Term
| Conditions Influencing the Effectiveness of Antimicrobial Agent Activity |
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Definition
population size
population composition
concentration or intensity of an antimicrobial agent
Contact time - duration of exposure
temperature
local environment |
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Term
| Physical method: Steam Sterilization |
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Definition
must be carried out above 100oC which requires saturated steam under pressure
using an autoclave 121 C at 15 psi for 10-15 min
effective against all types of microorganisms including spores
quality control - includes strips with Geobacillus stearothermophilus |
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Term
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Definition
controlled heating at temperatures well below boiling (55 - 60 C)
used for milk, beer, and other beverages
process does not sterilize but does kill pathogens present and slow spoilage by reducing the total load of organisms present |
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Term
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Definition
Intermittent sterilization
30-60 min of steam repeated 3 times with 23-24 hr incubations between
Used to kill spores – spores germinate and are then killed by the steam treatment |
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Term
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Definition
less effective than moist heat sterilization, requiring higher temperatures and longer exposure times (e.g. incineration or oven)
items subjected to 160–170oC for 2 to 3 hours
oxidizes cell constituents and denatures proteins
E.g., C. botulium – 5 min at 121C or 2 hrs at 160C |
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Term
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Definition
reduces microbial population or sterilizes solutions of heat-sensitive materials by removing microorganisms
also used to reduce microbial populations in air
Can use depth filters or membrane filters |
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Term
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Definition
porous membranes with defined pore sizes that remove microorganisms primarily by physical screening
have replaced depth filters for the most part
Removes microorganisms from heat sensitive liquids (e.g., pharmaceuticals, antibiotics, vitamin solutions, culture media, etc) |
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Term
| high-efficiency particulate air (HEPA) filters |
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Definition
used in laminar flow biological safety cabinets
Removes 99.97% of particles 0.3 um or larger |
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Term
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Definition
wavelength of 260 is most bactericidal (DNA absorbs)
causes thymine dimers in DNA preventing replication and transcription
UV limited to surface sterilization because it does not penetrate glass, dirt films, water, and other substances
has been used for water treatment |
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Term
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Definition
gamma radiation penetrates deep into objects
destroys bacterial endospores; not always effective against viruses
used for sterilization and pasteurization of antibiotics, hormones, sutures, plastic disposable supplies, and food |
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Term
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Definition
A disinfectant must be effective against wide variety of infectious agents at low concentrations (and only on the surface)
must be effective in the presence of organic matter; should be stable in storage
Pleasant odor, soluble in water and lipids, low surface tension and relatively inexpensive (like cleaning stuff in the bathroom)
overuse of antiseptics such as triclosan has selected for triclosan resistant bacteria and possibly antibiotic resistance (e.g., Pseudomonas aeruginosa) |
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Term
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Definition
Phenol was 1st widely used antiseptic and disinfectant. Used in 1867 by Joseph Lister
commonly used as laboratory and hospital disinfectants (e.g., Lysol)
act by denaturing proteins and disrupting cell membranes
tuberculocidal, effective in presence of organic material, and long lasting
disagreeable odor and can cause skin irritation
E.g., triclosan is used in hand sanitizers |
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Term
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Definition
among the most widely used disinfectants and antiseptics (use on your skin before getting injection)
two most common are ethanol and isopropanol (60 – 80 %)
bactericidal, fungicidal, but not sporicidal (not kill the viral but can reduce some)
inactivate some viruses
denature proteins and possibly dissolve membrane lipids |
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Term
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Definition
skin antiseptic
oxidizes cell constituents and iodinates proteins
at high concentrations may kill spores
skin damage, staining, and allergies can be a problem
E.g., Wescodyne
iodophore
iodine complexed with organic carrier
released slowly to minimize skin burns |
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Term
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Definition
oxidizes cell constituents
important in disinfection of water supplies and swimming pools, used in dairy and food industries, effective household disinfectant
destroys vegetative bacteria and fungi,
chlorine gas is sporicidal
can react with organic matter to form carcinogenic compounds
E.g., Bleach is highly effective (10% with a little vinegar) |
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Term
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Definition
oxidizes cell constituents
important in disinfection of water supplies and swimming pools, used in dairy and food industries, effective household disinfectant
destroys vegetative bacteria and fungi,
chlorine gas is sporicidal
can react with organic matter to form carcinogenic compounds (in drinking water)
E.g., Bleach is highly effective (10% with a little vinegar) |
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Term
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Definition
e.g., ions of mercury, silver, arsenic, zinc, and copper (e.g., CuSO4 as algaecide in swimming pools, Silver nitrate to prevent ophthalmic gonorrhea) -> germicide
effective but usually toxic (in paint, on the surface of the ships)
combine with and inactivate proteins; may also precipitate proteins |
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Term
| Quaternary Ammonium Compounds |
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Definition
detergents that have antimicrobial activity and are effective disinfectants
amphipathic organic cleansing agents
act as wetting agents and emulsifiers
Disrupt membranes and denature proteins
kill most bacteria, but not Mycobacterium tuberculosis or endospores
safe and easy to use, but inactivated by hard water and soap
E.g., Benzalkonium chloride (food utensils) |
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Term
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Definition
commonly used agents are formaldehyde and glutaraldehyde
highly reactive molecules
sporicidal and can be used as chemical sterilants
combine with and inactivate nucleic acids and proteins
These are for preservatives. CAN’t use this on skin or food products.
Toxic and only use on the surface |
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Term
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Definition
used to sterilize heat-sensitive materials like plastics
microbicidal and sporicidal
ethylene oxide sterilization is carried out in equipment resembling an autoclave - rapidly penetrates packing materials, even plastic wraps (5-8 hrs at 38C or 3-4 hrs at 54C at 40-50% RH) – very toxic to humans (high penetrating ability)
betapropiolactone and vaporized hydrogen peroxide
combine with and inactivate DNA and proteins |
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Term
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Definition
Best known disinfectant screening test
potency of a disinfectant is compared to that of phenol
useful for screening but may be misleading
Uses carefully controlled conditions that don’t really resemble actual use conditions
Uses standard amounts of Salmonella enterica serovar Typhi and Staphylococcus aureus – looks for the highest dilution that kills bacteria in 10 min. Don’t see in the standard temp |
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