Pythium insidiosum, an aquatic oomycete with pathogenic potential in mammals, causes gastrointestinal and cutaneous disease in dogs. Mefenoxam, an agricultural anti-oomycotic compound, has a demonstrated the ability to inhibit P. insidiosum growth in vitro and has been associated with efficacy in treating gastrointestinal pythiosis in several case reports. Electronic medical records of dogs seen at University of Florida Small Animal Hospital and treated with mefenoxam between 2013 and 2020 were searched. Dogs were included in this study upon previous definitive diagnosis with either organism identification using culture, PCR, or antibody ELISA, or a combination of these tests with or without supportive histopathological analysis. Since 2013, mefenoxam had been administered to 25 dogs with cutaneous pythiosis and 16 dogs with gastrointestinal pythiosis. In both gastrointestinal and cutaneous pythiosis groups, the administration of mefenoxam was associated with a survivability rate of approximately 51%. There was a statistically significant difference in the time to death between cutaneous (245 days (52-530)) and gastrointestinal (90 days (21-203)) groups; dogs infected with cutaneous pythiosis survived significantly longer after being diagnosed with the disease (p = 0.035). The dogs in this study experienced increased survival rates and time to death, in the absence of side effects due to mefenoxam, compared with previously published literature. The results of this retrospective study, with some limitations, are promising and should prompt further investigation into the use of mefenoxam in the treatment of both gastrointestinal and cutaneous pythiosis.

暂无摘要。

Pythiosis is an endemic disease in northeastern Brazil and we now report the epidemiological, clinical and pathological findings in a retrospective study of naturally occurring cases in domestic animals. From January 1985 to December 2020, the Laboratory of Animal Pathology of the Federal University of Campina Grande examined 13,542 tissue samples from necropsies and biopsies. Among these samples, 306 were diagnosed as pythiosis: 195 cases in horses, 75 in sheep, 19 in dogs, six in mules, four in cattle, three in cats, two in goats, one in a donkey and one in an ostrich. Affected equids had lesions in the skin, mammary glands and nasal cavities. Affected sheep had cutaneous, nasal and digestive lesions while cattle and goats had cutaneous lesions. Carnivores developed lesions, mainly in the alimentary tract, of sufficient severity to cause death or result in euthanasia. The single affected bird had lesions in the alimentary tract and surgical excision resulted in remission. The disease had a long and life-threatening clinical course in most affected species but resolved spontaneously in cattle. Clinical signs were directly related to the location of the lesions, which were invariably characterized by chronic inflammation associated with intralesional hyphae. Veterinary clinicians and pathologists should be familiar with the clinicopathological features of pythiosis and the wide range of susceptible animal species.

Ocular pythiosis is the second most common form of human pythiosis, and the rates of evisceration/enucleation in Thailand are 55-79%. This prospective study was conducted to evaluate treatment outcomes of the combination therapy protocol and the potential use of serum (1→3)-β-glucan (BG) and Pythium insidiosum-specific antibody (Pi-Ab) as an aid to diagnosis and monitoring of ocular pythiosis. Thirty patients were enrolled in the study and 14 (non-globe salvage) required evisceration/enucleation. The globe salvage group was significantly younger, and first ocular surgeries were performed significantly sooner than in the non-globe salvage group. Serum BG and Pi-Ab levels were similar among the 2 groups over time. In vitro susceptibility testing of antifungal agents revealed relatively high minimum inhibitory concentrations and lack of synergistic effect. Serum BG and Pi-Ab would not be useful in diagnosis and monitoring of ocular pythiosis. Until effective antimicrobial agents are discovered, ocular surgeries are still the mainstay therapy in Thailand.

OBJECTIVE: Human pythiosis is a life-threatening disease for which no standard treatment protocols with proven efficacy exist. We present the results of our institutional pythiosis treatment protocol, composed of surgery, antifungal agents, iron chelator (only vascular cases) and immunotherapy.
METHODS: We retrospectively analysed patients with proven vascular and ocular pythiosis in King Chulalongkorn Memorial Hospital from April 2003 to May 2013. Fisher\'s exact test and Wilcoxon\'s rank-sum test were used. The MICs of seven antifungal agents and combination drugs were investigated in eight clinical Pythium insidiosum strains.
RESULTS: Eighteen patients were evaluated. Disease-free surgical margins were obtained in all surviving patients with vascular pythiosis (P = 0.08). Patients who underwent eye enucleation were significantly older than those who did not (P < 0.05). Patients with vascular or ocular pythiosis did not differ significantly in the median time from disease onset to first surgery or in the relationship between the type of P. insidiosum antigen and treatment outcomes. In vitro susceptibility profiles of all isolates demonstrated that no single agent or combination treatment was substantially more effective than the others. The highest MIC was detected for amphotericin B, followed in order by voriconazole, fluconazole, anidulafungin, caspofungin, itraconazole and terbinafine. No synergistic effects of the combination drug treatments were found.
CONCLUSIONS: Surgery with adequate surgical margins is a crucial determinant of survival in patients with vascular pythiosis. Itraconazole and terbinafine do not have synergistic effects on Thai P. insidiosum strains. The role of immunotherapy remains inconclusive for both vascular and ocular pythiosis.

Twenty-one cases of pythiosis in horses (n = 10), dogs (n = 9) and cattle (n = 2) were investigated. The aetiology in all cases was confirmed by immunohistochemistry. Data related to the clinical course and outcome and localization of the lesions were obtained from pathology reports. The equine lesions consisted of fibrotic tissue with multiple, often coalescing, areas of immature granulation tissue encircling eosinophilic cores. Affected dogs had gastrointestinal and/or cutaneous lesions with either or both of a granulomatous/pyogranulomatous or necrotizing eosinophilic inflammatory reaction. In cattle, cutaneous lesions were characterized by multifocal to coalescing granulomas with surrounding fibrosis. The number of intralesional hyphae, the distribution of hyphae, the presence of angioinvasion and the nature of the local inflammatory reactions were associated with the different types of lesions observed.