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