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Coliform Bacteria and Illness in Humans

written by: Vasanth•edited by: dianahardin•updated: 4/17/2011

Coliform is a group of bacteria found in the environment and in the fecal matter of warm-blooded animals, including humans. Drinking water is tested for coliform to ensure safety, although most strains of coliform are harmless. E-coli can infect the GI and urinary tract.

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    What is Coliform?

    Coliform is a group of bacteria that is found in the environment and in the fecal matter of warm blooded animals. It can cause illness if consumed, but this is unlikely. Most strains are harmless and naturally found in the soil. Some are found in the gastrointestinal tract (GI tract) of humans.

    Coliform is used as an indicator for water quality. The presence of coliform in drinking water is a sign that the water supply is contaminated. There is a greater chance that disease causing pathogens are present in the drinking water if it contains coliform.

    Total coliform, fecal coliform, and E-coli are three indicators of drinking water quality. Total coliform consists of bacteria that is found in the soil and vegetation, and its presence in water indicates an environmental contamination. Fecal coliform consists of bacteria found in the GI tract of animals and humans, and its presence in water indicates a greater risk of disease causing pathogens. The presence of E-coli usually indicates recent fecal contamination and the presence of pathogens.

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    Types of Bacteria in Coliform

    Escherichia coli, or E-coli, is one type of bacteria present in coliform. It is a gram-negative bacteria that has a rod shape. It can survive without oxygen by using fermentation. It is present in the GI tract of warm-blooded animals. The majority of E-coli strains are harmless, but the O157:H7 strain can be deadly.

    Enterobacter aerogenes is another type of bacteria present in coliform. It is a gram-negative, rod shaped bacteria found in the GI tract. Normally, it does not harm the host.

    Klebsiella pneumoniae is a gram-negative, rod shaped bacteria normally found in the mouth, on the skin, and in the GI tract.

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    Diseases and Symptoms Caused by Coliform Bacteria

    The link between coliform bacteria and illness has been noted in places where the drinking water is contaminated and not properly treated. Most of the illnesses caused by coliform bacteria are associated with the GI tract. Consuming the O157:H7 strain of the E-coli bacteria can cause a severe infection of the GI tract. Some of the symptoms include vomiting and diarrhea. It can also cause urinary tract infections, which are characterized by frequent urination and pain during urination.

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    Treatment Options and Prevention

    Most infections associated with coliform bacteria and illnesses caused by it are treated with antibiotics. Since most coliform bacteria are gram-negative bacteria, they are resistant to many antibiotics that are effective against gram-positive bacteria. Amoxicillin and ciprofloxacin are effective against E-coli.

    There are several ways to treat coliform in drinking water or prevent it from contaminating the water to begin with. Boiling tap water for several minutes will kill most bacteria that are present. In order to avoid coliform contamination in water, a well should be built at least 100 feet away from any septic system and placed away from surface runoff. A sanitary seal should be used at the top of the well casing.

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    1. "What are Coliforms." Benton Franklin Health District.

    2. "Coliform Bacteria and Drinking Water." Washington State Department of Health.

    3. "Coliform Bacteria." Encyclopedia Britannica.