Question 1

Which of the following best describes the difference between -cidal and -static antimicrobial agents?

Accepted Answer

-Cidal agents kill microbes, while -static agents only inhibit their growth.

Question 2

A hospital technician is using an autoclave to sterilize surgical instruments. Which of the following best explains how the autoclave achieves sterilization?

Accepted Answer

By using moist heat under increased pressure to reach temperatures above 100°C.

Question 3

Which of the following is the most accurate definition of decimal reduction time ($$D_{10}$$)?

Accepted Answer

The time required to reduce a microbial population by 90% at a given temperature.

Question 4

Why is a 70% ethanol solution more effective as an antimicrobial than a 100% ethanol solution?

Accepted Answer

Because 70% ethanol denatures proteins more efficiently due to the presence of water.

Question 5

Which of the following statements about bacterial death following antimicrobial treatment is correct?

Accepted Answer

Bacterial cells die at a logarithmic rate, so death is best plotted on a logarithmic scale.

Question 6

Which of the following is NOT a main mechanism by which antimicrobial agents kill or inhibit microbes?

Accepted Answer

Increasing microbial metabolic rate

Question 7

A laboratory is using a filter to sterilize a heat-sensitive solution. What is the typical pore size of a bacterial filter used for this purpose?

Accepted Answer

$$0.22\ \mu m$$

Question 8

Which of the following statements about pasteurization is correct?

Accepted Answer

Pasteurization reduces microbial numbers to safe levels but does not sterilize.

Question 9

Which of the following chemical antimicrobials is classified as a halogen and is commonly used as a surgical scrub?

Accepted Answer

Betadine

Question 10

Which of the following methods is most effective for destroying prions?

Accepted Answer

Incineration

Question 11

A nurse cleans her hands with an alcohol-based hand sanitizer after caring for a patient with C. difficile-associated diarrhea. Is this procedure adequate, and why?

Accepted Answer

No, because alcohol-based sanitizers are ineffective against C. difficile endospores.

Question 12

Which of the following statements about ionizing and nonionizing radiation is correct?

Accepted Answer

Ionizing radiation is more penetrating and can sterilize through packaging.

Question 13

Which wavelength is most damaging to DNA when using nonionizing radiation?

Accepted Answer

$$260\ nm$$

Question 14

Which of the following chemical antimicrobials is effective against mycobacteria and remains active in the presence of organic matter?

Accepted Answer

Phenolics

Question 15

Which of the following best describes the mechanism of action of filtration as a physical control method?

Accepted Answer

Removes microbes physically by passing liquid or air through a filter with small pores.

Question 16

Which of the following is a correct statement about quaternary ammonium compounds (quats)?

Accepted Answer

They are inactivated by organic matter and not effective against endospores.

Question 17

Which of the following is the main reason why the effectiveness of an antimicrobial treatment can vary?

Accepted Answer

The number and type of microbes, environmental conditions, and exposure time.

Question 18

Which of the following best describes the difference between a tincture and an iodophore?

Accepted Answer

A tincture is an iodine solution in alcohol, while an iodophore is iodine combined with an organic molecule for slow release.

Question 19

Which of the following best describes oligodynamic action?

Accepted Answer

The ability of heavy metals to exert antimicrobial activity even at low concentrations.

Question 20

A researcher is testing a new disinfectant using the disk-diffusion method. What result would indicate that the disinfectant is effective?

Accepted Answer

A large zone of inhibition around the disk.

Microbiology: Control of Microbial Growth – Study Guidance

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