The fourth Thursday of November marks the annual tradition in the U.S. called Thanksgiving. Originally Thanksgiving was a religious holiday that has sinced turned secular and became a national holiday in 1941. Now, for families celebrating Thanksgiving, it is a time to cook a whole lot of food and eat way too much pumpkin pie.

Since everyone is going to be focused on food next week, I thought it would be a good time to go over some important facts about food microbiology and the bacteria that can infect your food if you undercook it, cross-contaminate it, or let it sit out all night. After all, pumpkin pie is full of sugars, protein, and fats- everything that a lovely swarm of bacteria also enjoys as a midnight snack.

First lets discuss what are the sources of bacterial contamination in food.

From the Animal:

Microbes are everywhere in our environment and on our bodies so there are many opportunities for bacteria to infect sources of food. In the case of beef and poultry, the microorgansisms are often found in the intestines of healthy animals and are spread during slaughter. Fruits and vegetables may become infected when they are washed or irrigated with water contaminated with animal manure. Salmonella can infect the hen egg before it is formed so the egg can be contaminated (which is why you shouldn’t eat raw cookie dough!)

From Food Handlers

Some types of microbial pathogens can be passed on to your food via the staff working in the kitchen (sorry, Mom. This includes you). Shigella and some viruses (Norwalk and Hepatits A) come from human contact with food. Another source is using cutlery on raw foods and not cleaning them before re-using. Similarly, cutting boards and utensils used for handling raw food need to be cleaned before use. Even if the food was cooked, the contamination can be reintroduced with contact with surfaces or drippings from raw or contaminated food.

Improper Storage

Most likely, mom and her helpers in the kitchen all washed their hands and the utensils after handling the raw turkey and moving on to the mashed potatoes or cranberry sauce. So another source of food poisoning is by simply not storing the cooked food properly once it has cooled down. That’s right- the leftovers!  Make sure to store your leftover food correctly so bacteria that may be present from the environment and the little kids hands isn’t allowed to flourish.

What are the best storage temperatures? According to the Arizona Dept. of Health, food should be stored at 34 to 40°F (1 to 3°C). Above 3°C foods will spoil rapidly. Frozen food should be kept at 0°F (-17°C). The temperature should not reach higher than 5°F (-15°C). Check the temperature with a thermometer, or use this rule of thumb: If the freezer can’t keep ice cream brick-solid, the temperature is above the recommended level. Some additional food storage tips can be found on the Santa Barbara Dept. of public health website also.

What critters should you watch out for?

Now let’s discuss the bacteria that can cause the post-celebration blues. What are the most typical pathogens that infect foods, both pre and post cooking? Based on statistics collected by the CDC between the years of 1983 and 1997, Campylobacter spp. contamination resulted in the majority of bacterially caused food borne illnesses (2.4 million cases, almost 50%) followed by non-typhoidal Salmonella (1.4 million cases). However, there can be a high degree of under-reporting in bacterial infections because not everyone will go to a hospital when they are sick. The level of under-reporting for Salmonella is estimated at ~38 fold and for E.coli (0157:H7), ~20 fold. However, Norwalk viruses caused far more food-borne illness, approximately 23 million  cases out of a total of 30 million.

Name that Food Pathogen:

The following information comes from the Iowa State Food Safety website. The symptoms of all of these are very similar. You can pretty much count on having abdominal cramps and diarrhea if you become infected with any of these microorganisms and for some, you’ll get to experience the additional symptom of vomiting:

Bacillus cereus

Incubation period: 30 minutes to 15 hours

Possible contaminants: meats, milk, vegetables, fish, rice, potatoes, pasta, and cheese

Steps for prevention: pay careful attention to food preparation and cooking guidelines.

Campylobacter jejuni

Incubation Period: One to seven days

Possible Contaminant: Raw milk, eggs, poultry, raw beef, cake icing, water

Steps for Prevention: Pasteurize milk; cook foods properly; prevent cross-contamination.

Clostridium botulinum

Incubation Period: 12 to 36 hours

Possible Contaminant: Low-acid canned foods, meats, sausage, fish

Steps for Prevention: Properly can foods following recommended procedures; cook foods properly.

Clostridium perfringens

Incubation period: 8 to 22 hours

Possible contaminants: meats and gravies

Steps for prevention: proper attention to cooking temperatures.

Escherichia coli 0157:H7

Incubation Period: Two to four days

Possible Contaminant: Ground beef, raw milk

Steps for Prevention: Thoroughly cook meat; no cross-contamination.

Hepatitis A

Possible contaminants: water, fruits, vegetables, iced drinks, shellfish, and salads

Steps for prevention: carefully wash hands with soap and water after using a restroom, changing a diaper, and before preparing food.

Listeria monocytogenes

Incubation Period: Two days to three weeks

Possible Contaminant: Vegetables, milk, cheese, meat, seafood

Steps for Prevention: Purchase pasteurized dairy products; cook foods properly; no cross-contamination; use sanitary practices.

Norwalk, Norwalk-like, or norovirus

Incubation Period: Between 12 and 48 hours (average, 36 hours); duration, 12-60 hours

Possible Contaminant: raw oysters/shellfish, water and ice, salads, frosting, person-to-person contact

Steps for Prevention: Adequate and proper treatment and disposal of sewage, appropriate chlorination of water, restriction of infected food handlers from working with food until they no longer shed virus.

Salmonellosis

Incubation Period: 12 to 24 hours

Possible Contaminant: Meat, poultry, egg or milk products

Steps for Prevention: Cook thoroughly; avoid cross-contamination; use sanitary practices.

Staphylococcus

Incubation Period: One to six hours

Possible Contaminant: Custard- or cream-filled baked goods, ham, tongue, poultry, dressing, gravy, eggs, potato salad, cream sauces, sandwich fillings

Steps for Prevention: Refrigerate foods; use sanitary practices.

Shigella

Incubation period: 12 to 50 hours

Possible contaminants: salads, raw vegetables, dairy products, and poultry

Steps for prevention: practice proper washing and sanitizing techniques.

Vibrio

Incubation period: four hours to four days

Possible contaminants: fish and shellfish

Steps for prevention: cook fish and shellfish thoroughly

Yersiniosis

Incubation Period: One to three days

Possible Contaminant: Raw milk, chocolate milk, water, pork, other raw meats

Steps for Prevention: Pasteurize milk; cook foods properly; no cross-contamination; use sanitary practices

 Summary:

As you can see, proper food handling and storage is serious business. But prevention is simple; don’t eat raw chicken,  clean cutlery and counters between handling raw meats, wash your hands after using the bathroom, wash your hands after changing a diaper, don’t sneeze on food and then leave it out on the counter all night, and make sure you have a half-gallon block of ice cream in your freezer that is frozen solid (as a measure of how well your freezer is working).

Joking aside, getting sick on your vacation is not fun or a safe way of losing the extra holiday pounds. So use common sense and enjoy a hot and tasty meal with all the trimmings and the leftovers too.

Thanks for reading and please leave us a comment if you have more  food safety advice or a personal experience involving food-borne pathogens you’d like to share.

~Suzanne (twitter.com/SuzyScientist)

~MO BIO Facebook page

Check out the MO BIO PowerFood Microbial DNA Isolation Kit for high purity isolation of bacterial DNA from contaminated food as well as any inhibitor rich bacterial culture.

For 20% off your next PowerFood Kit, use the promo code “turkeyday20“. Offer good until the end of November and applies to one kit only.

This entry was posted on Sunday, November 15th, 2009 at 9:04 am and is filed under News. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.