Analysis on the etiological and molecular epidemiological characteristics of Vibrio parahaemolyticus in Beijing

Objective To understand the etiological and molecular-epiderniological characteristics of Vibrio parahaemolyticus in Beijing.Methods Stool specimens from sporadic diarrheal patients were collected during April to December,2010.Culture and serotyping were used to detect the Vibrio parahaemolyticus from the 2118 specimens.All the positive strains were tested for drug sensitivity by Kirby-Bauer method.Real-time PCR was used to detect the existence of three virulence genes tlh,tdh and trh.Molecular typing on Vibrio parahaerrolyticus isolates was completed by pulsed field gel electrophoresis(PFGE).Results 114 out of the 2118 specimens were Vibrio parahaemolyticus positive,with the positive rate as 5.38％.114 isolates belonged to 23 serotypes,with the dominant (63.16％)serotype as O3:K6.Strains isolated from clinical manifestation patients were resistant to antibiotics-ampicillin and gentamicin,while with high sensitivity to amoxicillin,ceftriaxone,chloromycetin,imipenem,nalidixic acid and tetracycline.Virulence gene detection was positive to tlh for all the strains,but most to tdh,while only one strain to trh.The positive rate oftdh among O3:K6 strains(98.61％)was higher than that in those non-O3:K6 strains(85.71％)(P=0.0098).114 isolates were discriminated into 54 different PFGE patterns,while 72 O3:K6 strains into 34 patterns without the clustering characteristic.Conclusion Vibrio parahaemolyticus strains isolated from diarrheal patients in Beijing were dominated by O3:K6 strains,with stronger virulence.The positive rates of genes tlh and tdh were high.Vibrio parahaemolyticus strains showed high sensitivity to most antibiotics.The prevalent Vibrio parahaemolyticus strains in Beijing had various sources of clones. Key words: Vibrio parahaemolyticus ;  Etiology;  Molecular typing