Transferable, multiple antibiotic and mercury resistance in Atlantic Canadian isolates of Aeromonas salmonicida subsp salmonicida is associated with carriage of an IncA/C plasmid similar to the Salmonella enterica plasmid pSN254
Transferable, multiple antibiotic and mercury resistance in Atlantic Canadian isolates of Aeromonas salmonicida subsp salmonicida is associated with carriage of an IncA/C plasmid similar to the Salmonella enterica plasmid pSN254
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DOI：
10.1093/jac/dkn123
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发表时间：
2008-06-01
影响因子：
5.2
通讯作者：
Ritchie, Rachael
中科院分区：
文献类型：
--
作者：
McIntosh, Douglas;Cunningham, Michelle;Ritchie, Rachael
目的：本研究旨在研究加拿大沙门氏气单胞菌亚种多种抗生素和汞耐药性的分子基础。salmonicida。方法：采用表型和基因型方法鉴定多药耐药沙门氏菌质粒相关的抗生素和汞耐药基因，并确定这些基因的组织。结果：以大肠杆菌、嗜水气单胞菌和迟发爱德华菌为受体，MDR表型可通过偶联转移。抗生素和汞抗性基因由结合的IncA/C质粒携带。三个不同的抗生素耐药磁带被表征；第一类整合子含有编码氨基糖苷-3′-腺苷转移酶的aadA7基因，第二盒与先前在肠沙门氏菌IncA/C质粒pSN254中鉴定的盒具有99.9%的核苷酸序列同源性，包含floR、tetA、suIII和strA/strB序列。第三盒显示与转座子样元件核苷酸序列100%相似，含有bla(CMY-2) β -内酰胺酶，与糖基和blc序列相关。这种成分在亚洲和美国广泛分布于临床和食源性沙门氏菌和其他肠杆菌科。汞抗性与存在一个与质粒pSN254携带的mer操纵子核苷酸序列100%同源的mer操纵子有关。结论：每一株MDR沙门氏菌分离株均携带同一质粒，该质粒均与pSN254质粒相关。这是北美首次报道质粒介导的氟苯尼考耐药沙门氏菌。此外，这是在气单胞菌科成员中首次报道的质粒相关AmpC β -内酰胺酶序列。
Objectives: The aim of this study was to examine the molecular basis for multiple antibiotic and mercury resistance in Canadian isolates of Aeromonas salmonicida subsp. salmonicida.Methods: Phenotypic and genotypic methods were employed to identify plasmid-associated antibiotic and mercury resistance genes and to determine the organization of those genes in multidrug-resistant (MDR) A. salmonicida isolates.Results: The MDR phenotype was transferable via conjugation using Escherichia coli, Aeromonas hydrophila and Edwardseilla tarda as recipients. Antibiotic and mercury resistance genes were carried by a conjugative IncA/C plasmid. Three distinct antibiotic resistance cassettes were characterized; first a class I integron containing an aadA7 gene encoding for an aminoglycoside-3'-adenyltransferase, the second cassette showed 99.9% nucleotide sequence homology to a cassette previously identified in the Salmonella enterica IncA/C plasmid pSN254, containing floR, tetA, suIII and strA/strB sequences. The third cassette showed 100% nucleotide sequence similarity to a transposon-like element, containing a bla(CMY-2) beta-lactamase in association with sugE and blc sequences. This element is known to be widely distributed among clinical and food-borne Salmonella and other Enterobacteriaceae throughout Asia and the United States. Mercury resistance was linked to the presence of a mer operon that showed 100% nucleotide sequence homology to the mer operon carried by plasmid pSN254.Conclusions: Each MDR A. salmonicida isolate carried the same plasmid, which was related to plasmid pSN254. This is the first report of plasmid-mediated florfenicol-resistant A. salmonicida in North America. In addition, it is the first report of a plasmid-associated AmpC beta-lactamase sequence in a member of the Aeromonadaceae.