Question 1

Which of the following best defines sterilization in the context of microbial control?

Accepted Answer

The removal and destruction of all microbial life

Question 2

A hospital autoclave is set to operate at $$121\ ^\circ \mathrm{C}$$ and 15 psi for 15 minutes. What is the primary reason this method is preferred for sterilization in healthcare environments?

Accepted Answer

It kills all organisms and endospores except prions

Question 3

Which of the following statements about the decimal reduction time (DRT) is correct?

Accepted Answer

It is the time required to kill 90% of a specific population of bacteria at a given temperature

Question 4

A solution contains $$1 	imes 10^6$ bacteria. If a microbial control agent kills 90% of the bacteria every minute, how many bacteria will remain after 3 minutes?

Accepted Answer

$$1 	imes 10^3$

Question 5

Which of the following is a key reason why gram-negative bacteria are generally more resistant to chemical biocides than gram-positive bacteria?

Accepted Answer

They possess an outer membrane containing lipopolysaccharides

Question 6

Which physical method of microbial control is most appropriate for sterilizing heat-sensitive solutions such as certain vaccines?

Accepted Answer

Filtration

Question 7

A food processing plant uses high concentrations of salt to preserve meat. What is the primary mechanism by which this method suppresses microbial growth?

Accepted Answer

Plasmolysis due to osmotic pressure

Question 8

Which of the following statements about alcohol-based hand sanitizers is correct?

Accepted Answer

They require water to be effective

Question 9

A laboratory is testing the effectiveness of a new disinfectant using the disk-diffusion method. What result would indicate the disinfectant is effective against a particular bacterium?

Accepted Answer

A large zone of inhibition around the disk

Question 10

Which chemical agent is most appropriate for sterilizing heat-sensitive medical equipment and is classified as a gaseous chemosterilant?

Accepted Answer

Ethylene oxide

Question 11

Which of the following best explains why nonenveloped viruses are generally more resistant to disinfectants than enveloped viruses?

Accepted Answer

Nonenveloped viruses lack a lipid envelope, making them less susceptible to agents that target lipids

Question 12

A can of pork takes longer to sterilize than a can of soup containing pieces of pork at the same temperature. What is the most likely explanation?

Accepted Answer

The pork pieces are larger and require more time for heat to penetrate

Question 13

Which of the following is the primary mode of action for ionizing radiation in microbial control?

Accepted Answer

Ionization of water to form hydroxyl radicals that damage DNA

Question 14

Which of the following chemical agents is most effective for skin antisepsis before surgery?

Accepted Answer

Povidone iodine (Betadine®)

Question 15

A use-dilution test is performed to evaluate a new disinfectant. Which result would indicate the disinfectant is NOT effective?

Accepted Answer

Bacterial growth is observed in the culture media after treatment

Question 16

Which of the following best describes the effect of moist heat sterilization (such as autoclaving) on microbial cells?

Accepted Answer

It coagulates and denatures proteins

Question 17

Which of the following is a major advantage of glutaraldehyde over other chemical disinfectants?

Accepted Answer

It is a true sterilant and can kill endospores with prolonged exposure

Question 18

A patient is treated for a wound infection with hydrogen peroxide. Why is hydrogen peroxide not a good antiseptic for open wounds?

Accepted Answer

It is rapidly broken down by catalase in human tissues

Question 19

Which of the following best explains why prions are exceptionally difficult to destroy using standard sterilization methods?

Accepted Answer

They are resistant to heat, radiation, and most chemicals

Question 20

A hospital is deciding between using phenol and phenolics for disinfection. What is a key advantage of phenolics over phenol?

Accepted Answer

Phenolics are less irritating and more effective than phenol

Chapter 7

Guida di studio - Domande di pratica

Study guide - Flashcard