Microbiology: Sterilization, Disinfection, and Infection Control Flashcards
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Read the first 7 Microbiology: Sterilization, Disinfection, and Infection Control flashcards as text
High-level disinfection is defined as a process that eliminates:
Answer: All microorganisms except bacterial spores
High-level disinfection kills all microorganisms except high numbers of bacterial endospores; sterilization is required to eliminate spores completely.
Which chemical agent is classified as a high-level disinfectant and is commonly used for reprocessing heat-sensitive flexible endoscopes?
Answer: Glutaraldehyde 2%
2% glutaraldehyde (e.g., Cidex) is an aldehyde-based high-level disinfectant widely used for endoscope reprocessing when sterilization is not possible.
Chlorine-based disinfectants such as sodium hypochlorite exert their antimicrobial activity primarily by:
Answer: Oxidizing cellular components and denaturing proteins
Hypochlorite releases hypochlorous acid, a powerful oxidizer that destroys proteins, enzymes, and nucleic acids through oxidation, causing broad-spectrum microbial death.
Which antiseptic is preferred for surgical hand scrubs and preoperative patient skin preparation due to its persistent residual antimicrobial activity?
Answer: Chlorhexidine gluconate
Chlorhexidine gluconate binds to skin proteins and provides prolonged residual activity lasting several hours after application, making it preferred for surgical antisepsis.
Quaternary ammonium compounds (quats) are LEAST effective against which category of microorganisms?
Answer: Mycobacteria and bacterial endospores
Quats have low activity against mycobacteria and no sporicidal activity; their cationic surfactant mechanism is ineffective against the waxy mycobacterial cell wall and resistant endospores.
The correct sequence for reprocessing contaminated reusable medical instruments before they are returned to service is:
Answer: Cleaning → Disinfection → Sterilization
Cleaning must occur first to remove organic material that would otherwise protect microorganisms, followed by disinfection or sterilization as appropriate for the item's classification.
Under the Spaulding classification, 'non-critical' items such as blood pressure cuffs and stethoscopes that contact only intact skin require which level of reprocessing?
Answer: Intermediate or low-level disinfection
Non-critical items contact only intact skin, which is a natural barrier to infection, so intermediate or low-level disinfection is sufficient per the Spaulding framework.