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Sylvia Rose

Food Pathogens: Family Health & Safety

Pathogens of food include Bacillus cereus, Salmonella typhimurium, Aeromonas hydrophila, and Pseudomonas fragi. Each of these microorganisms has unique traits and health implications in food safety. Knowing potential food dangers helps protect home and family.



happy family dinner

Bacillus cereus


Bacillus cereus is a gram-positive, rod-shaped bacterium commonly found in soil and food. It's a major pathogen, producing the toxins of food poisoning, with two main types of illnesses associated with it: emetic and diarrheal syndromes.


The emetic syndrome is often linked to the consumption of fried rice kept warm for long periods, while the diarrheal syndrome is associated with a variety of foods, including meats, dairy products, and vegetables.


Bacillus cereus is particularly resilient and can form spores that survive cooking and food processing. This makes it a significant concern in the food industry, emphasizing importance of proper food handling and storage practices to mitigate the risk of contamination.



Bacillus cereus under electron microscope
Bacillus cereus under electron microscope

Salmonella typhimurium


Salmonella typhimurium is a gram-negative bacterium, a common cause of foodborne illness worldwide. The bacterium lives in intestines of animals, especially poultry and livestock, and is transmitted to humans through undercooked meat, eggs, and unpasteurized dairy products.


Infection with Salmonella typhimurium can lead to salmonellosis, which manifests as diarrhea, fever, and abdominal cramps. In healthy people, the illness is typically self-limiting, but it can pose severe risks to young children, the elderly, and immunocompromised individuals.


Prevention strategies focus on proper cooking practices, hygienic food handling, and food safety awareness. According to the CDC, Salmonella causes about 1.35 million infections in the United States each year, 26,500 hospitalizations and 420 deaths.



Salmonella bacteria
Salmonella bacteria

Aeromonas hydrophila


Aeromonas hydrophila is a gram-negative bacterium found in fresh and saltwater. An opportunistic pathogen, it typically affects individuals with pre-existing health conditions or compromised immune systems.


Aeromonas hydrophila is associated with gastrointestinal illnesses, wound infections, and more severe infections like septicemia. Ingestion of contaminated water or food, especially undercooked or raw seafood, can transmit Aeromonas infections.


Symptoms of gastrointestinal infection include diarrhea (which may be bloody), abdominal pain, nausea, and vomiting. Due to its environmental prevalence, it serves as a reminder of the importance of food hygiene and safe water practices.



Aeromonas hydrophila colonies on blood agar.
Aeromonas hydrophila colonies on blood agar.

Pseudomonas fragi


Pseudomonas fragi is a gram-negative bacterium commonly found in soil and water. Not typically associated with human diseases, it can spoil food, especially refrigerated items. In German folklore this spoilage is associated with an angry Kobold peeing in the milk.


Pseudomonas fragi can thrive in cool temperatures and is often associated with dairy and meat products. In a laboratory setting, Pseudomonas fragi is important in the degradation of compounds, and has applications in bioremediation.


However, its presence in foods highlights the need for stringent refrigeration and storage practices to prevent spoilage and maintain product quality. It can cause foodborne infections in those with compromised immune systems, especially in healthcare settings.



Pseudomonas fragi is often responsible for dairy spoilage
Pseudomonas fragi is often responsible for dairy food spoilage

If working with food wash hands, keep food work and storage areas clean, check fridge and freezer temperatures. Refrigerate uneaten food. If food smells bad throw it out. Mold spores like to travel, so any such science projects should be promptly removed.



Non-Fiction Books:


Fiction Books:

READ: Lora Ley Adventures - Germanic Mythology Fiction Series

READ: Reiker For Hire - Victorian Detective Murder Mysteries




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