New technology sheds light on bacterial pathogens
The operating principle of a highway patrol officer and of a new pathogen testing technology is the same: when you see the bad guys, light ‘em up.
Sample6 provides a new way of performing pathogenic testing, said company CEO Tim Curran. This alternative approach offers an alternative to the three most common ways to check for the presence of pathogens: polymerase chain reaction (PCR), immunoassay tests (also known as lateral flow) or simple culture tests. Each of these methods uses an enrichment step, where microbes are allowed to multiply in enriched media under controlled lab conditions.
Sample6 bypasses the enrichment step and performs direct detection using a technology developed by two doctoral students from MIT and Boston University called bioillumination. The key players are bacteriophages, which are tiny organisms that are natural enemies of pathogens.
In nature, phages search out and attack their enemies. The Sample6 process slightly changes the genomes of these phages and programs them to produce an enzyme.
“When the phage attaches itself to the bacteria, it is programmed to produce an enzyme in great quantities. This enzyme is originally from a deep sea shrimp that glows in the dark, so the enzyme produces light,” Curran said. “So if listeria is there, the phage is going to find it, produce the enzyme and the enzyme is going to glow. Our instrument is a light reader. If it lights up, there’s listeria. If there’s no light, there’s no listeria.”
One advantage of the new technology is speed, Curran said. The other three methods need time for the sample — whether it is of the environment, equipment or product — to grow in the enriched media. Often, the time needed for this step is 48 hours.
“You need to do this because these methods are only sensitive enough to pick up many bacteria. So there is the 48-hour enrichment and then you run a diagnostic, which needs time for the results. That’s the status quo today,” Curran said.
The three methods pose other problems, Curran said. Reading the results requires the skills of a trained microbiologist. The enrichment step itself, which involves growing pathogenic bacteria, has risks.
“It’s scary. You don’t want to be growing bags of listeria anywhere near your food processing,” Curran said. “What that usually means is that many of the produce companies send samples offsite. Now there’s a shipping step. So add 8 to 12 more hours for shipping on top of the time result issue.”
By enabling direct analysis of samples and bypassing enrichment and shipping, Curran said results from Sample6 come back in 6 to 7 hours.
Sample6 provides an added degree of sensitivity, Curran said. The technology is capable of producing enough light from a single cell of listeria to trigger a positive test result.
The company was launched in late 2011. It now offers two products. Detect is the diagnostic that uses the bioillumination technology while Control is a software that allows a company to map a food processing facility and monitor all the areas where testing and sampling occur.
The initial focus of Sample6 is food safety in manufacturing environments. “That will keep us busy for quite a while,” Curran said. The diagnostic platform for detection has potential for much wider application, he said, including hospitals and other industries where bacterial contamination is a concern such as food retailers, restaurants and farms.
“The way we fit in is the simplicity of the diagnostic, the ability to be consistent and to be flexible,” Curran said. “We can run it onsite and not be at the mercy of a lab that may be miles or states away. On the software application side, it’s about having systems in place for control and transparency of data.”
