[Incidence of Plesiomonas shigelloides in tilapia tetrahibrids (Oreochromis sp.)]

Plesiomonas shigelloides, a member of the family Vibrionaceae, is a Gram negative rod associated with several gastroenteritis outbreaks, especially in tropical and subtropical countries. In same way, it has been related to some septicemia, meningitis and cholecystitis cases. The microorganism is normally found in water, fish and birds. The aim of this work was to study the incidence of Plesiomonas shigelloides in tetrahybrids of Oreochromis sp. (Pink Tilapia) located at the central region of Venezuela. Once the samples were homogenized, the techniques of enrichment and direct streaking were used simultaneously for the isolation of the microorganism. A high incidence of P. shigelloides was determined (73%), being higher in the intestinal tract (60%), followed by the skin (36.7%) and the gills (26.67%), without any correlation among them. In the fish pond, the microorganism isolation frequency was 41.67%. The direct streaking technique presented the highest isolation values in the different Tilapia tissues (60%) and in the water as well (41.60%). No significant differences were observed on the effectivity of the selective agars used for the isolation of P. shigelloides (Plesiomonas Agar and Inositol-Brilliant Green-Bile Salts Agar). A positive correlation was observed between the microorganism incidence and the pluviosity levels. A high incidence of E. coli was observed in the samples of Tilapia tissues and the water pond. No correlation was observed between incidence of P. shigelloides and E. coli. Due to the high prevalence of P. shigelloides found in the present study, it is important to assure a proper evisceration, washing and storage at temperatures lower than 8 degrees C, and a proper product cooking to diminish the customeris risk.