Question

Environmental Microbiology.

Please help me answering this question. Be specific

Why is it important that an indicator organism have a reasonably longer survival time than the hardiest enteric pathogen, and that it should not grow in water?

Answer 1

According to the US environmental protection agency,the ideal indicator organism must follow the following 5 criteria:-

1. They should be present along with the enteric pathogens.

2. Can be used in all types of water.

3. Should have a longer survival time than that of the hardiest enteric pathogen.

4. Should not grow in water .

5. Should be found in intestine of warm blooded animals.

Athough no such ideal indicator has been found to follow all these criteria but many countries have considered the coliforms and some other bacterial groups as an official standard for drinking water, recreational bathing waters,waste water discharges and various foods.

The reason behind why these indicator organism shouldn't be grown in water for human consumption is that it has a greater risk to public health because presence of microbes indicates the contamination of water through animal or human excreta. In EPA the total coliform rule states that a water system is out of compliance if it contains more than 5% coliforms in its monthly water sample.

Also the differential survival is generally preferable that the indicator be more resilent than the pathogen so as to be more protective for the public health.