上海凡纳滨对虾源副溶血弧菌耐药性及其耐药基因检测分析

Resistance of Litopenaeus vannamei from Shanghai to Vibrio parahaemolyticus and detection and analysis of resistance genes

  • 摘要: 【目的】掌握上海地区养殖凡纳滨对虾源副溶血弧菌的耐药性及耐药基因携带情况,并明确耐药表型与耐药基因间的相关性,为科学防控凡纳滨对虾副溶血弧菌病及揭示耐药机制提供理论依据。【方法】通过K-B纸片扩散法检测21株上海凡纳滨对虾源副溶血弧菌对14种常见抗生素的敏感性,采用二倍稀释法测定高度敏感抗生素对副溶血弧菌的最小抑菌浓度(MIC)和最小杀菌浓度(MBC),并以PCR检测其耐药基因的携带情况,包括β-内酰胺类耐药基因blaTEMblaCARB、磺胺类耐药基因Sul II和Sul III、氨基糖苷类耐药基因strAstr B、四环素类耐药基因tetA及I类整合子inT1基因。【结果】21株上海凡纳滨对虾源副溶血弧菌对14种常见抗生素表现出不同程度的多重耐药性,六重耐药1株(4.76%),五重耐药3株(14.29%),四重耐药5株(23.81%),三重耐药8株(38.10%),二重耐药4株(19.05%);AMP/PG/SMX和PG/SMX为优势耐药菌谱。上海凡纳滨对虾源副溶血弧菌对恩诺沙星的敏感率最高(90.48%),对应的MIC为0.10~1.60μg/mL、MBC为3.20~12.80μg/mL。blaTEMblaCARBSul II、Sul III、str BinT1等耐药基因的检出率分别为23.81%、71.43%、33.33%、19.05%、9.52%和23.81%,未检测出strAtetA基因。从21株上海凡纳滨对虾源副溶血弧菌中共检出11种耐药基因型,其优势耐药基因型有blaCARB(28.57%)、blaCARB-blaTEM(14.29%)、blaCARB-Sul II(14.29%)和Sul III-inT1(9.52%)。除str A基因和tetA基因外,其余耐药基因与其对应抗生素耐药表型间均存在相关性,但其相关性不显著(P>0.05)。【结论】上海凡纳滨对虾源副溶血弧菌对14种常见抗生素表现出不同程度的敏感性,对恩诺沙星的敏感性最高,故可考虑将恩诺沙星作为上海地区凡纳滨对虾副溶血弧菌病防控的备选药物。此外,针对对虾源副溶血弧菌日趋严重的多重耐药问题,应同时加强副溶血弧菌耐药基因及整合子携带情况的监测,掌握其流行趋势,以提高对虾副溶血弧菌病的防控策略。

     

    Abstract: 【Objective】In order to provide theoretical basis for scientific control of Vibrio parahaemolyticus disease in Litopenaeus vannamei and further reveal the antibiotics resistance mechanism of V. parahaemolyticus, the antibiotics resistance and the carrying status of related resistance genes were detected in V. parahaemolyticus isolated from L. vannamei in Shanghai, the correlation between resistance phenotype and resistance genes was also studied.【Method】The susceptibility of 21 strains of V. parahaemolyticus(isolated from L. vannamei in Shanghai) against 14 common antibiotics were detected by K-B disc diffusion test, and the minimum inhibitory concentration(MIC) and minimum bactericidal concentration(MBC) of more sensitive antibiotics were determined by double dilution method. The carrying statuses of blaTEM and blaCARB of β-lactam resistance genes, Sul II and Sul III of sulfanilamide resistance genes, strA and strB of aminoglycoside resistance genes, tet A of tetracycline resistance genes and inT1 of integrons of class I genes in V. parahaemolyticus were detected by PCR method.【Result】The 21 strains of V. parahaemolyticus showed multi-drug resistance to 14 antibiotics, which were one strain of resistance manifested to 6(4.76%), three strains of resistance manifested to 5(14.29%), five strains of resistance manifested to 4(23.81%), eight strains of resistance manifested to 3(38.10%) and four strains of resistance manifested to 2(19.05%). The dominant antibiotic resistance phenotypes were AMP/PG/SMX and PG/SMX. For the sensitivity rates of the tested antibiotics in the strains of V. parahaemolyticus, enrofloxacin was the most sensitive antibiotic(90.48%). MIC and MBC of enrofloxacin were 0.10-1.60μg/mL and 3.20-12.80μg/mL. PCR results of resistance genes showed that the detection rates of gene blaTEM, blaCARB, Sul II, Sul III, strB and inT1 were 23.81%, 71.43%, 33.33%, 19.05%, 9.52% and 23.81%, respectively. str A and tetA were not detected. A total of 11 drug-resistant genotypes were detected from 21 strains of V. parahaemolyticus from L. vannamei in Shanghai, the dominant genotypes including blaCARB(28.57%), blaCARB-blaTEM(14.29%), blaCARB-Sul II(14.29%) and Sul III-inT1(9.52%). Except str A and tetA, other resistance genes were correlated with their antibiotic resistance phenotypes, but the correlation was not significant(P>0.05).【Conclusion】The strains of V. parahaemolyticus isolated from L. vannamei in Shanghai showed different sensitivity levels to 14 antibiotics, enrofloxacin with the most sensibility. So, enrofloxacin can be considered as an alternative drug for the prevention and control of V. parahaemolyticus in L. vannamei in Shanghai. Besides, to solve the problem of multiple drug resistance of V. parahaemolyticus, detecting drug resistance genes and integrons in V. parahaemolyticus frequently and studying the trends are recognized as the effective strategies in V. parahaemolyticus prevention and control in L. vannamei.

     

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