Mahboub Heba H, Tartor Yasmine H
Fish Diseases and Management Department, Faculty of Veterinary Medicine, Zagazig University, 44511 Zagazig, Egypt.
Dis Aquat Organ. 2020 Sep 17;141:1-14. doi: 10.3354/dao03506.
This study investigated the antifungal activity of 5 essential oils (EOs) towards yeasts recovered from diseased fishes; and focused on the efficacy of one EO (carvacrol) on growth performance, non-specific immunity, and disease resistance of Nile tilapia Oreochromis niloticus against Cryptococcus uniguttulatus challenge. Thymoquinone, thymol, carvacrol, eugenol, and cinnamon were first tested in vitro against 20 clinical yeast strains in comparison with antifungal drugs (fluconazole, ketoconazole, itraconazole, amphotericin B, nystatin, and clotrimazole) using disc diffusion and broth microdilution methods. For the in vivo challenge, fish (n = 150) were divided into 5 groups (carvacrol prophylaxis, carvacrol treatment, itraconazole treatment, unchallenged control, and positive control; 30 fish group-1) with 3 replicates. Phagocytic activity, reactive oxygen species production, reactive nitrogen species production, myeloperoxidase, lysozyme activity, and total immunoglobulins were tested before and after challenge. Relative percent survival (RPS) and mortality percent were determined as indicators for functional immunity. EOs displayed divergent degrees of antifungal activity, and carvacrol was the most effective against the tested yeasts. The dietary additive of carvacrol significantly enhanced growth performance, all immunological parameters, and the RPS values (90%) compared to other treatments. This unique experimental model indicates that carvacrol seems promising not only for enhancing immunity and promoting fish growth, but also for controlling emerging fungal infections. Future studies should investigate different concentrations of carvacrol as well as its antifungal activity in different fish species.
本研究调查了5种精油（EOs）对从患病鱼类中分离出的酵母的抗真菌活性；并着重研究了一种精油（香芹酚）对尼罗罗非鱼奥利亚罗非鱼生长性能、非特异性免疫和抗隐球菌感染抗病能力的影响。首先，采用纸片扩散法和肉汤微量稀释法，将百里醌、百里香酚、香芹酚、丁香酚和肉桂与抗真菌药物（氟康唑、酮康唑、伊曲康唑、两性霉素B、制霉菌素和克霉唑）进行体外对比试验，检测它们对20株临床酵母菌株的抗菌活性。对于体内攻毒试验，将150尾鱼分为5组（香芹酚预防组、香芹酚治疗组、伊曲康唑治疗组、未攻毒对照组和阳性对照组；每组30尾鱼，共3个重复）。在攻毒前后检测吞噬活性、活性氧产生、活性氮产生、髓过氧化物酶、溶菌酶活性和总免疫球蛋白。测定相对存活率（RPS）和死亡率作为功能免疫指标。精油表现出不同程度的抗真菌活性，香芹酚对受试酵母的抗菌效果最佳。与其他处理相比，香芹酚作为饲料添加剂显著提高了生长性能、所有免疫参数和RPS值（90%）。这种独特的实验模型表明，香芹酚不仅有望增强免疫力和促进鱼类生长，还能控制新出现的真菌感染。未来的研究应探讨不同浓度的香芹酚及其在不同鱼类中的抗真菌活性。
