General information:
The total coliform bacteria are gram negative bacteria (bacilli), aerobic or optional anaerobic, unsporulated, capable of fermenting lactose with gas and acid production at 37°C while 24-48h. In this group include bacteria from the genera: Escherichia, Citrobacter, Klebsiella, Enterobacter.
Referential after which the analysis is performed:
The analysis for the determination of total coliforms is performed in its own laboratory according to the standard national SR EN ISO 9308-1:2004.
Principle of the method:
The determination of total coliforms to drinking water is performed using the membrane filtration system using as a culture medium TTC agar.
Sample rejection cases – quantity of inappropriate sample, sample 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.
The analysis method - membrane filtering and sowing on the TTC agar lactose culture medium.
Reference values according to the Law of Drinking Water 1)
| Parameter / Unit of measurement | CMA value (Maximum permissible concentration) |
|
| absent |
| ldin care E. coli: Absent |
Recommendations for performing the analysis/ Effects of exceeding the reference values –
Colform names were adopted in 1914 by the Public Health Service (usa) for the Enterobactericeae family. Enterobacteria = Family of bacilli (bacteria in the shape of a stick) Gram negative. The family of enterobacteria groups about 20 different genera having in common some biochemical characteristics, as well as their habitat: the digestive tract of man or that of animals. They are used to determine whether or not drinking water is good to drink from a microbiological point of view. Generally coliforms are found in large quantity in the excrement of "warm-blooded animals ". If they appear in a water sample generally indicate contamination with fecal pathogens of the source.
The question of whether these coliforms are toxic the answer would be: most coliforms cause disorders in the digestive tract such as vomiting, dizziness, diarrhea. However, some strains of E. Coli (especially 0157:H7 which induce hemolytic uremic syndrome) can cause quite serious illnesses going as far as death. Always total coliforms are larger than fecal coliforms. The presence of coliforms generally indicates a recent pollution.
In order to reduce the level of coliforms in the water, a number of methods of water chlorination can be applied depending on the severity of the infestation or UV lamps can be used.
