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.
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.