Difference between Sterilization and Disinfection

Microorganisms come in all shapes and sizes. The means used to fight them work like a specific key to a specific lock – one has to know what kind of microbes one is battling with in order to choose a weapon. Although both sterilization and disinfection describe microbial control, these techniques are applied in different cases. In this article, we will discuss the differences between the two and will learn how to apply them properly.


Sterilization vs Disinfection
A front-loading autoclave sterilization machine

Sterilization describes a process in which chemical agents reduce bacteria and other microorganisms to a safe level (according to public health standards).

This is an effective procedure that kills all free forms of microorganisms, including their spores.

There is a variety of sterilization methods. Among them are autoclaving (a high pressure/temperature steam sterilization process which utilizes high temperature and pressure to kill microorganisms), low-temperature toxic gas, and liquid sterilants.

Disinfection can be performed on a floor using a disinfecting liquid applied to a mop

Disinfection describes a process of chemical destruction resulting in irreversible inactivation of bacteria. Most disinfectors kill only living cells, which is why the microbial population is only controlled to an extent when disinfected.

Disinfectors can be of various strengths. In the United States, all disinfecting products must be approved and registered by the Environmental Protection Agency (EPA) before they go on the market. The EPA classification divides all disinfectors into four categories:

  • sporicides: have the ability to kill spores when used in sufficient concentration and under suitable conditions).
  • hospital strength disinfectants: can kill all the viable microorganisms in the presence of 400 ppm (parts per million) hard water and 5% organic serum.
  • broad spectrum disinfectors: can kill all most viable microorganisms, but may not kill spores.
  • simple sanitizers: for example, commonly used and relatively cheap chlorine bleach.

Sterilization vs Disinfection

What is the difference between Sterilization and Disinfection?

  • Sterilization, if performed with proper chemical agents or intense heat, according to guidelines, must reduce microorganism count by 100,000 Fold in under 1 minute contact time. An effective disinfector, on the other hand, requires a 10 minute contact time (the exact amount of time may differ depending on a specific disinfecting product).
  • Sterilization describes the process of eliminating a microbial or pathogenic population entirely. On the other hand, disinfection usually only reduces the population of such microorganisms.

We advise you to look carefully at directions provided by the manufacturer of the specific sterilizing/ disinfecting product before applying it to the specific task.

Comparison chart

Sterilization Disinfection
Uses more robust methods. High heat or chemicals. Uses less robust methods. Chemicals only.
Is applied to food, medical instruments, clothes. Is applied to surfaces, mainly.
Kills all viable microorganisms. Reduces the population of all viable microorganisms.
Requires 1 minute contact time. Requires 10 minute contact time.


In this video you can see the complete process of sterilization and disinfection of dental Instruments at Roselle Dental Center in Roselle, Illinois: