Fowler hopes his samples might help answer a broader question related to varied patient responses to the blood infection bacteremia.
"Staphylococcus aureus infections of prosthetic devices are devastating to patients and expensive to health-care systems. For this reason, the best way to treat these infections is to prevent them in the first place. I believe that our research is a critical first step towards understanding, and eventually preventing, cardiac device infections caused by Staphylococcus aureus," Fowler said.
For this study, the researchers used 80 Staph isolates from three different groups: patients with a blood infection and a confirmed cardiac device infection, patients with a blood infection and an uninfected cardiac device, and Staph from the noses of healthy people living in the same area.
Single-cell studies of bacteria are complicated by their tiny size, one millionth of a meter, so an atomic-force microscope is required to visualize their behavior. Co-author and Ohio State postdoctoral researcher Nadia Casillas-Ituarte performed these experiments, connecting single Staph bacteria to a protein-coated probe to allow bonds to form, and then rupturing the bonds to measure the strength of each connection.
Casillas-Ituarte simulated the human heartbeat, allowing bonds to form over the course of a second and then pulling the probe away. By doing this at least 100 times on each cell and verifying the work on hundreds of additional cells, she generated over a quarter-million force curve measurements for the analysis.
"The first step in all of this is to determine how a bacterium feels a surface," she said. "You can't stop that process until you first understand how it happens."
The researchers coated the probe with fibronectin, a common human blood protein found on the surface of implanted devices. Staph bacteria can create a biofilm by forming bonds with this protein through a protein on
|Contact: Steven Lower|
Ohio State University