Abstract

Activated charcoal (AC) has been utilized in the absorption of toxins from the intestinal tract of animals as well as humans. Some studies however have implied microbial adsorption at the interstices of AC surface. Activated charcoal has also been suggested and used as a treatment option for diarrhea. Metronidazole, a nitroimidazole derivative has been successfully utilized in the treatment of Clostridium difficile-associated diarrhea (CDAD) as well as anaerobic infections. It has little or no activity against Escherichia coli 0157:H7. The purpose of this study is to compare the activity of metronidazole-AC combination to that of AC alone in the management of E. coli 0157: H7. Utilizing an in vitro pharmacodynamic model in triplicate, E. coli 0157:H7 was exposed to peak concentrate of 32 mg/L of metronidazole daily. Time kill curve was analyzed for time to 3 log killing slope and re-growth of the micro-organism. Minimal inhibitory concentrations (MICs) for pre-exposure to metronidazole were 1 mg /L. Metronidazole alone did not decrease the starting inoculums of E. coli 0157:H7. However, the metronidazole - AC combination achieved a 2 – log killing against E. coli 0157:H7 as well as a significant reduction in the starting inoculums below the lower limit of bacterial counting accuracy (LLA) when AC alone was used. The metronidazole -AC MIC for E.coli increased 5 fold when compared to utilization of AC alone or metronidazole alone. Metronidazole -AC will be useful in the treatment of mild to moderate diarrhea associated with E.coli 0157:H7.

Key words: Metronidazole, a