Isolation of specific bacteriophages against multi drug resistant vibrio parahaemolyticus obtained from penaeid shrimps

Abstract- One of the greatest threats faced by aquaculture industry is infectious bacterial diseases, among which Vibrosis is a major concern. Vibrio parahaemolyticus is one of the main vibrio sp. responsible for this disease causing mass mortalities in aquaculture systems and some strains of them can cause acute hepatopancreatic necrosis disease or early mortality syndrome in culture shrimps.
In this study, 10 shrimp farms in the Ernakulam area were considered as the sampling stations. A total of 21 isolates of V.parahaemolyticus were obtained from the 30 penaeid shrimp samples collected which is identified by conventional methods and further confirmed by PCR targeting the species specific markers like toxR and tlh genes. None of the isolates were identified pathogenic when checked for the presence of virulence genes such as tdh and trh encoding the production of thermostable direct hemolysin and thermostable related hemolysin respectively. This corresponds to the low prevalence of pathogenic genes of V.parahaemolyticus in the environmental isolates of the study area. Antibiogram analysis of the isolates were done against a set of 13 commonly used antibiotics and revealed the presence of multidrug resistant V. parahaemolyticus in the culture ponds of Ernakulam.
In this study, specific phages were isolated against these multi drug resistant bacteria with a view to apply them as therapeutics in shrimp aquaculture systems that may represent a viable alternative to antibiotics to inactivate bacteria, the main pathogenic agents in aquaculture industry. Virulent phages are natural, sustainable antimicrobials that are nontoxic and when correctly selected and prepared do not pose any risk to plant, animal or environment. The present study aimed at isolation of lytic phages of multi- drug resistant V.parahaemolyticus with potential for phage therapy against vibrio- related diseases in shrimp aquaculture systems.