Peer-reviewed veterinary case report
Cat with persistent Cytauxzoon felis infection after atovaquone
By Hartley, Ashley N et al.·Published in Journal of veterinary internal medicine·2020·Department of Clinical Sciences, United States·View original on PubMed →
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Original publication title: Cytauxzoon felis cytochrome b gene mutation associated with atovaquone and azithromycin treatment.
- Species:
- cat
Plain-English summary
A cat with cytauxzoonosis, a serious infection caused by a parasite, was treated with atovaquone and azithromycin but remained persistently infected. Although the cat's anemia improved slightly after treatment, tests showed that the parasite had developed mutations that made it resistant to the medication. Even after receiving a higher dose of atovaquone, the mutations persisted, indicating that the treatment was not effective in clearing the infection. This case highlights the potential for resistance in parasites and the need for alternative treatment options.
People also search for: cat cytauxzoonosis treatment · atovaquone resistance in cats · azithromycin for cat infections
Abstract
BACKGROUND: Atovaquone and azithromycin (A&A) with supportive care improve survival rates in cats with cytauxzoonosis. Resistance to atovaquone via parasite cytochrome b gene (cytb) mutations occurs in other Apicomplexan protozoans but is not described in Cytauxzoon felis. OBJECTIVE: To serially characterize the C. felis cytb sequences from a cat that remained persistently infected after A&A treatment. ANIMAL: A cat with naturally occurring C. felis infection. METHODS: Case report of the anemic cat persistently infected with C. felis before, during and after A&A treatment. Cytauxzoon felis cytb genes were amplified and sequenced before, during and after A&A treatment. RESULTS: Cytauxzoon felis was detected before, during and after A&A treatment including samples collected 570 days after treatment. After A&A treatment, the cat's anemia improved slightly. Cytb sequencing revealed only wild-type cytb methionine (M128) in samples collected before treatment. In samples collected after treatment, the cytb coded for isoleucine (M128I) and valine (M128I) at 2- and 4-months after treatment. These M128I and M128V mutations persisted even after a repeat treatment course with a higher dose atovaquone combined with the standard dose of azithromycin. CONCLUSIONS AND CLINICAL IMPORTANCE: This report documents C. felis atovaquone resistance associated with M128 cytb mutations. This study suggests parasites with mutations of cytb M128 can be selected and impart resistance to A&A treatment even with higher atovaquone dosing.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/33146909/