广东省2013年副溶血弧菌暴发与散发菌株的病原学特征

目的 了解2013年广东省副溶血弧菌暴发与散发分离株的血清型别、抗菌药物耐药性、毒力基因携带情况以及分子分型特征.方法 对36株暴发分离株和43株散发分离株进行血清分型、药敏试验以及耐热直接溶血毒素基因(tdh)、耐热相关溶血毒素基因(trh)、GS-PCR和orf8基因的PCR检测,并进行脉冲场凝胶电泳(PFGE)分型.结果 36株暴发分离株全部为O3:K6血清型,43株散发分离株的优势血清型为O3:K6型(23株,53.49%).药敏检测结果显示,对氨苄西林(96.20%)和头孢噻吩(40.50%)的耐药率较高;对复方新诺明和氯霉素则高度敏感,敏感性均为100%.多重耐药分析显示,83.33%(30/36)的暴发分离株同时耐受≥3种抗菌药,37.21%(16/43)的散发分离株同时耐受≥3种抗菌药物.毒力基因PCR检测显示,36株暴发分离株均为tdh⁺tdh^-型菌株.86.05%(37/43)的散发分离株为tdh⁺tdh^-型菌株,11.63%(5/43)为tdh^-tdh⁺型菌株,仅1株为tdh⁺tdh⁺型菌株.暴发分离株全部携带GS-PCR和/或orf8基因,51.16%(22/43)的散发分离株携带GS-PCR和/或orf8基因.PFGE显示,79株副溶血弧菌经NotⅠ酶切后的PFGE图谱可分为3个聚类,32种PFGE型别,相似值为59.8%～100.0%.暴发菌株聚集在同一个聚类中,散发菌株散布在各个聚类中.结论 2013年广东省副溶血弧菌优势血清型为O3:K6型,菌株对多数抗菌药物仍然比较敏感,但存在多重耐药现象,多数菌株携带tdh基因,大部分O3:K6型菌株携带GS-PCR和/或orf8基因;PFGE结果提示广东省副溶血弧菌存在遗传多样性.

Etiologic characteristics of Vibrio parahaemolyticus strains causing outbreaks and sporadic cases in Guangdong,2013

Objective To study the serotypes,antimicrobial resistance,virulence genes and molecular characteristics of Vibrio parahaemolyticus isolated from outbreaks and sporadic cases in Guangdong,2013. Methods 36 Vibrio parahaemolyticus strains isolated from outbreaks and 43 strains from sporadic cases were sero-typed and tested for antimicrobial resistance. PCR was used to detect for tdh (thermostable direct hemolysin gene),trh (tdh^- related hemolysin gene),GS-PCR and orf8 genes. All the samples were analyzed by pulsed-field gel electrophoresis (PFGE). Results 36 isolates from outbreaks were all identified as O3:K6,and among the 43 sporadic isolates,O3:K6 (23,53.49%) was the dominant serotype. Vibrio parahaemolyticus isolates showed high resistance rate to ampicillin(96.20%) and cefalotin (40.50%),but were high sensitive to cotrimoxazole(100%) and chloramphenicol (100%). 83.33%(30/36) outbreak isolates were resistant to multi-drugs but only 37.21%(16/43)of the sporadic isolates showed so. Results from virulence gene detection suggested that all the 36 outbreak isolates belonged to tdh⁺trh^- strains,while 86.05%(37/43) of the sporadic isolates were tdh⁺trh^- and 11.63%(5/43) were tdh^-trh⁺. Only one tdh⁺trh⁺ strain was found. All the outbreak isolates contained GS-PCR and/or orf8 genes,whereas among the sporadic isolates only 51.16% (22/43) of them carrying the similar genes. Results from PFGE analysis suggested that 79 isolates were discriminated into 3 clusters and 32 different PFGE patterns with the similarity value between 59.8% and 100.0%. Outbreak isolates seemed to gather in the same cluster,while the sporadic isolates spreading in all the three clusters. Conclusion O3:K6 was the dominant serotype in Vibrio parahaemolyticus strains isolated in Guangdong,2013. These strains showed high sensitivity to most antibiotics,but with multi-drug resistance. Positive rate of tdh gene was high,and most O3:K6 strains contained GS-PCR and/or orf8 genes. PFGE analysis revealed genetic diversity was within the Vibrio parahaemolyticus strains in Guangdong.