南昌市市售水产品中副溶血性弧菌的污染状况及耐药性和分子分型

Research on the contamination,drug resistance and molecular typing of Vibrio parahaemolyticus isolated from aquatic products in Nanchang City market

目的 了解南昌市市售水产品中副溶血性弧菌的污染状况和耐药性、毒力基因携带情况及分子分型特征。方法 2021年3—9月采集南昌市各农贸市场市售小龙虾、淡水鱼蛙及相关涂抹样本170份,分离副溶血性弧菌菌株,进行抗生素耐药检测、毒力基因检测以及采用脉冲场凝胶电泳(Pulsed-Field GelElectrophoresis,PFGE)进行分子分型分析。结果 在采集的样品中,仅在小龙虾和小龙虾涂抹样本中分离到副溶血性弧菌,总共分离副溶血性弧菌35株,其他淡水鱼、蛙及其涂抹样品均未分离到副溶血性弧菌。针对受试的17种常见抗生素,35株副溶血性弧菌中仅有2株显示对氨苄西林耐药、1株对链霉素耐药,而对其他抗生素均敏感;35株副溶血性弧菌都携带tlh基因,但只有1株携带耐热相关溶血毒素基因trh,未发现直接耐热溶血毒素基因tdh阳性菌株;PFGE图谱聚类显示没有PFGE图谱完全一致的菌株,且这些菌株中没有明显的优势簇,亲缘关系较为疏远。结论 南昌市售水产品中小龙虾中副溶血性弧菌污染比较严重。这些污染小龙虾的副溶血性弧菌菌株一般不携带tdh等关键毒力基因,对常见抗生素较为敏感,仅对氨苄西林和链霉素存在低水平耐药。PFGE图谱聚类显示副溶血性弧菌没有明显的优势簇,这些菌株具有丰富的遗传多样性,显示具有不同的来源。

Objective To understand the contamination status,drug resistance,virulence gene carrying status,and molecular typing characteristics of Vibrio parahaemolyticus(VP)in aquatic products sold in Nanchang City.Methods A total of 170 commercial crayfishes,freshwater fish frogs and related smears samples were collected from various farmers′markets in Nanchang from March to September 2021.The strains of V.parahaemolyticus were detected and isolated from the samples.Antibiotic resistance test,virulence gene test,and pulsed-field gel electrophoresis(PFGE)molecular typing analysis were carried out.Results Among the collected samples,V.parahaemolyticus was only isolated from crayfish and crayfish smear samples,with a total of 35 strains of VP isolated.No V.parahaemolyticus strain was isolated from other freshwater fish,frogs,and their smear samples.Among the 17 common antibiotics tested,only two trains showed resistance to ampicillin,and one strain to streptomycin,,and all were sensitive to other antibiotics;all 35 strains of V.parahaemolyticus carried the gene,but only one strain carried the heat-resistant related hemolysin gene trh,and no direct heat-resistant hemolysin gene tdh positive strain was found;PFGE pattern clustering showed that there was no strain with the same PFGE pattern,and there was no obvious dominant cluster among these strains,and their genetic relationship was relatively distant.Conclusions The contamination of V.parahaemolyticus in small and medium-sized crayfish sold in the market in Nanchang City is relatively serious.The V.parahaemolyticus isolates in these polluted crayfish generally do not carry key virulence genes such as tdh,are sensitive to common antibiotics,and only have low-level resistance to ampicillin and streptomycin.PFGE pattern clustering showed that V.parahaemolyticus does not have no obvious dominant cluster,and these strains have rich genetic diversity,indicating that they may have different sources.