In vivo assessment of antibacterial capacity of Oedogonium capillare against Vibrio fluvialis in Golden fish Carassius auratus

The indiscriminate use of antibiotics for the control of bacterial infections in cultures of aquatic organisms, administered in a systemic way, has provoked the presence of R plasmids in bacterial strains of high risk for aquaculture; therefore, it is important to study new natural alternatives not only to prevent bacterial infections, but to prevent the use of antibiotics. Oedogonium capillare alga presented, in previous in vitro studies, the capacity to inhibit the growth of different bacterial species of ichthyopathogenic importance. The objective of the present study is to prove in vivo the antibacterial capacity of the alga against infections caused by the pathogen Vibrio fluvialis in Carassius auratus Golden fish. The activity of the hexanic extract of O. capillare alga was proved from the start of the treatment's administration through three different channels: intramuscular, food and baths, after fishes were experimentally inoculated with V. fluvialis. The use of the extract by these channels was not effective; therefore, different ways of treatments were tested by administering them before and after the infection was experimentally provoked. Fish treated with additional dry alga in feed before and after being infected, surpassed the infection in 80% of cases. Fish treated with alcoholic extract of 0. capillare registered higher than 80% of survival. Significant differences were obtained in relation to the control group and the hexanic extract by intramuscular and feed channels. The significant differences between treatments were proved by analysis of multiple comparisons of Kruskal Wallis.Original Abstract: El uso de antibioticos de forma indiscriminada para el control de infecciones de origen bacteriano en cultivos de organismos acuciticos, administrados de forma sistematica, ha provocado la presencia de plasmidos-R en cepas bacterianas de alto riesgo para la acuicultura, por lo que es importante estudiar nuevas alternativas naturales no solamente para prevenir las infecciones bacterianas, tambien para evitar el uso de antibioticos. El alga Oedogonium capillare presento, en estudios previos in vitro, la capacidad para inhibir el crecimiento de diferentes especies de bacterias de importancia ictiopatogenica. El objetivo del presente estudio es probar in vivo la capacidad del alga como antibacterial contra infecciones provocadas por el patogeno Vibrio fluvialis en pez Dorado Carassius auratus. Se comprobo la actividad del extracto hexanico del alga