Résumé
Background: Most clinical isolates of Vibrio parahaemolyticus produce a major virulence factor known as the thermostable direct hemolysin (TDH). TDH is encoded by the tdh gene which is located in a genomic pathogenicity island (PAI). Most environmental isolates are described as tdh negative. Aim: To assess if environmental strains lack the full pathogenicity island or if only the tdh gene is deleted. Material and methods: Thirty eight clinical and 66 environmental strains of Vibrio parahaemolyticus were studied. PAI was characterized by polymerase chain reaction (PCR). The presence of tdhA and tdhS genes, was determined by Southern blot. Results: Fifty three environmental strains (80%) lacked a full PAI when compared with clinical strains. In environmental strains, Southern blot and sequence analysis showed that a genetic región of 80 kilobase pairs including genes from VPA1310 to VPA1396 was missing. Conclusions: These results highlight the genetic dynamism of Vibrio parahaemolyticus pathogenecity island región and suggest that new pathogenic strains could appear by horizontal transfer of the island between toxigenic and non-toxigenic strains.
Sujets)
Humains , Ilots génomiques/génétique , Hémolysines/génétique , Vibrio parahaemolyticus/génétique , Toxines bactériennes/génétique , Séquence nucléotidique , Chili , ADN bactérien/isolement et purification , Microbiologie de l'environnement , Données de séquences moléculaires , Réaction de polymérisation en chaîne , Fruits de mer/microbiologie , Vibrio parahaemolyticus/isolement et purification , Vibrio parahaemolyticus/pathogénicité , Facteurs de virulenceRésumé
The San Vicente de Paul Hospital was the first Clinical Hospital of the University of Chile and was located at the same place of present School of Medicine. The School are contains several old buildings, which are probably remains of the San Vicente de Paul Hospital. After a careful study of the current plans of the Faculty of Medicine of the University of Chile and those of the San Vicente de Paul Hospital, and after checking measurements on the actual site, we were able to demonstrate that two and a half clinical rooms of the original building and some parts of the old laundry still remain intact. At present, these constructions are being used as storerooms, student's union offices, and other activities. We expect that this article may contribute to improve the knowledge of our roots by our own as well as by future generations and that it may inspire our authorities to take care and preserve this important patrimonial remains of our national medicine