Chapter 11 Flashcards
What is sterilization?
The destruction of all microbial life
What is disinfection?
The destruction of most microbial life, reducing contamination on inanimate surfaces
What is antisepsis/degermination?
The destruction of most microbial life, reducing contamination on living surfaces
What is decontamination/sanitization?
The mechanical removal of most microbes from an animate or inanimate surface
What are the primary targets of microbial control?
Microorganisms capable of causing infection or spoilage
What is the relative resistance of microbes, from most resistant to least resistant?
Prions, bacterial endospores, mycobacterium, protozoan cysts, most gram-negative bacteria, fungi/fungal spores, non-enveloped viruses, most gram-positive bacteria, enveloped viruses
What are the characteristics of bacterial endospore resistance?
- Considered the most resistant microbial entities
- Destruction of endospores is the goal of sterilization
- Any process that kills endospores will also kill less-resistant microbes
What does it mean for a material to be sterile?
The material was subjected to a successful sterilization process
What is sepsis?
The growth of microorganisms in blood and other tissues
What is asepsis?
Any practice that prevents the entry of infectious agents into sterile tissues and prevents infection
What is antisepsis?
The application of antiseptic chemical agents to exposed body surfaces, wounds, and incisions to destroy or inhibit vegetative pathogens
What are germicides and microbicides?
Chemical agents that kill microorganisms (generally)
What are bactericides?
Chemicals that destroy vegetative bacteria (not endospores)
What are fungicides?
Chemicals that kill fungal spores, hyphae, and yeasts
What are virucides?
Chemicals that inactivate viruses, especially on living tissue
What are sporicides?
Chemicals capable of killing endospores
What are bacteristatic agents?
Chemicals that prevent the growth of bacteria on living tissues and inanimate objects
What are fungistatic agents?
Chemicals that inhibit fungal growth
What are microbistatic agents?
Chemicals used to control microorganisms in the body
What is a sanitizer?
A soap or detergent used to sanitize
What are critical medical devices?
Any device expected to come into contact with sterile tissues
What are semi-critical medical devices?
Any device that comes into contact with mucosal membranes
What are non-critical medical devices?
Devices that do not touch the patient or are only expected to touch intact skin
What is the definition of microbial death?
The inability of a microbe to reproduce
What factors affect the microbial death rate?
- Number of microbes
- Nature of microbes in the population
- Type of microbial growth
- Temperature and pH of environment
- Concentration of the agent
- Mode of action of the agent
- Presence of solvents, organic matter, and inhibitors
What are the cellular targets of physical and chemical agents?
- Cell wall
- Cell/cytoplasmic membrane
- Cellular synthetic processes (DNA and RNA)
- Proteins
What are the effects of antimicrobial agents on the cell wall?
Blockage of cell wall synthesis, digestion of cell wall, break down of cell wall surface
What are the properties of cells with damaged cell walls?
Fragile and easily lysed
How do detergents and alcohols affect the cell wall?
They disrupt the cell wall
How do antimicrobial agents affect the cell membrane?
Cause loss of selective permeability, loss of vital molecules, and allow the entry of damaging chemicals
What are surfactants?
Polar molecules with hydrophilic and hydrophobic regions that bind to the lipid layer and penetrate the internal hydrophobic region of membranes
How do surfactants lead to cell damage?
They open up leaky spots that allow damaging chemicals to seep into the cell and important ions to leak out
What affects do antimicrobials have on protein and nucleic acid synthesis?
- Substances that inhibit ribosomes also inhibit protein synthesis
- Agents impede DNA transcription and replication
- Agents change the genetic code of microbes
What is the native state of a protein?
The normal 3D configuration of a protein that allows for normal function
What is denaturation?
The disruption of proteins by breaking the bonds of secondary and tertiary structure, rendering the proteins nonfunctional
What methods are used to denature proteins?
- Moist heat
- Strong organic solvents and phenolics
- Metallic ion binding of the active site
What methods of physical control are applied to microbes?
Heat, radiation, filtration, ultrasonic waves, cold
How can the temperature of steam be regulated?
By adjusting its pressure in a closed container
How does moist heat differ from dry heat?
Moist heat operates at lower temperatures and shorter exposure times
What are the main microbicidal affects of moist heat?
Coagulation and denaturation of proteins
What are the main microbicidal affects of dry heat?
Cell dehydration, cell oxidation
What is the general trend concerning heat temperature and exposure time?
Higher Temperatures = Lower Exposure Times
What is thermal death time?
The shortest length of time required to kill all test microbes at a specified temperature
What is thermal death point?
The lowest temperature required to kill all microbes in a sample in 10 minutes
What are the four main disinfection methods of moist heat?
Boiling water, pasteurization, flash heat, batch heat
What is the sterilization method of moist heat?
Steam under pressure
What are the two main sterilization methods of dry heat?
- Incineration via a flame or incinerator
2. Hot air oven
What effect does cold treatment typically have on microbes?
Slows down the activities of most microbes
What is desiccation?
Dehydration of vegetative cells directly exposed to normal room air
What is lyophilization?
A combination of freezing and drying
What is radiation?
Energy emitted from atomic activities and dispersed at high velocity through matter or space
What forms of radiation are suitable for microbial control?
Gamma rays, X rays, UV radiation
What is irradiation?
Bombardment of microbes with radiation
What is cold sterilization?
Ionizing radiation used as an effective alternative for sterilizing chemicals that are sensitive to heat and/or chemicals
What is ionizing radiation?
Radiation that ejects orbital electrons from an atom, causing ions to form
What is non-ionizing radiation?
Radiation that excites atoms, raising them to a higher energy state and leading to the formation of abnormal bonds within molecules
Which form of radiation is more penetrating?
Ionizing radiation
What are pyrimidine dimers?
Abnormal linkages between adjacent pyrimidines in DNA that interfere with normal replication and transcription and are caused by UV radiation
What is decontamination by filtration?
An effective method for removing microbes from air and liquids that works by straining fluids through a filter with openings that are too small for microbes to pass through
How can osmotic pressure play a role in microbe control?
Adding large amounts of salt or sugar to foods creates a hypertonic environment that causes plasmolysis in bacteria and makes it impossible for them to multiply
What are aqueous solutions?
Solutions containing pure water as the solvent
What are tinctures?
Antimicrobial chemicals dissolved in pure alcohol or water-alcohol mixtures
What are desirable qualities of a germicide?
- Rapid action in low concentrations
- Solubility in water/alcohol with long-term stability
- Broad-spectrum microbicidal action without toxicity to human and animal tissues
- Penetration of inanimate surfaces
- Resistance to becoming inactivated by organic matter
- Noncorrosive and nonstaining
- Sanitizing and deodorizing
- Affordable and readily available
What are high-level germicides?
Germicides that kill endospores, can be used as sterilants, and are able to be used on critical items that are not heat-sterilizable
What are intermediate-level germicides?
Germicides that kill fungal (but not bacterial) spores, resistant pathogens, and viruses, can be used to disinfect semi-critical items
What are low-level germicides?
Germicides that only eliminate vegetative bacterial and fungal cells and some viruses, can be used to clean non-critical materials
What factors affect the microbicidal activity of chemicals?
- Nature of microbes being treated
- Nature of material being treated
- Degree of contamination
- Time of exposure
- Strength and chemical action of germicide
What microbes are killed by chlorine compounds?
Bacteria, endospores, fungi, viruses
Which chlorine compounds are typically used in disinfection and antisepsis?
Hypochlorites and chloramines
What is the application of aqueous iodine?
Topical antiseptic, treatment for burned and infected skin
What is the application of iodine tincture?
Used in skin antisepsis
What is the application of iodine tablets?
Used for disinfecting water
What are iodophors?
Iodine and alcohol complexes used in medical antisepsis
What are phenolics?
Phenol derivatives with a detergent action that destroy vegetative bacteria, fungi, and most viruses
What are cresols?
Phenolic derivatives combined with soap
What are bisphenols?
Aerosol sprays and cleansing soaps
What is triclosan?
A disinfectant and antiseptic chemical once added to many products
what is chlorhexidine?
A phenolic derivative used for hand scrubbing, surgical prep, and other medical uses
Which forms of alcohol are appropriate for microbial control?
Ethyl and Isopropyl
Which microbes can alcohols destroy?
Vegetative microbial forms
Which type of viruses are alcohols more effective against?
Enveloped viruses
What are ethyl and isopropyl alcohol used for?
Skin degerming and disinfection of some medical equipment
What are the germicidal effects of hydrogen peroxide caused by?
Toxic reactive oxygen
What microbes can hydrogen peroxide kill?
Bacteria, viruses, fungi, and endospores at high concentrations
What are the two cleaning categories of hydrogen peroxide?
Antiseptic and disinfectant
When is hydrogen peroxide used as a sterilant?
When sterilizing delicate reusable instruments
What are quats?
Soap disinfectants mixed with cleaning agents to sanitize a variety of objects/surfaces
Why are heavy metal compounds considered oligodynamic?
They are toxic in minute quantities
Compounds of which metals have germicidal significance?
Mercury and silver
What is glutaraldehyde?
A rapid, broad spectrum accepted as a sterilant
What is formaldehyde?
An intermediate- to high-level disinfectant
What is Ortho-phthalaldehyde (OPA)?
A germicide similar to glutaraldehyde that is unable to destroy endospores
What is the use of ethylene oxide?
Chemical sterilization
What is the use of chlorine dioxide?
Treatment of drinking water, wastewater, food-processing equipment, and medical waste
What are the uses of aqueous ammonium oxide?
Detergents, cleansers, deoderizers
What is the use of organic acids?
Food preservation
