Experimental Pythium aphanidermatum Infection in Rabbits.

Pythium aphanidermatum is a common plant pathogen, reportedly capable of human infection. This study investigated whether P. aphanidermatum can infect domestic rabbits. Four rabbits were inoculated with P. aphanidermatum subcutaneously and evaluated for 30 days. Blood and tissue samples were collected from all animals. The animals developed palpable nodules 5-10 days after inoculation. Necropsy revealed caseous nodular lesions characterized histopathologically by pyogranulomatous inflammation containing hyphae in the necrotic areas. P. aphanidermatum was isolated from the caseous material and anti-P. aphanidermatum antibodies were detected by serological examination. This is the first report of experimental P. aphanidermatum infection in mammals. The results demonstrate that this oomycete can produce infection at the inoculation site and induce an immune response. The results suggest that P. aphanidermatum may be undergoing adaptation to vertebrate hosts.

Isolamento e caracterização de espécies de Pythium de ambientes aquáticos no Estado do Rio Grande do Sul e avaliação da patogenicidade em modelo experimental / Isolation and characterization of Pythium species from swampy areas in the Rio Grande do Sul, Brazil, and evaluation of pathogenicity in an experimental model

Foram coletadas 186 amostras de água de ambientes pantanosos em 13 municípios das regiões Sul, Central e Oeste do Rio Grande do Sul, Brasil, com o objetivo de isolar e caracterizar espécies de Pythium e avaliar a sua patogenicidade empregando coelhos como modelo experimental. Em 11,8% (n=22) das águas coletadas foram isoladas diferentes espécies de Pythium incluindo: P. insidiosum (n=1), P. catenulatum (n=3), P. pachycaule voucher (n=1), P. rhizo-oryzae (n=3), P. torulosum (n=4) e Pythium spp. (n=10). Zoósporos desses micro-organismos foram produzidos in vitro e inoculados por via subcutânea em coelhos, os quais foram avaliados durante 45 dias. Dentre os oomicetos testados, apenas P. insidiosum evidenciou patogenicidade, causando pitiose no modelo experimental, evidenciando que, em nossas condições, apenas esta espécie de Pythium é patógena para mamíferos.(AU)

One hundred and eighty-six water samples from swampy areas were collected in 13 municipalities of South, Central and West regions of Rio Grande do Sul, Brazil, in order to isolate and characterize Pythium species and assess their pathogenicity using rabbits as experimental model. Different Pythium species were isolated from 22 (11.8%) water samples, including P. insidiosum (n=1), P. catenulatum (n=3), P. pachycaule voucher (n=1), P. rhizo-oryzae (n=3), P. torulosum (n=4) e Pythium spp. (n=10). Zoospores of these microorganisms were produced in vitro and inoculated subcutaneously into rabbits, which were assessed over 45 days. Only P. insidiosum showed pathogenicity, causing pythiosis in the experimental model.(AU)

Treatment of experimental pythiosis with essential oils of Origanum vulgare and Mentha piperita singly, in association and in combination with immunotherapy.

This study investigated the in vivo antimicrobial activity of the essential oils of Origanum vulgare and Mentha piperita both singly, associated and in combination with immunotherapy to treat experimental pythiosis. The disease was reproduced in 18 rabbits divided into six groups (n=3): group 1, control; group 2, treated with essential oil of Mentha piperita; group 3, treated with essential oil of Origanum vulgare; group 4, treated with commercial immunotherapic; group 5, treated with a association of oils of M. piperita and O. vulgare and group 6, treated with a combination of both oils plus immunotherapy. Essential oils were added in a topical cream base formula, and lesions were treated daily for 45 days. The animals in groups 4 and 6 received a dose of immunotherapeutic agent every 14 days. The results revealed that the evolution of lesions in groups 5 and 6 did not differ from one another but differed from the other groups. The lesions of group 5 increased 3.16 times every measurement, while those of group 6 increased 1.83 times, indicating that the smallest growth of the lesions occurred when the combination of therapies were used. A rabbit from group 5 showed clinical cure at day 20 of treatment. This research is the pioneer in the treatment of experimental pythiosis using essential oils from medicinal plants and a combination of therapies. This study demonstrated that the use of essential oils can be a viable alternative treatment to cutaneous pythiosis, particularly when used in association or combination with immunotherapy.