Therapeutic and Histopathological Effect of Aloe vera and Salvia officinalis Hydroethanolic Extracts against Streptococcus iniae in Rainbow Trout

Document Type: Short Communication


1 Department of Fisheries, Faculty of Natural Resources, Urmia University, Urmia, Iran

2 Department of Food Hygiene and Quality Control, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran

3 Department of Microbiology, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran

4 Department of Clinical Science, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran

5 Department of Aquaculture, Artemia & Aquaculture Institute, Urmia University, Urmia, Iran


Some of the medicinal plants have antibacterial contents and appear to be proper alternatives for antibiotics in the treatment of streptococcal disease, which causes plenty of mortalities in fish farms annually. Therefore, this study investigated the therapeutic effect of Aloe vera and Salvia officinalis hydroethanolic extracts against Streptococcus iniae in rainbow trout. Plant extracts components were analyzed by Gas chromatography-mass spectrometry method and tested in vitro against S. iniae by disk diffusion assay. In in vivo, 480 rainbow trout (10±0.1 g) were distributed in 9 groups (with 3 replication), and all groups (except for the first group as the negative control that was injected with 100 µl of physiologic serum) were injected by 100 µl of LD50 (3.66×108.5CFU/ml) of S. iniae suspension, intraperitoneally. The fish of groups were treated by A. vera and S. officinalis extracts in doses 0 (positive control group was fed by commercial diet without plant extract), 0.5, 1, and 1.5% (supplemented diet) and 80 mg/kg body weight erythromycin for the next 10 days. At the end of the study period, tissue samples of the gills and livers of all groups were taken for the histopathological lesion assay. The results showed that A. vera and S. officinalis had antibacterial components as Cineol, and S. iniae was sensitive to both A. vera (MBC=4.067 mg/ml) and S. officinalis (MBC=5.185 mg/ml) extracts. At the end of the treatment period, there were no significant differences among erythromycin, A. vera (1.5%), and A. vera (1%) in terms of the mortality of the infected fish (P˂0.05). Moreover, A. vera (1.5%) showed a significantly lower mortality rate, compared to the positive control (P˂0.05). A. vera (1.5%) was the best group to moderate all histopathological lesions, compared to other groups. Accordingly, A. vera (1.5 %) is useful to treat streptococcosis (caused by S. iniae) and alter gill and liver histopathological lesions in rainbow trout.


Article Title [French]

Effet Thérapeutique et Histopathologique des Extraits Hydroéthanoliques d'Aloe vera et de Salvia officinalis contre Streptococcus iniae chez la Truite Arc-en-ciel

Abstract [French]

Certaines des plantes médicinales ont un contenu antibactérien et semblent être des alternatives appropriées aux antibiotiques dans le traitement des maladies streptococciques, à l’ origine de nombreuses mortalités dans les piscicultures chaque année. Par conséquent, cette étude a examiné l'effet thérapeutique des extraits hydroéthanoliques d'Aloe vera et de Salvia officinalis contre Streptococcus iniae chez la truite arc-en-ciel. Les composants des extraits de plantes ont été analysés par chromatographie en phase gazeuse couplée à l'exception du premier groupe (contrôle négatif traité avec 100µl de sérum physiologique) ont reçu 100µl de DL50 (3,66 × 108,5CFU/ml) de suspension de S. iniae par voie intrapéritonéale. Les poissons des différents groupes ont reçu différentes concentrations d’ extraits d' A. vera et de S. officinalis aux doses 0 (le groupe de contrôle positif a été nourri par un régime commercial sans extrait de plante), 0,5, 1 et 1,5% (régime complémentaire) et 80 mg/kg de corps poids d'érythromycine pour les 10 prochains jours. À la fin de la période d'étude, des échantillons de tissus des branchies et des foies de tous les groupes ont été prélevés pour l’examen des lésions histopathologiques. Les résultats ont montré que A. vera et S. officinalis avaient des composants antibactériens comme Cineol, et S. iniae était sensible à la fois à A. vera (MBC = 4,067 mg/ml) et à S. officinalis (MBC = 5,185 mg/ml). À la fin de la période de traitement, il n'y avait aucune différence significative entre l'érythromycine, A. vera (1,5%) et A. vera (1%) en termes de mortalité des poissons infectés (P˂0.05). De plus, A. vera (1,5%) a montré un taux de mortalité significativement plus faible par rapport au contrôle positif (P˂0,05). A. vera (1,5%) était le meilleur groupe pour modérer toutes les lésions histopathologiques,. En conséquence, A. vera (1,5%) est utile pour traiter le streptocoque (causée par S. iniae) et modifier les lésions histopathologiques des branchies et du foie chez la truite arc-en-ciel.

Keywords [French]

  • Cineol
  • Histopathologie
  • Herbes médicinales
  • Oncorhynchus mykiss
  • Streptococcus iniae
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