ABSTRACT
Pythium insidiosum is an important pathogen of mammals' species, including humans. Equine is the main species affected by this oomycete. P. insidiosum requires an aquatic environment to develop its life cycle, and the susceptible hosts are contaminated when they contact the microorganism in swampy areas. The equine pythiosis is characterized by the formation of irregular masses within the cutaneous lesions, called kunkers, which easily detach from the lesion. From these structures, it is possible to isolate P. insidiosum in pure cultures. The present study aimed to reproduce in vitro the life cycle of P. insidiosum from kunkers of equine clinical lesions. Fifteen kunkers from different horses were tested. It was observed that the discharge of zoospores occurred after 24-48 h of incubation at 37 °C in, respectively, 40 and 47 % of the kunkers evaluated. Only two samples showed no development of the asexual cycle of P. insidiosum under the conditions tested. It was possible to demonstrate that kunkers are able to restart the asexual cycle of P. insidiosum. Based on our in vitro results, we highlight the importance of these structures in the epidemiology of the pythiosis, since kunkers can be a potential source of contamination of this oomycete for aquatic environments.
Subject(s)
Horse Diseases/microbiology , Horses/microbiology , Pythiosis/microbiology , Pythiosis/veterinary , Animals , Horse Diseases/epidemiology , Pythiosis/epidemiology , Pythium/isolation & purification , Reproduction, AsexualABSTRACT
Com o aumento da produtividade na piscicultura, os peixes são expostos a altas densidades de estocagem que podem levar ao estresse e imunossupressão. Essa condição favorece a ocorrência de infecções, entre elas a saprolegniose que afeta os peixes e seus ovos, causando sérios prejuízos econômicos aos piscicultores. Dessa forma, compostos químicos eficazes e "ambientalmente amigáveis" são almejados para o controle da doença. O objetivo do presente estudo foi avaliar a suscetibilidade in vitro de 12 isolados de Saprolegnia spp., provenientes dos peixes-rei dulceaquícolas Odontesthes bonariensis e O. humensis. Para isso, testes de suscetibilidade, avaliando a inibição do crescimento micelial de Saprolegnia spp., foram realizados frente a seis químicos (cloreto de sódio, formaldeído, permanganato de potássio, iodopovidona, sal marinho e sal marinho iodado) nas concentrações seriadas de 0 a 10.000ppm. Os resultados obtidos evidenciaram que o formaldeído e o permanganato de potássio, em concentrações a partir de 10 e acima de 100ppm, respectivamente, inibiram o crescimento micelial de isolados Saprolegnia spp.. Já a iodopovidona e os compostos salinos não evidenciaram atividade antimicrobiana em nenhuma das concentrações testadas (0-10.000ppm). Embora os resultados in vitro demonstrem que formaldeído e permanganato de potássio sejam promissores no controle da saprolegniose, estudos futuros deverão avaliar a eficácia e o efeito in vivo desses compostos nos peixes-rei O. bonariensis e O. humensis.
The productivity in fish farming has been increasing and consequently the fish are submitted to high stocking densities which usually cause stress and immunosuppression. These conditions determine the occurrence of a series of infections, including saprolegniosis. This disease affects fish and eggs from freshwater determining relevant economic losses to fish farmers. Thus, to avoid outbreaks, are being sought effective chemical agents that are "environmentally friendly". The aim of this study was to evaluate the in vitro susceptibility of 12 isolates of Saprolegnia spp. from the silversides Odontesthes bonariensis and O. humensis. Susceptibility tests evaluating inhibition of mycelial growth of Saprolegnia spp. were performed using six chemicals (sodium chloride, formaldehyde, potassium permanganate, povidone-iodine, sea salt and iodized sea salt) in concentrations from 0 to 10,000ppm. The results displayed that formaldehyde at the concentration of 10ppm, and potassium permanganate at concentrations above 100ppm, were able to inhibit the mycelial growth of isolates of Saprolegnia spp. However, povidone-iodine and saline compounds exhibited no antimicrobial activity on Saprolegnia spp. Although the in vitro results showed that formaldehyde and potassium permanganate could be promising in controlling saprolegniosis, further studies should be performed to evaluate the in vivo efficacy of these compounds as well as to verify the toxicity of the chemicals to the silversides O. bonariensis and O. humensis.
