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July 1, 2024

Ask The Expert: How to keep bacteria at bay on grilling day

Summer is the time for grilling, but as cooking moves from the kitchen to the patio, unwelcome bacterial guests can tag along for dinner.

While most bacteria are actually beneficial, certain germs can grow on food and cause foodborne illness, or food poisoning, when eaten. The Centers for Disease Control and Prevention estimates 48 million people are sickened by foodborne bacteria every year.

Most illnesses result in minor, flu-like symptoms, including upset stomach, nausea and vomiting, diarrhea, fever and dehydration. But some illnesses can result in hospitalization and even death.

Shannon Manning
MSU Research Foundation Professor Shannon Manning

Now, researchers like Shannon Manning, an MSU Research Foundation Professor, are showing foodborne illnesses pose another threat: They’re spreading antibiotic resistance.

With grilling season in full swing, the College of Natural Science took this opportunity to catch up with Manning to discuss the harmful bacteria that can ruin a summer party.

The following discussion has been edited for length and clarity.

How big of a problem is foodborne illness in Michigan and the U.S. in general?

About one in six Americans are sickened by food poisoning every year. The old, young, immunocompromised and pregnant patients are the most susceptible. According to the CDC, foodborne illness hospitalizes about 128,000 people every year, resulting in 3,000 deaths.

The CDC maintains a surveillance program called FoodNet, which separates the country into ten regions. FoodNet tracks 31 different disease-causing bacteria that can be transmitted through food products in the ten regions to identify hot spots for disease and emerging infections.

FoodNet represents only 15% of the U.S. population so Michigan is not surveilled directly. The Michigan Department of Health and Human Services does monitor foodborne illness and has determined that the rates in the state mirror the FoodNet sampling of the upper Midwest region. Because Michigan may have unique features relative to other states, it is important to continue to monitor these infections at the state level as well.

How can people protect themselves from foodborne illness?

It is important to follow simple food safety practices that are recommended by the FDA. To prevent foodborne illness, follow these four steps.

Clean: Wash your hands before, during and after cooking. Wash the outside rind of fruits and vegetables, including melons, before cutting.

Separate: Use different cutting boards, knives and utensils for meat and vegetables to avoid cross contamination. Use different plates and utensils for raw and cooked meat.

Cook: Cook meat to the proper minimum internal temperature.

Chill: Transport foods in an insulated cooler and store leftovers in shallow containers in the refrigerator or freezer.

How does the public’s perception of foodborne bacteria match with reality?

In 2018, the Pew Research Center released a report that examined the public’s perception of food safety, especially regarding the use of antibiotics in food animals and genetically-modified foods. They found that one-third of respondents were concerned by the use of antibiotics in animals and pesticides on plants. I was surprised this number was so low.

In reality, we are really concerned about antibiotic use in livestock. If you give livestock antibiotics, the pathogenic, or disease-causing, bacteria could acquire or harbor resistance genes.

These genes allow the bacteria to evade the effects of antibiotics and survive in the food products like meat, which can get transmitted to consumers. The FDA and the World Health Organization have implemented new guidelines that limit the use of certain antibiotics in food animals, especially those that are considered clinically important to treat human infections.

Bacterial baddies infographic
Don’t invite these bacterial baddies to your next barbeque: (1) Salmonella infections are most common in summer and affect 1.3 million people in the U.S. every year. (2) Although most forms of E. coli are harmless, there are six different “pathotypes” or categories, that cause illness in more than 250,000 people each year in the U.S. (3) Although listeria infects only about 2,000 people in the U.S. each year, it is one of the leading causes of death among foodborne illnesses. Listeria poses a heightened risk to newborns and people who are pregnant. (4) Campylobacter jejuni infect an estimated 1.5 million people in the U.S. every year, which is likely an underestimate because most infections go unreported. There are a number of harmful bacteria that can lurk on food, but safe handling and preparation practices can keep you safe. Credit: Andrew Ward/MSU College of Natural Science

Can you tell us a little bit about what you work on in your lab?

In my lab, we are looking for and characterizing the bacterial foodborne pathogens that most commonly affect human patients. For example, we are analyzing the genome sequences to understand which bacterial traits are most important for human infections and which may be needed for survival in livestock or poultry. Some of these bacteria are restricted to specific environments or reservoir species like cattle, whereas others have the ability to survive in food products to cause human infections.

How do foodborne bacteria develop resistance to the antibiotics used to treat human illness?

Bacteria that possess certain resistance genes or acquire specific mutations can develop resistance allowing them to survive in the presence of some antibiotics. These resistance genes can be shared with other bacteria in a process called horizontal gene transfer.

Some resistance genes are very specific to one antibiotic, but others can resist multiple antibiotics.

Many of the bacterial foodborne pathogens that cause the highest rates of disease are increasingly becoming resistant to various antibiotics. This is problematic for patients with foodborne infections because the antibiotics commonly used to treat these infections are no longer effective.

Both salmonella and campylobacter — two disease-causing bacteria — are very good at acquiring resistance genes in the environment, and both have been placed on the CDC watchlist of antibiotic resistance threats in the United States.

Campylobacter is the disease-causing bacteria most commonly associated with diarrheal illness, but these illnesses are rarely reported.

How can this pathogen successfully stay under the radar compared to illnesses caused by salmonella and E. coli?

People who become ill from eating food contaminated with campylobacter often do not feel sick enough to seek medical care. If they don’t seek care, then a stool sample would not be collected for culture and testing. This lack of testing means that we are likely underestimating the number of these infections.

Even if a stool is collected, campylobacter is very difficult to culture in the laboratory. Without a culture, clinicians cannot make a final diagnosis regarding the cause of the illness.

Other tools are now being used to detect bacterial DNA, proteins or antigens to determine if this bacterium is the cause of the illness. This process is necessary to begin an investigation to track down the source of the infections and determine whether it is part of an outbreak.

By: Stacy Kish

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