Pre-Enrichment of Estuarine and Fresh Water Environmental Samples with Sodium Chloride Yields in Better Recovery of Vibrio parahaemolyticus

Vibrio parahaemolyticus organisms cause acute gastroenteritis in humans. These bacteria are natural inhabitants of both marine and estuarine ecosystems. In the present study, we investigated the effectiveness of a non-selective enrichment of sediment samples with sodium chloride prior to selective enrichment with alkaline peptone water for a better recovery of V. parahaemolyticus. Sediment samples were collected with or without 1% NaCl from the river Buriganga, located besides Dhaka city and about 400 km away from the Bay of Bengal, and from the estuary of the river Karnaphuli which flows into the Bay of Bengal. Very small number of V. parahaemolyticus (<30 MPN/g) were detected in the sediments of both river and estuary, where NaCl was not added. On the other hand, the number of V. parahaemolyticus increased to more than 40 times (1500 MPN/g) in the river and 32 times (960 MPN/g) in the estuary where NaCl were added. River sediment sample contained the serotype O9:K41 of V. parahaemolyticus and the estuarine sample contained O3:K41 and O3:KUT Our results suggest that a pre-enrichment of environmental samples with 1% NaCl helps V. parahaemolyticus to survive for at least 7 days until they are enriched with alkaline peptone water, for better recovery.