What are the Three Levels of Decontamination in Infection Control?

Instructor: Jennifer Pettigrew

Jennifer has a master's degree in nursing and been a clinical instructor for BSN students.

You've been charged with make sure a piece of medical equipment has been properly decontaminated. How do you choose the method of decontamination? Read this lesson to find out!

Pyramid of Decontamination

You've heard of the food pyramid, but have you heard of the decontamination pyramid? Probably not, because we made it up! What's it about? The pyramid illustrates the relative quantity of items requiring each type of decontamination.

The decontamination pyramid has three major levels. The bottom level is the largest because any item that was used by a patient and needs to be used for another must be cleaned at the very least. In fact if you put an object through all of the procedures for sterilization and then find out at the end that there is still organic matter on the object, you've wasted your time and have to start over.

The next level is sterilization, which is required of objects that would like carry enough microbes (microscopic and potentially disease-causing organisms or particles such as bacteria, viruses, fungi) and come into enough contact with a person to transfer those microbes to that person. Disinfection kills most, but not necessarily all microbes.

Pyramid of Decontamination

The top level in this hierarchy of decontamination is sterilization, which kills all microbes and is required for all items coming into contact with sterile body cavities.

When items in medical facilities have been used and need to be used again, a decision has to made about the best way to decontaminate it to keep the next person who uses it from getting infected. The type of materials (or machines) you should use to accomplish decontamination depend on what the item is made of, what it was used for and what it will be used for next.



Cleaning can be thought of as the lowest intensity of the three levels of contamination, but that doesn't make it less important. Cleaning involves the act of removing organic material such as dirt and other impurities including blood, feces etc that may be contaminating the object you are decontaminating using water and detergent as well as friction when possible. In reality scrubbing with detergent and hot water is likely to remove most microbes as well.


This method removes microbes but doesn't necessarily kill them. Any item that you know will come into contact with the inside of the body should first be cleaned and then either disinfected or sterilized. It's important to understand that in order for an object to be either disinfected or sterilized it must have been properly and thoroughly cleaned first.

What Do You Clean?

Cleaning should be sufficient for items that come into contact with intact skin. In order for an item to be considered clean all visible soiling must be removed. This can be accomplished through scrubbing with a brush or other instrument (friction) or by using water/fluids under pressure (fluidics). Examples of items that can safely be used after being cleaned are floors, walls and windows.



Disinfection involves using chemicals or physical means (such as heat) to reduce the number of microbes on an object to such levels that they won't cause infection. This means that an item that has been disinfected can actually still have microorganisms, even disease-causing ones, on it.


The item must have been thoroughly prior to disinfection cleaned for disinfection to have taken place. Spores are not destroyed by typical disinfection processes. Objects thought to have been exposed to a spore-caused disease should be sterilized.

What Do You Disinfect?

Disinfection should be used on items that will touch non-sterile body spaces and mucous membranes. This includes endoscopes, vaginal specula, and ultrasound probes that are inserted into areas with mucous membranes (such as vaginal or rectal ultrasound probes). Disinfection can be accomplished using many methods including chemicals, metals, pasteurization, UV radiation.


Now imagine someone drops an endoscope (a tool that doctors use to look into a patient's stomach by inserting a tube down the throat and esophagus) on the ground in a procedure room. The gastrointestinal tract is not a sterile body area, so the best thing to go would be to immediately disinfect the object, right?


The item has to be cleaned first, as all objects have to be cleaned before attempting disinfection or sterilization. After the object is cleaned and disinfected it can be used again.



In order for an item to be considered sterilized all microbes, including spores, must be removed or destroyed. Historically steam has been used to accomplish this but as more and more medical devices are being made of plastics a greater number of low-temperature sterilization techniques are being developed.

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