Bacterial Hazards

Food Standard and Quality Control

Lesson 14 : Food Hazards - Microbiological

Bacterial Hazards

Bacteria pose a common food safety risk due to their omnipresence in our environment. Pathogenic bacteria potentially contaminate produce in all stages of the production chain. The number of individual bacteria that must be present to cause actual human disease varies with the type of organism as well as the age and condition of the host. Milk, shell eggs, poultry, fish, meat and shellfish are common food items that support the growth of bacteria. Most bacteria are not harmful to us while some can make people ill by living and multiplying inside human bodies.

Some bacterial pathogens and their effect on human health

Salmonella spp:
Salmonella bacteria are the most frequently reported cause of food borne illness. The bacteria live in the intestinal tracts of infected animals and humans. Salmonellosis is an infection causing diarrhoea, abdominal cramps and fever within 8 to 72 hours after ingestion of the contaminated food

Shigella spp:
Shigella infections may be food borne and are usually passed on fresh produce by improper hygiene of food handlers or contamination in fields due to infected human sewage and crop production water. Common symptoms of Shigellosis include diarrhoea, fever and stomach cramps starting 1-2 days after exposure. Shigellosis usually resolves in 5 to 7 days.

Staphylococcus aureus:
S .aureus is the causing agent for the gastrointestinal illness referred to as staphylococcus food poisoning. It is caused by contamination of foods with bacterial toxins that are resistant to heat and therefore cannot be destroyed by cooking. S. is a common bacterium found on the skin and in the noses of up to 25% of healthy persons and animals. The most common cause of contamination with SI is improper hygiene during food handling.

The other examples of pathogenic bacteria are: Entero haemorrhagic Escherichia coli, Campylobacter jejuni, Yersinia enterocolitica, Listeria monocytogenes, Bacillus anthracis, Bacillus Cereus, Clostridium botulinum, Clostridium perfringens, Vibrio Vulnificus, Vibrio parahaemolyticus.

Bacteria reproduce easily and quickly if the environmental conditions meet their specific requirements for growth and reproduction, such as adequate nutrients, humidity, acidity, oxygen level and temperature.

Last modified: Saturday, 18 February 2012, 7:02 AM