北京市副溶血弧菌病原学和分子流行病学特征分析

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

目的了解北京市副溶血弧菌腹泻病例分离株的病原学和分子流行病学特征。方法2010年4—12月从临床收集散发腹泻病例2118份粪便标本，进行副溶血弧菌的分离培养、生化鉴定。阳性菌株进行血清分型；采用药敏纸片法对12种抗生素进行敏感性检测；用实时荧光定量PCR方法检测毒力基因tlh、tdh和trh；用脉冲场凝胶电泳（PFGE）进行分子分型。结果2118份粪便标本分离出副溶血弧菌114株，阳性分离率为5．38％。114株副溶血弧菌分属于23种血清型，其中03：K6为优势血清型，占63．16％。临床分离株对氨苄西林和庆大霉素产生耐药；对阿莫西林、头孢曲松、氯霉素、亚胺培南、萘啶酸和四环素等均具有较高敏感性。全部菌株tlh基因阳性；tdh存在于大部分菌株中，所占比例为93．86％；只有1株菌trh阳性。03：K6型菌株tdh基因阳性率（98．61％）明显高于非03：K6型菌株（85．71％）（P=0．0098）。114株副溶血弧菌分成54种PFGE型别，72株03：K6型菌株分成34种PFGE型别，带型分散，元明显聚集性。结论北京地区感染性腹泻病例副溶血弧菌分离株以03：K6型为主。毒力基因￡肌和tdh携带率高，且03：K6型临床分离株毒力更强。副溶血弧菌对多数抗生素均具有较高敏感性。PFGE结果提示北京地区流行的副溶血弧菌存在多克隆来源。

Objective To understand the etiological and molecular-epidemiological 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 parahaemolyticus 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 03 ： 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 of tdh among 03 ： 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 03 ： K6 strains into 34 patterns without the clustering characteristic. Conclusion Vibrio parahaemolyticus strains isolated from diarrheal patients in Beijing were dominated by 03 ： 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.