Occurrence of mercury-resistant Pseudomonas in emulsion formulations preserved with phenylmercuric acetate.
Synopsis The occurence of mercury-resistant pseudomonads in a seemingly well-preserved toiletry formulation is reported. Microorganisms identified as presumptive Pseudomonas aeruginosa have been isolated from a water-in-oil emulsion despite the inclusion of 0.007%phenylmercuric acetate (PMA) as preservative and also from an emulsion containing 0.002% PMA. Pseudomonads were capable of surviving in these emulsions for up to 3 and 12 months respectively. Culture studies confirmed that the isolates were initially resistant to maximum levels of PMA permitted in shampoos and hair creams according to EEC regulations. Microbial resistance of this nature emphasises the importance of strict attention to plant hygiene and good manufacturing practice.
Dixon
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Beecham Products Research Department, Randalls Road, Leatherhead, Surrey KT22 7RX.
Dolan
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