Table 9.

Possible mechanisms of plasmid-encoded resistance to antiseptics and disinfectants

Chemical agentExamplesMechanisms
Antiseptics or disinfectantsChlorhexidine salts(i) Inactivation: not yet found to be plasmid mediated; chromosomally mediated inactivation; (ii) efflux: some S. aureus, some S. epidermidis; (iii) Decreased uptake(?)
QACs(i) Efflux: someS. aureus, some S. epidermidis; (ii) Decreased uptake(?)
Silver compoundsDecreased uptake; no inactivation (cf. mercury compounds)
Formaldehyde(i) Inactivation by formaldehyde dehydrogenase; (ii) Cell surface alterations (outer membrane proteins)
Acridinesa Efflux: some S. aureus, some S. epidermidis
DiamidinesEfflux: some S. aureus, someS. epidermidis
Crystal violeta Efflux: some S. aureus, some S. epidermidis
Other biocidesMercurialsb Inactivation (reductases, lyases)
Ethidium bromideEfflux: someS. aureus, some S. epidermidis
  • a Now rarely used for antiseptic or disinfectant purposes.

  • b Organomercurials are still used as preservatives.