Water Analysis: Microbiology and Parasitology PDF

MICROBIOLOGY AND PARASITOLOGY WATER ANALYSIS Atty. Ma. Theresa Panes, M.D. | Oct. 23, 2024 Water Sampling and Analysis Water Analysi...

MICROBIOLOGY AND PARASITOLOGY WATER ANALYSIS Atty. Ma. Theresa Panes, M.D. | Oct. 23, 2024 Water Sampling and Analysis Water Analysis for Detection of Pathogenic Challenges: Bacteria Numerous pathogens causing waterborne diseases Individual pathogen numbers may be too low to detect in a reasonable-sized water sample LEARNING RESOURCES Isolation and detection of some pathogens can take McCartney Bottle several days, weeks, or months Water Samples (from various samples) WATER POLLUTION BY FECAL TYPES OF WATER TESTING METHOD CONTAMINATION Microbiological Water Analysis Concentrations of pathogens from fecal → Fecal Indicator Bacteria: Coliform Bacteria contamination are small, and the number of Mineral tests different possible pathogens is large. pH testing It is not practical to test for pathogens in every Other types of testing water sample collected. → Conductivity The presence of pathogens is determined with → Odor indirect evidence by testing for an "indicator" → Sediments organism such as coliform bacteria; which Purpose indicates that water is indeed contaminated with ○ There is a need to test water for the feces presence of pathogenic bacteria ○ Limitation: They occur in small INDICATOR ORGANISMS numbers and might be missed by It is more practical to screen the water for the sampling presence of fecal contamination by testing for the presence of an indicator microorganism. Water Borne Pathogens and Disease- Diarrhea, MINIMUM BURDEN: 10 coliforms/100ml Enteritis, Dysentery The microorganism is not naturally found in water and will be present in the water only when a sample Bacterial Flora in Water is contaminated or polluted Natural water bacteria: commonly found in water The density of the microorganisms present should free from gross pollution; potable water be proportional to the degree of contamination; Soil Bacteria: not normal inhabitants of water but higher the density, more polluted are found after being washed into the water during heavy rains; breach the water system Sewage bacteria: not normal inhabitants of water INDICATOR ORGANISM CONCEPT but are found in water after being contaminated with sewage; improper sewage system Correlated to the presence of SOURCE OF WATER BACTERIA pathogens NATURAL WATER BACTERIA Micrococcus, Pseudomonas, Population large enough to Acinetobacter, Serratia, isolate in small water samples Alcaligenes, (100 mL) Flavobacterium Rapid SOIL BACTERIA WASHED Bacillus subtilis, Inexpensive INTO WATER Enterobacter cloaca, Enterobacter aerogenes COLIFORM BACTERIA Aerobic or facultative anaerobic Gram-negative bacilli SEWAGE BACTERIA Non-spore forming Ferments lactose with acid Proper Sewage Bacteria Clostridium perfringes, Can produce gas (hydrogen sulfide) Proteus sp. Thermotolerant coliforms - grow at 44 or 44.5ºC Escherichia coli, Citrobacter freundii, Intestinal Flora Through Escherichia coli, Enterobacter, Klebsiella pneumoniae, Serratia Sewage Enterococcus faecalis, Proteus sp. Total Coliforms Klebsiella sp. Include bacteria that are found in the soil, in water Clostridium perfringes that has been influenced by surface water, and in human or animal waste Transcribed by: NMD 2027  Water Analysis Most basic test for bacterial contamination of water; different filtration volumes are suggested depending gives a general indication of the sanitary condition on the source of the water sample. of water supply Fecal Coliforms The group of the total coliforms that are considered to be present specifically in the gut and feces of warm-blooded animals. Fecal coliforms are considered a more accurate indication of animal or human waste than the total coliforms. ESCHERICHIA COLI a member of the family Enterobacteriaceae, and is characterized by possession of the enzymes β-galactosidase and β-glucuronidase grows at 44–45°C on complex media, ferments lactose and mannitol with the production of acid and gas, and produces indole from tryptophan Both selective and differential some strains can grow at 37°C but not at 44–45°C, and some do not produce gas. E. coli does not produce oxidase or hydrolyze urea E. coli is the species of coliform bacteria that is the best indicator of fecal pollution and the possible presence of pathogens. Methods for Water Analysis MULTIPLE TUBE FERMENTATION METHOD In this method a measured sub-sample (perhaps 10 ml) is diluted with 100 ml of sterile growth medium and an aliquot of 10 ml is then decanted into each of ten tubes. The remaining 10 ml is then diluted again and the process is repeated. The multiple tube test is used to assess total and fecal coliforms in drinking water. The result would depend on color change and gas formation. Most laborious 3 Stages: 1. PRESUMPTIVE TEST Dilution from a water sample is added to lactose fermentation tubes POSITIVE REACTION: Fermentation of Lactose to Acid and Gas DETECTION OF TOTAL COLIFORMS- 2. CULTURE Samples from the positive mEndo agar LES presumptive tube are streaked This growth medium contains lactose and a pH into EMB (Eosin-Methylene Blue) indicator that changes color when acid is produced agar (from lactose fermentation). POSITIVE CULTURE: Colored Coliforms typically produce a metallic (golden) colonies sheen, which is due to the extensive production of 3. COMPLETED TEST aldehydes and acid from the fermentation of Isolated Lactose-positive colonies lactose. from EMB -inoculated into Some total coliforms may also be dark red, mucoid, Lactose broth and Nutrient agar or have a dark center but without a metallic sheen; slant. these are considered to be atypical total coliform POSITIVE TEST: Production of colonies. acid and gas and a E. coli will form colonies with a metallic sheen. gram-negative, non-spore-forming rod DETECTION OF FECAL COLIFORMS- mFC agar MEMBRANE FILTRATION This growth medium contains bile salts. An appropriate volume of the sample is filtered mFC agar also contains rosolic acid, which inhibits through a membrane with a pore size of 0.45 mm. bacteria other than fecal coliforms. The membrane is incubated on an agar plate. Aniline blue, a pH indicator, turns dark blue upon Bacterial (and other) cells trapped on the acid production, helping in the identification of membrane will grow into colonies that can be lactose-fermenting bacteria counted, and a bacterial density can be calculated. Fecal coliforms form blue colonies on this medium; When using the membrane filtration technique to E. coli will form flat dark blue colonies. test for the presence of indicator microorganisms, 2 of 4  Water Analysis Filters used to detect the presence of fecal Swing spouts coliforms in a sample of water should be Faucets positioned close to sink or ground incubated at 44.5 C for 22 – 26 hours. Leaky faucets FREEDOM WALL MCCARTNEY METHOD- PAPER STRIP METHOD With folded tissue paper which contains: Peptone - medium for bacterial growth Dipotassium Hydrogen Phosphate - buffer Sodium thiosulfate - source of hydrogen sulfide; gas formation Ferric ammonium citrate - indicator Teepol water - mimic intracolonic environment Principle: Coliforms oxidize sulfate or thiosulfate to hydrogen sulfide (H2S) END POINT: black color; positive result 12-18 hours incubation at room temperature Some Tips on Collecting Samples: Remove any attachments on the faucet Allow water to flow for 5 or 6 minutes before sampling Do not rinse or overfill container Always collect cold water; never sample hot water Do not touch the inside of the sample bottle or its cap Avoid These Sampling Sites for Total Coliform, if Possible Outdoor faucets Faucets connected to cisterns, softeners, pumps, pressure tanks or hot water heaters New plumbing and fixtures or those repaired recently Faucets that hot and cold water come through Threaded taps 3 of 4 Water Analysis 4 of 4