What is the key difference between disinfection and sterilization?

• A. Disinfection reduces but does not eliminate all pathogens; sterilization inactivates all microorganisms
• B. Sterilization reduces pathogens but not all; disinfection eliminates all
• C. Disinfection and sterilization are the same
• D. Sterilization only targets viruses

Answer: (A)

The essential difference is the extent of microbial inactivation. Disinfection lowers the number of viable microorganisms to a level considered safe but does not guarantee that all are eliminated; some resistant organisms, including spores in many cases, may survive. Sterilization is the complete destruction or inactivation of all forms of microbial life, including bacteria, viruses, fungi, and spores. Methods used for sterilization—such as steam under pressure, dry heat, or validated chemical sterilants—are designed and tested to achieve true sterility, while disinfection aims to reduce the microbial load to a safe level rather than to total elimination. In practice, items that must contact sterile body sites are sterilized, whereas surfaces and instruments that only touch skin or mucous membranes are disinfected to an acceptable level.