Aislamiento, identificación y caracterización molecular de Vibrio parahaemolyticus en muestras de agua, sedimento y moluscos bivalvos de la costa atlántica de Buenos Aires.

Vibrio parahaemolyticus is a natural inhabitant of coastal marine environments and estuaries worldwide. It is known as an important foodborne human pathogen associated with raw or undercooked seafood, particularly bivalves. It causes gastroenteritis with watery diarrhea and abdominal cramps. In recent years, it has spread and caused major outbreaks worldwide. It has been reported in South America since 1997. In Argentina, there is no data about cases or outbreaks caused by this microorganism and there are very few reports of its isolation in seafood products. However, there have been reported cases of gastroenteritis due apparently to the consumption of raw bivalves. Therefore, this study aimed to study the presence of V. parahaemolyticus in the coastal environment of Buenos Aires province, to detect virulence genes and to characterize isolates. During one year, between October 2008 and September 2009, samples of water, sediment and bivalve molluscs were collected in the beaches of Mar Azul, Villa Gesell and Santa Teresita, province of Buenos Aires. In water samples, the presence/absence qualitative test was used. In bivalve molluscs and sediment samples, the most probable number (MPN) semiquantitative method was applied. Of the 74 studied samples, 27 (36.5%) resulted positive for V. parahaemolyticus. The highest frequency of isolation was detected in water (54%), compared to bivalve molluscs (32%) and sediment samples (23%). Values between 0.36 and 34 MPN/g of bivalve were obtained in the different samples. The greatest presence of the pathogen (63%) and its greatest abundance (max. 34 MPN/g of bivalve) were detected in the summer months, coinciding with the period of maximum temperature of sea water (20-24°C) and salinities ranging between 24.83 and 32.74 ups. The identification of V. parahaemolyticus was confirmed detecting the species-specific gene toxR by polymerase chain reaction (PCR). Of the 289 recovered isolates, 100 were confirmed as V. parahaemolyticus. Also, the presence of virulence genes tdh (thermostable direct hemolysin) and trh (TDH-related hemolysin) was studied by PCR. Only in one isolate of V. parahaemolyticus (1%), recovered in January/09 from Mar Azul, virulence genes tdh and trh were detected. A selection of isolates of V. parahemolyticus was characterized by pulsed-field gel electrophoresis (PFGE) using PulseNet International standardized protocol. PFGE was highly discriminatory, as sixteen SfiI-PFGE profiles were found among the twenty-five compared isolates. Five genetically similar groups were identified, having between two and four isolates each. These results demonstrate the presence of V. parahaemolyticus in the coastal environment of Buenos Aires.and show a seasonal pattern of occurrence of this microorganism. Its isolation in water, sediment and bivalve samples was confirmed and the presence of both virulence markers tdh and trh was demonstrated. This finding represents the first evidence of potentially pathogenic environmental isolates in Argentina and suggests the need to expand these studies, as well as to reinforce the clinical diagnosis of this pathogen in the areas of greater risk and activate its surveillance in seafood products.

Bibliographic Details

Main Author:	Jurquiza, V.
Format:	Thesis/Dissertation biblioteca
Language:	Spanish / Castilian
Published:	Universidad Nacional de San Martín 2014
Subjects:	Vibrio parahaemolyticus, Biología molecular, Bacteria, Análisis microbiológico, Salud y seguridad, Bivalvos, Agua de mar, Sedimentos, ASFA15::M::Molecular biology, ASFA15::B::Bacteria, ASFA15::M::Microbiological analysis, ASFA15::H::Health and safety, ASFA15::S::Shellfish, ASFA15::S::Sea water, ASFA15::S::Sediments,
Online Access:	http://hdl.handle.net/1834/6828
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