Depression and Sleep

 

Microorganisms

What is a foodborne disease?

Many people worldwide experience episodes of foodborne illnesses without realizing that their sickness is caused by contaminated food. A foodborne disease is any illness resulting from consuming contaminated food.

How does this happen?

Foodborne illnesses are caused by harmful germs (microorganisms) or toxic chemicals. This issue affects both developing and developed countries. Vulnerable groups such as infants, young children, the elderly, and the sick are particularly at risk. Consequently, foodborne diseases impact national economies, development, and international trade.

Food contamination occurs in two primary ways:

1. Microorganisms
2. Chemicals

What are microorganisms?

Microorganisms are tiny living organisms that are invisible to the naked eye. These include bacteria, viruses, yeasts, molds, and parasites. There are three main categories of microorganisms:

1. Beneficial microorganisms
2. Spoilage microorganisms
3. Harmful microorganisms

Beneficial microorganisms

These are useful microorganisms that help produce certain foods like cheese, yogurt, beer, and wine. Some are also involved in producing medicines, such as penicillin. Additionally, beneficial microorganisms assist in digesting food in the gut.

Spoilage microorganisms

Spoilage microorganisms typically don’t make people sick. However, they cause food to spoil, making it smell bad, taste unpleasant, and appear unappetizing.

Harmful microorganisms

Harmful microorganisms, often dangerous, don’t necessarily change the food's appearance. Thus, food can seem normal but still be dangerous. These microorganisms can make people seriously ill and, in severe cases, cause death. Some common harmful microorganisms include:

• Bacteria: Salmonella, Shigella, Campylobacter, and E. coli O157
• Parasites: Giardia
• Viruses: Hepatitis A, Norovirus

Dangerous microorganisms are often found in feces, waste from humans and animals, soil, water, rats, mice, insects, and pests. These microorganisms can be transferred to food via contaminated surfaces, hands, utensils, and cutting boards. This transfer, known as contamination, can lead to foodborne diseases.

How do microorganisms grow in food?

Certain foods, such as meat, seafood, cooked rice, pasta, milk, cheese, and eggs, provide ideal conditions for microorganisms to grow. Under optimal conditions, one bacterium can multiply every 15 minutes, reaching over 16 million within six hours. Some microorganisms must grow to high levels to cause harm, while others need only small amounts. Though viruses don’t grow in food, they use it as a transmission vehicle.

Symptoms of foodborne diseases

The common symptoms of foodborne diseases include stomach pains, vomiting, and diarrhea. The onset of symptoms depends on the cause and can appear quickly, especially with chemical toxins, or take days or even weeks to manifest. Most cases occur 24-72 hours after consuming contaminated food. Approximately 3% of foodborne illness cases can lead to long-term health problems, including serious conditions such as cancer, arthritis, and neurological disorders. It’s essential to seek medical advice if symptoms arise.

Foodborne diarrhoeal disease

Foodborne diarrhoeal disease is one of the most common illnesses worldwide. In developing countries (excluding China), 1.3 million children under the age of five die each year because of diarrhoeal diseases. Up to 70% of these cases may be caused by foodborne pathogens. The US Centers for Disease Control and Prevention estimated that about one in three persons in the USA falls ill each year due to a foodborne disease. 

 In Australian,  children, pregnant women, the immunocompromised and the elderly are at greatest risk of both contracting foodborne diseases and suffering more serious adverse health effects. Other health complications related to foodborne disease are common. For example, 2-3% of all cases of salmonellosis lead to long-term health problems caused by reactive arthritis.

In addition to microorganisms, poisonous chemicals, such as natural toxins, metals, environmental pollutants, improperly used pesticides, cleaning chemicals, and food additives, can cause foodborne illnesses.

Improving food safety globally

Foodborne diseases remain a significant health issue worldwide. Many nations are striving to improve food safety, with the World Health Organization (WHO) leading efforts. WHO has introduced the “Five Keys to Safer Foods” to reduce the risk of foodborne illnesses.

The Five Keys to Safer Foods

Key 1: Keep Clean

• Provide Basic Infrastructure

  • Install facilities for sanitation such as toilets, handwashing stations, safe water supplies, and cleanable walls and floors.
  • Ensure proper drainage to maintain hygiene.

• Sanitation of Stalls and Equipment

  • Ensure regular cleaning and sanitization of stalls and all market equipment.

• Waste Management

  • Collect and dispose of waste materials, including both solid and liquid waste, regularly ideally at least once daily.

• Protection from Environmental Hazards

  • Protect market areas and food from potential environmental hazards like rain, sun, dust, insects, rodents, and other animals.

Why?

While most microorganisms are harmless, disease-causing ones are commonly found in soil, water, animals, and people.  These microorganisms can be carried on hands, cloths, and utensils (e.g., cutting boards), and even minimal contact can contaminate food, leading to foodborne illnesses. Waste, especially liquid waste, can carry disease-causing organisms and must be stored properly and removed regularly.

Key 2: Avoid Contamination

• Separate clean and contaminated food areas (e.g., cooked, ready-to-eat foods, raw meat, fish, poultry, etc.).
• Keep ready-to-eat food separate from raw foods like meat, fish, and poultry.
• Use separate equipment (knives, cutting boards) for raw and cooked foods.
• Ensure vendors practice good personal hygiene (handwashing with soap after using the toilet).
• Separate displayed and stored raw and cooked foods to prevent cross-contamination.

Why?
Raw foods, especially meat, poultry, seafood, and their juices, as well as live animals and food waste, can carry harmful microorganisms. Proper hygiene by vendors helps prevent food contamination.

Key 3: Destroy Hazards When Possible

• Cook food thoroughly (meat, poultry, eggs, seafood) to at least 70°C.
• Bring soups and stews to boiling; ensure meat and poultry juices run clear (not pink). Use a thermometer if possible.
• Reheat cooked food thoroughly.

Why?
Proper cooking kills harmful microorganisms and destroys certain toxins. Cooking food to 70°C ensures it is safe to eat.

Key 4: Minimize Growth of Microorganisms in Food

• Cool raw meats, fish, and poultry using refrigeration, ice, or protection from sunlight and heat.
• Do not leave cooked food at room temperature for more than 2 hours; refrigerate promptly (below 5°C).
• Keep cooked food steaming hot (above 60°C) before serving.
• Avoid storing food for too long in the refrigerator, and do not thaw frozen food at room temperature.

Why?
Microorganisms multiply quickly at room temperature. Storing food below 5°C or above 60°C slows or stops microbial growth. Some microorganisms, like Listeria, can grow even below 5°C on certain foods.

Key 5: Use Safe Water and Raw Materials

• Use safe water or treat it to make it safe.
• Ensure food is sourced from safe and reliable suppliers.
• Select fresh, undamaged foods and foods processed for safety (e.g., pasteurized milk).
• Wash and peel fruits and vegetables, especially if consumed raw.
• Do not sell, buy, or use perishable food beyond its expiry date.

Why?
Raw materials, including water and ice, can be contaminated with harmful microorganisms and chemicals. Damaged or moldy foods may contain toxic chemicals. Careful selection, washing, and peeling reduce these risks.

References

1. Food safety -, An essential public health issue for the new millennium, WHO/SDE/PHE/FOS/99.4 WHO GENEVA 1999.
2. Baseline study of hazards and critical control points of street- vended foods in Bdija-Market, Ibadan Nigeria. https://www.witpress.com/Secure/ejournals/papers/SSE020406f.pdf
3. A guide to healthy food markets WHO.
https://iris.who.int/bitstream/handle/10665/43393/9241593938_eng.pdf 

by 

Subha Lasanthi : BMLS (Hons),
School of Medical Laboratory Technology - Colombo

INFOGRAPHIC

Bacterial Culture

Not all bacterial species grow optimally at the same temperature, so it is important to know the right conditions for the species you are trying to culture.
Read More...