Yesterday I warned pregnant women not to eat pre-packed sandwiches because of the Listeria monocytogenes contamination risks. By the way, the same goes for anyone else with immune system problems. Maybe I should explain a bit more why ready-to-eat sandwiches are so risky.
The dangerous L. monocytogenes bacterium is often present in the fillings used for such sandwiches - deli meats and poultry, cheeses, prepared salads, seafood products, and so on. And even if these bacteria are not in the ingredients used, they can enter at the sandwich-making facility in both contact and non-contact surfaces. L. monocytogenes is widely present in nature (soil, water, plants) and from there moves to drains, floors, machinery, packaging surfaces, cutting boards and even the air of the sandwich making facility. A high percentage of workers are also carriers (estimates vary).
Over the years, a number of sandwich-making facilities in the U.S. have had to gone out of business because of bad Listeria contamination. In some cases, the government, in the form of the U.S. Food and Drug Administration (FDA) has had to step in and actually get a court order to close the plant down. This happened just a month ago ( December, 2011) in the case of Triple A Services, Inc because inspections of the plant repeatedly turned up Listeria bacteria.
Unfortunately, unlike most other dangerous bacteria, Listeria monocytogenes can multiply in low-oxygen environments and at refrigerator temperatures. Ten bacteria become a hundred, then a thousand, and then ten thousand. In other words, the longer that sandwich sits there, the more dangerous it can become.
As I said yesterday - pass on that pre-packaged sandwich. I have even started making my own to take on flights. Besides, it tastes better. And isn't loaded with preservatives.
To your good health,