Figure 2.

Quaternary ammonium compound (QAC) resistance and structure

(A) Overview of QAC resistance mechanism in S. aureus. Once a QAC enters the cell it engages with the negative transcriptional regulator QacR. Upon binding qacA is overexpressed, resulting in the production and incorporation of QacA efflux pumps on the cell surface to expel QACs. Homologous mechanisms occur in other organisms.

(B) Structures of common QAC compounds (benzylalkonium chloride (BAC), cetylpyridinium chloride (CPC), didecyldimethylammonium chloride (DDAC)).