What Are Bacteria and How Can We Control Them?

Bacteria are microscopic living organisms that are found almost everywhere — in soil, water, on surfaces, and in food. While some bacteria are harmless or even helpful, others can be dangerous. Harmful bacteria that cause illness when consumed in food are known as pathogens. Examples include Salmonella, E. coli, and Listeria monocytogenes.

When food becomes contaminated and is kept at unsafe temperatures or not handled properly, bacteria can grow rapidly. This can lead to foodborne illnesses, also called food poisoning. According to the FDA’s Model Food Code, these illnesses are a major public health concern and are often caused by:

• Improper cooking or reheating of food
• Inadequate handwashing or hygiene by food handlers
• Cross-contamination between raw and ready-to-eat foods
• Failing to keep food at safe temperatures

Symptoms of foodborne illness may include vomiting, diarrhea, abdominal cramps, fever jaundice, and dehydration. In severe cases, hospitalization or death can occur — especially for vulnerable groups like the elderly, young children, and people with weakened immune systems.

How Can We Control Bacteria?

The FDA Model Food Code outlines key steps to reduce the risk of bacterial contamination:

• Cold Holding: Keep cold foods at 41°F (5°C) or below to slow bacterial growth.
• Hot Holding: Keep hot foods at 135°F (57°C) or above to prevent bacteria from multiplying.
• Cooking Temperatures: Cook foods to their minimum safe internal temperatures. For example, poultry must be cooked to 165°F (74°C).
• Avoid Cross-Contamination: Separate raw meat from ready-to-eat foods. Use separate cutting boards and utensils.
• Handwashing: Wash hands with warm water and soap for at least 20 seconds before handling food and after using the restroom.
• Time Control: Never leave food in the Temperature Danger Zone (41°F–135°F) for more than 4 hours total.

Using FATTOM to Prevent Bacterial Growth

FATTOM is a helpful acronym to remember the six conditions that support the growth of foodborne pathogens. By controlling these factors, food workers can help stop harmful bacteria from multiplying.

What Does FATTOM Stand For?

• F – Food: Bacteria thrive in foods rich in protein and carbohydrates, such as meat, poultry, seafood, dairy, cooked pasta, and rice.
• A – Acidity: Bacteria grow best in neutral to slightly acidic foods (pH between 4.6 and 7.5). High-acid foods like vinegar and citrus fruits inhibit growth.
• T – Time: The longer food stays in the Temperature Danger Zone, the greater the risk. Limit total exposure to no more than 4 hours.
• T – Temperature: Maintain proper holding temperatures—cold below 41°F and hot above 135°F.
• O – Oxygen: Some bacteria need oxygen, while others thrive in oxygen-free environments. Packaging methods like vacuum sealing can impact growth.
• M – Moisture: High-moisture foods (high water activity) are more likely to support bacterial growth. Dry foods or those with reduced water activity are safer. Foods with a water activity (A_w) of 0.85 or higher are considered TCS foods allowing bacteria to multiply easily to dangerous levels. The range of water activity runs from 0.0 to 1.0

How to Use FATTOM in Food Safety

• Keep foods out of the Temperature Danger Zone to control both Time and Temperature.
• Limit exposure to moisture and seal foods to control Oxygen and Moisture.
• Choose low-risk foods when serving high-risk populations.
• Monitor pH levels for food products as part of HACCP or preventive controls.

Of the six conditions represented by the acronym FATTOM, Time and Temperature are the conditions you can easily control in a foodservice operation.

The Bottom Line

Bacteria are everywhere, but most foodborne illnesses are preventable. By understanding how bacteria grow — and using practices recommended by the FDA Model Food Code and FATTOM — food handlers can reduce the risk and serve food safely.