Term
| Physical Control of microbes |
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Definition
Heat
Cold temperatures
Desiccation
Radiation |
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Term
| Chemical Control of microbes |
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Definition
Halogens
Phenolics
Chlorhexidine
Alcohols
Hydrogen peroxide
Detergents & soaps
Heavy metals
Aldehydes |
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Term
| Mechanic Control of microbes |
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Definition
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Term
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Definition
Destruction or removal of vegetative pathogens but not bacterial endospores.
Usually used on inanimate objects. |
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Term
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Definition
| Complete removal/destruction of all microorganisms, used on inanimate objects |
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Term
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Definition
| Chemicals applied to body surfaces to destroy/inhibit vegetative pathogens |
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Term
| Highest resistance of microbes |
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Definition
Prions
Bacterial endospores |
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Term
| Moderate resistance of microbes |
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Definition
Pseudomonas sp.
Mycobacterium tuberculosis
Staphylococcus aureus
Protozoan cysts
Naked viruses
HBV, poliovirus |
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Term
| Least resistance of microbes |
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Definition
Most bacterial vegetative cells
Fungal spores & hyphae
Enveloped viruses
Yeasts
Protozoan trophozoites |
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Term
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Definition
| (germicide) any chemical agent that kills pathogenic organisms |
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Term
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Definition
| any process that temporarily prevents microbes from multiplying |
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Term
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Definition
| any cleansing technique that mechanically removes microbes |
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Term
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Definition
| any process to reduce the number of microbes on the human skin |
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Term
| “Sterilization” by microbicidal agents (bactericide, fungicide, virucide, sporicide, germicide) |
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Definition
| Aimed at killing a certain group of pathogens so may not actually sterilize |
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Term
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Definition
| growth of microorganisms in the tissues |
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Term
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Definition
permanent loss of reproductive capability even under optimum growth conditions.
The antimicrobial agent’s effect on the cell is known as its mechanism of action. |
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Term
| Factors that influence action of antimicrobial agents |
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Definition
Number of microbes
Nature of microbes in the population
Temperature & pH of environment
Concentration or dosage of agent
Mode of action of the agent
Presence of solvents, organic matter, or inhibitors |
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Term
| Cellular targets of control |
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Definition
Cell wall – antibiotics, detergents and alcohols
Cell membrane – detergents
Cellular synthetic processes (DNA, RNA) – antibiotics, chemicals, radiation
Proteins(enzymes) – heat and chemicals |
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Term
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Definition
| disrupt the lipid layers of the cell membrane altering permeability and destroying the cell |
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Term
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Definition
use of hot water or steam
Mode of action – denaturation of proteins, destruction of membranes & DNA
Sterilization
Autoclave 15 psi/121oC/10-40min
Intermittent sterilization – unpressurized steam at 100oC 30-60 min for 3 days
Disinfection
Pasteurization <100oC for seconds; kills Salmonella, Listeria & overall microbe count
Boiling at 100oC for 30 minutes to destroy non-spore-forming pathogens |
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Term
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Definition
Dry heat is not nearly as effective as moist heat.
Moist heat operates at lower temperatures and shorter exposure times than dry heat
Dry heat using higher temperatures than moist heat and can also sterilize
Incineration – 800-6500oC combusts & dehydrates cells
Dry ovens – 150-180oC for 2-4 hrs – destroys spores and coagulates proteins |
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Term
| Cold temperatures (Microbistatic) |
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Definition
slows the growth of microbes, does not eliminate them.
Pathogens known to survive in cold temperatures are Staphylococcus aureus, Clostridium species, Streptococcus species, yeasts, molds, viruses and others.
Refrigeration 0-15oC & freezing <0oC
Used to preserve food, media and cultures |
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Term
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Definition
Gradual removal of water from cells, leads to metabolic inhibition
Not effective microbial control – many cells retain ability to grow when water is reintroduced.
Chilling, freezing and desiccation are not methods of disinfection or sterilization. |
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Term
| Radiation – “Cold sterilization” |
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Definition
Ionizing radiation – deep penetrating power, breaks DNA
gamma rays, X-rays, cathode rays
used to sterilize medical supplies & food products
Nonionizing radiation – little penetrating power – used to sterilize air, water & solid surfaces
UV light damages the pyrimidines, which causes abnormal bonding and interferes with replication |
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Term
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Definition
Mechanical removal of microbes by passing a gas or liquid through a filter.
Filtering out the microbes that are too large to pass through the filter.
Used to sterilize heat sensitive liquids & air in hospital isolation units & industrial clean rooms |
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Term
| Chemical control-Ideal qualities of a microbicide (germicide) |
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Definition
Rapid action even in low concentrations
Solubility in water or alcohol with long term stability
Broad spectrum without toxicity to humans and animals.
Penetration of inanimate objects.
Resistant to inactivation
Noncorrosive and non-staining
Sanitizing and deodorizing properties
Inexpensive and readily available |
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Term
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Definition
Cl2, hypochlorites (chlorine bleach), chloramines
Denaturation of enzymes is permanent
Kills bacteria, endospores, fungi and viruses. |
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Term
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Definition
I2, iodophors (betadine)
Denatures proteins
Also kills all microorganisms if proper concentration and exposure time.
Milder medical & dental degermation agents, disinfectants, ointments. |
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Term
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Definition
Phenol (carbolic acid)
Disrupts cell walls, cell membranes & proteins; bactericidal, fungicidal, virucidal, but not sporicidal
Lysol spray (bisphenol)
Triclosan (dichlorophenoxyphenol) - antibacterial additive to dozens of products – soaps to kitty litter. |
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Term
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Definition
Hibiclens, Hibitane
A surfactant (disrupts cell membrane) & protein denaturant with broad bactericidal properties – variable against fungi and viruses
Not sporicidal.
Used as skin degerming agents for preoperative scrubs, skin cleaning & burns |
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Term
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Definition
Ethyl alcohol (ethanol), isopropyl alcohol (rubbing alcohol)
Act as surfactants dissolving membrane lipids and coagulating proteins of vegetative bacterial cells and fungi
Not sporicidal
Hand sanitizer – 70-95% solution of ethyl alcohol – safer than isopropyl alcohol |
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Term
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Definition
H2O2 – weak (3%) to strong (25%)
Produce highly reactive hydroxyl-free radicals that damage protein & DNA while also decomposing to O2 gas – toxic to anaerobes
Kills bacteria, viruses, fungi, and strong solutions are sporicidal. |
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Term
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Definition
polar molecules that act as surfactants and alter membrane permeability.
Quaternary ammonium compounds – benzalkonium chloride (eye drops)
Effective against some gram + bacteria, viruses & fungi at high concentrations
Not effective against bacillus, hepatitis, or pseudomonas and not sporicidal.
Only used for low level disinfection |
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Term
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Definition
mechanically remove soil and grease containing microbes but not germicidal
combined with chlorhexidine or iodine are more germicidal but will never “sterilize” the skin. |
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Term
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Definition
Solutions of silver & mercury kill vegetative cells in low concentrations by inactivating proteins
Oligodynamic action – heavy metals have antimicrobial properties in very small concentrations but can also be toxic.
Not sporicidal |
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Term
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Definition
Glutaraldehyde & formaldehyde kill by alkylating the proteins in the cell and disrupting the enzymatic activities.
Glutaraldehyde in 2% solution (Cidex) is very effective and is used as a sterilant for heat sensitive instruments.
Formaldehyde – a gas added to water (formalin). Used as a disinfectant and preservative but very toxic (carcinogenic). |
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Term
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Definition
Ethylene oxide is an explosive gas that is a sterilizer. Mixed to CO2 for stability and used in a “chemiclave.” Also carcinogenic.
Microbicidal by blocking DNA replication and enzymes (proteins).
Chlorine dioxide is less toxic to humans and recently used to decontaminate a few offices of the Senate after an antrax attack. |
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