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Peer-reviewed veterinary case report

Feline trichomonosis infection cleared without treatment despite drug

By Rush, Gemma Marie & Šlapeta, Jan·Published in Veterinary parasitology·2021·Sydney School of Veterinary Science, United Kingdom·View original on PubMed

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Original publication title: Evidence of self-resolution of feline trichomonosis in a pair of single household cats due to ronidazole-resistant Tritrichomonas foetus.

Species:
cat

Plain-English summary

Two cats from the same household were suffering from chronic diarrhea caused by a parasite called Tritrichomonas foetus, which is often hard to treat. Over three years, it was found that these cats had a strain of the parasite that was resistant to the common treatment, ronidazole. Surprisingly, both cats eventually cleared the infection on their own without any medication, as confirmed by follow-up tests that showed no signs of the parasite. This case suggests that some cats may recover from this infection naturally, which could help veterinarians reconsider the need for certain treatments.

People also search for: cat diarrhea treatment · Tritrichomonas foetus in cats · ronidazole resistance in cats

Abstract

Tritrichomonas foetus causes chronic large-bowel diarrhoea in cats, complicated not only by its chronicity but for its difficulty to treat, with few registered or effective products available, subsequently resulting in ronidazole frequently used off-label. The extent of T. foetus resistance to ronidazole is unknown. To demonstrate in vitro resistance of feline T. foetus to ronidazole and the self-resolution of the infection, we isolated novel T. foetus "feline" genotype strains from two cats in 2017 from the same household and monitored these cats over a three-year period. Axenic cultures of T. foetus from the cats were tested for in vitro resistance to metronidazole and ronidazole using anaerobic and aerobic culture assays. The minimum lethal concentration for the novel strains after incubation in aerobic conditions for 48 h were 50-100 μg/ml and 6.25-12.50 μg/ml for metronidazole and ronidazole, respectively. For susceptible T. foetus strains, the minimum lethal concentrations ranged from 1.56-12.50 μg/ml for metronidazole, and 0.39-3.13 μg/ml for ronidazole. The self-resolution of the infection was assessed using repeat diagnostic qPCR and culture. Whilst positive in 2018, the cat samples are no longer returning positive qPCR results in 2020 and 2021, indicating self-resolution over this period. This study demonstrated resistance to ronidazole for the first time in Australian cats and infection self-resolution without antimicrobial intervention is demonstrated. This study provides clinicians with the evidence to reduce the use of off-label ronidazole, and advice on the resolution timeframe for cats in single households.

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Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/34735847/