Microbiology: Sterilization, Disinfection, and Infection Control Flashcards
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Read the first 7 Microbiology: Sterilization, Disinfection, and Infection Control flashcards as text
Which sterilization method uses saturated steam under pressure to destroy all microorganisms, including bacterial endospores?
Answer: Autoclave (moist heat)
Autoclaving uses saturated steam at 121°C and 15 psi for 15–20 minutes, which is sufficient to denature proteins and kill all microbial life including heat-resistant spores.
What are the standard conditions for gravity-displacement autoclave sterilization?
Answer: 121°C for 15–20 minutes at 15 psi
Standard gravity autoclaving requires 121°C, 15 psi, for a minimum of 15–20 minutes to ensure complete sterilization of wrapped instruments.
Which sterilization method is most appropriate for heat-labile materials such as plastics, rubber tubing, and electronic components?
Answer: Ethylene oxide (EtO) gas
Ethylene oxide is a low-temperature (37–63°C) alkylating gas that sterilizes heat-sensitive materials without causing thermal damage.
Dry heat sterilization of glassware and metal instruments typically requires which conditions?
Answer: 160°C for 1–2 hours
Dry heat sterilization requires 160°C for 1–2 hours (or 170°C for 1 hour) because dry heat is less efficient than moist heat at penetrating and killing microorganisms.
Which biological indicator is used to validate the effectiveness of steam autoclave sterilization cycles?
Answer: Geobacillus stearothermophilus spores
Geobacillus stearothermophilus (formerly Bacillus stearothermophilus) produces highly heat-resistant spores that serve as the gold-standard biological indicator for autoclave validation.
Which statement correctly describes a limitation of ethylene oxide (EtO) sterilization?
Answer: Items must undergo a lengthy aeration period to remove toxic residues before use
EtO leaves toxic residues on processed items, requiring an aeration period of several hours to days to off-gas before the items are safe for patient use.
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:
Answer: High-level disinfection
Semicritical items (those contacting mucous membranes or non-intact skin) require high-level disinfection, which eliminates all microorganisms except high numbers of bacterial spores.