Microbial barriers and how they work

Microbial barriers and how they work

There is a wide range of materials that can be used to create an effective microbial barrier. The basis of an effective microbial barrier is to ensure that it does not have openings that are large enough for microbes to pass through. Human skin is considered a very effective barrier to microbes. However, it can be compromised. Skin that has a hole, such as a wound, is no longer effective as a barrier and microbes can enter the body through the wound. In addition, mucous membranes -- which are similar to skin but thinner and line areas such as the inside of the mouth, throat and urogenital tracts -- are less-effective barriers to microbes.

Porosity is used to refer to the amount of empty space in a material.  A non-porous material is an effective microbial barrier because there is no space for the microbes to travel through. However, it is possible to create an effective barrier by putting several layers of porous materials together or controlling the pore sizes of a single layer so that they are too small for the microbes to pass through.

Most molecules in the air are extremely small, consisting of a few atoms. Microbes, although microscopic, are much larger than any gas molecule. Microbial spores can exist as individual entities or clusters, or they can be attached to inert particles such as dust particles. Therefore, many effective microbial barriers can be penetrated by sterilising gases but not microbes.

The packaging around medical devices that allow those devices to be sterilised, provides a microbial barrier and maintains sterility effectively up to the point of use is known as a sterile barrier system. A sterile barrier system is an essential part of a sterile medical device.


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