More Than 500 Infected - Elusive Salmonella Saintpaul in America's Tomatoes

According to the Centers for Disease Control, more than 500 people in 32 states have been infected by the potent and rare Salmonella Saintpaul strain through tomatoes that appear to have come from farms in Florida and Mexico. While the FDA is investigating the source of the contamination, scientists studying the Salmonella bacteria have recently found it to be a surprisingly sophisticated animal. Salmonella is usually associated with contaminated kitchen surfaces, inadequately cooked foods, and improper storage temperatures – and it has also been a concern in handling captive reptiles and rodents. Among these associations, the FDA is currently studying the storage conditions of the tainted tomatoes. The USDA Food Safety and Inspection Service estimates that Salmonella alone is responsible for a whopping 300,000 to 4,000,000 cases of foodborne illness in the United States. Researchers at the University of Rochester Medical Center have now uncovered a behavioral mechanism of the Salmonella bacteria, establishing the bug as trickier than previously considered. The team has identified a protein in the bacteria’s arsenal that allows Salmonella to maintain a low profile in the body. This protein yields the net benefit of a silent foothold. Jun Sun, PHD at the University of Rochester Medical Center and leader of the team explains, “Salmonella is especially equipped with tools to allow it to evade the immune system early on, growing quietly and then really making the host quite ill. Salmonella is trickier than we imagined.” Getting past the human immune system is something to appreciate. However, this penetration of killer T-cell’s natural defenses cannot be performed without first surviving the inhospitable environment of our stomach. Given this, scientists are also studying Salmonella’s resistance to digestive acids. In a 2005 study published by the Journal of Applied Microbiology, the research team found that “acid resistance could be an indicator of virulence since acid resistant strains are able to better survive the human stomach passage and in macrophages.” It is not an easy feat to swim through a sea of acid and enter the blood stream with ninja-like evasive maneuvers. While we have only this year discovered Salmonella antibodies in Malawi children – which could lead us to a vaccine – we would certainly be wise to respect this sophisticated animal.