The Development of Resistance to Antibiotics From Bacteria Exposed to Triclosan and Triclocarban in Lake Ontario

Triclocarban (3,4,4'-trichlorocarbanilide) (TCC) and Triclosan (2,4,4'-trichloro-2'-hydroxydiphenyl ether) (TCS) are antimicrobials used extensively in soaps and detergents. They're known to bypass wastewater treatment plants and bioaccumulate in aquatic sediments. Their accumulation leads to an increase in bacterial exposure, which may lead to both antiseptic and antibiotic resistance, known as cross-resistance. This study investigates the occurrence of cross-resistance with bacteria exposed to TCS and TCC in Lake Ontario sediments. Sediment samples were chosen at various sites with a high probability of TCS and TCC exposure. The bacteria were enriched with 5mg/L TCS (equivalent to environmental concentrations) and the top biodegraders were tested for antibiotic resistance. Relationships were seen with top TCS and TCC degraders in Lake Ontario and antibiotic resistance. A site along Durand Eastman Beach in Lake Ontario had TCS and TCC degraders that were resistant to almost 95% of common antibiotics. Few TCS and TCC degraders had little antibiotic resistance. Future applications with non-antibiotic resistant TCS and TCC degraders, however, could be used in wastewater treatment to decrease concentrations of antiseptics and therefore decrease bacterial exposure in our environment.