High-level disinfection is defined as which of the following?

• A. Kills all microorganisms except spores.
• B. Kills all organisms.
• C. Removes debris.
• D. Killing only viruses.

Answer: (A)

High-level disinfection aims to inactivate most pathogenic microorganisms on surfaces or instruments, including bacteria, viruses, fungi, and many mycobacteria, but it does not destroy bacterial spores. Spore-forming organisms are highly resistant and require sterilization methods that are sporicidal to guarantee their elimination. So, the description that high-level disinfection kills all microorganisms except spores matches this goal: it neutralizes a broad spectrum of pathogens while stopping short of eradicating spores. The other ideas don’t fit the purpose: killing everything would be sterilization, removing debris is cleaning, and killing only viruses misses the full range of organisms high-level disinfection targets.