IAHCSMM (CRCST) COMPREHENSIVE
PROFESSIONAL EXAM 2026 QUESTIONS
AND ANSWERS
1. Which microorganism is used as the biological indicator for monitoring Ethylene Oxide
(ETO) sterilization cycles?
A. Geobacillus stearothermophilus
B. Bacillus atrophaeus
C. Bacillus subtilis
D. Clostridium difficile
Answer: B
Conceptual Explanation: Bacillus atrophaeus is the standard biological indicator used for
ETO and dry heat sterilization, whereas Geobacillus stearothermophilus is used for steam
and H2O2.
2. When preparing for sterilization, which of the following is the most critical factor regarding
the ‘passivation layer’ of stainless steel instruments?
A. It is a chromium oxide layer that protects the instrument from corrosion
,B. It is a permanent coating that never requires maintenance
C. It should be removed during every cleaning cycle using abrasive pads
D. It is applied only to titanium-based surgical tools
Answer: A
Conceptual Explanation: The passivation layer is a thin, transparent chromium oxide film
that protects the steel from oxidation. If damaged by abrasives or harsh chemicals, the
instrument will rust.
3. In the decontamination area, the ventilation system should be designed to provide:
A. Positive pressure with at least 10 air exchanges per hour
B. Negative pressure with at least 4 air exchanges per hour
C. Positive pressure with at least 6 air exchanges per hour
D. Negative pressure with at least 10 air exchanges per hour
Answer: D
Conceptual Explanation: ANSI/AAMI ST79 standards require the decontamination area to
maintain negative air pressure relative to surrounding areas and a minimum of 10 air
exchanges per hour to prevent the spread of contaminants.
4. Which of the following best describes ‘cavitation’ in an ultrasonic cleaner?
A. The process of using high-pressure water spray to remove debris
B. The use of electrical current to sanitize metal surfaces
, C. The creation and collapse of microscopic bubbles to dislodge soil
D. The chemical reaction between enzymes and protein soils
Answer: C
Conceptual Explanation: Cavitation occurs when high-frequency sound waves create
vacuum bubbles that implode, pulling debris away from the surfaces and crevices of
instruments.
5. What is the minimum recommended temperature for the final rinse in a thermal
disinfection cycle of a washer-disinfector?
A. 140°F (60°C)
B. 180°F (82°C)
C. 270°F (132°C)
D. 212°F (100°C)
D. 212°F (100°C)
Answer: B
Conceptual Explanation: Thermal disinfection is typically achieved by maintaining a
temperature of at least 180°F (82°C) for a specific period to ensure the destruction of most
microorganisms.
6. A Bowie-Dick test should be performed in which type of sterilizer?
A. Gravity displacement steam sterilizers
PROFESSIONAL EXAM 2026 QUESTIONS
AND ANSWERS
1. Which microorganism is used as the biological indicator for monitoring Ethylene Oxide
(ETO) sterilization cycles?
A. Geobacillus stearothermophilus
B. Bacillus atrophaeus
C. Bacillus subtilis
D. Clostridium difficile
Answer: B
Conceptual Explanation: Bacillus atrophaeus is the standard biological indicator used for
ETO and dry heat sterilization, whereas Geobacillus stearothermophilus is used for steam
and H2O2.
2. When preparing for sterilization, which of the following is the most critical factor regarding
the ‘passivation layer’ of stainless steel instruments?
A. It is a chromium oxide layer that protects the instrument from corrosion
,B. It is a permanent coating that never requires maintenance
C. It should be removed during every cleaning cycle using abrasive pads
D. It is applied only to titanium-based surgical tools
Answer: A
Conceptual Explanation: The passivation layer is a thin, transparent chromium oxide film
that protects the steel from oxidation. If damaged by abrasives or harsh chemicals, the
instrument will rust.
3. In the decontamination area, the ventilation system should be designed to provide:
A. Positive pressure with at least 10 air exchanges per hour
B. Negative pressure with at least 4 air exchanges per hour
C. Positive pressure with at least 6 air exchanges per hour
D. Negative pressure with at least 10 air exchanges per hour
Answer: D
Conceptual Explanation: ANSI/AAMI ST79 standards require the decontamination area to
maintain negative air pressure relative to surrounding areas and a minimum of 10 air
exchanges per hour to prevent the spread of contaminants.
4. Which of the following best describes ‘cavitation’ in an ultrasonic cleaner?
A. The process of using high-pressure water spray to remove debris
B. The use of electrical current to sanitize metal surfaces
, C. The creation and collapse of microscopic bubbles to dislodge soil
D. The chemical reaction between enzymes and protein soils
Answer: C
Conceptual Explanation: Cavitation occurs when high-frequency sound waves create
vacuum bubbles that implode, pulling debris away from the surfaces and crevices of
instruments.
5. What is the minimum recommended temperature for the final rinse in a thermal
disinfection cycle of a washer-disinfector?
A. 140°F (60°C)
B. 180°F (82°C)
C. 270°F (132°C)
D. 212°F (100°C)
D. 212°F (100°C)
Answer: B
Conceptual Explanation: Thermal disinfection is typically achieved by maintaining a
temperature of at least 180°F (82°C) for a specific period to ensure the destruction of most
microorganisms.
6. A Bowie-Dick test should be performed in which type of sterilizer?
A. Gravity displacement steam sterilizers
