Biofilm inhibitory activity of selected medicinal plants against enterotoxigenic Escherichia coli ATCC 35401 strain

Abstract

Enterotoxigenic Escherichia coli (ETEC), a pathotype of E. coli, accounts for a significant episode of diarrhea among under five years children. In infectious diarrhea, biofilms contribute to treatment failures. Using crystal violet-based biofilm inhibition assay, we investigated chloroform and acetone extracts of nine selected medicinal plants for biofilm inhibitory activity against ETEC. Extracts that inhibit biofilm without affecting planktonic bacterial growth were further profiled by phytochemical screening and infrared spectroscopic analysis. Of the eighteen extracts investigated, only two chloroform extracts, namely; Psidium guajava and Nauclea latifolia, gave reproducible biofilm inhibitory activity of 44% and 30%, respectively, against ETEC while inhibiting growth by less than 10%. The two extracts, found to be rich in phytochemicals, showed relatively good antibiofilm activity against ETEC. Psidium guajava and Nauclea latifolia could be sources of lead compounds for development of drugs to control infectious diarrhea caused by ETEC with less selection pressure on the pathogen.