In 1885, Theodor Escherich first isolated Bacterium coli from children's fecal samples. After the 1920s, this bacterium underwent a name change and became known as Escherichia coli.

Food adulteration is classified as the intentional addition of a foreign or inferior quality substance or element; by replacing a more valuable substance or element with less valuable or inert ingredients.

Legionnaire's Disease, caused by Legionella pneumophila bacteria, is a severe illness. In Portugal, this bacterium was first detected in 1979 and is listed as a mandatory reportable disease.

Listeria monocytogenes is described as a ubiquitous pathogenic bacteria, majorly responsible for isolated cases and outbreaks of listeriosis in humans and animals. When it first was discovered, it was only recognized as being dangerous to animals. Later in the 80s, due to several outbreaks of bacteria-contaminated food, this bacteria were seen as a threat to public health.

Food poisoning caused by pathogenic agents is one of the major public health problems worldwide. Among the most frequent poisonings is Salmonellosis, a zoonotic infection that causes high rates of mortality and morbidity in almost all countries [1-3].