Pathogen testing made simple

Testing for deadly food, air and water pathogens may get a lot easier and cheaper, thanks to a team of Michigan State University researchers.

Syed Hashsham, associate professor in the Department of Civil and Environmental Engineering and the Center for Microbial Ecology, is developing a portable, hand-held device capable of detecting up to 50 microbial threat agents in air, water and food.

"This device will give us the ability to measure pathogens in a manner and at a price that really matters for human health," Hashsham said. "If we can screen for all pathogens together, we can minimize the threat significantly."

Hashsham intends for the portable, hand-held device to be an all-in-one pathogen testing center where DNA amplification and pathogen identification will happen on the same DNA biochip. A DNA biochip has signature pieces of DNA attached to a silica surface similar to that of a computer chip, and is about the size of a thumbnail.

Today, testing air, water or food for pathogens that cause diseases such as cholera and dysentery must be done one pathogen at a time. Testing for each pathogen singly is dangerous, expensive and time-consuming. Simultaneous testing simplifies the process, making it safer and more cost-effective.

Hashsham; James Tiedje, professor of crop and soil sciences, researcher and director of the Center for Microbial Ecology; and Erdogan Gulari, professor of chemical engineering at the University of Michigan, formed a cross-disciplinary team to develop this technology.

The pathogen detector project grew out of a desire to make good use of data on microorganisms already housed at MSU, Tiedje said. The Center for Microbial Ecology manages the Ribosomal Database Project, an internationally used database of information on microorganisms.

"Maybe five or six years ago, we began thinking about how that data resource could be used in a platform to help identification," Tiedje said.

In 2006, the research team was awarded $966,608 from Michigan's 21st Century Jobs Fund to develop and commercialize the device. AquaBioChip, L.L.C., a Lansing-based high-tech firm formed by the same team through a previous grant from the Michigan Economic Development Corp., will test the device under field conditions.

To begin the testing, processing extracts DNA from all microorganisms present in the sample. The DNA is then introduced into the device, where it undergoes polymerase chain reaction (PCR) for the selected harmful pathogens. PCR is a process that takes a small amount of DNA and makes billions of copies so the pathogens can be easily detected, Hashsham explained.

Most of the genetic material in any bacterium isn’t harmful. For instance, the bacterium Vibrio cholerae, responsible for the waterborne illness cholera, has many genes that maintain the organism but are not dangerous to humans by themselves. It's the gene producing the cholera toxin that is harmful. The harmless genes serve as good markers for detection. Hashsham’s device will be designed to look for such marker genes.

"This technology is rugged and highly parallel; it can analyze lots of marker genes in a lot of samples and has significantly fewer false positives than current technology," Hashsham said.

He said the hand-held testing device could be used anywhere that cost-effective testing of food, water or air for a number of pathogens is needed. Current single-pathogen testing devices typically cost about $30,000. Hashsham expects the MSU team's detector to cost about $1,000 per unit.

"Because of the lower cost, there also will be applications in countries where fewer resources are available for drinking water safety," Hashsham said.

Looking toward the future, Hashsham has been in touch with several organizations that might be interested in the device. It could eventually be used on cruise ships, in hospitals or in schools. Most importantly, he said, the technology would move testing "away from the lab and into the field where it's needed."