Unseen enemies in water and food:
Dr. Nikhil Thomas tackles E. coli and other dangerous bacteria
Even in North America, our food supply is not safe from bacterial contamination. Recent news reports of Listeria in melons, Salmonella in poultry and E. coli on Romaine lettuce and alfalfa sprouts highlight the dangers lurking as close as your refrigerator.
“It’s a significant public health issue when bacteria contaminate our food or water supplies, and it’s also a huge economic issue,” says Dr. Nikhil Thomas, a microbiologist and infectious diseases researcher at Dalhousie Medical School. “Food and waterborne bacteria kill millions of people around the world every year, taking their biggest toll on children and the elderly. And for farmers, especially those who specialize in a single crop, a massive product recall can be financially devastating.”
Dr. Thomas is examining exactly how two particularly nasty pathogens penetrate and infect human cells. The most notorious of these is E. coli, which recently struck two young people in New Brunswick with severe illness. E. coli can be found in water and some fresh produce, although it's greatest health impact is through undercooked ground meat. The other pathogen of interest is Vibrio parahaemolyticus – often found in shellfish like oysters, clams and mussels – which causes intestinal bleeding and diarrhea.
“Both of these bacteria have a complex needle-like structure on their cell surface that they use to literally pierce the intestinal wall within our bodies during infection,” notes Dr. Thomas. “From there they inject a plethora of toxins that destroy cells and shut down the local immune response, creating tissue damage and disease.”
Learning how these bacteria wreak havoc is the key to disarming them, according to Dr. Thomas. “My goal is to find ways to block these toxins before they do damage,” he says. “We’re also studying how the host responds to the bacteria… perhaps we can custom-design an immune response to fight them off.”