Microbiology Chapter 9: Physical and Chemical Control of Microbes
True or False: The autoclave is not a good choice to sterilize plastic Petri dishes before disposal because they are heat sensitive.
False (because they are heading for disposal, the heat sensitivity is not important)
____ rays and X rays are types of ionizing radiation.
Gamma
____ are chemical agents that kill non-endospore forming pathogens.
Germicides
The dosage of radiation is measured in ____.
Grays
Which is the most common physical agent used to control microbes?
Heat
Which level of chemical decontamination by a germicide can result in sterilization?
High level
____ are complexes of iodine and alcohol.
Idophors
Bactericides ____ bacteria.
Kill
__ is a method for preserving microorganisms (and other substances) by freezing and then drying them directly from the frozen state.
Lyophilization
____ involves the permanent termination of a particular organism's vital processes and special qualifications are often needed to define and delineated this phenomenon in microbes.
Microbial death
Glutaraldehyde affects what type of macromolecules?
Proteins
____ is electromagnetic waves or rays, such as those of light given off from an energy source.
Radiation
Prions are:
Resistant to heat and chemicals
What cellular structure is involved in translation?
Ribosome
What is the thermal death time?
Shortest length of time required to kill all test microbes at a specified temperature.
Antiseptics are used to destroy vegetative bacterial on?
Skin
What type of agent specifically destroys bacterial endospores?
Sporicide
An object is ____ if it is free of all viable microorganisms including viruses.
Sterile
The goal of ____ is to remove or destroy all viable microorganisms including viruses.
Sterilization
____ is the destruction of all microbial life, whereas ____ destroys most microbial life, thus reducing contamination on inanimate surfaces.
Sterilization; disinfection
What is the thermal death time?
The shortest length of time required to kill all test microbes at a specified temperature.
True or False: The two primary iodine preparations are free iodine and iodophors.
True
____ radiation is a type of nonionizing radiation.
Ultraviolet
All of the following describe the typical microbial population targeted by antimicrobial drugs EXCEPT: a. Microbes with variable pathogenic capabilities b. Complex mixtures of types of microbes c. Uniform populations of like microbes d. Microbes with variable resistance
Uniform populations of like microbes
Disinfectants can be toxic or harmful to ____ tissues.
animal
Chlorhexidine solutions are commonly used for
antisepsis of skin
What microbial agent is the most resistant to physical and chemical control methods?
bacterial endospores
Which type of agent will kill bacteria?
bactericidal
Which is the term used for any process or agent that inhibits bacterial growth?
bacteriostatic
Iodine compounds ____ kill endospores.
can
gaseous and liquid ___ compounds are mostly used for large-scale water disinfection.
chlorine
Iodine compounds are commonly used in the ____ setting.
clinical
The lowest temperature that achieves sterilization in a given quantity of broth culture upon a 10-minute exposure is referred to as the thermal ____ ____.
death point
Iodine compounds typically kill microbes by
denaturing proteins
The goal of regular pasteurization methods is the _____ of the liquid.
disinfection
____ is the use of a physical process or chemical to destroy vegetative pathogens but not bacterial endospores, usually on inanimate surfaces.
disinfection
Cationic detergents typically work by
disrupting the cell membrane
High concentrations of alcohols usually affect microbes by
dissolving membrane lipids.
Flaming the inoculating loop in the laboratory is an example of ____ heat sterilization.
dry
An object can be:
either sterile or not sterile
The straining of a fluid or air through a membrane to trap microorganisms is known as ____.
filtration
The __ method od pasteurization exposes liquids to higher temperature for a very short time, whereas the __ method uses lower temperatures for a longer period.
flash; batch
__ is electromagnetic waves or rays, such as those of light given off from an energy source.
fungicide
Sepsis is defined as
growth of microorganisms in the blood or other tissues.
Which of the following is the practical definition of microbial death?
inability to reproduce
A virucides _____ viruses.
inactivates
Ethyl and ____ alcohols are effective in microbial control.
isopropyl
Quaternary ammonium compounds are considered ____-level disinfectants.
low
An agent's effect on cells is known as its ___ of action
mechanism
The cell __ is responsible for preventing the loss of important molecules and stopping the entry of damaging substances.
membrane
Regarding the use of the terms microbicidal and microbistatic, higher temperatures are usually ____, whereas lower temperatures are usually ____.
microbicidal; microbistatic
Cold treatment and desiccation are reliably used for
preventing microbial growth
The synthesis of proteins involves organielles known as ____ in a process called translation.
ribosomes
The main effect of cold treatment is to __ the activity of microbes.
slow
Which compounds are commonly used for sanitation of the home and food preparation areas/utensils?
soaps and quats
Alcohols are not effective against naked viruses and bacterial ____.
spores
An autoclave is a sterilization chamber that allows the use of ____ to sterilize materials.
steam under pressure
A sporicide agent can also be a ____ because it can destroy bacterial endospores and leave an object free of all life.
sterilant
Chemical agents that can destroy all forms of life, including endospores are called _____.
sterilants
A ____ is an agent that disrupts the lipid bilayer of membranes and alters the membrane's permeability.
surfactant
What is desiccation?
the dehydration of microbes for preservation
What is incineration?
the use of dry heat to destroy all microbes
Death of microorganisms is hard to detect because
they have no obvious vital signs
To adequately sterilize using heat, temperature and length of ____ must be considered.
time
Antimicrobial solutions with alcohol or water-alcohol mixtures as the solvent are called ____.
tinctures
Phenol is now limited in its use to
- Animal quarters - Cesspools - Drains
The effect of a germicide is affected by which of the following factors?
- Concentration of germicide - Chemical action of a germicide - Nature of a microbial population - Material being treated - Time of exposure to germicide - Contamination with organic matter
What are the modes of action for chlorhexidine?
- Disrupts cell membranes - Targets proteins
Which items can be sanitized by boiling water prior to safe, acceptable use in humans?
- Drinking Water - Utensils - Bedding & Clothing
What types of items are often sterilized using a dry oven?
- Glassware - Metallic instruments
Which of the following are advances to the use of ionizing radiation for sterilization?
- High penetrating power through most materials - Rapid processing of materials
Match each item commonly found in a health care setting with its level of chemical decontamination.
- High: Urinary catheter - Intermediate: respiratory equipment - Low: electrodes on an EKG machine
Which of the following are examples of degermination?
- Immersing skin in chemicals - surgical handscrub
UV radiation is effective at disinfecting which types of materials?
- Liquids - Solid surfaces - Air
Which of the following are examples of sanitization?
- Scouring a countertop with soap - Doing laundry - Washing utensils
Hydrogen peroxide is commonly used for:
- Skin and wound cleansing - Disinfection of medical equipment - Sterilization of diagnostic instruments
Which of the following compounds is/are typical examples of sanitizers?
- Soap - Detergent
The four general cellular targets of antimicrobial agents are
- The cell membrane - Nucleic acid synthesis - Protein function - The cell wall
Which of the following are examples of antisepsis?
- Using iodine compounds on skin before a surgical incision - Swabbing an open root canal with hydrogen peroxide
Which are examples of using moist heat to sterilize or disinfect materials?
- autoclaving - boiling - pasteurization
Ethylene oxide typically kills microbes by
- blocking DNA replication - disrupting enzyme function
Moist heat occurs in the forms of
- boiling water - steam
Which of the following are some of the desirable qualities in a germicide?
- broad-spectrum action - penetrating ability - rapid action - selective toxicity - solubility in a solvent
Which of these items is considered noncritical for sterilization?
- crutches - stethoscope
Filtration has been used in which of the following?
- decontamination of air - decontamination of milk products - sterilization of medical products - water purification
Alcohols are commonly used for:
- degermation of skin - antiseptic preparation for skin
Phenolics typically kill microbes by
- denaturing metabolic enzymes - disrupting the cell wall - disrupting the cell membrane
If an agent acts on the cell wall, it can
- digest the cell wall - block cell wall synthesis
Which are examples of using dry heat to sterilize materials?
- hot air oven - incineration
Which of the following heavy metals are still used in germicidal preparations?
- mercury - silver
Heavy metal germicides come in which of the following forms?
- ointments - aqueous solutions
Which of the following are not suited for sterilization in an autoclave?
- powders - oils
Although they do have some drawbacks heavy metals are used for
- preservatives - prevention of infection - Controlling microbial growth on objects - skin cleansing
Which of the following substances should be removed from items before decontamination?
- saliva - blood
Sterilization methods are often used
- to prepare instruments for surgery - for inanimate objects
Chlorohexidine can kill/inactivate most
- viruses - bacteria
Aldehydes are organic substances that contain a ____ functional group on a terminal carbon.
-CHO
Which root indicates the ability to kill microorganisms?
-cide
The root -_____ is used to indicate the inhibition of microbial growth.
-stasis
Which root(s) indicated the ability to prevent microbial growth?
-stasis -static
Which root(s) indicates
-stasis -static
Which of these items are considered critical for sterilization? -An artificial hip -Stethoscope -An endoscopy tube -Crutches -A syringe needle
- An artificial hip - A syringe needle
Ultraviolet radiation is most lethal from ____.
240-280nm
What is sterilization?
A process that completely removes or destroys all viable microorganism, including viruses, from an object or habitat.
A chemical agent applied directly to exposed body surfaces (skin and mucous membranes), wounds, and surgical incisions to destroy of inhibit pathogens is a(n) ____.
Antiseptic
____ is a term referring to a procedure of process designed to prevent entry of infectious agents into sterile tissues.
Asepsis
Any process or agent that inhibits bacterial growth is referred to as _____.
Bacteristatic
Ethylene oxide and ____ dioxide are commonly used as gaseous sterilants of disinfectants.
Chlorine
____ is the general term used for the reduction of the microbial load in order to lower the possibility of infection or spoilage.
Decontamination
____ and antisepsis can be accomplished with the same procedure.
Degermation
____ is the physical removal of surface oils, debris, and soil from skin to reduce the microbial load.
Degermation
The disruption of proteins from their native state is known as ____.
Denaturation
Examples of ____ include immersing thermometers in an iodine solution between uses.
Disinfection
UV radiation is usually used for
Disinfection
_____ heat requires longer exposure times and higher temperatures than _____ heat.
Dry; moist