Targeting pathogenic bacteria

During the AVS 63rd International Symposium and Exhibition being held November 6-11, 2016, in Nashville, Tennessee, Stephane Evoy, an applied physicist from the University of Alberta, will explain how the team recognized the limited reliability of antibodies in providing bacteria detection with specificity. Instead they used phage-derived proteins, proteins developed from the bacteria-invading viruses, for detection of pathogenic bacteria to address this deficiency. This work has implications not only in disease diagnosis, but also in food and water safety.

"The high specificity of phages offers a potent alternative for the targeting of pathogens," Evoy said. "More specifically, recombinant phage-receptor-binding proteins (RBPs) responsible for phage-host specificity can be used as biological probes and present numerous advantages over the use of a whole phage."

The study used skim cow milk spiked with different phages or combinations of phages, such as mycobacteria (MAP) and Escherichia coli cells, and a unique process to capture the DNA after incubation. The entire process took less than 24 hours and resulted in significantly better sensitivity of detecting targeted DNA.

"The use of phage-derived proteins in such a manner was quite unique when we started that work back in 2005, but since then the approach thrived, and multinational companies integrated this into their product line," Envoy said. "However, there is still a lot of work to be done in terms of applying the technology to diseases such as tuberculosis and staphylococcus infections."

In addition to demonstrating this capture technique, the research team designed and developed a sophisticated bacteria detector comprised of an array of microresonators, able to enumerate bacteria over a large area and detect the attachment of a single cell anywhere on the array. The devices were prepared with their phage proteins, adding this high specificity of detection to the spatial precision offered by the array design.

"We are looking forward to adapting this technology for the rapid diagnosis of drug-resistant bacteria," Evoy said. "It could go a long way toward make microbial testing methods both more rapid and affordable."