Table 11.

qac genes and resistance to quaternary ammonium compounds and other antiseptics and disinfectants

Multidrug resistance determinantaGene locationResistance encoded to
qacA pSK1 family of multiresistant plasmids, also β-lactamase and heavy-metal resistance familiesQACs, chlorhexidine salts, diamidines, acridines, ethidium bromide
qacB β-Lactamase and heavy-metal resistance plasmidsQACs, acridines, ethidium bromide
qacCb Small plasmids (<3 kb) or large conjugative plasmidsSome QACs, ethidium bromide
qacDb Large (50-kb) conjugative, multiresistance plasmidsSome QACs, ethidium bromide
  • a The qacK gene has also been described, but it is likely to be less significant thanqacAB in terms of antiseptic or disinfectant tolerance.

  • b These genes have identical target sites and show restriction site homology.