Rhamdia quelen is an autochthonous fish used for aquaculture in the Northeast of Argentina. Antibiotics as growing factors in fish production had been criticized in the last years and the use of microorganisms emerged as a putative replacement. The aim of this study was to isolate autochthonous yeasts from R. quelen and to evaluate the effect of the administration over biometrical parameters of larvae under intensive culture system. Fungi were isolated from the digestive tract of wild specimens, phenotypically identified and evaluated on their ability to exert beneficial properties. One selected fungal isolate was administered, four times a day, dead or alive at 1 or 2% together with balanced feed to R. quelen larvae for 15 days. After treatment larvae were counted and weighted in order to obtain the values of survival, mean weight and total biomass. Only four Candida tropicalis isolates were obtained. None of them expressed beneficial properties. One fungal isolate was randomly selected for in vivo assays. Results indicated that only dead yeast at 1% induced a significant increment of biomass when compared with the control group (p<0.05). Survival rate was boosted significantly (p<0.05) with dead yeast and not significantly (p>0.05) with the fungal isolate. None of the treatments induced significant increments in mean weight (p<0.05). These results allowed us to propose the treatment with dead yeast at 1% as a growing factor for R. quelen, considering this microorganism as an effective prebiotic in the aquaculture of this specie.

Rhamdia quelen es un pez autóctono cultivado en el nordeste argentino. El uso de antibióticos como factores de crecimiento en acuicultura fue criticado en los últimos años y la administración de microorganismos surgió como una opción posible. El objetivo de este trabajo fue aislar levaduras autóctonas de R. quelen y evaluar el efecto de su administración sobre parámetros biométricos de larvas en cultivo intensivo. Los hongos se aislaron del tracto digestivo de especímenes de vida silvestre, se identificaron fenotípicamente y se evaluaron en cuanto a la expresión de propiedades benéficas. Se seleccionó una de las cepas y se administró cuatro veces por día, muerta o viva al 1 o 2% junto con el alimento balanceado durante 15 días. Luego del tratamiento las larvas se contaron y pesaron para obtener los valores de sobrevida, peso medio y biomasa. Sólo se obtuvieron cuatro aislamientos de Candida tropicalis. Ninguno expresó propiedades benéficas y uno fue elegido al azar para los ensayos in vivo. Solo la levadura muerta al 1% incrementó significativamente la biomasa en comparación con el control (p<0,05). La sobrevida mejoró significativamente (p<0,05) con la levadura muerta y sin significancia (p>0,05) con el hongo vivo. Ninguno de los tratamientos induce incrementos significativos del peso medio (p<0,05). Estos resultados nos permiten proponer al tratamiento con levadura muerta al 1% como un factor de crecimiento para R. quelen, considerando al microorganismo como un prebiótico efectivo para su uso en esta especie.

Os efeitos terapêuticos da formulação em gotas óticas de própolis procedentes da Argentina foram avaliados no tratamento da otite externa canina. Quarenta e oito cães com sintomas de otite externa foram distribuídos aleatoriamente em ensaio clínico duplo-cego controlado para avaliar a eficácia da formulação tópica com a própolis contra um placebo tópico no tratamento da otite externa. A preparação de própolis e placebo foi administrada em ambos os canais da orelha externa, duas vezes por dia, durante 14 dias. Ao longo do estudo, os cães foram submetidos a exame físico e à análise microbiológica de exsudatos auriculares. Os mais frequentes microrganismos isolados em meios de cultura foram: Malassezia pachydermatis (54,2%), Staphylococcus aureus (43,8%), Staphylococcus coagulase-negativo (25,0%), Pseudomonas aeruginosa (20,8%), Candida albicans (18,8%), Proteus mirabilis (16,7%), Streptococcus spp.(16,7%), Enterococcus faecalis (12,5%), Escherichia coli (12,5%), Staphylococcus intermedius (6,3%), Klebsiella spp.(4,2%) e Candida glabrata (2,1%). A preparação de própolis apresentou atividade antimicrobiana contra a maioria dos microrganismos isolados de amostras do grupo de tratamento, sendo que os do grupo-controle não se recuperaram da doença infecciosa auricular, e não foram observados efeitos adversos à própolis. Isso permitiu aos pacientes tratados com própolis melhora significativa dos parâmetros clínicos. Essa nova formulação da própolis argentina para o ouvido apresenta potencial utilidade no tratamento tópico da otite externa em cães.

The therapeutic effects of Argentine propolis ear drop formulation on canine otitis externa were evaluated. Forty-eight dogs with symptoms of otitis externa were randomly assigned to double-blinded, controlled clinical trial to evaluate the efficacy of topical formulation with propolis versus a topical placebo in the treatment of otitis externa. The propolis preparation and placebo were administrated into both external ear canals, twice daily for 14 days. Throughout the study, clinical examination and microbiological analysis of dogs ear exudates were made. The most frequent microorganisms isolated in culture media were: Malassezia pachydermatis (54.2%), Staphylococcus aureus (43.8%), coagulase-negative Staphylococcus (25.0%), Pseudomonas aeruginosa (20.8%), Candida albicans (18.8%), Proteus mirabilis (16.7%), Streptococcus spp. (16.7%), Enteroccocus faecalis (12.5%), Escherichia coli (12.5%), Staphylococcus intermedius (6.3%), Klebsiella spp. (4.2%), andCandida glabrata (2.1%). Whereas the control group did not recover from the infectious ear disease, the propolis preparation exhibited antimicrobial activity against most of the microorganisms isolated from samples of the treated group. In addition, no propolis-adverse effects were observed. This allowed propolis-treated patients to show a significant improvement of the clinical parameters. Thus, this new Argentine propolis ear drop formulation may be used for topical treatment of otitis externa in dogs.