Microbiology Ch 11

The minimum sterilizing conditions in a steam autoclave are

. 121°C at 15 psi for 15 minutes.

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

. Salting of meat

The compound that is an organic base containing chlorine and two phenolic rings, and is used increasingly for wound degerming, neonatal washes, hand scrubbing, and prepping surgical skin sites is ______

.chlorhexidine

Which of the following methods of microbial control is mismatched?

A. Pickling eggs - osmotic pressure

Which of the following is not a heavy metal?

A. Tincture of iodine

Which control method would not be a suitable choice for killing Mycobacterium in a capped culture tube?

A. Ultraviolet (germicidal) light

Iodophors include ______.

A. betadine

The chemical agent/s that produce/s highly reactive hydroxyl-free radicals and also decomposes to O2 gas is ______.

A. hydrogen peroxide

Cold temperatures are considered microbistatic, whereas excessive heat is considered microbicidal. This is due to the fact that

A. in cold temperatures, the energy of activation is not sufficient to drive chemical reactions regardless of the presence of enzymes, whereas excessive heat denatures enzymes and/or incinerates the cell causing irreparable damage.

Which of the following is not a factor that affects germicidal activity? A. Material being treated B. Length of exposure C. Strength of the germicide D. Microorganism being treated E. All of the choices are factors.

All of the choices are factors.

Which of the following is not used as an antiseptic?

Aqueous glutaraldehyde

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

Bacterial endospores

Which is correct regarding the rate of microbial death?

Cells in a culture die at a constant rate

Antimicrobial agents can target the cell wall by A. blocking its synthesis. B. digesting it. C. denaturing proteins. D. All of the choices are correct.

D. All of the choices are correct.

Alcohols A. denature proteins when in a 50-95% alcohol-water solution. B. disinfect items when soaking method is utilized. C. are skin degerming agents. D. at 50% or higher concentrations dissolve cell membrane lipids. E. All of the choices are correct.

E. All of the choices are correct.

Endospores can be inactivated by A. dry heat at 170°C for 2 hours. B. incineration. C. glutaraldehyde for 3 or more hours. D. ethylene oxide for 3 or more hours. E. All of the choices are correct.

E. All of the choices are correct.

Which of the following germicides is/are also sporicidal? A. Betadine B. Chlorine C. Phenolics D. Chlorhexidine E. All of these except phenolics.

E. All of these except phenolics.

All of the following pertain to hypochlorites except A. they cause denaturation of enzymes. B. they release hypochlorous acid in solution. C. they are found in common household bleach. D. they are used to disinfect dairy, restaurant, and medical equipment. E. they are found in iodophors.

E. they are found in iodophors.

Which of the following is true regarding the use of osmotic pressure as an antimicrobial agent?

Exposing a microbe to a hypertonic environment draws water out of the cell, causing plasmolysis.

Which of the following forms of radiation are in order from the most penetrating to the least penetrating?

Gamma, X rays, cathode

Which of the following is not a primary target of milk pasteurization?

Lactobacillus

Which is mismatched?

Merthiolate - silver

Which antimicrobial method does not sterilize?

Pasteurization

Your aim is to sterilize prosthetic devices like heart valves and artificial joint structures before being used in the patient. Considering where they will be placed and the probable composition of the devices, what would be the best chemical to use?

Quaternary ammonium compounds

Which of the following represents microbial control by osmotic pressure?

The crew of the Mayflower using salted meats throughout their voyage to the New World

You have some old plastic Petri dishes that you would like to use for pouring bacteriological agar plates. The only method of physical sterilization is ultraviolet radiation sterilization with your UV light (you cannot use the autoclave because it will disfigure and melt the plastic). After sterilizing the plates, pouring the sterilized agar medium, and then leaving the plates out at room temperature for a day or two to let them solidify and dry, you find contaminating bacterial colonies growing on the agar. Predict what has happened in this situation.

The lids of the Petri dishes were inadvertently left on while being sterilized.

Which of the following is an advantage to using phenolics as antimicrobial agents?

The presence of organic matter does not limit its antimicrobial qualities.

Your friend Joe recently visited the doctor for steroid injections into his knee to reduce swelling due to a previous knee injury. Within a couple of days, he had an infection caused by Pseudomonas, a very pathogenic and drug resistant bacterium. Luckily, Joe went to the doctor immediately and received antibiotics. The doctor tells him that the same problem has occurred to many other people across the United States. Predict the most likely cause of this situation.

The staff giving the steroid injections did not use proper aseptic technique. D. The needles were re-used and already contaminated before being used on th

Which of the following is not true of chloramines?

They form trihalomethanes with organic compounds.

You have inherited some old glass baby milk bottles from your grandmother, and you would like to use them instead of plastic bottles. The bottles are placed into a large metal container and placed in the oven at 325o F for about 2 hours. What factor would you change if you wanted the sterilization to occur much quicker?

Use a pressure cooker to sterilize the bottles with steam

Which of the following is a disadvantage of dry heat methods such as using a Bunsen burner to incinerate microbes from an inoculating loop and the use of a hot air oven?

Use of an open flame can be dangerous and hot air ovens take much longer to sterilize than autoclaves.

All of the following are phenols or phenolics except ______.

Zephiran

Hydrogen peroxide is A. sporicidal. B. fungicidal. C. bactericidal. D. virucidal. E. All of the choices are correct

all

Which of the following factors will influence the action of microbial agents? A. The number of microorganisms B. The type of microorganisms present C. Temperature and pH D. Mode and dosage of the agent E. All of the choices will influence the action

all

Which of the following items are typically irradiated in order to kill microbes? A. Cured meats B. Human tissues such as heart valves and skin C. Operating room air D. Surgical gloves E. All of the choices are correct.

all

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

anitsepsis

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

antisepsis

The method of removing vegetative life forms from living surfaces is termed ______.

antisepsis

What instrument is most effective for pressure-temperature sterilization?

autoclave

Placing organisms at 4o C is ______.

bacteriostatic

All of the following act as surfactants except ______. A. detergents B. quaternary ammonia C. iodine D. soaps E. alcohols

c. iodine

The use of filtration for sterilization

can remove viruses

_____ is a halogen used in gaseous and liquid form for large scale disinfection of drinking water and sewage.

chlorine

Each of the following is a target of antimicrobial agents except ______.

cytoplasm

Scrubbing or immersing the skin in chemicals to reduce the numbers of microbes on the skin is ______.

degermation

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

Removal of moisture by dehydration is called

desiccation

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

disenfection

Surfactants work by

disrupting membrane integrity

Using a HEPA filter in a vacuum or furnace is an example of which microbial control method?

dry control

The sterilizing gas used in chemiclaves is ______.

ethylene oxide

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

gamma rays and X rays

Physical agents for controlling microbial growth include all of the following except ______.

hydrogen peroxide

Heavy metals work by

inactivating proteins

In lab, inoculating loops are sterilized using ______.

incineration

All of the following are alkylating control agents except ______.

iodophor

Dry heat

is less efficient than moist heat

Which of the following is not true of glutaraldehyde?

its a carcinogen

Vials of microorganisms that undergo the freeze-drying process, called _____, will remain preserved and viable for years.

lyophilization

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

moist - dry

Which of the following does not affect microbial nucleic acids?

moist heat

Which of the following acids is not used to destroy or inhibit microbial cells in food?

phosphoric acid

Pasteurization

reduces the number of vegetative forms.

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

sanitization

_____ solution was introduced in the late 19th century for p

silver nitrate

Ethylene oxide is

sporicidal

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

sporicide

Sterilization is achieved by

steam autoclave

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

sterilization

The lowest temperature needed to kill or inactivate all microbes in 10 minutes is the

thermal death point TDP

The shortest time required to kill or inactivate all the microbes in a sample at a specified temperature is called the

thermal death time (TDT).

The difference between thermal death time and thermal death point in microbicidal activity is that

thermal death time is the shortest amount of time required to kill an organism at a specific temperature, . whereas thermal death temperature is the lowest temperature required to kill an organism in 10 minutes.

When considering time and temperature as factors in microbicidal activity,

they are inversely proportional to each other.

Intermittent sterilization, which uses 3 days of lower temperature steam for short periods of time, is also called ______.

tyndallization

A method for sterilizing milk, called _____ treatment, uses 134°C for 1 to 2 seconds.

ultra high temp

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

ultraviolet

The easiest microbial forms to kill or inhibit are ______.

vegetative bacteria and fungi

Agents that can denature microbial proteins include all of the following except ______.

x rays