Key Takeaways on How Eggs Can Be Contaminated with Salmonella
- Eggs can be obtained Salmonella from feces or contaminated litter that enters the hen's reproductive tract. Bacteria can colonize where the egg white and shell are formed, contaminating the egg.
- Salmonella poses a continuing risk to poultry farmers despite modern antibiotics and control measures. Even touching a damaged surface can turn eggshells into disease carriers.
- Cooking exposes bacteria to heat, which can kill Salmonella. The FDA recommends heating eggs to an internal temperature of 165 degrees Fahrenheit (about 74 degrees Celsius).
At first glance, a clean, whole egg seems harmless enough, but the smooth shell can hide some prickly enemies.
In August 2025, the Centers for Disease Control and Prevention (CDC) released multi-state recall brown eggs after nearly 100 people fell ill, 18 of whom were hospitalized with high fever, severe diarrhea and a variety of other illnesses.
The culprit: a particularly persistent foodborne bacterium known as Salmonella Enteritidis. The microbe thrives in animal guts and raw meat, absorbing any nutrients it encounters and multiplying rapidly.
Patients who are unlucky enough to experience this symptoms of indigestion also not uncommon. In 2010 paper V Clinical infectious diseasesresearchers estimate that worldwide Salmonella causes approximately 93 million cases of infectious diarrhea and more than 100,000 deaths worldwide each year.
Despite the bacteria's impressive infectiousness, it's hard to imagine that the microbe will ultimately survive. inside egg in shell. But, as often happens in nature, life finds a way out.
How to get eggs Salmonella?
According to Dr. Alexandra Grote, assistant professor of infectious diseases at Northwestern University Feinberg School of Medicine: “Salmonella through feces or contaminated bedding, they can enter the hen's reproductive tract, says Grote. “From there, the bacteria can colonize the oviduct, where the egg white and shell are formed, leading to infection before the shell has even hardened.”
The microbe's impressive array of adaptations allows it to survive in a variety of challenging environments.
“Salmonella “It’s a station wagon,” says Grote. “It can use nutrients that other microbes cannot, resist bile and acidic conditions, and compete with resident microbiota.”
Salmonella well known for his Acid resistance reaction (ATR), which allows it to regulate internal pH and survive the journey through the stomach. 2014 study from Current opinion in microbiology found that cells can remodel the structure of their outer membrane to better withstand the salt and acidity of an inflamed gut.
Grote notes that even the shell of an egg is not safe, as bacteria can produce stress response proteins and go into a quasi-dormant state to survive dry conditions. Under certain circumstances, they can migrate inward through tiny pores and cracks on the surface of the egg.
Salmonella can also cleverly manipulate the host's immune system, using the inflammatory response it causes to suppress competitors.
“Salmonella does not always want to reproduce quickly,” adds Grote, “It may slow down its growth or go into a dormant state. These 'persistent' bacteria can survive attacks from antibiotics and the immune system, only to reappear later.”
Read more: What are the different types of food poisoning and how to avoid them?
How common is it? Salmonella in eggs?
With all these abilities at your disposal, Salmonella poses a continuing risk to poultry farmers despite modern antibiotics and control measures. 2000 study V International Journal of Food Microbiology It is estimated that 1 in 20,000 eggs in the United States may be “internally contaminated” with the bacteria.
Even touching a damaged surface can turn eggshells into disease carriers. In their official egg safety rulesThe US Food and Drug Administration (FDA) emphasizes the importance of purchasing refrigerated egg cartons and storing them at home below 40 degrees Fahrenheit (4 degrees Celsius).
Can cooking eggs kill? Salmonella?
The cold of the refrigerator slows the growth of bacteria, but the fire of the stove finishes the job. Fortunately for all people, Salmonella I just can't handle the heat.
2016 paper published in Journal of Food Science found that prolonged immersion in water of about 130 degrees Fahrenheit resulted in a 99.99 percent reduction in the number of living creatures. Salmonella cells.
To completely reduce the threat, the FDA recommends heating eggs to an internal temperature of 165 degrees Fahrenheit (about 74 degrees Celsius).
“Cooking exposes bacteria to heat, which destroys them at the molecular level,” Grote says. “The proteins in the bacterial cell unfold and lose their function. The membrane itself becomes leaky. Once these systems are destroyed, the bacteria can no longer survive.”
Some highly specialized microbes, such as residents of Yellowstone hot springs are adapted to thrive in scalding hot water, but infectious diseases such as Salmonella wants this.
As long as the eggs are thoroughly cooked, this hidden threat is not a risk, but it never hurts to be careful. If you're unsure whether your egg sandwich will cause digestive upset, it may be best to err on the side of caution before you become infected.
This article does not contain medical advice and should be used for informational purposes only.
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