What Is the Difference Between Sterile and Aseptic?

What Is the Difference Between Sterile and Aseptic?

For proper cleanroom operation with the best possible outcomes, it is critical to understand the difference between two often misunderstood terms, sterile and aseptic. Sometimes these two terms are used interchangeably. However, they are distinct concepts and techniques that are often used together. What they have in common is the fact that they are both used to control contamination by microbial contaminants.


According to the CDC, sterilization is “the use of a physical or chemical procedure to destroy all microorganisms, including large numbers of resistant bacterial spores.” [https://www.cdc.gov/oralhealth/infectioncontrol/glossary.htm#S] With this in mind, a truly sterile environment requires the complete elimination and therefore, absence of any type of microorganism. These organisms include bacteria, fungus, and spores.

Sterilization requires an understanding of the types and sources of contamination and rigorous protocols to avoid and eliminate contamination. Humans are the most common source of contamination in cleanrooms and maintaining sterile conditions. Therefore, in addition to proper cleaning protocols, training, gowning, and other cleanroom best practices are required.


An aseptic process is still related to microorganisms; however, this is about creating and maintaining a specific state of sterility. This does not eliminate all microorganisms. Instead, it is about eliminating contamination from unwanted microorganisms and ensuring none will be introduced into the sample. Asepsis is the prevention of contamination from microorganisms in the cleanroom and on tissues and materials to maintain the state that was achieved through killing, removing, or excluding specific organisms.

Sterilization and Aseptic Processes

While both terms are related to microorganisms, the real difference is exposed in the techniques used to achieve these states. In many ways, sterilization is a much simpler process. Because the desired outcome is to remove any and all contaminants, much more direct approaches can be used. There is no need to use caution regarding specific types of microorganisms because the idea is to eliminate all of them. Reaching aseptic conditions is much more complex and requires more specific and detailed protocols. It is essential to understand what microorganisms must remain intact, and what could be harmful to the product or sample.

Helpful Terms

In order to better understand the differences between sterile and aseptic, it is helpful to understand some of the terms related to the processes. For instance, an antiseptic either destroys or inhibits microorganisms on living tissue, whereas a disinfectant destroys microorganisms on inanimate objects and surfaces, though not necessarily their spores. More specifically, a sanitizing agent is designed to reduce all forms of microbial life on inanimate surfaces, and a sterilant is a liquid or vapor-phase agent that destroys microbial life in any form including virus, bacteria, fungi and their spores.

As you can see, the two concepts, sterile and aseptic, have much in common. However, through a better understanding of the differences, we can ensure a cleanroom and outcomes free of contamination.