Which of the following are intermediate-level disinfectants?

• A. Alcohol and bleach (sodium hypochlorite)
• B. Hydrogen peroxide
• C. Glutaraldehyde
• D. Phenolics

Answer: (A)

Disinfectants are categorized by how broadly they inactivate microorganisms. Intermediate-level disinfectants can kill most bacteria (including mycobacteria), most viruses, and fungi, but they do not reliably kill bacterial spores. That is why alcohols and sodium hypochlorite (bleach) fit this level. Alcohols rapidly inactivate vegetative bacteria and enveloped viruses and are useful on many surfaces and noncritical instruments, but they don’t destroy spores. Bleach, when diluted and used with proper contact time, is broad-spectrum and can be tuberculocidal, making it effective for environmental surfaces and many items without becoming a sterilant.

Hydrogen peroxide is typically used as a high-level disinfectant or sterilant at the concentrations used for instrument sterilization. Glutaraldehyde is a high-level disinfectant/chemical sterilant. Phenolics are older agents with strong activity in some formulations, but they aren’t generally described as intermediate-level disinfectants in contemporary healthcare classifications.