Rapid Detection of Bacteria in Drinking Water: Fid-Bau Portal

Rapid Detection of Bacteria in Drinking Water

Deininger, R.A. / Lee, J.

Abstract A heterotrophic plate count (HPC) is a measure of the total number of heterotrophic bacteria in a water sample. It does not indicate whether the bacteria are harmful or harmless to humans, but serves as an indicator of the cleanliness of the raw water and treatment processes. The most sensitive test uses the R2A agar and an incubation time of 7 days. Other media and shorter incubation times lead to lower counts. Whichever test is used, an incubation of 2–7 days makes the test clearly useless for operational decisions and intervention. Intentional or accidental contamination of a water supply must be determinable in minutes. We have studied over the past three years several water sources, such as municipal water, bottled water, beach and pool water, and ballast water on ships. Using portable equipment, we have determined the ATP in the water sample by lysing the bacteria, adding luciferine/luciferase to develop light, and measuring the light emission in a luminometer. The test is not new and is described in Standard Methods. What is new is that the present test is more sensitive, the instrumentation fits on a clipboard, and the test can be done in the field at the location where the sample is taken. If the estimated HPC is high, a second step may be necessary to identify if there are pathogens in the water sample. A rapid test for E.coli O157:H7, Pseudomonas, and Legionella pneumophila has been developed using immunomagnetic separation. These tests take longer, but are still under an hour for each target bacterium. The detection of spores in the water sample is also possible. The essence of the method is that a contamination of bottled water with bacteria can be detected while the batch of bottled water is still on the shipping dock.