MicroPara: Control of Microorganisms
Non-ionizing Radiation
Excites electrons; damages DNA
Dry Heat
Hot-air Oven Incineration
Non-ionizing Radiation
Impenetrable to materials
Radiation
Ionizing Radiation Non-ionizing Radiation
Non-ionizing Radiation
UV rays
Membrane Filters
Used to sterilize fluids by removing microorganisms
Dessication
• By light • By temperature • By moisture • By lyophilization • By high concentrations of salt or sugar
Liquid-Nitrogen Refrigerators
-196 °C
Quarternary Compounds (eg. detergents)
0.1-0.2%
Phenol and Related Compounds
0.5-3.0% aqueous solution
Chlorine Compounds
0.5-5.0g available chlorine per liter
Mercurial Compounds
1.0%
Iodine
1.0-2.0%
Boiling Water
100 °C, 10 min
Autoclave
121 °C, 15 psi, 15-30 min
Hot-air Oven
170-180 °C, 1-2 hrs
Pasteurization
62.8 °C, 30 min or 71.7 °C, 15 min
Alcohols
70-90%
Ionizing Radiation
Able to penetrate packaging and products and sterilize their interiors (packaged food, medical equipment, commercial machines)
Antiseptics
Agents that inhibit the growth of microorganisms on living surfaces
Viricide
Agents that kills viruses
Germicide
An agent that kills germs, especially pathogenic microorganisms; a disinfectant
Bactericidal
Antibiotics that kill bacteria directly
Bacteriostatic
Antibiotics that stop bacteria from growing
Disinfectant
Antimicrobial agent that is applied to non-living objects to destroy microorganisms
Moist Heat
Autoclave Boiling Water Pasteurization
Mercurial Compounds
Bacteriostatic agents
Fungicide
Biocidal chemical compound that is used to kill parasitic fungi or their spores
Antimicrobial activity Solubility Stability Lack of toxicity Homogeneity Minimum inactivation by extraneous material Activity at ordinary temperatures Ability to penetrate Material safety Deodorizing ability Detergent ability Availability and low cost
Characteristics of an Ideal Chemical Agent
Alcohols
Denatures protein and disrupts cell membranes
Hot-air Oven
Destructive to materials that cannot withstand high temperatures
Ionizing Radiation
Difficult to control due to emission of isotopes
Phenol and Related Compounds
Disinfection of inanimate objects such as instruments,floor and table surfaces, and (with cresols) rectal thermometers
Mercurial Compounds
Disinfection of skin, instruments; also used as a preservative in some biological materials
Iodine
Disinfection of skin, minorcuts, and abrasions; also used for disinfection of water & swimming pools
Alcohols
Disinfection of skin,delicate surgical instruments,thermometers
Chlorine Compounds
Disinfection of water, nonmetal surfaces, dairy equipment, restaurant utensils, household items
Quarternary Compounds
Disrupt membranes & denatures proteins
Ionizing Radiation
Drive away electron and split molecules
Disinfection
Eliminates many or all pathogenic microorganisms except bacterial spores in inanimate objects
Boiling Water
Endospores are not killed; can't be relied upon to sterilize
Quarternary Compounds
Environmental sanitation of surfaces and equipment
Tube-Dilution Technique Agar-Plate Technique Phenol-Coefficient Technique
Evaluation of Antimicrobial Potency of Disinfectants and Antiseptics
Population size Population composition Concentration or intensity of an antimicrobial agent Duration of exposure Temperature Local environment
Factors Influencing the Effectiveness of an Antimicrobial Agent
Lyophilization
Freeze drying; for preservation of cultures
Low Temperatures
Freezers Liquid-Nitrogen Refrigerators
Ionizing Radiation
Gamma rays and X-rays
Liquid-Nitrogen Refrigerators
High cost of liquid nitrogen
Autoclave
Ineffective against organisms in materials impervious to steam; can't be used for heat- sensitive articles
Pasteurization
Killing vegetative cells of disease- causing microorganisms and of many other organisms in milk, fruit juices, and other beverages
Boiling Water
Killing vegetative cells on instruments, containers
Freezers
Less than 0 °C
Freezers
Mainly microbiostatic instead of microbicidal
Filtration
Membrane Filters High-Efficiency Particulate (HEPA) Filters
Physical Methods
Moist Heat Dry Heat Low Temperature Radiation Filtration Dessication
Chlorine Compounds
Oxidize cellular constituents
Iodine
Oxidizes cellular constituents
Freezers
Preservation of foods and other materials
Liquid-Nitrogen Refrigerators
Preservation of microorganisms
Sanitation
Process of reducing the number of microorganisms to a level that has been officially approved as safe
Sterilization
Process that eliminates all forms of microbial life
Phenol and Related Compounds Alcohols Iodine Chlorine Compounds Quarternary Compounds Mercurial Compounds
Some Commonly Used Disinfectants and Antiseptics
Incineration
Sterilization of transfer loops and needles; disposal of carcasses of infected animals; disposal of contaminated objects that cannot be reused
Autoclave
Sterilizing instruments, linens, utensils, treatment trays, media, other liquids
Hot-air Oven
Sterilizing materials impermeable to or damaged by moisture, e.g. oils, glass, sharp instruments, metals
Algicide
Substance that is used to kill algae
Bactericide
Substance that kills bacteria; disinfectant, antiseptic or antibiotic
Antimicrobial agent
Substance that kills or slows the growth of microbes
Antisepsis
Use of chemical solutions for disinfection
Non-ionizing Radiation
Used to reduce number of microorganisms in air & on surfaces (hospitals, aseptic rooms where sterile products are being dispensed)
HEPA Filters
Used to remove or reduce the number of microorganisms in air to prevent their spread in laboratories & hospital environments (e.g.biosafety cabinet)
Phenol Coefficient
highest dilution of phenol that kills the microorg after 10 min but not after 5 min; highest dilution of test chemical that kills the microorg after 10 min but not after 5 min
Incineration
hundreds of °C
