Seasonal variation in abundance of total and pathogenic Vibrio parahaemolyticus bacteria in oysters along the southwest coast of India.
The seasonal abundance of Vibrio parahaemolyticus in oysters from two estuaries along the southwest coast of India was studied by colony hybridization using nonradioactive labeled oligonucleotide probes. The density of total V. parahaemolyticus bacteria was determined using a probe binding to the tlh (thermolabile hemolysin) gene, and the density of pathogenic V. parahaemolyticus bacteria was determined by using a probe binding to the tdh (thermostable direct hemolysin) gene. Furthermore, the prevalence of V. parahaemolyticus was studied by PCR amplification of the toxR, tdh, and trh genes. PCR was performed directly with oyster homogenates and also following enrichment in alkaline peptone water for 6 and 18 h. V. parahaemolyticus was detected in 93.87% of the samples, and the densities ranged from <10 to 10(4) organisms per g. Pathogenic V. parahaemolyticus could be detected in 5 of 49 samples (10.2%) by colony hybridization using the tdh probe and in 3 of 49 samples (6.1%) by PCR. Isolates from one of the samples belonged to the pandemic serotype O3:K6. Twenty-nine of the 49 samples analyzed (59.3%) were positive as determined by PCR for the presence of the trh gene in the enrichment broth media. trh-positive V. parahaemolyticus was frequently found in oysters from India.
Department of Fishery Microbiology, University of Agricultural Sciences, College of Fisheries, Mangalore 575 002, India.
A
A
Deepanjali
H Sanath
HS
Kumar
I
I
Karunasagar
I
I
Karunasagar
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D001431:Bacteriological Techniques; D015169:Colony Count, Microbial; D003470:Culture Media; D004269:DNA, Bacterial / Q000032:analysis; D007194:India; D010125:Ostreidae / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D012621:Seasons; D012758:Shellfish / Q000382:microbiology*; D014736:Vibrio parahaemolyticus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity*; D037521:Virulence Factors / Q000235:genetics
D001426:Bacterial Proteins; D003470:Culture Media; D004269:DNA, Bacterial; D037521:Virulence Factors