Bivalve aquaculture is generally influenced by bacterial pathogens that cause high mortality-related losses in hatcheries. Six bacterial phenotypes had been previously isolated as the most predominant microorganisms in carpet shell clam (Tapes decussates) samples collected from natural beds in representative Egyptian clam fisheries. The main aims of this study were to investigate the nature of the pathogenic strains that significantly affect clam survival and test their susceptibility to commercially available antibiotics. Based on their 16S rRNA sequences and some biochemical features, two potent clam pathogens were emerged; one of which is gram-positive and the other is gram-negative. The former isolate was identified as Micrococcus luteus and the latter as Vibrio alginolyticus. Experimental challenges with the two bacterial pathogens introduced at different initial cell concentrations (2.5 X 10 4-7.5 X 10 4 cfu ml-1) showed markedly diverse clam mortality results. However, the pathogenic interaction of M. luteus with clam survival was generally higher than that of V. alginolyticus. When introduced at a relatively low initial cell density, the infectious records of V. alginolyticus were significantly increased suggesting that the expression of its key virulence factors is mainly triggered as a response to host contact. Antibiotic susceptibility tests suggested chloramphenicol and tetracycline as markedly effective agents that can be used to control the spread of these two bacterial pathogens in aquaculture applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.