Chapter 11 "Control of Microbes"

The easiest microbial forms to kill or inhibit are ______.

vegetative bacteria and fungi

Removal of moisture by dehydration is called ______.

desiccation

In lab, inoculating loops are sterilized using ______.

incineration

The minimum sterilizing conditions in a steam autoclave are _______.

121°C at 15 psi for 15 minutes

Which of the following microbial forms has the highest resistance to physical and chemical controls?

Bacterial endospores

The use of chemical agents directly on exposed body surfaces to destroy or inhibit vegetative pathogens is _______.

antisepsis

Microbial death occurs when there is _______.

no reproduction

Ionizing radiation is more effective than nonionizing radiation in killing or inactivating microbes.

true

Which of the following represents the use of osmotic pressure as a microbial control method?

Salting of meat

Pasteurization _______.

reduces the number of vegetative forms

Chlorine and ethylene oxide are sterilizing gases.

true

All microbicidal agents are sterilants.

false

Alcohols are more effective at inactivating enveloped viruses than naked viruses.

true

_____ heat is more rapidly effective and efficient compared to _____ heat.

Moist; dry

A microorganism that is not motile and has stopped metabolizing is considered dead.

false

Sterilization is achieved by _______.

steam autoclave

Physical agents for controlling microbial growth include all of the following

ultraviolet radiation

pasteurization

boiling water

Dry heat _______.

is less efficient than moist heat

_____ radiation excites atoms to a higher energy state within molecules such as DNA, which leads to the formation of pyrimidine dimers.

Ultraviolet

Disinfection of beverages such as apple juice, milk, and wine is optimally achieved by ______.

pasteurization

_____ is a control method that removes microorganisms rather than inhibiting or killing them.

Filtration

Which is correct regarding the rate of microbial death?

Cells in a culture die at a constant rate.

Each of the following is a target of antimicrobial agents

ribosomes

cell membranes

cellular proteins

cell walls

Exposing a microbe to a ________ environment (increased osmotic pressure) draws water out of the cell, causing plasmolysis.

hypertonic

Some microbial control agents are able to _____ cell proteins by breaking bonds that maintain the native state, the three-dimensional configuration of the proteins.

denature

Bacteriostatic agents kill bacterial cells.

false

Electrons are ejected from atoms in cells when organisms are exposed to ______.

gamma rays and X rays

Which of the following methods of microbial control is mismatched?

Causing irreversible breaks in DNA strands with X-rays - osmotic pressure

Surfactants work by _______.

disrupting membrane integrity

When a control agent targets the metabolic processes of microbial cells, active younger cells typically die more rapidly than older cells.

true

The method of removing vegetative microbial life forms and debris to reduce contamination to safe levels is termed ______.

sanitization

The process that destroys or removes all microorganisms and microbial forms, including bacterial endospores, on inanimate objects is ______.

sterilization

The alcohol wipe used on a patient's skin before an injection is an example of ______.

antisepsis

Antimicrobial agents can target the cell wall by _______.

digesting it,denaturing proteins, blocking its synthesis

Placing organisms at 4oC is ______.

bacteriostatic

HEPA filters are used to remove microbes from _______.

air

Which of the following factors will influence the action of microbial agents?

Temperature and pH, The type of microorganisms present, The number of microorganisms, Mode and dosage of the agent

The use of a physical or chemical process to destroy vegetative pathogens on inanimate objects is ______.

disinfection

Which of the following is not used as an antiseptic?

Aqueous glutaraldehyde

Which of the following types of control agents would be used to achieve sterility?

Sporicide

Ethylene oxide is ______.

sporicidal

The removal of all life forms from inanimate objects is termed ______.

sterilization

Prions require more extensive methods of sterilization than are needed for bacterial endospores.

true

Which antimicrobial method does not sterilize?

Pasteurization

Which method is most appropriate to sterilize heat- and moisture-sensitive medical equipment (e.g., plastic catheters)?

Ethylene oxide gas sterilization

________________________ differs from all other types of control methods because it refers to processes that reduce the number of microorganisms to safe levels as determined by public health standards but may or may not kill microbes.

Hint: sterilization, antisepsis, degerming, pasteurization, disinfection, or decontamination.

decontamination

Although bacterial endospores can be very difficult to control, ________________________ are the hardest pathogenic agents to eliminate.

Hint: cysts, trophozoites, prions, microspores, viruses, or amoebas.

prions

Which type of heat (moist or dry) allows the elimination of microbes at lower temperatures and in a shorter time, and why? To receive full credit, you must provide an explanation.

Hint: Consider which method transfers heat more efficiently and penetrates microorganisms more effectively, leading to faster microbial destruction.

Moist heat kills microbes faster and at lower temperatures because it transfers heat more efficiently and penetrates cells better, causing rapid protein denaturation. Dry heat is less efficient, so it requires higher temperatures and longer exposure times.

Non-ionizing radiation, such as UV radiation, can be useful in the control of microbes in water supplies by causing the formation of _________________________ (purine or pyrimidine) dimers within their DNA that often leads to their death.

pyrimidine

When faced with a solution that cannot be sterilized with heat or chemicals, it is still possible to achieve sterility through the process of _________________________ by using a membrane to block the passage of microbes and a vacuum to pull the fluid.

Hint: autoclaving, radiation, pasteurization, filtration, centrifugation, or evaporation.

filtration

Which of the following bacterial infections might cause a doctor to place silver nitrate solutions into the eyes of infants following his/her birth?

gonorrhea

The refrigerator is one of the best microbicidal tools available for most people to use within their homes.

False

A sterilizing gas that can be used with a chemiclave to achieve sterility of large, porous items (such as hospital bedding) is:

Ethylene oxide

Which pair correctly completes the statement: "_____ kills most microbial organisms (not endospores) on benches and other hard surfaces, while _____ kills them on living tissues"?

disinfection; antisepsis