‘Quat’ preservatives in cosmetics could play a role in antibiotic resistance

The Norwegian Scientific Committee for Food Safety (VKM) claims that the use of quaternary ammonium compounds (QACs) may be contributing to a growing problem of resistant microorganisms.

In addition, the report claims that the use of QACs may not only be driving QAC resistance but also resistance to other, more important anti-microbials often used in medical treatment.

QACs, otherwise known as quats, are used as preservatives in cosmetics formulations. They can also be incorporated as conditioning agents to hair and skin care products, although the characteristics of the conditioning materials are slightly different to the preservative as they generally have longer carbon chain lengths.

According to the report, the QACs most often added to cosmetic products include benzalkonium chloride, stearalkonium chloride, cetrimonium chloride, cetrimonium bromide and cetylpyridin chloride.

VKM published the risk assessment after the Norwegian Food Safety Authority asked to know the scale of the problem related to cosmetics products.

Although VKM says that there is a lack of data on the topic, the organisation concludes that is ‘likely’ that QACs in cosmetic products will add to the selection pressure pushing towards QAC resistant products.

“QACs in cosmetic products will inevitably come into very intimate contact with skin or the mucosal linings in the mouth, and it is likely that in such products they will add to the selection pressure towards more QAC resistant microorganisms among the skin and mouth flora,”​ wrote VKM.

Resistance to QAC as an anti-microbial may in itself not present a significant concern. But, according to the researchers, resistance to one anti-microbial will often bring with it resistance to other agents that may be more commonly used in a medical setting.

One mechanism through which bacteria can become resistant relates to changes in their efflux pumps – the pumps that eject foreign bodies such as toxins and antibiotics from inside the organism. These pumps eject both QAC but also other clinically important antimicrobial agents.

If high use of QAC leads to more bacteria that can successfully eject antibiotics and toxic substances from their cells, it could lead to more widespread resistance, the report argues.

Not in ‘real life’ conditions​

While accepting that laboratory studies have shown some evidence for QAC resistance under very specific conditions, the UK cosmetics trade association says there is no evidence for this in real life situations.

“Review of the available information leads to the conclusion that these substances do not induce nor select for resistance against antibiotics used for the therapy of human diseases under actual use or “real-life” conditions,”​ he told CosmeticsDesign.

He said the ingredients are well established in the industry and no concerns have been expressed by the European Commission regarding their use.