Determination of Escherichia coli

General information:

Escherichia coli (abbreviated name: E. coli) is a bacterium that lives in the intestines of warm-blooded organisms. E. coli is a lactozo-positive bacterium (breaks down lactose), gram-negative, oxidase-negative, which appears under a microscope in the form of sticks. He belongs to the group of enterobacteria that live as epiphytes in the digestive tract. In some cases of imbalance of the intestinal microflora, these bacteria can produce diseases, through a massive multiplication or the appearance of toxicogenic strains. The bacterium was named in 1919 after the name of the German-Austrian bacteriologist Theodor Escherich, who discovered it.

Referential after which the analysis is performed:

The analysis for the determination of Escherichia coli is performed in its own laboratory according to the standard national SR EN ISO 9308-1:2004.

Principle of the method:

Determination Escherichia coli is performed using the membrane filtration system using as a lactose culture medium TTC agar and confirmation by indole reaction (with Kovacs reagent).

Canss of sample rejection – amount of unsuitable sample, samples collected in inappropriate containers, samples not properly labelled, etc.

Columient – sterile container required. (purchased commercially - human pharmacies or requested from the laboratory).

The amount of sample required to perform the analysis - minimum 250ml.

Processing required after harvesting – not required.

Stable sample – freshly harvested water is stable for 3 hours at a temperature of 2...5⁰C.

assay method - membrane infiltration and sowing on lactose culture medium TTC agar followed by insemination on the confirmation media Tryptone Soy Agar and Kovacs reagent respectively.

Reference values according to the Law of Drinking Water ¹⁾

Recommendations for performing the analysis/ Effects of exceeding the reference values

Escherichia coli has adverse effects on human health. Children are more likely than adults to have digestive infections with E coli O157:H7 (E. coli enterohemoragic). Most people with infection will have the following symptoms:

• cramps in the stomach and sensitive abdomen
• the initial aqueous heart that can become sanguinolenta evolution
• greata and vomiting.

Some people who have infection with the E. Coli bacterium may not have any symptoms. They can spread the infection without being aware of it. There are many other conditions that have symptoms similar to those of E. coli infection. Diagnosing E coli infection can be difficult because most bacterial infections with E. coli that cause diarrhea are accompanied by high fever. If the fever is of medium intensity or is absent, the doctor may suspect that another bacterium has produced the symptomatology.

Sublenta diarrhea is common in confirmed cases of E. coli infection but the bacteria can also produce unsanguinolenta diarrhea.

The usual asymptomatology of E. coli infection ends after about a week without further complications. However, serious hematological problems and kidney problems may occur 2-14 days after the appearance of diarrhea. These problems can cause kidney failure and sometimes altered long-term health or death in some children and the elderly.

Infections with E. coli are easily suitable for confusion with other conditions with similar symptoms such as infectious diseases. The doctor may suspect a person of E. coli infection if they have been exposed to the bacterium.

In order to reduce the level of coliforms in the water, a series of water chlorination methods can be applied depending on the severity of the infestation or UV lamps can be used.