Comprehensive assessment of triclosan-induced toxicity: impacts on zebrafish development, mammalian cell viability and microbial activity

PURPOSE: The aim of the study was to evaluate the toxicity of triclosan in the Danio rerio model and mammalian cells, as well as to assess its antimicrobial and antibiofilm activity against selected bacterial pathogens. METHODS: Triclosan toxicity was assessed in Danio rerio embryos in accordance with OECD Test Guideline 236: Fish Embryo Acute Toxicity (FET) Test. Cytotoxicity was evaluated in vitro using the MTT assay on human dermal fibroblasts (BJ) and rat cardiomyoblasts (H9c2). Antimicrobial activity was assessed via broth microdilution method following EUCAST guidelines and antibiofilm effects were evaluated through minimum biofilm inhibitory concentration (MBIC) assays for each tested strain. RESULTS: ​= ​28.44 ​μg/mL for BJ cells and 25.36 ​μg/mL for H9c2 cells). Antimicrobial tests demonstrated MIC values ranging from 0.24 ​μg/mL (Lactobacillus acidophilus) to 3.9 ​μg/mL (Enterococcus faecalis), with corresponding MBC values up to 7.8 ​μg/mL. MBIC values ranged from 0.03 to 0.12 ​μg/mL, confirming potent antibiofilm activity. CONCLUSIONS: Triclosan demonstrates high antimicrobial efficacy and inhibits bacterial biofilm formation. However, its toxicity towards aquatic organisms, including Danio rerio, and its cytotoxic effects on mammalian cells raise concerns.