University of Rochester Medical Center scientists demonstrated a new technology that accurately and rapidly detects E. coli bacteria.

The unique technology uses a protein from the suspect bacteria as part of a sensing system that also includes a silicon chip and a digital camera. The journal Biosensors and Bioelectronics detailed the technology in its February issue.

Researcher Benjamin Miller says, “We've developed a very inexpensive technology that can detect an infectious agent. It's clearly faster and cheaper than any competing technology. It's another step on the way to point-of-care diagnostics.”

The technology could potentially detect any biological entity, says Miller, who is with the university's Center for Future Health. For example, a physician might someday use it to confirm streptococcal infection in a patient with a sore throat.

The research team calls the technology “arrayed imaging reflectometry.” It utilizes a silicon chip made so laser light reflected off the chip is invisible unless target bacteria are present. The target bacteria are E.coli.

A protein from the bacteria, Translocated Intimin Receptor (Tir), is placed on the chip. The Tir can be seen as a “molecular harpoon,” Miller says. The E. coli sends out the harpoon into a cell. Once it is in the cell, the Tir then binds with an E. coli protein called Intimin. A similar process occurs between the Tir placed on the chip and any E. coli in the sample being tested.

The binding of the probe and bacteria alters the chip's surface. A digital image of the chip captures the changes for analysis and confirmation of detection.

Traditional bacteria-detection methods can take days. “This takes as much time as it takes for a snapshot,” Miller says.

Scientists are defining the sensitivity levels of the technology, previously called reflective interferometry, and extending it to other biological targets.
University of Rochester Medical Center news release

In an animal research “first,” USDA Agricultural Research Service (ARS) researchers found disease-causing bacteria can gain strength from interaction with single-celled organisms called protozoa. The protozoa are naturally present inside animals' digestive tracts, which is where the bacteria can develop.

At the ARS National Animal Disease Center in Ames, IA, researchers discovered the antibiotic-resistant strain of Salmonella becomes especially virulent when tucked inside the protozoa in the rumen of cattle. They noted that, while inside the protozoa, Salmonella appeared to resist destruction.

Researchers studied the relationship between rumen protozoa and Salmonella, and its resistance to antibiotics, focusing on the S. enterica strain — the foodborne pathogen believed more virulent than other antibiotic-susceptible strains. Calves are 13 times more likely to die from this strain than others.

In most animals, salmonellosis infections cause diarrhea, and animals recover without antimicrobial therapy. But in systemic infections, animals require antibiotics, to which many Salmonella strains are resistant.

Scientists used a method similar to deworming to clean out the animals and eliminate hidden bacteria on a regular basis. Fewer cells were recovered from tissue of infected animals after the method, known as defaunation, was used.

ARS says the research opens doors to learning more about what goes on inside an animal.
ARS News Service