Cheat Sheet 18+Controlling Microbes PDF

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Summary

Breakwell...

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CONTROLING MICROBIAL GROWTH Definitions) Antisepsis:!Prevention!of!infection!by!killing!or!inhibiting!the!growth!of! pathogens!on!living!tissue.! Disinfection:!Killing,!inhibiting!the!growth!of!microorganisms,!or!the!removal! of!microorganisms!on!inanimate!objects.! Sanitization:!Reduction!of!the!numbers!of!microorganisms!to!a!level! determined!to!be!safe!by!public!health!standards.! Sterilization:!!Killing!or!removal!of!all!microorganisms!in!an!environment.!

Decimal)Reduction)Time)(D)value)) The!time!taken!to!reduce!a!population!of!microorganisms!by!1-log!or!90%!

The smaller the D value, the faster ) they die

Method Boiling water

Pasteurization

Autoclave Hot-Air Oven Incineration Freezing Ionizing radiation

Ultraviolet light

Filtration

0.2µm membranes

HEPA

0.3µm filters

Factors affecting antimicrobial activity - Size (more bacteria = more activity - Time exposure - Intensity, concentration - Temperature - nature of material

Sterility!is!an!absolute.!!Either! something!is!sterile!or!it!is!not!!

Breakwell’s)Rule)of)Nines:) Count)the)9’s) 1!log!reduction=90%! 2!log!reductions=99%! 3!log!reductions=99.9%! 4!log!reductions=99.99%! 5!log!reductions=99.999%! 6!log!reductions=99.9999%!

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Physical Ways of Controlling Microbial Growth Conditions Use 100oC, 10-30 Kills vegetative cells on objects; minutes often used for sanitization. Reduces the population of the 62.8oC for 30 vegetative cells of pathogenic o min/71.7 C for 15 microbes in milk, juices, and other sec. beverages. Sterilization of biohazardous waste, o 2 121.6 C, 15lb/in , surgical dressings, glassware, for 15-30 min microbiological media, liquids. Sterilization of glassware, metal, o 170 C for 1 hour oils Sterilization of inoculating loops, 870oC for 6-7 sec. for inoculating loop needles, and glassware. Bacteriostatic control of growth. 12.5.) Sporicidal Used for skin

Iodine and iodophors (povidone-iodine—Betadine)

Heavy Metals

Silver

Mercury

Peroxygens

Copper, zinc, nickel Hydrogen peroxide

Peracetic acid

Effective at low concentrations (as low as 12.5 ppm) and for fast sanitizing times (1 min.) Requires pH 3-6. Silver sulfadiazine (1%)

Oxidizes amino acids and prevent protein synthesis. Effective against vegetative bacteria, enveloped viruses, fungi and some mycobacteria. Inactivated by organic dirt. Prevents infection of burn wounds. Increases activity of some antibiotics.

Mercurochrome (2%); merthiolate

Broad spectrum bacteriostatic agent; Binds to cysteine and methionine residues in proteins. No longer available in U.S.

3% for home use as antiseptic or disinfectant.

Strong oxidizers and react with cell proteins, lipids, and DNA. Effective against bacteria, enveloped and non-enveloped viruses, fungi, and bacterial spores.

Phenolics

Phenol, Lysol

Effective at 0.02%, but is unstable. 0.05-1%

Bisphenols

Triclosan...