Coli Forms

7/28/2019 Coli Forms

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COLIFORMS

Indicator Bacteriaand

Water Quality Testing


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FECAL POLLUTION

Exposure to fecally contaminated water does not always translate intoinfection. However, the higher the fecal bacterial levels in water, thehigher the chances of pathogens to be present in significant numbers too.

Among the diseases associated with poor microbial water quality, those

causing dehydrating diarrhea are of critical importance as they could leadto death within 48 hours after the initial symptoms. These extreme casesare more predominant in countries where overcrowding and poor sanitaryconditions are the norm.

Examples of fecal waterborne diseases are gastroenteritis, typhoid andparatyphoid fevers, salmonellosis, cholera, meningitis, hepatitis,encephalitis, amoebic meningoencephalitis, cryptosporidiosis, giardiasis,dysentery, and amoebic dysentery (Table 3

From

Jorge W. Santo Domingo, Nicholas J. Ashbolt (Lead Author);Avanish K. Panikkar (Topic Editor) . "Fecal pollution of water". In:

Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for

Science and the Environment). [First published in the Encyclopedia of Earth March 18, 2010; Last revised Date March 18, 2010;Retrieved October 10, 2010
http://www.eoearth.org/profile/Jorge.santodomingohttp://www.eoearth.org/profile/Nicholas.ashbolthttp://www.eoearth.org/profile/Avanish.panikkarhttp://www.eoearth.org/article/Fecal_pollution_of_waterhttp://www.eoearth.org/article/Fecal_pollution_of_waterhttp://www.eoearth.org/profile/Avanish.panikkarhttp://www.eoearth.org/profile/Nicholas.ashbolthttp://www.eoearth.org/profile/Jorge.santodomingo


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Table 3. Examples of waterborne pathogens

Name of micro-organisms Major diseasesMajor reservoirs and primary

sources

Bacteria

Salmonella typhi Typhoid fever Human feces

Salmonella paratyphi Paratyphoid fever Human feces

OtherSalmonella Salmonellosis Human and animal feces

Shigella spp. Bacillary dysentery Human feces

Vibrio cholera CholeraHuman feces and freshwater

zooplankton

EnteropathogenicE. coli Gastroenteritis Human feces

Yersinia enterocolitica Gastroenteritis Human and animal feces

Campylobacter jejuni Gastroenteritis Human and animal feces

Leptospira spp. Leptospirosis Animal and human urine

Various mycobacteria Pulmonary illness Soil and water


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sources

Enteric viruses

Polio viruses Poliomyelities Human feces

Coxsackie viruses A Aseptic meningitis Human feces

Coxsackie viruses B Aseptic meningitis Human feces

Echo viruses Aseptic meningitis Human feces

Norovirus Gastroenteritis Human feces to fomites and water

Rotaviruses Gastroenteritis Human feces

AdenovirusesUpper respiratory and

gastrointestinal illnessHuman feces

Hepatitis A virus Infectious hepatitis Human feces

Hepatitis E virusInfectious hepatitis; miscarriage and

deathHuman feces


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sources

Protozoa

Acanthamocba castellani Amoebic meningoencephalitis Human feces

Balantidium coli Balantidosis (dysentery) Human and animal feces

Cryptosporidium homonis, C.

parvumCryptosporidiosis (gastroenteritis)

Water, human and other mammal

feces

Entamoeba histolytica Amoebic dysentery Human and animal feces

Giardia lamblia Giardiasis (gastroenteritis) Water and animal feces

Naegleria fowleriPrimary amoebic

meningoencephalitis

Warm water

Helminths

Ascaris lumbricoides ascariosis Animal and human feces

Adapted from Ashbolt, 2004


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Indicator Organisms

organisms that behave in approximately the

same manner as the pathogens of concern,

but are present in higher numbers or are

otherwise easier to detect


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Indicator Organisms A good indicator microorganism has qualities which make it

Easy to test for in the lab.

Present in greater numbers than the pathogens they indicate.

Safer to work with in the lab than pathogens since the indicators causeno or only mild illnesses.

Indicators must not only be easy to work with in the lab, they mustalso predict the presence of pathogens.

Coliform bacteria are good indicators because they only reproducein the intestines of animals, so they will not be present in waterunless the water has been contaminated with sewage.

Coliform bacteria are also able to survive outside animals'intestines, so they will be present in water for several days after thewater has been contaminated.


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Indicator Organisms

Total Coliforms

Fecal Coliforms

E. coli

Fecal Streptococci

Enterococci


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Indicator Organisms

Total Coliforms not all from fecal origin

Fecal Coliforms

E. coli

Fecal Streptococci

Enterococci


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Indicator Organisms


Fecal Coliforms grow at higher temps

E. coli

Fecal Streptococci

Enterococci


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Indicator Organisms


Fecal Coliforms grow at higher temps

E. coli best indicator of health risk

Fecal Streptococci

Enterococci


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Indicator Organisms

Total Coliforms

Fecal Coliforms

E. coli

Fecal Streptococci previously used to test for

human origin Enterococci


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Indicator Organisms

Total Coliforms

Fecal Coliforms

E. coli

Fecal Streptococci previously used to test for

human origin Enterococci best indicator for salt water


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Escherichia coli

E. coli normally colonizes an infant'sgastrointestinal tract within 40 hours of birth,arriving with food or water or with the individuals

handling the child. In the bowel, it adheres to the mucus of the large

intestine. It is the primary facultative anaerobe ofthe human gastrointestinal tract.

As long as these bacteria do not acquire geneticelements encoding for virulence factors, theyremain benign commensals.


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Definitions of (Total) Coliforms

Multiple-Tube Fermentation

All aerobic and facultative anaerobic, Gram-negative,non-spore-forming, rod shaped bacteria that fermentlactose with gas and acid formation within 48 hr. at35C.

Membrane Filtration

All aerobic and many facultative anaerobic, Gram-negative, non-spore-forming, rod-shaped bacteriathat develop a red colony with a metallic sheen within24 hr. at 35C on an Endo-type medium containinglactose.


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Other Properties

-galactosidase positive

Enzyme that hydrolyzes lactose into glucose and

galactose

Oxidase negative

Indicates the absence of Cytochrome-c in theelectron transport chain.


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Typical Coliform Genera

Citrobacter

Enterobacter

Escherichia Hafnia

Klebsiella

Serratia


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Typical Coliform Genera

Citrobacter

Enterobacter

Escherichia Hafnia

Klebsiella

Serratia

Enterobacteriacea


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Traditional Methods

Multiple-Tube Fermentation

very low-tech

flexible

depends on growth

slow


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Traditional Methods

Membrane-Filtration

suitable for highly dilute samples

prone to interference

eliminates injured cells


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Enzymatic Methods

Coliform specific enzymes

-Galactosidase (lacZ)total coliforms

Ability to breakdown lactose

-D-Glucuronidase (uidA)fecal coliforms

Ability to breakdown complex sugars


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Enzymatic Methods

Presence / Absence Tests

like MTF but with enzymes


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Enzymatic Methods

Membrane Filtration

more specific than traditional method so it does

not require confirmation steps
http://www.chromagar.com/images_multimedia/000113-500x500.jpg?PHPSESSID=3447f057981a750eb969888a3aa208a2


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Enzymatic Methods

Direct Fluorimetry

Similar to presence/absence test but fluorescenceis monitored over time to determine relative

numbers of bacteria

Solid-Phase Cytometry

Filtered cells are induced and exposed to

fluorescent substrate.

Scanning fluorimeter detects individual cells andmicro-colonies.


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Molecular Methods

Nucleic Acid based techniques

Polymerase Chain Reaction (PCR)

phylogenetic primers

enzyme specific primers

detection limit

viability


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Molecular Methods

Nucleic Acid based techniques

In Situ Hybridization

radioactive vs. fluorescent

very high-tech

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