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Microorganisms (The Coliform Group Bacteria) S. D. Spence
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Microorganisms w single-celled w generally microscopic w include bacteria, protozoa, algae, fungi, viruses w may or may not be disease causing
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Implications of Microbial Contamination of Water w potential for transmission of disease causing microorganisms (pathogens) via water contact - oral fecal route w contact includes ingestion, primary contact, and secondary contact
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Water Borne Diseases/Pathogens w Bacteria Vibrio cholera - cholera Yersinia enterocolitica - gastroenteritis Escherichia coli - gastroenteritis Shigella sp.- gastroenteritis Listeria monocytogenes - flu-like symptoms Salmonella sp. - gastroenteritis, typhoid Campylobacter jejuni - gastroenteritis (animals sources)
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Vibrio cholerae
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Yersinia enterocolitica
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E. coli
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Shigella
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Clostridium perfringens
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Water Borne Diseases/Pathogens w Viruses Polio Virus - paralytic poliomyelitis Rotaviruses - gastroenteritis Norwalk Viruses - gastroenteritis Hepatitis Type A and E - liver inflammation
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Polio Virus
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Rotavirus
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Norwalk Agent
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Water Borne Diseases/Pathogens w Protozoa Entamoeba histolytica - amoebic dysentery Giardia lamblia - intestinal disease Cryptosporidium - intestinal disease
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Giardia lamblia
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Difficulties With Routine Testing Of Pathogens in Water w present in low numbers w limited survival time w numerous pathogens to analyze w time and cost prohibitive
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Testing of Indicator Organisms w need an indicator of potential pathogen contamination of water which is easy, reliable, inexpensive, quick, etc.
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Requirements of Indicator Organisms w present when pathogens present in water w absent in uncontaminated water w present in higher numbers than pathogens in contaminated water w better survival in water than pathogens w easy to analyze
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Coliform Bacteria - Indicators of Fecal Contamination w bacteria in the family Enterobacteriaceae w generally include the genera Enterobacter, Klebsiella, Citrobacter, and Escherichia w present in the intestinal tract of numerous organisms w gram negative, non-spore forming rods w ferment lactose with acid and gas production in 48 hours at 35 °C
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Total Coliform Bacteria w inhabit the intestinal tract of animals w sources: fecal material, soil, water, grain w some capable of reproduction in the environment w non-fecal examples include: Klebsiella sp., Citrobacter sp., Enterobacter sp.
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Fecal Coliform Bacteria w subset of the total coliform group w separated from non-fecal coliforms by growth at 44.5 °C w sources: fecal material w capable of limited survival and growth in the environment w primary example is Escherichia coli (E. coli)
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Can Stagnant Water Result in Positive Coliform Results? w presence of coliform bacteria indicates influence from a source - human activity, fecal material, soil, water, grain w stagnation of water - environment for reproduction of bacteria allowing great enough numbers to be detected
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Coliform Sample Preservation
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w sodium thiosulfate added to chlorinated samples w no additives for nonchlorinated samples w recommended-drinking water samples iced w required-source water samples iced
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Coliform Sample Holding Times and Analyses Methods
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Source Water vs. Drinking Water w Drinking water and source water have different requirements for coliform analysis methods and holding times
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Coliform Sample Holding Times w drinking water - 30 hours [40 CFR 141.21(f)] w surface/source water - 8 hours [40 CFR 141.74 (a)(1)]
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Effects of Holding Time on Samples w coliform numbers may decline w coliform numbers may increase w hetertrophic (non-coliform) bacteria may increase and inhibit detection of coliforms in the sample
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Heterotrophic Interference w Non-coliform bacteria which are better than coliforms at surviving in the environment may be present in the sample. If these organisms are given a chance to grow, they may out-compete coliforms during analysis and may limit the analysts ability to detect coliforms. The effect of HI is an underestimation of coliform numbers or a false negative result.
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Holding Times Are Critical w greater chance of heterotrophic interference in untreated source water - hence, shorter allowable holding time
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Coliform Methods
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Choosing a Laboratory for Testing w laboratory must be certified by the State or EPA to conduct analyses of compliance drinking water and surface/source water samples [40 CFR 141.28(a), 40 CFR 141.74(a)]
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Certified Laboratory w granted certification by State or EPA w meets QA/QC requirements w analyzes blind audit samples w audited every 3 years w documentation of certification w certified for specific methods
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Approved Drinking Water Methods
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Approved Source Water Methods
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Approved Drinking Water Methods [40 CFR 141.21 (f)] w Membrane Filter Method - total coliforms, fecal coliforms, E. coli w Multiple Tube Fermentation Method- total coliforms, fecal coliforms, E. coli
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Approved Drinking Water Methods [40 CFR 141.21 (f)] w Presence/Absence Method - total coliforms, fecal coliforms, E. coli w Colilert Method - total coliforms, E. coli w Colisure Method - total coliforms, E. coli
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Membrane Filter Method 4 to 5 day test w metallic green colonies on endo medium- presumptive coliform positive w growth/gas in LTB and BGBB - confirmed total coliform positive w growth/gas in LTB and EC medium - confirmed fecal coliform positive w growth and gas in LTB and growth and fluorescence in EC + MUG - confirmed E. coli positive
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Membrane Filter Method (Endo agar with coliform growth)
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Multiple Tube Method 5 day test w growth/gas in LTB- presumptive coliform positive w growth/gas in BGBB - confirmed total coliform positive w growth/gas in EC medium - confirmed fecal coliform positive w growth and fluorescence in EC + MUG - confirmed E. coli positive
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Multiple Tube Fermentation Method (Total Coliforms)
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Fecal Coliform/E. coli Multiple Tube Method - EC medium + MUG
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Presence Absence Method 5 day test w growth/acid in PA broth - presumptive coliform positive w growth/gas in BGBB - confirmed total coliform positive w growth/gas in EC medium - confirmed fecal coliform positive w growth and fluorescence in EC + MUG - confirmed E. coli positive
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Colilert and Colisure Methods 1 day test w color change in culture media - confirmed total coliform positive w production of fluorescence under 366 nm UV light - confirmed E. coli positive
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Colilert Method
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Useful References w Standard Methods for the Examination of Water and Wastewater, 18th Edition, 1992, American Public Health Association, 1015 Fifteenth Street NW, Washington, D.C., 20005 w Total Coliform Rule (40 CFR 141.21) w Surface Water Treatment Rule (40 CFR 141.74)
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Photo References w Microorganism photos scanned from Microbiology Concepts and Applications, Pelczar et al., McGraw-Hill, Inc., 1993 w Media vials and plate photos scanned from Products and Analysis 1999, Hach Company, P.O. Box 608, Loveland Colorado, 80539-0608
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