Methods of microbial control used outside of the body (4)
The destruction of all microbial life. Process that destroys or removes all viable microorganisms, including viruses.
Destroys most microbial life, reducing contamination on inanimate surfaces. The physical process or a chemical agent ( a disinfectant) to destroy vegetative pathogens but not bacterial endospores. Normally used only on inanimate object - concentrations toxic to humans and animal tissue.
Destroys most microbial life on living surfaces.
Processes that remove the harmful products of microorganisms (toxins) from materials.
The mechanical removal of most microbes from an animate or inanimate surface.
The resistance level of prions and bacterial endospores to physical and chemical methods of control. (high, moderate, least)
The resistance level of most bacterial vegetative cells, fungal spores and hyphae, enveloped viruses, yeasts, and protozoan trophozites.
Resistance level of protozoan cysts, zygospores, some viruses.
T/F? In general, enveloped viruses are more resistant than naked viruses.
False. Among the most resistant viruses are the hep B virus and poiliovirus.
These are traditionally considered the most resistant microbial entities.
bacterial endospores, destroyed through sterilization
Sterilants can be classified as sterilizing agents because of their ability to do what?
The growth of microorganisms in the blood and other tissues.
Term that refers to any practice that prevents the entry of infectious agents into sterile tissues thus preventing infection.
Chemical agents that are applied directly to exposed body surfaces, wounds, and surgical incisions to destroy or inhibit vegetative pathogens
A chemical that destroys bacteria except for those in the endospore stage.
Chemical that can kill fungal spores, hyphae, and yeasts.
Chemical known to inactivate viruses, especially on living tissue.
An agent capable of destroying bacterial endospores. Can also be a sterilant.
Prefix that means to "stand still", denotes a condition in which microbes are temporarily prevented from multiplying but are not killed.
stasis or static
A compound such as soap or detergent.
Air sanitization reduces airborne microbes in hospital rooms, vet clinics, and labs through the use of these.
T/F? Sanitation is often preferable to sterilization.
Process of reducing the numbers of microbes on the human skin by scrubbing the skin or immersing it in chemicals, or both, emulsifying the oils that lie on the outer cutaneous layer and mechanically removing the potential pathogens on the outer layers of the skin.
The most practical way to determine the death of a cell.
determine if it can reproduce when exposed to a suitable environment
T/F? Microbial death continues in a logarithmic manner as the time or the concentration of a microbicidal agent is increased and the younger cells tend to die more quickly.
True, younger cells are more metabolically active.
T/F? A higher number of microorganisms requires more time to destroy.
UV radiation is most effective at how many nm?
T/F? The presence of saliva, blood, or feces will not inhibit the actions of disinfectants.
False. The presence of solvents, interfering organic matter, and inhibitors can inhibit the actions of disinfectants and even heat
Four general categories of the cellular targets of physical and chemical agents.
cellular synthetic processes (DNA, RNA)
Detergents and alcohol can disrupt this part of the cell, especially in gram-neg bacteria.
These detergents work as microbicidal agents lower the surface tension of cell membranes. They are polar molecules that physically bind to the lipid layer and penetrate the internal hydrophobic region of membranes.
This antibiotic binds to the ribosomes of bacteria in a way that stops peptide bonds from forming.
Occurs when the bonds that maintain the secondary and tertiary structure of a protein are broken.
Two ways a protein can be denatured through coagulation.
The temperature range of moist heat when used in practice.
60 - 135 C
The temperature range used when using dry heat.
160 - several thousand C
T/F? Moist heat operates at lower temperatures and shorter exposure times to achieve the same effectiveness as dry heat.
The most microbicidal effect of moist heat is this.
coagulation and denaturation of proteins
Dry heat not only denatures a protein but it also does this to a cell.
T/F? Dry heat decreases the stability of some protein conformations.
False. Lack of water increases the stability of some protein conformations, necessitating the use of higher temps. At very high temp, cells are oxidized = ash
Term defined as the shortest length of time required to kill all test microbes at a specific temp.
thermal death time (TDT)
Defined as the lowest temp required to kill all microbes in a sample in 10 minutes
thermal death point (TDP)
Four ways that moist heat is employed to control microbes
steam under pressure
The most efficient pressure-temp combination for achieving sterilization is how many psi at what temp?
Technique that requires a chamber to hold materials and a reservoir for boiling water. Items are exposed to free-flowing steam for 30 to 60 min.
tyndallization or intermittent sterilization
T/F? Tyndallization does not reliably kill spores in a single exposure.
True. After one treatment, items are incubated for 23 - 24 hours to allow for germination before being treated again. Repeat for 3 days in a row.
Technique in which heat is applied to liquids to kill potential agents of infection and spoilage while retaining the liquid's flavor and food value.
Term used to describe the dehydration of vegetative cells directly exposed to normal room air.
A common method of preserving microorganisms and other cells in a viable state for many years that involves a combination of freezing and drying. Cultures are frozen instantaneously then exposed to a vacuum that rapidly removes water
Energy emitted from atomic activities and dispersed at high velocity through matter or space.
Types of radiation that are suitable for microbial control. (3)
Actual physical effect of radiation.
Type of radiation that leads to the formation of abnormal bonds within molecules such as DNA = source of mutations.