Are disinfectants making microorganisms resistant?

For many years the go-to method of disinfection of surfaces and equipment has been using chemicals. Whether with chlorine or alcohol-based products, wiping surfaces has enabled the removal of microbial contamination and has been the number one tool in the fight against cross infection.

In a recent article we showed evidence that the use of chemical wipes is far less effective in killing bacteria and viruses than the use of UV-C light (link) but there is a deeper and more insidious problem with the widespread use of chemical disinfection – resistance.

In simple terms organisms that survive the cleaning process, either because as an individual they are more resistant to a substance (e.g spores) or because they have received only a partial dose, can, over time, reproduce and through mutations in their DNA pass on this trait and give rise to offspring that are increasingly resistant. Ultimately this process can lead to microorganism species that are entirely unaffected by certain chemicals removing that product as a means of combating infection.

Studies have shown (1) that certain bacteria adapt, either through cellular mutation or by the acquisition of genetic elements, to possess increasingly impermeable cell walls, meaning that the active chemical cannot enter the organism and kill it.

UV-C works differently. UV-C radiation passes directly through the cell membrane and acts directly on the organism’s DNA and RNA, breaking the molecules, resulting ultimately in the death of the organism but also preventing it from reproducing; consequently, it has no offspring and the ability to adapt or become resistant is removed. Indeed, even were some organisms to survive, due to shadowing or too low a UV dose, the nature of the germicidal process means that it is almost impossible for an organism to adapt its cell wall to such an extent that damage to its DNA would not occur with the correct exposure to UV-C.

So, in practice, the more we rely on chemical disinfection, the greater the risk that we unwittingly engineer microorganisms that are no longer killed by this means. Couple this with the relatively low kill-rate achieved in the real world and the other safety and environmental disadvantages of aggressive chemicals and wipes, and reliance on chemical disinfection becomes decreasingly attractive.

Uvisan UV-C cabinets and Cleanroom whole-room disinfection systems are proven to kill 99.99% of bacteria, viruses, spores and protozoans in minutes, without chemicals, with minimum user effort, 100% safety and importantly – no chance of resistance.

Reference:

(1) Bacterial resistance to disinfectants: present knowledge and future problems
Journal of Hospital Infection- Volume 43, Supplement 1, December 1999, Pages S57-S68
A.D.Russell