Ranitidine bismuth citrate and clarithromycin, alone or in combination, for eradication of Helicobacter mustelae infection in ferrets

Objective-To determine whether ranitidine bismuth citrate, clarithromycin, or a combination of ranitidine bismuth citrate and clarithromycin would be efficacious in eradication of Helicobacter mustelae infection in ferrets. Animals-60 seven-month-old ferrets. Procedure-To determine dosages of clarithromycin and ranitidine bismuth cit rate that would suppress growth of, but not eradicate infection with, H mus telae, ferrets (n = 6/group) were treated PO with clarithromycin or ranitid ine bismuth citrate at various dosages. Efficacy of treatment was then dete rmined by treating ferrets with clarithromycin alone, ranitidine bismuth ci trate alone, or clarithromycin and ranitidine bismuth citrate. Gastric biop sy specimens were obtained before, during, and at various times after treat ment and submitted for quantitative bacterial culture and histologic evalua tion. Minimum concentrations of clarithromycin that inhibited 90% of the gr owth of isolates obtained before and after treatment were determined. Results-Dosages of clarithromycin and ranitidine bismuth citrate that suppr essed growth of H mustelae were 12.5 and 24 mg/kg of body weight, PO, every 8 hours, respectively. Infection was not eradicated in ferrets treated wit h ranitidine bismuth citrate alone but was eradicated in ail 6 ferrets trea ted with clarithromycin and ranitidine bismuth citrate and in 4 of 6 treate d with clarithromycin alone. A decrease in susceptibility to clarithromycin was detected for H mustelae isolates obtained after treatment. Mild or mod erate antral gastritis was observed even in ferrets from which infection wa s eradicated. Conclusions and Clinical Relevance-A combination of ranitidine bismuth citr ate and clarithromycin was efficacious in eradicating H mustelae infection from ferrets.