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Occurrence of mercury-resistant Pseudomonas in emulsion formulations preserved with phenylmercuric acetate

H Dixon1, C S Dolan

  • 1Beecham Products Research Department, Randalls Road, Leatherhead, Surrey KT22 7RX.

International Journal of Cosmetic Science
|May 28, 2009
PubMed

Insights

Mercury-resistant Pseudomonas aeruginosa were found in toiletry formulations preserved with phenylmercuric acetate (PMA). These bacteria survived in products with PMA levels permitted by regulations, highlighting hygiene concerns.

Area of Science:

  • Microbiology
  • Cosmetic Science
  • Environmental Health

Background:

  • Preservatives are crucial in preventing microbial contamination in toiletry formulations.
  • Phenylmercuric acetate (PMA) is a commonly used preservative in cosmetics.
  • Microbial resistance to preservatives poses a significant challenge in product safety.

Purpose of the Study:

  • To investigate the occurrence of mercury-resistant pseudomonads in toiletry formulations.
  • To determine the survival capability of these microorganisms in the presence of PMA.
  • To assess the implications of microbial resistance on cosmetic product preservation.

Main Methods:

  • Isolation and identification of microorganisms from water-in-oil emulsion toiletry formulations.
  • Microbiological culture studies to assess survival rates in different PMA concentrations.
  • Determination of mercury resistance levels in isolated bacterial strains.

Main Results:

  • Presumptive Pseudomonas aeruginosa strains were isolated from emulsions containing 0.007% and 0.002% PMA.
  • Pseudomonads survived in these emulsions for up to 3 and 12 months.
  • Isolated strains exhibited resistance to PMA levels permitted in cosmetic products by EEC regulations.

Conclusions:

  • The presence of mercury-resistant pseudomonads in preserved toiletry formulations is a concern.
  • This finding underscores the potential for microbial adaptation and resistance to preservatives.
  • Strict adherence to plant hygiene and good manufacturing practices is essential to prevent contamination.

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