Characterization of Vibrio parahaemolyticus causing acute hepatopancreatic necrosis disease in southern Thailand

Abstract

Vibrio parahaemolyticus was isolated from shrimp of five farms located in the Pattani and Songkhla provinces of southern Thailand. Using a PCR method targeted to the unique DNA sequences derived from the plasmid (AP2 primers) and the toxin gene (AP3 primers) of V. parahaemolyticus that caused acute hepatopancreatic necrosis disease (AHPND), a total of 33 of 108 isolates were positive. In contrast, all 63 and 66 isolates of clinical and environmental V. parahaemolyticus, respectively, obtained previously from 2008 to 2014 from the same area were negative. This implied that these strains were likely to be the cause of the outbreak of AHPND in this area. Intestinal samples proved to be a better source for the isolation of V. parahaemolyticus AHPND than the hepatopancreas. All isolates were investigated for haemolytic activity, virulence genes, serotypes, genotypes and antibiotic susceptibility. All the AHPND isolates had a unique O antigen, but small variations of the K antigens were detected from different farms. In addition, the DNA profiles of V. parahaemolyticus AHPND isolates were similar, but distinct from those clinical and environmental isolates. It is postulated that the causative agent of AHPND might have originated from one clone and then slightly different serotypes subsequently developed.

Characterization and growth conditions of Vibrio parahaemolyticus strains with different virulence degrees that cause acute hepatopancreatic necrosis disease in Litopenaeus vannamei

“…Traditionally, vibrios have been considered highly susceptible to virtually all antimicrobials. All Vp strains from this study were susceptible to most of the antibiotics tested, particularly to nalidixic acid, but Vp was resistant to ampicillin and carbenicillin, previously reported for Vp from farmed shrimp affected with AHPND (Kongrueng et al, 2015;Lai et al, 2015). In contrast, the results of the disk diffusion test with Vp AHPND+ showed that the 2S01 strain was only susceptible to florfenicol, and this susceptibility level was intermediate to that of ceftriaxone, nitrofurantoin, and norfloxacin (Dong et al, 2017).…”

The opportunistic marine pathogen Vibrio parahaemolyticus becomes virulent by acquiring a plasmid that expresses a deadly toxin

“…As for the bacterium itself, Kongrueng et al found that several AHPND V. parahaemolyticus strains isolated from southern Thailand were serologically similar, had closely related pulsed field gel electrophoresis DNA profiles, and possessed the same repertoire of virulence factors (26). This led them to postulate that all these strains might have originated from a single clone.…”

A Natural Vibrio parahaemolyticus Δ pirA Vp pirB Vp+ Mutant Kills Shrimp but Produces neither Pir Vp Toxins nor Acute Hepatopancreatic Necrosis Disease Lesions

“…Differences in the results may also be related to individual characteristics of the isolates used. For example, two recent studies from Thailand revealed that isolates of V. parahaemolyticus positive for the pVA plasmid comprised a variety of serotypes ( 24 , 25 ). In another study on the pathogenesis of VP AHPND isolates ( 12 ), immersion challenges with isolate M1-1, which carried the pVA plasmid containing the pirAB Vp toxin genes, gave negligible mortality at 96 h. Differences in virulence might be clarified upon sequencing and comparison of whole genomes for the presence and location of other factors that may control virulence.…”