Influence of Temperature on the Efficacy of 2-Phenoxyethanol as a Preservative for Adsorbed Diphtheria-Purified Pertussis-Tetanus Combined Vaccine

The efficacy of two antimicrobial preservatives, 2-phenoxyethanol (2-PE) and Thimerosal, was compared in adsorbed diphtheria-purified pertussis-tetanus combined vaccine (DPT vaccine). Thimerosal had strong microbicidal activity against Gram-positive bacteria, Gram-negative bacteria, yeast and fungi at 25°C and 4°C. 2-PE also had microbicidal activity against these microorganisms, only had microbistatic activity against fungi at 4°C. Neither 2-PE nor Thimerosal affected the potency or toxicity of the DPT vaccine. These data suggest that 2-PE has weaker antimicrobial activity than Thimerosal against yeast and fungi in DPT vaccine at low temperatures.