Prevalence of Vibrio parahaemolyticus in seafoods and their processing environments as detected by duplex PCR

Abstract

A duplex polymerase chain reaction (PCR) procedure targeting the genes gyrB and tl was established for specific identification of Vibrio parahaemolyticus from seafoods and processing environments. It could detect as few as 2.5 × 10 2 colony-forming units mL −1 in pure cultures. Direct detection of V. parahaemolyticus was also possible from artificially contaminated shrimp samples if combined with proteinase treatment. The homogeneous colonies on thiosulfate/citrate/bile salts/sucrose agar suspected to be V. parahaemolyticus or closely related species (n = 37) out of 259 samples of seafoods and processing environments were identified using the conventional method and duplex PCR. Both methods identified 17 isolates as V. parahaemolyticus from among the suspected isolates. Only one of the 17 V. parahaemolyticus isolates possessed the thermostable direct haemolysin gene (tdh) fragment as detected by different primer pairs in single PCR.

Detection of ctx gene positive non-O1/non-O139 V. cholerae in shrimp aquaculture environments

“…The sensitivity of multiplex PCR for the detection of toxigenic and pathogenic V. cholerae from direct water sources using specific primers targeting ompW, ctxB, rfbG, zot and tcpB was 5×10 4 V. cholerae cells per reaction (Goel et al 2007). A duplex PCR targeting the genes gyrB and tl for specific identification of V. parahaemolyticus could detect as few as 250 CFU/ml in pure cultures (Vongxay et al 2006). In the multiplex PCR (vvh fragment and viuB) for V. vulnificus, the sensitivity of detection for both targeted genes was 10 pg of purified DNA, which correlated with 10 3 CFU/ml of pure culture (Panicker et al 2004b) The suitability of V. cholerae-duplex PCR in detecting V. cholerae in fish (rohu, tuna) and crustaceans (black tiger shrimp, three spot crab) samples was studied to know whether inhibitory substances present in these foods might adversely affect the performance of PCR.…”