New Ways to Test the Waters
Genetic technologies detect contamination faster
SATURDAY, Jan. 19, 2002 (HealthDayNews) -- New genetic testing methods could mean faster and more accurate detection of harmful bacteria and viruses in water.
"The new advances actually go after the genetic sequence, or the genes. We can actually identify microbes just like we do people, by looking at specific genetic information," says Joan B. Rose, steering committee co-chairwoman of a recent American Academy of Microbiology report on the new methods.
Gene probes, genotyping and polymerase chain reaction (PCR) are among the molecular techniques being researched that could replace the current -- and outdated -- method for testing water.
"These methods allow us to look for microbes that we could not look for before," says Rose, a professor of water microbiology at the College of Marine Sciences at the University of South Florida.
And she adds, they provide information on such questions as: What is in the water? How many are there? Are they able to make us sick? "In some cases, the methods are much faster. Biosensors, for example, could give an answer in 20 minutes," Rose says.
The current testing method detects and counts so-called indicator bacteria. With this method, water samples are exposed to nutrients and incubated to encourage the growth of bacteria that usually thrive in the human colon. The growth of coliform bacteria indicates fecal contamination in the water.
However, such tests can't detect disease-causing viruses like hepatitis A or E, bacteria like Helicobacter, or such parasites as cryptosporidium. They also can't identify waterborne intestinal diseases that each year kill as many as 2 million children worldwide, the report says.
The new technologies could help identify microbes suspected of causing disease, and confront antibiotic-resistant bacteria and the spread of harmful microbes that can come from increased globalization.
One of these new methods is the PCR, where "we can open up the microbe, extract the genetic material and then specifically copy it in a machine [like a photocopier]. This makes the method specific and sensitive, and we can look for low levels of contamination," Rose says.
The PCR is one of the new technologies that's ready to be used in water testing. It's already being used to counter bioterrorism and in food safety.
The new molecular water-testing methods are an important advance, but they face some hurdles, says Jami L. Montgomery, research program director of the Water Environment Research Foundation.
While able to detect a dangerous organism's DNA, some of the molecular methods can't determine whether that organism is alive and potentially infectious, Montgomery says.
Additionally, the water itself can pose a problem.
"A lot of these techniques are adapted from medical uses and research, and they work very well in pure samples. It's trickier to work with environmental sampling," and so-called dirty water, Montgomery explains.
Rose says the new methods shouldn't prove too expensive for developing countries, where they may be especially important.
"These methods are useful worldwide and, in fact, may be cheaper than conventional methods for developing countries. This allows countries to develop kits and focus on their issues first, like cholera rather than viruses. It allows for the gathering of data that will be useful in prioritization," she says.
"Safe water is very much tied to economic well-being and health," Rose notes.
What To Do
Read the full report from the American Academy of Microbiology.