Chapter 9 Flashcards
What is Sterilization?
Removal or destruction of all microbes, including viruses and endospores.
How does phenolics stop microbial growth, what is it level of activity, and name some uses.
Denatures protein and disrupts cell membranes
Intermediate to low level
Disinfectants and antispetics
What are Antiseptics?
chemicals used in antisepsis or removal of pathogens from skin or living tissue.
What does Boiling kill?
vegetative cells of bacteria and fungi, the trophozoites of protozoa, and most viruses within 10 minutes. (Pg. 268)
Why is moist heat in general more effective, or more efficient than dry heat?
Moist heat is more effective in microbial control than dry heat because water is a better conductor of heat than hair.
Describe the Use Dilution test for evaluating disinfectants
. Three metal cylinders are dipped into broths and dried before being immersed into the disinfectants.
After 10 minutes each is then put into a medium and evaluated two days later.
Each agent is measured againist each other at different dilutions
The winner is the one that prevents growth at the large dilution.
What is Sanitization?
the process of disinfecting places and utensils used by the public to reduce the number of pathogens to accepted public health standards.
What is dry heat mostly used for? With what temperatures and how long?
For dry powders or corrosive metals.171C for an hour or 160C for 2 hours for sterilization.
How does applying pressure to boiling water succeeds in achieving sterilization?
the reason that applying pressure succeeds in achieving sterilization is that the temp. at which water boils (and steam is formed) increases as pressure increases.
What is Microbial Death?
permanent loss of reproductive ability under ideal conditions.
What type of bacteria survive after pasteurization?
Thermoduric and thermophillic—heat tolerant and heat loving—prokaryotes survive pasteurization, but do not cause spoilage over a short period of time if properly refrigerated and such prokaryotes are generally not pathogenic. (Pg. 270)
What organisms do survive after desiccation?
Most molds can grow on dried raisins and apricots, which have as little as 16% water content. (Pg. 270-271)
What can withstand up to 20 hours of boiling:
Bacterial endospores can withstand boiling for more than 20 hours, which is why boiling is not recommended when true sterilization is required.
Boiling is effective for?
sanitizing restaurant tableware or disinfecting baby bottles.
How does phenol stop microbial growth, what is it level of activity, and name some uses.
Denatures proteins, and disrupts cell membrane
Intermediate to low
Orginally used for surgical antiseptic
What is ultrahigh-temperature sterilization?
*involves flash heating milk or other liquids to rid them of all living organisms.
* The process involves passing the liquid through superheated steam at 140C for 1-3 secods and then cooling it rapidly.
Drying (desiccation) inhibits the growth of what specific bacteria?
Inhibits the growth of most pathogens, including the bacteria that causes syphilis, gonorrhea, and the more common forms of bacterial pneumonia and diarrhea.
What is Aseptic?
Describes an environment or procedure that is free of contamination by pathogens.
What is Desiccation?
Inhibition of microbial growth by drying because metabolism requires liquid water.
What are Disinfectants?
chemicals or methods including UV light, heat, and chemicals such as alcohol used in disinfection of inanimate objects.
Filtration can be used to sterilize….
sterilize such heat-sensitive materials as ophthalmic solutions, antibiotics, vaccines, liquid vitamins, enzymes and culture media.
Describe the Kelsey-Sykes test for evaluating disinfectants.
Suspension of bacteria is added to dilutions of disinfectant
At timed intervals a sample is added to growth medium + disinfectant deactivator
After incubation no growth indicates the agent to be effective.
What does filtration trap?
traps large microbes larger that the pore size, allowing smaller to pass through.
What is Disinfection?
The use of physical or chemical agents to inhibit or destroy microorganisms, especially pathogens. Not sterilization.
What is not a means of sterilization?
Refrigeration and freezing
______ Occurs at temperatures between (0C - 7C) and ________ occurs (below 0C)
Refrigeration; Freezing
What was the problem with filters in the 1800s?
Filters were able to trap cells, but their pores were too large to trap the pathogens of such diseases as rabies and measles. Now there’s filters with pores small enough to trap even viruses..
Hot air is an effective sterilizing agent because?
Because it denatures proteins and fosters the oxidation of metabolic and structural chemicals.
Drying either in the sun or by dehydration does what?
removes water necessary for microbial metabolism
An autoclave consists of?
consists of a pressure chamber, pipes to introduce and evacuate steam, valves to remove air and control pressure, and pressure and temperature gauges to monitor the procedure. (Pg. 268)
In order to sterilize, dry heat requires?
Higher temperatures for longer times than moist heat because dry heat penetrates more slowly.
What is an autoclave?
Device that uses steam heat under pressure to sterilize chemicals and objects that can tolerate moist heat.
The first method we consider for controlling microbes using moist heat is:
boiling
How is osmotic pressure used to control microbes?
High salt or sugar concentratons (hypertonic solution) inhibit microbial growth by drawing away water need for cellular metabolism.
What is lyophilization?
A technique combining freezing and drying, to preserve microbes and other cells for many years(Pg. 271)
What is Degerming?
the removal of microbes from a surface by scrubbing. Hand washing, or prepping patient for surgery.
Moist heat is commonly used for? How does it kill bacteria?
It is used to disinfect, sanitize, sterilize, and pasteurize.
It kills bacteria by denuturing proteins
How does nonionizing radiation (UV light) work to control microbial growth?
Irradiation with 260nm wavelegnth radation
Forms thymine dimers that inhibit DNa transcription and replication
Used for disinfection of surfaces and transparent fluids and gases
What is the process of lyophilization?
In this process, scientists instantly freeze a culture in liquid nitrogen or frozen carbon dioxide (dry ice), then subject it to a vacuum that removes frozen water and goes through sublimation, in which the water is transformed directly from a solid to a gas.
What is the ultimate means of sterilization?
Incineration
Describe the Phenol coefficient test for evaluating disinfectants
Compares the chemical to phenol under standardized conditions.
-Historical measurement, also outdated.
What is Pasteurization?
Use of heat to kill pathogens and reduce the number of spoilage organisms in food and beverages.
What is Ionizing radiation and how is it used to control microbial growth?
Because their energy ejects electrons from the atoms creating ions
Destroys hydrogen bonding and denatures DNA
Second to hours of exposure
Used for lab equipment and food
Describe the In-Use test for evaluating disinfectants
Swabs are take from real world setting before and after the use of the agent.
They are cultured on a media and exaimed for growth in each specific situation.
For substances such as powders and oils that cannot be sterilized by boiling or with steam, or for materials that can be damaged by repeated exposure to steam, sterilization is achieved with?
Dry heat (Pg. 270)
What are factors to consider when selecting a microbial control method?
Site: living tissue vs fragile objects; risk of infection
Susceptiblity: most resistant to least.
Disinfectectant potency: High level (endospores), intermediate level (fungal spores,protozoan cyst,viruses), and low (bacteria, fungi, protozoa)
Environmental conditions: Tempature, pH, cleaning debris.
What is filtration?
The passage of a fluid (either liquid or a gas) through a sieve designed to trap particles—-in this case cells or viruses—-and separate them from the fluid.
How do alchols stop microbial growth, what is it level of activity, and name some uses.
They denature proteins and disrupt cell membranes
Level of activity: Intermediate
Use include disinfectants, antieptics, and as a solvent in tinctures.
How do halogens (iodine, chlorine, bromine and fluroine) stop microbial growth, what is the level of activity, and name some uses.
They are presumed to denature proteins
Level lf activity: Intermediate
Disinfectants, antiseptics, and water purification
How do Oxidizing agents (peroxides, ozone, and peracetic acid) stop microbial growth, what is the level of activity, and name some uses.
Denatures proteins by oxidation
Level of Activity: High
Disinfectants, antiseptics for deep wounds, water purification, and sterilization of food-processing and medical equipment.
How does surfactants (soaps and detergents) stop microbial growth, what is it level of activity, and name some uses.
Surfactants decrease surface tension of water and disrupt cell membrane
Low of Activity: Low
Soaps, degerming; detergents: antiseptic
How does heavy metals stop microbial growth, what is the level of activity, and name some uses.
Heavy metals denature proteins
Level of Activity: Low
Silver nitrate cream, burn creams, and catheters, wter reserviors, pool, and aquariums
How does aldehydes (glutaraldehyde and formaldehyde) stop microbial growth, what is the level of activity, and name some uses.
Denature Proteins
Level of Activity: High
Disinfectant and embalming fluid
How does gaseous agents (ethylene oxide, proplyene oxide, and beta-propiolactone) stop microbial growth, what is the level of activity, and name some uses.
They Denature Protein
Level of activity: High
Sterilization of heat- and water sensitive objects
How do enzymes stop microbial growth, what is there level of activity and name of of there uses.
Enzymes denature protein
High against target substrate
Removal of prions on medical instruments
How do antimicrobials stop microbial growth, what is their level of activity, and name some of their uses.
Act aginist: cell walls, cell membrane, protein synthesis, and DNA transcription and replication
Level of activity: Intermediate to low
Disinfectants and treatment of infectious diseases.
Please define antisepsis.
The use of antiseptics to eliminate microogranisms that cause disease.
Why are bacterial endospores of Bacillus and Clostridium so resistant to antimicrobials?
Because they can survive enviromental extermes of temperature and acidity and withstand many chemical disinfectants.
Why are species of myobacterium such as M. tuberculosis highly resistant to antimicrobial methods?
They contain a large amount of wxy lipids. This wax allow these bacteria to survive drying and protects them from most water-based chemicals; therefore strong head or disinfectants are used.
Why are cysts of protozoa so resistant to antimicrobial agents?
Because the cyst’s wall prevents entry of most disinfectant, protects againist drying, and shields against radiation and heat.
Why are Prions the most resistant to antimicrobial agents?
Because prions are a protein that cause degenerative brain diseases and our body/microbial agents can not differentiate them from our own proteins.
