Bacteria only infest food when it's weeks old, right? And if food looks fresh at the grocery store, it’s probably safe to eat, isn’t it?
Unfortunately, you can't spot bacteria-riddled food just by looking at it. And food can spoil, even if refrigerated, faster than you might think. Learning how food contamination happens, and how to keep bacteria out of your kitchen and your meals, can help keep your family safe.
What Kinds of Bacteria Are to Blame?
Certain types of bacteria are responsible for most food contamination in the United States:
- Clostridium botulinum, which cause botulism, is found in canned, vacuum-sealed, or other packaged foods, as well as in garlic packed in oil.
- Escherichia coli 0157:H7 (E. coli) can be found in raw or undercooked ground beef, raw fruits and vegetables, unpasteurized milk, and apple juice, and can also be transmitted through human contact.
- Salmonella is found in poultry, meat, unpastureurized milk and dairy, raw or undercooked eggs, and seafood, and may be transmitted by people who prepare food.
- Staphylococcus aureus can be found in any food handled by an infected person who has touched food with staph-contaminated hands.
- Shigella can be found in any food handled by a person touching food with hands contaminated with shigella-infected fecal matter.
- Listeria monocytogenes is located in processed foods like deli and lunch meats and cheeses, hot dogs, some sausages, and unpasteurized milk and cheeses.
- Clostridium perfringens can be found in any food left at room temperature or on a warming tray or table for a significant amount of time.
- Campylobacter jejuni is found in unpasteurized milk, poultry, shellfish, raw or undercooked meats, and contaminated water.
Many of these bacteria cause very uncomfortable symptoms such as abdominal cramping, vomiting, and diarrhea that can last from several days to more than a week. Without treatment, some of these bacteria (like Clostridium botulinium) can actually lead to death.
How Food Contamination Happens
The food we eat can be contaminated during any of the many steps it takes to get it from the farm to our table. Food contamination can occur when:
- The animal that is eventually slaughtered for meat has bacteria in its intestinal tract.
- Meat becomes contaminated with bacteria during the slaughter.
- Produce is washed or watered with bacteria-contaminated water.
- A hen's ovaries are infected with bacteria.
- Bacteria in ocean water contaminate the fish that live there.
- Humans handle meat and other foods with unwashed hands during processing.
- Food processing equipment is contaminated.
- The same utensils are used for multiple foods, transferring bacteria from contaminated food to uncontaminated food.
- Food is left out of the refrigerator and sits at room temperature for more than a few hours.
- Food is left in a refrigerator for too long.
If you think there’s any chance you have food that has been contaminated, don’t risk eating it — throw it out right away.
Who’s Most at Risk From Food Contamination?
If you suspect that you ate food that was contaminated with bacteria, you may need to see a doctor, especially if you are at an increased risk of a severe or dangerous reaction to foodborne illness. People at a higher risk include those who are:
- Living with a chronic condition like diabetes or kidney disease
- Living with a compromised immune system
- Exposed to harmful organisms while traveling to a foreign country
You don't need an antibiotic to get over most illnesses caused by food contamination; instead, you usually must wait it out until the bacteria leaves your system. Be careful to drink plenty of fluids to avoid dehydration, and avoid dairy products to prevent making diarrhea more severe.
Foodborne illness can be extremely serious in some cases, but for most people it just causes serious discomfort. Protect yourself from foodborne illness by buying fresh foods, storing food properly, avoiding food contamination in the kitchen, and keeping your foods properly refrigerated.
Last Updated: 1/7/2010