Action de l'érythromycine et de l'acide oxolinique sur le déveloloppement larvaire de la coquille St Jacques Pecten maximus

For lack of antibiotics, King scallop larviculture faces high mortalities. In the experimental mollusc hatchery of Argenton (Brittany, France), the presence of a vibrio, Vibrio pectinicida, associated with the stocks seems to be responsible for this low survival rate. As prophylactic methods are difficult to implement in the current structures (water sterilization, egg decontamination, isolation of the stocks), the addition of chloramphenicol is the only solution to protect the stocks. However, the use of this antibiotic, considered as dangerous for man, has been prohibited in animal production throughout the whole of Europe since 1994. The action of two other antibiotics, the erythromycine and the oxolinic acid, has been searched for in Pecten maximus larvae. A monitoring of the larval stocks (growth and mortality) as well as the listing of bacterial populations (heterotrophic and vibrios) has been conducted in parallel. The main bacteria have been isolated, summarily characterized and their resistance to a number of antibiotics has been monitored by antibiograms. The obtained results confirmed the efficiency of the chloramphenicol but were not very convincing as far as the erythromyine and the oxolinic acid were concerned. Indeed, a resistant strain, which could be responsible for the observed weak growths, was selected in the presence of the erythromycine, and the oxolinic acid proved toxic for larvae at the concentrations used.