Isolation and Identification of Vibrio spp.

Total Vibrio and Vibrio species were isolated using a method described by Kaysner et al. [20 ]. Briefly, 25 g of the catfish or tilapia samples and 50 g of shrimp samples were added to 225 and 450 mL of alkaline peptone water (Becton Dickinson Diagnostic Systems, Sparks, MD, USA), respectively, stomached for 2 min and incubated at 35 °C for 24 h. The alkaline peptone water cultures were streaked onto thiosulfate citrate bile salts sucrose (TCBS) agar and modified cellobiose-polymyxin β-colistin agar (mCPC) (Becton Dickinson Diagnostic Systems, Sparks, MD, USA) plates for the isolation of V. parahaemolyticus and V. vulnificus, respectively. The plates were incubated at 35 °C for 24 h for TCBS agar and 40 °C for 24 h for mCPC agar. Five presumptive Vibrio colonies (green or bluish-green, round and 2 to 4 mm in diameter for V. parahaemolyticus on TCBS and flat yellow, fried-egg shape and 1 to 2 mm in diameter for V. vulnificus on mCPC) were picked for confirmation using BAX-real time PCR assay according to the manufacturer’s instructions (Qualicon Diagnostic, Camarillo, CA, USA). Total Vibrio levels were calculated by adding green and yellow colonies on TCBS plates.