[Pathogenicity island region of clinical and environmental strains of Vibrio parahaemolyticus, isolated in Chile].
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.


OBJECTIVE
To assess if environmental strains lack the full pathogenicity island or if only the tdh gene is deleted.


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 region of 80 kilobase pairs including genes from VPA1310 to VPA1396 was missing.


CONCLUSIONS
These results highlight the genetic dynamism of Vibrio parahaemolyticus pathogenecity island region and suggest that new pathogenic strains could appear by horizontal transfer of the island between toxigenic and non-toxigenic strains.
Núñez
Harold
H
Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile.
Ulloa
María Teresa
MT
Guerra
Fabiola
F
Osorio
Carlos G
CG
D001427:Bacterial Toxins / Q000235:genetics; D001483:Base Sequence; D002677:Chile; D004269:DNA, Bacterial / Q000302:isolation & purification; D004783:Environmental Microbiology; D044404:Genomic Islands / Q000235:genetics*; D006460:Hemolysin Proteins / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012758:Shellfish / Q000382:microbiology; D014736:Vibrio parahaemolyticus / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D037521:Virulence Factors
D001427:Bacterial Toxins; D004269:DNA, Bacterial; D006460:Hemolysin Proteins; D037521:Virulence Factors; C068489:thermostable direct hemolysin