There are two different types of bacteria involved with food.
The first types of bacteria involved with food are known as food spoilage bacteria and the second is known as food poisoning or pathogenic bacteria.
1. Food Spoilage Bacteria
These types of bacteria are easily detectable as they make the food go off (rancidification). We are able to see it, taste it and more commonly able to smell it. These act as warning signs to say do not eat this. They are generally not dangerous to your health, but certainly should not be consumed. These also require very high numbers of colonies to be consumed to be able to cause illness.
2. Pathogenic Bacteria
These types of bacteria involved with food, need very small amounts of bacterial colonies to be able to make you sick. These are the bacteria that we are most concerned with, as you cannot see it taste it or smell these bacteria. There are no indications that these bacteria are present in your food.
Within this broad category, there are specific bacteria that we are concerned with in the kitchen environment. This applies to both the home kitchen and a production kitchen such as restaurants, hotels and food service.
Escherichia coli (E.coli)
E.coli are one of the most commonly known food poisoning bacteria and are what we call an indicator organism. E.coli originates from our gut as well as in other mammals such as cattle. If E.coli originates in the gut, it, therefore, tells us that faecal matter is present, and occurs as a result of unhygienic practices.
E.coli is a gram-negative bacteria that is naturally occurring within the environment. Mostly in soil or in our gut.
Most E.coli strains are not pathogens, in other words, disease-causing bacteria. They do and can exist harmlessly with humans, and is an important part of our internal flora. This means the internal makeup of various bacteria in our gut that allows us to consume our food. These essentially keep bad pathogens at bay.
However, there are strains of E.coli that are dangerous such as E.coli O157:H7. These cause hemorrhagic gastroenteritis and can be severe. In general, E.coli is a bacterium that should be avoided.
E.coli mostly occurs in our gut and is present in raw meats. This bacteria becomes an indicator of unhygienic practices that may have taken place. Two perfect examples of this, are when we do not wash our hands after going to the toilet and when we do not wash our hands after the handling of raw meats.
Staphylococcus aureus (S.aureus)
S.aureus is a gram-positive bacteria that occurs naturally on the skin and nasal passages of humans. Usually, this bacterium is harmless in small numbers but, can cause skin infections if numbers get too high.
In food, S.aureus is concerning because it produces a heat-stable toxin, which can cause severe food poisoning. Heat-stable meaning that the toxin can survive cooking temperatures.
Can you guess why S.aureus is used as an indicator organism in food safety and hygiene?
Because S.aureus occurs in the nasal passages and on the skin, those that are natural carriers (10 to 15% of the world’s population) require antibiotic treatment to keep this bacteria at below infection levels.
This is so that those that work with food, do not cause further infection. Of course, hand-washing and preventing the touching of the nose are key areas in preventing contamination of food.
Finding this bacteria in food and/or on hands of food handlers tells us that there’s been some break in the food safety pillars. The potential for causing food poisoning increases dramatically when these are present.
These bacteria perfect examples of the two, most common causes of food poisoning.
Frequently Asked Questions
Bacteria Involved in Food Spoilage
Common bacteria involved in food spoilage:
- Lactic acid formation: eg. Lactobacillus
- Lipolysis: eg. Pseudomonas
- Pigment formation: eg. Flavobacterium
- Gas formation: eg. Lactobacillus
- Slime or rope formation: eg. Enterobacter, Streptococcus
Bacteria Involved in Food Poisoning
Other pathogenic bacteria involved in food poisoning include: