Ch.5 Microbiology

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

Select the correct statements about autoclaving.

-Biological indicators such as heat-resistant endospores are used to ensure that an autoclave is working properly -Autoclaving involved the use of broth temperature and pressure. -Autoclaving is consistently effective in sterilizing most objects -Adding pressure to the autoclave increases the temperature of the steam in it

HIV is highly resistant to antimicrobial chemicals and requires lengthy exposure to these products in order to be destroyed.

-False

Measures to prevent prion contamination of healthcare settings have been in place for the past several decades and fully control the risk.

-False

Which of the following chemicals is/are suspected carcinogens?

-Formaldehyde -Ethylene oxide

Which of the following kills food microbes, rather than just reducing their growth?

-Irradiation

Select the statements about ionizing radiation that are true. (NOTE: Please change all question marks to checkmarks for correct answers or empty boxes for incorrect answers.)

-It can be used to sterilize medical equipment -It can be used to sterilize medications -It can be used to reduce spoilage organisms on food

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

-Membrane filtration

Which of the following can be used to make drinking water safe? Check all that apply.

-Ozone -Halogens

Select the reasons sugar or salt can be used for food preservation. Check all that apply.

-They may cause plasmolysis -They create a hypertonic environment -They dehydrate the bacterial cells

A suffix used to describe a killing action would be

-cidal.

Moist heat primarily destroys microbes by

-denaturing their proteins

Chlorine has traditionally been used to disinfect water, preventing the spread of waterborne illnesses. However, chlorine (and other disinfectants) can react with naturally occurring water chemicals, forming ______, which can have long-term health risks.

-disenfection by products

Chlorine is safely used to disinfect waste liquids, some medical instruments, and various surfaces. It is readily available in liquid household bleach but bleach must be diluted because high concentrations are toxic and corrosive. To obtain an effective concentration of chlorine when using household bleach, a 1:100 dilution is made. This means that ______ mL of bleach is added to ______ mL of water.

1.0/99

In a one D process, how many D values would it take to reduce a population of 1010 cells to one survivor?

10

Typical conditions used for sterilization are

121°C at 15 psi for 15 minutes.

If a process kills 90% of the organisms per minute, how many minutes would it take to kill all organisms when starting with 100,000 organisms?

6 minutes

Microbial death rates may be affected by

All of the answer choices are correct.

To reduce or eliminate disease-/spoilage-causing organisms, food is often subjected to

All of the answer choices are correct.

Which of the following is (are) considered when selecting a germicidal chemical?

All of the answer choices are correct.

Chemical germicides

All of the answer choices are true.

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.

Please select the INCORRECTLY matched pair.

D-value - time to destroy 10% of microbes present.

Choose which of the following best describe the difference between a disinfectant and an antiseptic.

Disinfectants are antimicrobial chemicals used on inanimate surfaces or objects to remove most of the pathogenic microorganisms. Antiseptics are antimicrobial chemicals that can be used on skin or tissues to achieve the same result.

Which are essentially equivalent treatments?

Dry 200°C heat for 1.5 hours; wet 121°C heat for 15 minutes

Which of the following are resistant to destruction by typical disinfection methods?

Endospores of Bacillus and Clostridium

100% ethanol is twice as effective as 60% ethanol at controlling bacteria.

False

Aldehydes can be used to disinfect superficial wounds.

False

Handwashing with regular soap removes all normal microbiota from the skin.

False

Heat treatment is an effective method for sterilization or disinfection of all materials.

False

Hydrogen peroxide may be used as a sterilant on living tissue.

False

Pasteurization results in the sterilization of food products.

False

Prions are easily destroyed by common sterilization procedures.

False

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

False

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

False

Use the terms provided to complete the sentences in order to test your understanding of the difference between sterilants, high-level disinfectants, intermediate-level disinfectants, and low-level disinfectants.

Germicides known as sterilants can destroy all microbes including both bacterial endospores and all types of viruses. High level disinfectants destroy all viruses and vegetative cells but will not kill endospores. Intermediate level disinfectants destroy vegetative cells and some, but not all, viruses. They are unable to kill endospores even when used for a prolonged period of time. Germicides known as low level disinfectants kill vegetative cells except for mycobacteria and are unable to destroy nonenveloped viruses and endospores.

Select the FALSE statement regarding hydrogen peroxide.

It immediately kills all bacteria when applied to a wound.

Which is true of iodine?

It is usually found as tinctures or iodophors.

Which of the following about heat treatment is FALSE?

It produces toxic byproducts.

Lister developed his ideas on prevention of infection during medical procedures after studying the work of

Pasteur.

Which of the following is NOT a sterilization method?

Pasteurization

Which of the following is/are not (a) sterilization method(s)?

Pasteurization

______ is a brief heat treatment that reduces the number of spoilage organisms and destroys pathogens. It can be used on foods or inanimate objects.

Pasteurization

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

Pseudomonas aeruginosa.

Which would be most effective against Pseudomonas?

Radiation

Hexachlorophene has been particularly effective against

Staphylococcus aureus.

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

Steam autoclaving

Which is true of nosocomial infections?

They are acquired by susceptible people in the hospital.

Boiling is very effective at removing most common waterborne pathogens.

True

Generally, heavy metals, except silver, have been proven to be too toxic for use on human tissue and are no longer used medically.

True

Organic acids, such as benzoic acid, are often added to foods to prevent microbial growth.

True

The more bacteria one starts with, the longer it will take to kill them all.

True

The more bacteria present on or in something, the longer it takes to kill them all.

True

Upon heat treatment, bacteria die at a constant proportion.

True

Which of the following methods sterilize the materials?

Ultrahigh-temperature (UHT) method

Which of the following is a method of choice for achieving a sufficient level of microbial control in routine day to day situations?

Washing and scrubbing with soaps and detergents.

A sterile item is free of

all viable microbes, endospores, AND viruses

Gamma irradiation

can be used to either sterilize or pasteurize, depending on the dose of radiation.

One of the first chemicals used by Lister to prevent surgical infections was

carbolic acid.

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

carcinogenic

Quaternary ammonium compounds are

cationic detergents that help wash surfaces.

Phenolics

denature proteins and destroy cytoplasmic membranes.

Commercial canning processes

destroy Clostridium botulinum spores, are especially needed on low acid foods, AND are 12D processes (designed to kill 1012 endospores).

Upon treatment with heat or chemicals, bacteria will

die at a constant proportion.

Generally, membrane filters are not used to remove

enzymes from liquids.

Boiling is not reliable for sterilization because

heat-resistant endospores are unaffected.

The autoclave treatment may be monitored by

heat-sensitive tape AND heat-resistant endospores of Geobacillus stearothermophilus.

Match each of the following methods for preservation of perishable products with its description.

https://gyazo.com/10680161e3f0fbc2d6db37ccf21c17cb

Match each type of radiation with its description.

https://gyazo.com/29eab31c4afb2e4b578f53f720652756

Classify the given microbes and infectious agents into "sensitive" or "resistant" with regards to effect of antimicrobial procedures.

https://gyazo.com/4a080efd275f3344490f4ce96749bb4a

Identify each of the important areas of the electromagnetic spectrum on the figure.

https://gyazo.com/5929e1111a43287c4ea1e2138d8e38d8

Match the listed objects and compounds with the appropriate method used to destroy microbes and viruses on/in them.

https://gyazo.com/82f5a729f709a40882769c5ad07f13e3

Rank the germicides from most to least potent.

https://gyazo.com/951396e9351bc42538ff2fc1765702d8

This figure is displaying the same information twice—a D value related to logarithmic killing of microbes. Place the tags on the correct areas to identify a) what the D value is and b) what it means. Not all labels are used.

https://gyazo.com/9e146d70f07f2c5c0d82448461bdc837

Please match the term with its description to test your understanding of microbial control terminology.

https://gyazo.com/a0bd9d64a0eaed2c73b52cab71f49dc6

Match each of the following items that may influence the selection of an antimicrobial procedure with its correct description/rationale.

https://gyazo.com/a225bfca996b35a02cd5326759be4dd0

Categorize the given chemicals according to their uses.

https://gyazo.com/a4c1b6eda63d6748523b96e63d41bd24

Place the labels into the correct columns for moist heat and dry heat.

https://gyazo.com/a5b54c581e9e00168a54e39df3cbb25b

Match the important points regarding selection of an appropriate germicide with the description/rationale that fits it best.

https://gyazo.com/b53d86f845b11bd70793872273536b66

Which of the following destroys acellular infectious agents?

https://gyazo.com/b80169252c9bcde604024946986ba968

Match the germicide with its use.

https://gyazo.com/c72338bbdae0ad0e4df06923d96254d0

Categorize the given medical instruments.

https://gyazo.com/d929b884396990c0120ff8d19be95c8a

Match the term to its description to test your understanding of the use of moist heat to control microbial growth.

https://gyazo.com/db18346156c435fe574007f831a72acb

Oxidation of proteins is achieved most readily

in a hot air oven.

The most important function of nitrites in processed foods is to

inhibit the germination of Clostridium botulinum endospores.

Moist heat kills microorganisms by

irreversible denaturation of proteins.

Chlorhexidine

is extensively used in antiseptics.

Pasteurization

is the use of heat to reduce numbers of pathogenic/spoilage bacteria in a food item to a safe level.

Glutaraldehyde

is very good for use on heat-sensitive medical items.

Hand washing with plain soap is very effective in controlling spread of microorganisms because

it is very effective at the mechanical removal of microorganisms.

Liquid media containing heat-sensitive components would best be sterilized by

membrane filtration.

Alcohols are not reliably effective at destroying

non-enveloped viruses AND endospores.

Gamma rays cause biological damage in living systems by

producing reactive molecules such as superoxide and hydroxyl-free radicals.

Chlorine

readily reacts with organics to produce potentially carcinogenic trihalomethanes.

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

sterilization.

A common application of dry heat in the microbiology laboratory is to

sterilize the inoculating loop.

Microwaves do not kill organisms directly but kill by

the heat they generate in a product.

When filtering a liquid, it is a bad idea to use a membrane with a pore size smaller than necessary because

the smaller the pore size, the slower the filtration process, so you would be wasting time.

Compounds of tin, mercury, arsenic, and copper are no longer used to prevent microbial growth in cooling water primarily because

their use contributes to serious pollution of natural waters.