Abstract:

Enterobacter gergoviae is a conditional pathogen, which can cause urinary system, respiratory tract and blood infection in the immunocompromised population. It widely exists in water, soil and vegetables. Enterobacter gergoviae contamination is common in cosmetics, which is mainly related to its resistance to the most widely used cosmetic preservative methyl 4-hydroxybenzoate. In this paper, a batch of cosmetics contaminated by Enterobacter gergoviae were analyzed and studied in order to provide reference for the cosmetics enterprises to select appropriate preservatives. Aerobic bacterial was counted in 1 batch of cosmetics and the preservatives in 6 batches of cosmetics were tested according to the 2015 version of “Safety and Technical Standards for Cosmetics”. The contaminated bacteria in cosmetics were identified by VITEK MS and 16s rRNA gene sequencing, and transferred every month to observe the survival of Enterobacter gergoviae at room temperature. Enterobacter gergoviae was used to conduct preservative challenge test on 5 batches of cosmetics containing methylparaben. The results show that a batch of cosmetics with aerobic bacterial count exceeding the standard is identified as Enterobacter gergoviae, and the preservative methylparaben used in this batch of cosmetics is 0.15%. Enterobacter gergoviae can survive for more than 10 months under the condition of good nutrition at room temperature. Three batches of cosmetics with the methylparaben concentration of 0.2% and a batch of cosmetics with the methylparaben concentration of 0.1% + bisimidazolidinyl urea pass the preservative challenge test of Enterobacter gergoviae. Cosmetics with the methylparaben concentration of 0.1% fail the preservative challenge test of Enterobacter gergoviae. Enterobacter gergoviae is resistant to methylparaben, a commonly used preservative in cosmetics. When selecting this type of preservative, it is recommended to use Enterobacter gergoviae for preservative challenge test to determine its applicability.

Key words: Enterobacter gergoviae, preservative challenge test, methylparaben, 16s rRNA gene sequencing