Which of the following are classified as high-level disinfectants?

High-level disinfectants are substances that can kill all microorganisms, except large numbers of bacterial spores, and are often used for critical items that cannot withstand higher temperatures of sterilization. Glutaraldehyde and ortho-phthalaldehydes fit this classification because they are both effective against a broad spectrum of microorganisms, including bacteria, viruses, and fungi.

Glutaraldehyde is a well-known high-level disinfectant that is commonly used in healthcare settings for the disinfection of heat-sensitive medical instruments. It achieves its effectiveness through alkylation, which disrupts the bacterial cell wall. Ortho-phthalaldehydes, likewise, provide high-level disinfection through a similar mechanism, making them effective choices in environments requiring stringent infection control procedures.

In contrast, other substances listed, such as quaternary ammonium compounds and certain phenolics, do not meet the criteria for high-level disinfection as their antimicrobial spectrum is more limited. Quaternary ammonium compounds are typically classified as low- to intermediate-level disinfectants and may not effectively kill certain types of pathogens, particularly in the presence of organic matter. Similarly, phenolic compounds may also not achieve the required efficacy against all pathogens to be classified as high-level disinfectants.