Chapter 5

----oxide is an extremely useful gaseous sterilizing agent that destroys all microbes and is often used to sterilize fabric, equipment, and implantable devices.

Ethylene

Dry heat takes a much shorter time to sterilize material than wet heat. True or False

False

The endospores of Pseudomonas make that organism very difficult to kill. true or false

False

True or false: There is a standard antimicrobial procedure available from the Centers for Disease Control and Prevention (CDC) that can be used for all different microorganisms under any condition.

False

_____ is a physical means used for destroying or removing microorganisms.

Filtration

______ is a physical means used for destroying or removing microorganisms.

Filtration

_______ does not actually destroy microbes or inhibit their growth but instead removes them physically from samples.

Filtration

______ is the destruction of microbes by subjecting them to extremes of dry heat, reducing them to ashes.

Incineration

Which of the following are physical ways to remove or destroy microbes?

Incineration Autoclaving Ultraviolet radiation Filtration

______ provides an alternative to heat for sterilization and disinfection, but the process damages some types of plastics.

Irradiation

Select the FALSE statement regarding hydrogen peroxide.

It immediately kills all bacteria when applied to a wound.

Select the FALSE statement regarding hydrogen peroxide.

It is a sterilant for inanimate objects and is quickly inactivated on living tissue. It leaves no toxic residue and is safe on materials such as glass and plastic. It is broken down by catalase into water and oxygen. correct: It is even more effective when used in combination with peracetic acid. It immediately kills all bacteria when applied to a wound.

Select the method that would be used to sterilize a liquid containing vitamin B12 and human growth hormone.

Membrane Filtration

Identify the difference between the use of depth filters and membrane filters in sterilizing fluids.

Membrane filters have smaller pores than depth filters, but depth filters have complex passages that retain microbes while letting the fluid through. Both methods are efficient.

Which four of the following microbial groups are the most resistant to chemical control methods?

Mycobacterium species nonenveloped viruses bacterial endospores protozoan cysts and oocysts

Which of the following use moist heat to destroy microbes?

Pasteurization Pressurized steam Boiling

Controlling microbial growth is important in which of the following scenarios?

Preparing a patient for surgery Caring for an open wound Manufacturing of food products

A common environmental organism that may even grow in certain chemical disinfectants is

Pseudomonas aeruginosa.

Consider the use of low temperature storage for the preservation of food. Which of the following are accurate statements?

Psychrotrophic and some psychrophilic microorganisms can grow at refrigeration temperatures. Refrigeration inhibits the growth of many pathogens and spoilage microorganisms by slowing or stopping critical enzyme reactions.

Which metal compound is used as a disinfectant in burn creams and bandage pads?

Silver

Assuming strict adherence to recommended protocols, which of the following temperature treatments achieves sterilization?

Steam autoclaving

_____ destroy all microbes, including viruses and endospores.

Sterilants

Please select the INCORRECTLY matched pair.

Sterilants - destroy all microbes including endospores and viruses. incorrectly matched:D-value - time to destroy 10% of microbes present. Critical instrument - scalpels and needles. Bacterial endospores - highly resistant. Incineration - burns cells to ashes.

What is one disadvantage of using heat treatment to sterilize plastic items?

The items may melt.

Which is TRUE of HAIs?

They are acquired by susceptible people in the hospital.

True or false: The risk of developing a fatal infection after surgery has substantially decreased since the late 19th century because modern hospitals now have procedures in place to avoid microbial contamination.

True

Which of the following chemical classes destroy microorganisms by forming chemical bonds that cross-link and inactivate proteins and nucleic acids?

aldehydes

A sterile object is free of ______.

all viable microorganisms and viruses

Aldehydes typically kill microbes by ______.

altering nucleic acids altering proteins

It is often difficult to choose which germicide to use because often the most effective options ______.

are not the safest

Silver is used as an antimicrobial in which of the following products?

burn creams bandage pads

How do aqueous solutions of alcohol usually affect microbes?

by damaging lipid membranes by denaturing proteins

Ethylene oxide is a very effective microbial control compound. However, its use is somewhat risky because it is both explosive and---

carcinogenic

Adding sorbic, propionic, and benzoic acid to foods affects ______ of microbes.

cell membrane function

High pressure (130,000 psi) is thought to kill microbes by altering their ______.

cell membranes proteins

antimicrobial chemical

chemical method of control

A surgical scalpel is rated as a ______ instrument because it penetrates skin and mucous membranes and therefore must be sterile.

critical

Ultraviolet radiation at the bactericidal wavelength destroys bacteria by

damaging nucleic acid.

Moist heat primarily destroys microbes by

denaturing their proteins

Radio waves, X-rays, microwaves, UV light and gamma rays are all examples of ______.

electromagnetic radiation

The most highly resistant microbial structure is the bacterial

endospore

------oxide is an extremely useful gaseous sterilizing agent that destroys all microbes and is often used to sterilize fabric, equipment, and implantable devices.

ethylene

Regarding use of heat to control microbial growth, dry heat at lower temperatures is as effective as moist heat at the same temperature. true or false

false

True or false: Choosing which germicide to use is not that complicated since we only consider how effective it is against the target microbes.

false

A common dry heat sterilization method used in the microbiology laboratory is ______.

flaming the inoculating loop

Chlorine and iodine are common disinfectants that belong to a class of chemicals called

halogens

Boiling is not reliable for sterilization because

heat resistant endospores are unaffected

Disinfectants that destroy all viruses and vegetative organisms but not endospores are referred to as-----level disinfectants.

high

Salting and drying decrease the availability of water in food, resulting in an environment that is ______ relative to microbes, thereby preventing their growth.

hypertonic

Oxidation of proteins is achieved most readily

in a hot air oven

Adding preservatives such as benzoic acid to food is important because ______

inhibits growth of many bacteria and mold

Ozone ______.

is a strong oxidizing agent

Ethylene oxide is gaseous agent that ____

is very useful for sterilizing heat- or moisture-sensitive items

Ethylene oxide is gaseous agent that ______.

is very useful for sterilizing heat- or moisture-sensitive items

Adding preservatives such as benzoic acid to food is important because ______.

it inhibits growth of many bacteria and mold

All of the following are characteristics of bleach, a solution of sodium hypochlorite, EXCEPT ______?

it is only effective against a limited range of microorganisms

Although generally less reliable than heat, germicidal chemicals are especially useful for treating ______.

large surfaces heat-sensitive items

Microorganisms that are free living are ______ to chemical disinfectants than microorganisms in a biofilm.

less resistant

A solution of sodium hypochlorite is more effective against bacteria at _______ pH.

low

Soap generally does not destroy most microbes, but it aids in their ______.

mechanical removal

Washing hands with plain soap and water works by ______ removing microbes.

mechanically

Household bleach applied at 55C is ________ effective in killing bacteria than if it were applied at 50

more

Alcohols are not reliably effective at destroying

non-enveloped viruses AND endospores.

Halogens are highly reactive _______ agents that _______.

oxidizing; cause damage to proteins

Microbial death rates may be affected by

pH. temperature. the presence of organics. growth in a biofilm. All of the answer choices are correct.

heat treatment, filtration, irradiation

physical method of control

Heat treatment, irradiation and filtration are examples of ______ used to control microorganisms.

physical processes

A high-solute environment damages microbial cells by causing ______.

plasmolysis

The act of delaying spoilage is ______.

preservation

High----processing (HPP) is used to decrease the number of microbes in food while maintaining the color and flavor.

pressure

Silver sulfadiazine, which is a combination of silver and a sulfa drug, is used to

prevent infection of second- and third-degree burns.

When boiling or pasteurizing a sample, microorganisms are destroyed because their ______.

proteins are irreversibly denatured

Chlorine-releasing compounds such as sodium hypochlorite (bleach is a 5.25% solution) are used for all of the following EXCEPT ______.

sewage and waste water disinfection swimming pool treatments wound treatment and skin cleansing Reason: Sodium hypochlorite is too irritating to skin and mucous membranes. food equipment sanitation household cleaning

The main effect of low temperature storage is to ______

slow the activity of microbes Reason: Reduced temperatures only slow metabolic activities and growth of microbes. They are not effective at killing a majority of microbes.

All of the following are examples of electromagnetic radiation EXCEPT ______.

sound waves

Following treatment to remove all viable microorganisms, including viruses, an object is considered to be

sterile

Following treatment to remove all viable microorganisms, including viruses, an object is considered to be-------

sterile

The process of killing or removing all of the microorganisms in or on a material is called

sterilization.

When selecting an appropriate chemical disinfectant, it is important to realize that the death rate is significantly influenced by ______,------.

temperature pH

Microwaves do not kill organisms directly but kill by

the heat they generate in a product.

Boiling is very effective at removing most common waterborne pathogens. True or False

true

Choosing the correct antimicrobial procedure depends on many factors including ______.

type and number of microbes composition of item environmental conditions

Choosing the correct antimicrobial procedure depends on many factors including ______.

type and number of microbes environmental conditions composition of item

Germicidal chemicals ______.

usually react irreversibly with proteins, DNA, cytoplasmic membranes, or viral envelopes are often poorly understood with regards to mechanisms of actionusually react irreversibly with proteins, DNA, cytoplasmic membranes, or viral envelopes are often poorly understood with regards to mechanisms of action

The decimal reduction time is the time it takes to kill 90% of a given bacterial population under certain conditions. If 90% of a population of 100,000 bacteria is killed in 10 minutes, how long would it take to reduce the population to 10 cells?

40 minutes

Aqueous solutions of alcohol at a concentration of ______ are more effective than 100% alcohol.

60-80%

The straining of a fluid or air through a membrane to trap microorganisms is known as

Blank 1: filtration or filtering

Used as an alternative to chlorine for disinfecting water, ---is a strong but unstable oxidizing agent that must be generated on-site, usually be passing air or O2 between two electrodes.

Blank 1: ozone or O3

Used as an alternative to chlorine for disinfecting water,--- is a strong but unstable oxidizing agent that must be generated on-site, usually be passing air or O2 between two electrodes.

Blank 1: ozone or O3

Chemicals called--- are used to prevent the growth of undesirable organisms in foods and beverages.

Blank 1: preservatives or additives

Medical instruments are classified into three categories according to their risk for transmitting pathogens. These are: critical instruments,---instruments, and---instruments.

Blank 1: semicritical or semi-critical Blank 2: noncritical or non-critical

Which of the following concerns would lead a user to wash an item after it had been treated with a germicide?

Corrosive residue left after treatment.