the effect of sub-minimum inhibitory concentration (s-mic) of ciprofloxacin & ampicillin on hemolysin activity of escherichia coli

background and objectives: sub-minimum inhibitory concentration (s-mic) can induce changes in morphology, virulence factors and biochemical properties ofbacterial pathogens. the goal of this study is to determine the sub-mic effect of ciprofloxacin and ampicillin on the haemotytic activity of e. coli. material and methods:two clinical isolates of e. coli with high heamolytic activity was selected. changes in haemolytic activity of the isolates was assessed after exposing them to mic and sub-mic of ciprofloxacin and ampicillin. results: ciprofloxacin decreased haemolytic activity at 1/2, 1/4 and 1/8 sub-mic, whereas ampicillin showed no effect on haemolytic activity. conclusion: we conclude that sub-mic concentrations of ciprofloxacin decreased the haemolytic activity of e. coli, wherease ampicillin had no such effect