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Air water milk
This document discusses water, milk, and air quality from a microbiological perspective. It defines wholesome water and its biological, chemical, and physical properties. It describes factors that determine bacterial levels in water such as salinity, acidity, temperature, light, organic matter, and water type. It also discusses water-borne pathogens and their modes of transmission. The document then covers the microbiology of milk, common milk-borne diseases, and methods used to disinfect/sterilize milk. It describes methods for bacteriological examination of milk including colony counts, chemical tests, and detection of specific pathogens. Finally, it lists common airborne organisms and purposes of air sampling. It provides details
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Air water milk
- 1. WATER MILK AIR -Dr. ANKUR KUMAR
- 2. • Wholesome water waterthat is fit to use for drinking, cooking, food preparation or washing without any danger to human health. • Drinking water should have the following properties- Biological quality: should be free from potentially pathogenic microorganisms Chemical quality: should be free from harmful chemical substances such as metals, solvents, pesticides and hydrocarbons Physical quality: should have pleasant in taste, color & odor.
- 3. Bacterial flora inwater
- 4. Factors determining theNumber of Bacteria in Water Salinity: - more is the salinity, lesser is the number of bacteria. Acidity: - Acidity of water has a deleterious effect on most of the bacteria. Temperature: - Body temperature usually favours survival of the bacteria. Light: - Sunlight with the wavelength of 300–400 nm is highly bactericidal. Storage: - decreases bacterial count in stored water due to sedimentation . Organic matter: - When organic matter is plenty, the microorganisms tend to multiply and are present in large numbers whereas when it is less, the organisms are few. Type of water: - Surface water is more likely to be contaminated than the deep water.
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- 6. Transmission of waterrelated pathogens: Ingestion Inhalation & aspiration Skin, mucous membrane wounds, eye Contact (bathing) Gastrointestinal Respiratory Bacteria Campylobacter spp. E. coli Salmonella spp. Shigella spp. V. cholerae Y. enterocolitica Viruses Adenovirus Astrovirus Enterovieus Hepatitis A & E Rotavirus Norovirus Protozoal & Helminthes C. parvum E. histolytica G. intestinalis. D. medinensis L. pneumophila Atypical mycobacteria N. fowleri etc Acanthamoeba spp. Aerpmonas spp. B. pseudomallei Leptospira spp. p. aeruginosa S. mansoni
- 7. Bacteriological Examination ofwater It is impractical to detect the presence of all different kinds of water borne pathogens, any of which may be present intermittently. Instead, reliance is placed on testing the supply for microorgsnisms which indicate that fecal pollution has taken place.
- 8. Indicator organisms • Indicatororganisms themselves are not pathogens. • Their presence in water supplies- indicates contamination of sewage and the water supplies needs to be disinfected. • These organisms satisfy 2 properties---- 1. present in excess number than any pathogen & should not be able to proliferate in water to any extent 2. more resistant than the pathogens
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- 10. Indicator organisms 1. Coliforms(presumptive coliforms) 2. Faecal (Thermotolerant) coliforms 3. E. coli or ‘fecal E. coli’ 4. Faecal streptococci 5. Sulphite – reducing clostridia 6. Pseudomonas aeruginosa 7. Bacteriophage that infect Escherichia coli.
- 11. Methods of Analysis Membrane filtration method Multiple tube method. Membrane Filtration Method
- 12. Methods of Analysis •Presumptive coliform count (Multiple Tube Method) – for estimation of presumptive coliform count, which is expressed as most probable number (MPN) of coliform organisms in100 mLof water. – Medium: MacConkey broth (double strength and single strength) in bottles / tubes, Durham's tube- used to detect gas production. • Differential Coliform Count (Eijkman Test) – to confirm that coliform bacilli detected in the presumptive test are fecal E. coli. – Method- Sub culturing the positive tubes for detection of lactose fermentation with production of acid and gas at 440C – Demonstrating positive indole test at 440C.
- 14. McCrady's probability table forcalculating most probable number (MPN)/100 ml of water
- 15. Membrane Filtration Method •Method- measured volume of the water sample is filtered through a membrane of pore size small enough to retain the indicator bacteria to be counted on its surface. – The membrane is then placed on a suitable selective indicator medium and incubated- indicator bacteria grow – bacterial content of the water is calculated by counting the total number of colonies grown.
- 16. BACTERIOLOGY OF MILK •Microorganisms in raw milk are derived from: 1. Animals (fecal contamination or through infected udder, teat canals and skin) 2. Hands of the milk handlers 3. Environment
- 17. Milk borne diseases (ByJoint FAO/WHO Expert committee on Milk Hygiene 1970)
- 18. Methods used forDisinfecting/Sterilizing Milk • Thermized milk- raw milk heated at 57- 68°C for 15 seconds. Efficacy is tested by methylene blue reduction test • Pasteurization- Milk is heated to high temperature for short time (720C for 15 seconds). Efficacy is tested by phosphatase test. • Ultra heat treated milk- milk is heated to very high temperature of 1350C for 1 second • Sterilized milk- milk is heated at 1000c for long periods such that it can pass the turbidity test
- 19. Methods for BacteriologicalExamination of Milk • Colony count Viable count Coliform count • Chemical tests Methylene blue reduction test Phosphatase test Turbidity test • Detection of specific pathogens Tubercle bacillus Brucella
- 20. BACTERIOLOGICAL EXAMINATION OF MILK Viablecount Test for coliform bacilli Methylene blue reduction test Phosphatase test Turbidity test Examination for specific pathogens • Tubercle bacillus • Brucella
- 21. Viable Count • byplate counts with serial dilutions of the milk sample. • rough and indirect assessment of the visible bacteria in the milk. Test for coliform bacilli • by inoculating varying dilutions of milk into MacConkey’s broth. • Production of acid and gas is noted after incubation.
- 22. Methylene blue reductiontest • Depends on the reduction of methylene blue by bacteria in milk when incubated at 37°C in complete darkness. • Raw milk is considered satisfactory if it fails to reduce the dye in 30 minutes under standard conditions.
- 23. Phosphatase test • Checkon the pasteurization of milk. • Enzyme phosphatase is inactivated if pasteurization has been carried out properly. • Phosphatase test if positive after proper pasteurization of milk indicates contamination after pasteurization.
- 24. Turbidity test • Allheat coagulable proteins precipitates if the milk is boiled or heated to the temperature prescribed for ‘sterilization’. • No turbidity results if ammonium sulphate is then added to the milk.
- 25. Examination for specificpathogens Tubercle bacillus: • Microscopic examination for tubercle bacilli is unsatisfactory. • Tubercle bacilli may be isolated in culture- LJ media, BACT. • Milk is centrifuged at 3000 rpm for 30 minutes and the sediment inoculated into two guinea pigs. • Animals are observed for a period of three months for tuberculosis.
- 27. Organisms implicated – •Mycobacteria • Staphylococcus • Streptococcus • Bacillus • Nocardia • Actinomycetes • Pseudomonas • Burkholderia • Klebsiella • Escherichia • Proteus Airborne Agents Innumerable microorganisms are present in air. Apart from bacteria, moulds and viruses are also present and can be transmitted from person to person in the form of aerosols.
- 28. • The proportionof the dust particles or aerosols reaching the lung depends on their size. Air born infection : produced by respiratory droplets less than 5µm in size. Reach upto the lung and are retained in the alveoli. Droplet infection : produced by respiratory droplets more than 5µm in size retained in the nose
- 30. Purpose - measuremicrobial contamination in air Types: Passive air sampling - • Settle plate method Active air sampling - • Slit-type Impactors • Sieve-type Impactors • Centrifugal air samplers • Filtration samplers • Cascade impaction • Electrostatic precipitation Air Sampling
- 31. • Open platesof culture media exposed to room air - Nutrient media (Surface area 65cm2)– •BA •TSA(Trypticase soy agar) 1m height above floor 1m away from the wall for 1 hour. • Plates incubated at 37°C × 24 hrs → number of colonies counted. •Large bacteria-carrying dust particles settle on the medium. Settle Plate Method
- 32. Settle Plate Method •Gives an idea of relative no. & type of organisms- • Used for testing surgical theater and hospital ward air • The result is expressed as- the number of bacteria-carrying particles settling on a given area in a given period of time. • The method has the advantage of simplicity, but measures only the rate of deposition of large particles from the air.
- 33. Slit sampling machine Knownvol. of air is directed onto a plate containing culture medium through a slit 0.25 mm wide • Plate being mechanically rotated organism is evenly distributed • Valuable in areas of low microbial contamination •The efficiency of collection, even for the smallest bacterial particles, is very high. •Disadvantages of the slit sampler: noisy and relatively cumbersome. Slit Sampler
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