Ch. 12 Flashcards
Completely free of all life forms including endospores and virus particles
Sterile
What are 4 possible outcomes of microbial control outside the body?
Sterilization, disinfection, antisepsis, decontamination
The destruction of all microbial life
Sterilization
The destruction of pathogenic nonsporulating microbes or their toxins on inanimate surfaces
Disinfection
The same as disinfection, but on a living surface
Antisepsis
The mechanical removal or neutralization of infectious microbes from a site; Also called sanitization
Decontamination
The growth of microorganisms in blood and other tissue
Sepsis
Any practice that prevents the entry of infectious agents into sterile tissues and prevents infection
Asepsis
Sterile methods that exclude all microbes
Aseptic techniques
Application of chemical agents to exposed body surfaces and surgical incisions to destroy or inhibit vegetative pathogens
Antisepsis
Chemical agents that are exposed to body surfaces and surgical incisions to destroy or inhibit vegetative pathogens
Antiseptics
Chemical agents that kill microorganisms
Germicide and microbicide
A chemical that destroys bacteria except for those in the endospore stage
Bactericide
Kills fungal spores, hyphae, and yeasts
Fungicide
Inactivates viruses, especially on living tissue
Virucide
Capable of killing endospores
Sporicide
Prevent the growth of bacteria on tissues or objects in the environment
Bacteristatic agents
Inhibit fungal growth
Fungistatic chemicals
Chemicals used to control microorganisms in the body (antiseptics and drugs)
Microbiostatic agents
What is microbial death? Why is it harder to detect?
Death of microscopic organisms. It is harder to detect because there are no vital signs. Lethal agents do not alter the appearance of microbial cells. Loss of movement cannot be used to indicate death. Special qualifications are needed to define microbial death.
Name some factors that affect microbial death rate
Number of microorganisms. Nature of the microbes in the population. Type of microbial growth. Temperature and pH of the environment. Concentration of the agent. Mode of action of the agent. Presence of solvents, interfering organic matter, and inhibitors.
How do antimicrobial agents work?
They can be physical and chemical agents. They cellularly target the cell wall, the cell membrane, proteins, and DNA/RNA (cellular synthetic processes)
What is the affect of antimicrobial agents on the cell wall?
Can cause damage to the cell wall (BLOCKING cell wall synthesis, DIGESTING the cell wall, BREAKING DOWN surface of cell wall)
What happens to a cell with a damaged cell wall (damaged from agents on the cell wall)
A cell with a damaged cell wall is fragile and becomes lysed easily. Also, detergents and alcohols disrupt the cell wall.
Microbial cells depend on an orderly and continuous supply of proteins. What does this mean?
This means that substances that inhibit ribosomes will also inhibit protein synthesis
Nucleic acids are necessary for the continued functioning of microbes. What does this mean?
An agent that impedes the transcription of DNA replication or DNA transcription or changes the genetic code is antimicrobial
What is a native state?
The normal three dimensional configuration of a protein that allows proper function
Breaking the bonds that maintain the second and tertiary structure and disrupting proteins, making them nonfunctional
Denature
Irreversible solidification of an egg white when boiled
Moist heat
What is the most widely used method of microbial control? What are other methods?
Heat; radiation, filtration, ultrasonic waves, cold
What is an autoclave?
Sterilization chamber. Allows steam under pressure to sterilize materials. Most common temp/pressure combo is 121 degrees C and 15psi
What is pasteurization?
Heat treatment of perishable fluids such as milk,merit juices, or wine to destroy heat-sensitive vegetative cells, followed by rapid chilling to inhibit growth of survivors and germination of spores. It prevents infection and spoilage.
Explain moist heat verses dry heat
Moist heat operates at lower temp and shorter exposure than dry. Dry heat oxidizes cells at high temps, burning them to ashes.
What does desiccation mean?
To preserve by drying. Dehydration of vegetative cells directly exposed to normal room air. Can kill some delicate pathogens and preserve others. Can also preserve foods like fruit, meat.
A method for preserving microorganisms and other substances by freezing and then drying them directly from the frozen state
Lyophilization
Energy emitted from atomic activities and dispersed at high velocity through matter or space
Radiation
What are three types of radiation suitable for microbial control?
Gamma rays
X rays
Ultraviolet radiation
What is the difference between ionizing and nonionizing radiation?
Ionizing: causes the most damage to proteins; used for materials sensitive to heat or chemicals
Nonionizing: excites atoms; UV rays
Bombardment of microbes with radiation
Irradiation
Solutions containing pure water as the solvent
Aqueous solutions
Antimicrobial chemicals dissolved in pure alcohol or water-alcohol mixtures
Tinctures
What are iodophors?
Disinfectants containing iodine. If the right concentrations and exposure times are used, all classes of organisms are killed by iodine. Not adversely affected by organic matter.
What types of alcohol are appropriate for microbial control?
Ethyl and isopropyl
Are alcohols more effective against enveloped viruses or non-enveloped viruses?
Enveloped
Do alcohols destroy endospores?
No but they destroy vegetative microbial forms
What has similar effects as H2O2 (hydrogen peroxide)?
Ozone (O3)
Pertains to a molecule containing both polar (water-soluble) and nonpolar (not water soluble) portions in its structure
Amphipatic
A chemical having antimicrobial activity in minuscule amounts
Oligodynamic action
Sterilizes and disinfects plastic and delicate hospital instruments
Ethylene oxide
Used for water treatment; used to disinfect congress after the anthrax attacks in 2001
Chlorine dioxide
Less toxic and safer than ETO (ethylene oxide) for sterilization of foods
Propylene oxide
An effective method to remove microbes from air and liquids
Filtration
What are some criteria for disinfectant selection?
Fast-acting, easy to prepare, stable, non-toxic, stable around organics (because many disinfectants are deactivated by organic matter),
How can you evaluate effectiveness of antibiotics?
Filter paper method. Put antibiotic disc on plate pushed into agar region of bacterial growth and see if it kills it
What microbes have the highest resistance?
Prions, bacterial endospores
What microbes have moderate resistance?
Pseudomonas sp; mycobacterium tuberculosis; staphylococcus aureus; protozoan cysts
What microbes are least resistant?
Most bacterial vegetative cells; fungal spores and hyphae, yeast; enveloped viruses; protozoan trophozoites
