Physical and Chemical Methods of Microbial Growth Control (Chapter 9) Flashcards
Sterilization is… ;
used on inanimate objects or live tissues?
The process that destroys or removes all viable microbes including endoscopes and viruses ;
inanimate objects
What does disinfection mean?; used on inanimate objects or live tissues?
Physical process or chemical agent to destroy vegetative pathogens ;
inanimate
Decontamination/ Sanitization is… ; used on inanimate objects or live tissues?
Cleansing technique that mechanically removes microbes and debris ;
inanimate
Antisepsis/Degermation does what? ; used on inanimate objects or live tissues?
Reduces the number of microbes on the human skin ;
living tissue
What is the most resistant type of microbe?
Cysts, theyre like the eukaryotic version of endospores
Whats the standard in terms of cleansing?
If you take out bacterial endospores, you can pretty much take out anything else
Whats the least resistant microbes?
enveloped viruses
Sterilization and disinfection are _______
processes
What are the 5 agents used in process?
- Bactericide
- Fungicide
- Virucide
- Sporicide, 5.Germicide/microbiocide
-ide (killing)
What is sepsis? asepsis?
the growth of microorganisms in the blood and other tissues (infection)
Asepsis- (without infection)
any practice that prevents the entry of infectious agents into sterile tissues
What is an antiseptic?
antiseptics are applied to wounds to destroy or inhibit the growth of pathogens in wounds
What does stasis and static mean?
“to stand still” prevent the growth of
What are the 3 “-statics?”
- Bacteristatic
- Fungistatic
- Microbistatic
What are the 3 devices that need to be cleaned? describe them and give an example
Critical medical devices - expected to come in contact with sterile tissues
- Must be sterilized
ex: syringe needle or artificial hip.
Semicritical devices - come into contact with mucosal membranes (open mouth, eyes)
- high level disinfection/ preferably sterilized
ex: endoscope
Noncritical devices - do not touch the patient or only touch intact skin
- low level disinfection unless contaminated
ex: blood pressure cuffs or crutches
What are the 4 methods of microbial control?
- sterilization
- disinfection
- antisepsis (degermation)
- decontamination (sanitization)
What is microbial death?
The permanent termination of organisms vital processes
- permanent loss of reproductive capabilities
What 5 factors affect the action of antimicrobial agents?
- The number of microbes
- higher load of contaminants takes longer to destroy. - The nature of the microorganisms in the population.
- target population is a mixture of bacteria, fungi, spores and viruses - Temperature and pH of the environment.
- can affect the mechanism of action of the agent used - The concentration (dose, intensity) of the agent
- most disinfectants are more active at higher concentrations - The mode of action of the agent
- How does it kill or inhibit the microbes> - The presence of solvents, interfering organic matter and inhibitors
- saliva, blood and feces inhibit actions of disinfectants
What are the 4 cellular targets of physical and chemical agents?
- Cell wall
- Cytoplasmic membrane
- Cellular synthetic processes (DNA, RNA)
- Proteins
What agents are used for the cell wall?
Chemicals, detergents, alcohols
What agents are used for the cytoplasmic membrane?
Detergents and alcohol
What agents are used for cellular synthesis?
Formaldehyde, radiation and ethylene oxide
What agents are used for proteins?
Moist heat, alcohol, phenolics
What are examples of moist heat and the common temperature?
a method of physical control
Moist heat - hot water, boiling water or steam between 60C - 135 C
What is dry heat?
a method of physical control
Dry heat- hot hair or an open flame which ranges from 160C - several thousand degrees C
What is the difference between moist and dry heat in terms of methods
Moist- Operates at lower temperatures and shorter exposure times to achieve the same effectiveness as dry heat
Dry heat - dehydrates the cell, denatures the protein , can oxidate a cell causes it to burn to ashes
What are examples of moist heat?
boiling water , pasteurization, steam under pressure (autoclaving)
What are examples of dry heat?
Incineration, hot air oven
What are the affects of the cold?
To slow the growth of cultures, can preserve cultures (temp -70C to - 135C)
Tell me about non-ionizing radiation.
Its most lethal from 240 to 280 nm.
In order for it to DISINFECT properly, it must be directly exposed to it for full effect.
Tell my about ionizing radiation
Highly effective way for STERILIZING materials that are sensitive to heat or chemicals
Devices that use it are
- gamma-ray machines containing radioactive cobalt
- X ray machines similar to those used in medical diagnosis
- cathoderay machines
Items are placed in these machines for a short item with a carefully chosen dosage
What is filtration?
Effective method to remove microbes from air and liquids.
Fluid is strained through a filter with openings large enough for the fluid to pass through.
Pores can prevent viruses or large proteins from passing
Give examples of osmotic pressure.
Adding large amounts of salt or sugar to foods to create an hypertonic environment, drys out the bacteria (plasmolysis( and helps preserve food
What are the three germicides and their meaning?
High-level germicide kill endospores (sterilization)
Intermediate - level (kill fungal but not bacterial, spores, resistant pathogens or viruses)
Low-level- eliminate only vegetative bacteria, fungal cells and some viruses
What is the difference between aqueous and tinctures?
Aqueous- chemicals dissolved in pure water as the solvent
Tinctures- Chemicals dissolved in pure alcohol or alcohol - water mixtures
Glutaraldehyde affects what type of macromolecules?
Proteins ; it disrupts the activity of enzymes and other proteins within the cell
what four things are Soaps and quats commonly used for?
- Sanitization of food preparation equipment
- Disinfection of restrooms
- Skin cleansing
- Sanitization of the home
Phenolics typically kill microbes by ______.
disrupting cell walls and membranes and in lower concentrations, they inactivate certain critical enzyme systems(denaturing metabolic enzymes)
Which chemical is valuable for sterilization of heat-sensitive objects such as plastics, surgical and diagnostic appliances, and spices, but is more toxic than other available related gases?
- propylene
- ethylene oxide
- chlorine
- formaldehyde
ethylene oxide
Which of the following heavy metals are still used in germicidal preparations?
- copper
- arsenic
- gold
- silver
- zinc
- mercury
silver & mercury
Iodine compounds typically kill microbes by denaturing _____
enzymes
Which two alcohols are effective in microbial control?
- isopropyl
- methyl
- ethyl
- butyl
isopropyl & ethyl
True or false: Soaps and detergents are sufficient on their own for home cleaning, and additional antimicrobial agents are likely to lead to resistance in the microbes.
True
What is a common use for chlorhexidine solutions?
- sterilization
- antisepsis
- disinfection
- filtration
antisepsis
it is commonly used as an obstetrics antiseptic
Chlorine compounds typically kill microbes by ______.
denaturing metabolic enzymes
Temperature and radiation are two _______ methods used to control microbes.
physical
An example of using dry heat to sterilize materials is the _____of loops and needles in the laboratory.
flaming
Desiccation can preserve foods by reducing the availability of ____ to microbes for their metabolism.
water
A technique in which heat is applied to liquids to kill potential agents of infection and spoilage is ___
pasteurization
An effective method of controlling microbes in food products is ___
ionizing
Ultraviolet radiation affects the _____ of cells.
DNA
Which of the following are effects of ionizing radiation on food products?
Changes in texture of some foods
Small decreases in thiamine
Killing of bacterial pathogens
Filtration has been used in what?
Decontamination of air
Decontamination of milk products
Water purification
Sterilization of medical products
