Efficacy of tinidazole for treatment of cats experimentally infected with Tritrichomonas foetus

OBJECTIVE: To determine the efficacy of tinidazole for treatment of cats with experimentally induced Tritrichomonas foetus infection. ANIMALS: 8 specific-pathogen-free kittens. PROCEDURES: Tinidazole was tested for activity against a feline isolate of T foetus in vitro. Kittens were infected orogastrically with the same isolate and treated or not with tinidazole (30 mg/kg, PO, q 24 h for 14 days). Amoxicillin was administered 28 weeks after completion of tinidazole administration to induce diarrhea. Feces were repeatedly tested for T foetus by use of PCR assay and microbial culture for 33 weeks. RESULTS: Tinidazole killed T foetus at concentrations >or= 10 microg/mL in vitro. In experimentally induced infection, tinidazole administered at 30 mg/kg decreased T foetus below the limit of molecular detection in 2 of 4 cats. Recrudescent shedding of T foetus, as elicited by amoxicillin-induced diarrhea, was diminished in cats that received prior treatment with tinidazole. CONCLUSIONS AND CLINICAL RELEVANCE: Although tinidazole decreased the detection of T foetus and treated cats were resistant to later efforts to incite the infection, inability of tinidazole to eradicate infection in many cats poses a serious impediment to the drug's effectiveness in practice.