Sensitivity of Pseudomonas aeruginosa envelope mutants to alkylbenzyldimethylammonium chlorides

J Pharm Sci. 1979 Feb;68(2):146-9. doi: 10.1002/jps.2600680207.


A series of stepwise polymyxin-resistant envelope mutants of Pseudomonas aeruginosa was used to test the activity of a homologous series (C10-C18) of alkylbenzyldimethylammonium chlorides. A sterilization kinetics procedure in deionized water was devised to avoid amounts quaternary compound above the critical micelle concentration. In all cases, there was a linear relationship between the logarithm of the rate of change of the colony count with time and the logarithm of the homolog concentration. For all strains, there was a linear relationship between alkyl chain length and the concentration required to reduce the colony count to 10% in 2 hr. The stepwise series of polymyxin-resistant strains increased in resistance to polymyxin about threefold for each step. In general, this increase resulted in a similar increase in resistance to the quaternary compound. It is proposed that death in this system may primarily be a consequence of damage to the outer membrane rather than to the cytoplasmic membrane.

MeSH terms

  • Anti-Infective Agents, Local / pharmacology*
  • Cell Membrane / drug effects
  • Microbial Sensitivity Tests
  • Osmolar Concentration
  • Polymyxin B / pharmacology
  • Pseudomonas aeruginosa / drug effects*
  • Pseudomonas aeruginosa / genetics
  • Quaternary Ammonium Compounds / pharmacology*
  • Structure-Activity Relationship
  • Time Factors


  • Anti-Infective Agents, Local
  • Quaternary Ammonium Compounds
  • Polymyxin B