Effect of ciprofloxacin on stationary bacteria studied in vivo in a murine granuloma pouch model infected with Escherichia coli.

A granuloma pouch model in mice was used to investigate the effect of ciprofloxacin in vivo on cells of Escherichia coli (Neumann) under stationary growth conditions. The animals were treated up to three times intraperitoneally with 2.5, 10 or 40 mg/kg ciprofloxacin 24 h after infection. The numbers of viable bacteria in the pouch exudate were determined over a period of 24 h. A rapid decline of more than 1 logarithmic unit of the number of colony forming units was observed after 2-4 h with all treatment schedules. The effect on stationary cells was more pronounced with the high dose of ciprofloxacin and also dependent on the frequency of treatment. Ciprofloxacin penetrated well into the pouch exudate and reached concentrations of 2.08 +/- 0.16 microgram/ml and 0.1 +/- 0.05 microgram/ml 2 h after treatment with 40 and 2.5 mg/kg, respectively. The results of this study demonstrate that ciprofloxacin is effective in the treatment of a local inflammatory abscess in mice harbouring a stationary population of E. coli.