Vibrio parahaemolyticus: a review on the pathogenesis, prevalence, and advance molecular identification techniques

Vibrio parahaemolyticus, a gram-negative marine bacterium, is a worldwide cause of food-borne gastroenteritis. V parahaemolyticus strains of a few specific serotypes, probably derived from a common clonal ancestor, have lately caused a pandemic of gastroenteritis. The organism is phylogenetically close to V cholerae, the causative agent of cholera. The whole genome sequence of a clinical V parahaemolyticus strain RIMD2210633 was established by shotgun sequencing. The coding sequences were identified by use of Gambler and Glimmer programs. Comparative analysis with the V cholerae genome was undertaken with MUMmer. The genome consisted of two circular chromosomes of 3288558 bp and 1877212 bp; it contained 4832 genes. Comparison of the V parahaemolyticus genome with that of V cholerae showed many rearrangements within and between the two chromosomes. Genes for the type III secretion system (TTSS) were identified in the genome of V parahaemolyticus; V cholerae does not have these genes. The TTSS is a central virulence factor of diarrhoea-causing bacteria such as shigella, salmonella, and enteropathogenic Escherichia coli, which cause gastroenteritis by invading or intimately interacting with intestinal epithelial cells. Our results suggest that V parahaemolyticus and V cholerae use distinct mechanisms to establish infection. This finding explains clinical features of V parahaemolyticus infections, which commonly include inflammatory diarrhoea and in some cases systemic manifestations such as septicaemia, distinct from those of V cholerae infections, which are generally associated with non-inflammatory diarrhoea.

Food safety is a global health goal and the foodborne diseases take a major crisis on health. Therefore, detection of microbial pathogens in food is the solution to the prevention and recognition of problems related to health and safety. For this reason, a comprehensive literature survey has been carried out aiming to give an overview in the field of foodborne pathogen detection. Conventional and standard bacterial detection methods such as culture and colony counting methods, immunology-based methods and polymerase chain reaction based methods, may take up to several hours or even a few days to yield an answer. Obviously this is inadequate, and recently many researchers are focusing towards the progress of rapid methods. Although new technologies like biosensors show potential approaches, further research and development is essential before biosensors become a real and reliable choice. New bio-molecular techniques for food pathogen detection are being developed to improve the biosensor characteristics such as sensitivity and selectivity, also which is rapid, reliable, effective and suitable for in situ analysis. This paper not only offers an overview in the area of microbial pathogen detection but it also describes the conventional methods, analytical techniques and recent developments in food pathogen detection, identification and quantification, with an emphasis on biosensors. Copyright 2009 Elsevier Inc. All rights reserved.

Vibrio parahaemolyticus is recognized as a cause of food-borne gastroenteritis, particularly in the Far East, where raw seafood consumption is high. An unusual increase in admissions of V. parahaemolyticus cases was observed at the Infectious Diseases Hospital in Calcutta, a city in the northeastern part of India, beginning February 1996. Analysis of the strains revealed that a unique serotype, O3:K6, not previously isolated during the surveillance in Calcutta accounted for 50 to 80% of the infections in the following months. After this report, O3:K6 isolates identical to those isolated in Calcutta were reported from food-borne outbreaks and from sporadic cases in Bangladesh, Chile, France, Japan, Korea, Laos, Mozambique, Peru, Russia, Spain, Taiwan, Thailand, and the United States. Other serotypes, such as O4:K68, O1:K25, and O1:KUT (untypeable), that had molecular characteristics identical to that of the O3:K6 serotype were subsequently documented. These serotypes appeared to have diverged from the O3:K6 serotype by alteration of the O:K antigens and were defined as "serovariants" of the O3:K6 isolate. O3:K6 and its serovariants have now spread into Asia, America, Africa, and Europe. This review traces the genesis, virulence features, molecular characteristics, serotype variants, environmental occurrence, and global spread of this unique clone of V. parahaemolyticus.