Microbiology Chapter 13

True

(T/F) Ionizing radiation can penetrate surfaces, but nonionizing radiation cannot.

False

(T/F) Moist-heat sterilization protocols require the use of higher temperatures for longer periods of time than do dry-heat sterilization protocols do.

False

(T/F) Sanitization leaves an object free of microbes.

False

(T/F) Soaps are classified as disinfectants.

True

(T/F)Mercury-based compounds have fallen out of favor for use as preservatives and antiseptics.

Non critical

A medical item that comes into contact with intact skin and does not penetrate sterile tissues or come into contact with mucous membranes is called a(n) ________ item.

B. halogens

Bleach is an example of which group of chemicals used for disinfection? ​A. heavy metals ​B. halogens ​C. quats ​​D. bisbiguanides

Nisin and natamycin; they are naturally produced and effective against gram positive organisms, making cells more easy to lysis and help prevent fungal growth and meat preservation

Do you think naturally produced antimicrobial products like nisin and natamycin should replace sorbic acid for food preservation? Why or why not?

Copper; nickel; zinc

Doorknobs and other surfaces in clinical settings are often coated with ________, ________, or ________ to prevent the transmission of microbes.

Very high concentrations of sugar or salt cause the available amount of water in microbial cells to reduce dramatically because water is drawn from low solute concentration (inside cell) to areas of high solute concentration (outside cell)

How does the addition of salt or sugar help preserve food?

Greater

If a chemical disinfectant is more effective than phenol, then its phenol coefficient would be ________ than 1.0.

High level

If used for extended periods of time, ________ germicides may lead to sterility.

Yes; UV light can be used to sterilize; cells must be exposed directly to the light source because UV light doesn't penetrate surfaces unless direct contact

In 2001, endospores of Bacillus anthracis, the causative agent of anthrax, were sent to government officials and news agencies via the mail. In response, the US Postal Service began to irradiate mail with UV light. Was this an effective strategy? Why or why not?

Steam

In an autoclave, the application of pressure to ________ is increased to allow the steam to achieve temperatures above the boiling point of water.

Susceptibility or sensitivity

In the disk-diffusion assay, a large zone of inhibition around a disk to which a chemical disinfectant has been applied indicates ________ of the test microbe to the chemical disinfectant.

C.reduce a microbial population by 90%

The decimal reduction time refers to the amount of time it takes to which of the following? ​A. reduce a microbial population by 10% ​B. reduce a microbial population by 0.1% C.reduce a microbial population by 90% ​​D. completely eliminate a microbial population

A. phenol

The effectiveness of chemical disinfectants has historically been compared to that of which of the following? ​A. phenol ​B. ethyl alcohol ​C. bleach ​​D. formaldehyde

Commercial sterilization

The goal of ________ ________ protocols is to rid canned produce of Clostridium botulinum endospores.

Advantages of use-dilution and in-use test:

What are some advantages of use-dilution and in-use tests compared with the disk-diffusion assay?

-Contaminated air requiring constant supple of clean air, pathogenic/possibly need vaccination for microbe they are working with, air/blood born, special gear/training, use under hood

What are some characteristics of microbes and infectious agents that would require handling in a BSL-3 laboratory?

-length of exposure, concentration, temperature, pH

What are some factors that alter the effectiveness of a disinfectant?

Benefits: maintaining health Disadvantages: killing all microbes is bad, they can build resistance, stripping all microbes can result in death

What are the benefits of cleaning something to a level of cleanliness beyond what is required? What are some possible disadvantages of doing so?

HTST advantage: lowers bacterial numbers while preserving the quality of the milk UHT advantage: can be stored for long time in sealed containers without refrigerated (regions in which access to refrigeration is limited)

What is the advantage of HTST pasteurization compared with sterilization? What is an advantage of UHT treatment?

Iodophor: compound of Iodine complexed with an organic molecule, increasing iodines stability and in turn its efficacy

What is the advantage of using an iodophor rather than iodine or an iodine tincture?

Microbial numbers are significantly reduced by gently scrubbing living tissue with mild chemical to aboid transmission of pathogenic microbes(ex washing hands, alcohol swab on injection site) it removes MOST( but not all) microbes from surface

What is the purpose of degerming? Does it completely eliminate microbes?

Bactericidal: kills completely Bacteriostatic: stops growth without killing

When plotting microbial death curves, how might they look different for bactericidal versus bacteriostatic treatments?

B.BSL-2

Which biosafety level is appropriate for research with microbes or infectious agents that pose moderate risk to laboratory workers and the community, and are typically indigenous? A. BSL-1 ​B. BSL-2 ​C. BSL-3 ​​D. BSL-4

​C. formaldehyde

Which chemical disinfectant works by methylating enzymes and nucleic acids and is known for being toxic and carcinogenic? ​A. sorbic acid ​B. triclosan ​C. formaldehyde ​​D. hexaclorophene

Autoclaving; it's the most effective method of sterilization allowing moist heat on large scale without damaging items Freezing just stops growth of microbes

Which is more effective at killing microbes: autoclaving or freezing? Explain.

D.fungistatic

Which of the following best describes a microbial control protocol that inhibits the growth of molds and yeast? ​A. bacteriostatic ​B. fungicidal ​C. bactericidal ​​D. fungistatic

​B. sulfites

Which of the following chemical food preservatives is used in the wine industry but may cause asthmatic reactions in some individuals? ​A. nitrites ​B. sulfites ​C. propionic acid ​​D. benzoic acid

B.antiseptic

Which of the following is suitable for use on tissues for microbial control to prevent infection? ​A. disinfectant ​B. antiseptic ​C. sterilant ​​D. water

D.sonication

Which of the following methods brings about cell lysis due to cavitation induced by rapid localized pressure changes? ​A. microwaving ​B. gamma irradiation ​C. ultraviolet radiation ​​D. sonication

A.filtration

Which of the following microbial control methods does not actually kill microbes or inhibit their growth but instead removes them physically from samples? ​A. filtration ​B. desiccation ​C. lyophilization ​​D. nonionizing radiation

​A. hydrogen peroxide

Which of the following peroxygens is widely used as a household disinfectant, is inexpensive, and breaks down into water and oxygen gas? ​A. hydrogen peroxide ​B. peracetic acid ​C. benzoyl peroxide ​​D. ozone

​B. tincture

Which of the following refers to a disinfecting chemical dissolved in alcohol? ​A. iodophor ​B. tincture ​C. phenolic ​​D. peroxygen

C. low-level germicide

Which of the following refers to a germicide that can kill vegetative cells and certain enveloped viruses but not endospores? ​A. high-level germicide ​B. intermediate-level germicide ​C. low-level germicide ​​D. sterilant

C.thermal death time

Which of the following terms is used to describe the time required to kill all of the microbes within a sample at a given temperature? ​A. D-value ​B. thermal death point ​C. thermal death time ​​D. decimal reduction time

A.needles

Which of the following types of medical items requires sterilization? A. needles B. bed linens C. respiratory masks ​​D. blood pressure cuffs

70%; gains trust then takes em out at the knees (Alcohols coagulate proteins-Too much can over too it and defeat purpose)

Which solution of ethyl alcohol is more effective at inhibiting microbial growth: a 70% solution or a 100% solution? Why?

C. in-use test

Which type of test is used to determine whether disinfectant solutions actively used in a clinical setting are being used correctly? ​A. disk-diffusion assay ​B. phenol coefficient test ​C. in-use test ​​D. use-dilution test

-longer exposure means increasing efficacy of chemical disinfectant

Why is length of exposure to a chemical disinfectant important for its activity?

It is more persistent than iodophors, providing long lasting antimicrobial activity and acts faster -Over using daily would damage and build resistance

Why is the use of skin disinfecting compounds required for surgical scrubbing and not for everyday handwashing?

Historically they Often compared disinfections with phenol because phenol was the first chemical agent used

Why were chemical disinfectants once commonly compared with phenol?