete his research, verify, and collect statistics. With the results, he wrote and submitted an article for the Journal of Photochemistry and Photobiology, from which he expects to hear later this semester.
Steiner also encouraged him to submit an abstract of his research for the International Symposium on Staphylococci and Staphylococcal Infections. ISSSI accepted McDonnell’s work, and requested that he give a poster talk at the convention.
The symposium is a prestigious biennial convention of staph experts from around the world. In 2012, the convention was held in Vienna, Austria. On Aug. 26 and 27, McDonnell and Steiner traveled to Chicago for the first two days of symposium programs.
“At the conference, everything about the organism is presented and discussed,” Steiner said. “Things about virulence factors and antibiotic resistance and the the relationship to the immune system. It was a great opportunity for him because he presented his work in a group of people that was mainly graduate students or major research labs and noted researchers in the field.”
During the poster talk, McDonnell was approached by Dr. James Cassat of Vanderbilt University, who invited him to apply to their master’s program to study host pathogens. He also met several experts whose research he had relied on, as well as one of the reviewers of his journal manuscript.
“I was the only undergraduate. It’s an honor to be there,” McDonnell said. “To be able to give a poster talk to some people—Ph.D.s in some cases—that had never heard of photodynamic therapy and be able to give them an introductory lesson on something. How often does that happen, to get to lecture someone with seven years worth of degrees ahead of you and ‘doctor’ for a title?”
While McDonnell’s discovery does not slay the beast altogether, it is an effective method of treatment that avoids several problems with the antibiotic method.
“It’s not a cure. It’s a therapy method,” McDonnell explains. “One of the goals of our research was to look at ways of antimicrobial chemotherapy, but without using antibiotics. So ours is based on this concept called photodynamic therapy. They’ve been using that since the 80s to do things like imaging cancer cells, treating skin cancer.”
McDonnell’s treatment contributes to the field in two ways: He showed that both red and blue wavelengths of light are effective in rendering the bacteria inactive while previously, researchers have focused on red light. He also used significantly lower, non-toxic dosages of phototherapy as well as the photosynthesizer ALA than any other known researcher. McDonnell’s dose amounts to only 0.4% of the lowest dosage that’s been reported.
“It would be less expensive than current phototherapy methods because you don’t have to pay for a bunch of pharmaceuticals if you’re using a stock solution of such a low concentration,” McDonnell said. “Because there’s less photosynthesizer some of the side effects of the therapy would benefit the patient. When you’re working with a really concentrated amount of that a lot of people report feeling the tissue or their skin burn because it’s light energy. It would be a good option for physicians and patients alike.”
Although McDonnell took the Medical College Admission Test last week, he doesn’t plan to become a physician. Instead, he dreams to pursue a Ph.D and study host pathogen interactions and bacterial pathogenesis.
“What I love about science is that the more you learn the more you realize that you don’t know anything,” he said. “And the higher up you go, not only do you not know anything, but nobody else knows anything either.”
