AP-Micro Microbiology: Sterilization, Disinfection, and Infection Control

Question 1

Which sterilization method uses saturated steam under pressure to destroy all microorganisms, including bacterial endospores?

Accepted Answer

Autoclave (moist heat)

Answer

Dry heat oven

Answer

UV radiation

Answer

Pasteurization

Question 2

What are the standard conditions for gravity-displacement autoclave sterilization?

Accepted Answer

121°C for 15–20 minutes at 15 psi

Answer

100°C for 30 minutes at ambient pressure

Answer

134°C for 60 minutes at 30 psi

Answer

160°C for 10 minutes at 15 psi

Question 3

Which sterilization method is most appropriate for heat-labile materials such as plastics, rubber tubing, and electronic components?

Accepted Answer

Ethylene oxide (EtO) gas

Answer

Dry heat at 160°C

Answer

Steam autoclave at 121°C

Answer

Incineration

Question 4

Dry heat sterilization of glassware and metal instruments typically requires which conditions?

Accepted Answer

160°C for 1–2 hours

Answer

100°C for 2 hours

Answer

121°C for 30 minutes

Answer

250°C for 15 minutes

Question 5

Which biological indicator is used to validate the effectiveness of steam autoclave sterilization cycles?

Accepted Answer

Geobacillus stearothermophilus spores

Answer

Bacillus anthracis spores

Answer

Bacillus subtilis var. niger spores

Answer

Clostridium perfringens spores

Question 6

Which statement correctly describes a limitation of ethylene oxide (EtO) sterilization?

Accepted Answer

Items must undergo a lengthy aeration period to remove toxic residues before use

Answer

It is ineffective against bacterial endospores

Answer

It requires temperatures above 200°C to function

Answer

It cannot be used on rubber or plastic materials

Question 7

According to the Spaulding classification, a flexible gastrointestinal endoscope that contacts intact mucous membranes but does not penetrate sterile tissue is classified as 'semicritical' and requires:

Accepted Answer

High-level disinfection

Answer

Full sterilization

Answer

Intermediate-level disinfection

Answer

Low-level disinfection