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9- Control of Microbial Growth

9- Control of Microbial Growth. Mechanisms of action (MOA) membrane protein nucleic acid Factors number environment microbial structure/characteristics. & pseudomonads. Disinfectant evaluation Phenol coefficient American official Analytical Chemist’s use-dilution method

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9- Control of Microbial Growth

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  1. 9- Control of Microbial Growth

  2. Mechanisms of action (MOA) membrane protein nucleic acid Factors number environment microbial structure/characteristics

  3. & pseudomonads

  4. Disinfectant evaluation Phenol coefficient American official Analytical Chemist’s use-dilution method In-use test Disk diffusion test

  5. Heat

  6. standard measures thermal death point (TDP) thermal death time (TDT) Decimal Reduction Time (DRT = D value)

  7. Moist heat Steam Autoclave Pasteurization traditional High-Temperature Short-Time (HTST) Ultrahigh-Temperature treatment (UHT) UHT sterilization

  8. Dry heat flaming oven incineration

  9. Filtration air: High-efficiency particulate air (HEPA) liquid: porcelain & glass paper membrane

  10. Low temperature Dessiccation Osmotic pressure

  11. Electromagnetic radiation (4.1) Irradiated food

  12. Phenol -> carbolic acid Lister

  13. pine oil thymol eugenol (clove oil)

  14. Isopropyl alcohol = isopropanol Ethyl alcohol = ethanol Proof?

  15. Halogens Iodine (I2) iodophor tincture

  16. Halogens Chlorine Chlorine gas (Cl2) Cl2 + H2O -> HOCl hypochlorous acid Ca(OCl)2 calcium hypochlorite Na dichloroisocyanurate (Chlor-Floc) ClO2chlorine dioxide NaOCl sodium hypochlorite chloramine

  17. Oxidizing agents Ozone (O3) peracetic acid

  18. Surfactants= Surface-Acting agents Soap has a structure similar to that shown here for one type (sodium stearate). Soap works because it has the ability to interact with nonpolar (oily) substances as well as with water. In an oil droplet suspended in water, the hydrocarbon residues (R-groups) of soap molecules are immersed in the oil, and the ionic ends extend into the water. Attractive forces between water molecules and the ionic heads cause the oil droplet to be solubilized. emulsification sometimes added: triclosan & triclocarban

  19. What’s the difference?

  20. Antibacterial soap Alcohol gel (has triclosan) Use with water Do NOT use water Scrub 2-3 minutes Wipe on, wipe off

  21. cationic detergents = quaternary-ammonium detergents = (quats)

  22. Oligodynamic action: heavy metals Ag Ag Also: Zn, Hg, As Cu

  23. Aldehydes glutaraldehyde formaldehyde

  24. Gaseous chemosterilizers propylene oxide beta-propiolactone ethylene oxide

  25. Food preservatives SO2 = sulfur dioxide (and _____ bisulfite or _____ metabisulfite or _____ sulfite) benzoic acid/Na benzoate sorbic acid/K sorbate Na nitrite & Na nitrate Personal care methylparaben, propylparaben menthol

  26. Dyes methylene blue Antibiotics (not used for treatment) nisin natamycin = pimaricin Other antimicrobials tea tree oil (terpin-4-ol) manuka honey (methylglyoxal) crystal/gentian violet

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