Microemulsions are membrane‐active, antimicrobial, self‐preserving systems

• Published in: Journal of applied microbiology 2000-07, Vol.89 (1), p.32-39
• Main Authors: Al‐Adham, I.S.I., Khalil, E., Al‐Hmoud, N.D., Kierans, M., Collier, P.J.
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - pharmacology; Biological and medical sciences; Biotechnology; Chemical Phenomena; Chemistry, Physical; Emulsions - chemistry; Emulsions - pharmacology; Fundamental and applied biological sciences. Psychology; Health. Pharmaceutical industry; Industrial applications and implications. Economical aspects; microemulsions; Microscopy, Electron; Miscellaneous; Oleic Acids; Pseudomonas aeruginosa; Pseudomonas aeruginosa - drug effects; Pseudomonas aeruginosa - ultrastructure; Staphylococcus aureus - drug effects; Staphylococcus aureus - ultrastructure; Surface-Active Agents; Viscosity
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1046/j.1365-2672.2000.01078.x

Microemulsions are physically stable oil/water systems that have potential use as delivery systems for many pharmaceuticals which are normally of limited use due to their hydrophobicity, toxicity or inability to access the site of action. It has been suggested that microemulsions are self‐preserving antimicrobials in their own right, although there is little evidence to support this. In this experiment, microemulsions of various compositions were formulated and tested for their stability and antimicrobial action. The physical stability of the different microemulsions was assessed by centrifugation at 4000 g and by storage in a water bath at 37 °C for one month, during which no phase separation was observed. The antimicrobial activity of the microemulsions was tested using the compendial method, observation of the kinetics of killing, and transmission electron microscopy (TEM) of microemulsion‐exposed cultures of Pseudomonas aeruginosa PA01. These latter experiments on Ps. aeruginosa indicated distinct signs of membrane disruption. The results indicated that the microemulsions are self‐preserved, and that their killing of microbial cultures is very rapid and may be the result of membrane activity.