Boyd David, Cloeckaert Axel, Chaslus-Dancla Elisabeth, Mulvey Michael R
National Microbiology Laboratory, Health Canada, Winnipeg, Manitoba, Canada R3E 3R2.
Antimicrob Agents Chemother. 2002 Jun;46(6):1714-22. doi: 10.1128/AAC.46.6.1714-1722.2002.
Strains of multidrug-resistant Salmonella enterica serovar Typhimurium DT104 (DT104) and S. enterica serovar Agona (Agona) have been found to harbor Salmonella genomic island 1 (SGI1), a 43-kb genomic region that contains many of the drug resistance genes. Such strains are resistant to ampicillin (pse-1), chloramphenicol/florfenicol (floR), streptomycin/spectinomycin (aadA2), sulfonamides (sul1), and tetracycline [tet(G)] (commonly called the ACSSuT phenotype). All five resistance genes are found in a 13-kb multidrug resistance (MDR) region consisting of an unusual class I integron structure related to In4. We examined DT104 and Agona strains that exhibited other resistance phenotypes to determine if the resistance genes were associated with variant SGI1 MDR regions. All strains were found to harbor variant SGI1-like elements by using a combination of Southern hybridization, PCR mapping, and sequencing. Variant SGI1-like elements were found with MDR regions consisting of (i) an integron consisting of the SGI1 MDR region with the addition of a region containing a putative transposase gene (orf513) and dfrA10 located between duplicated qacEDelta1/sulI genes (SGI1-A; ACSSuTTm); (ii) an integron with either an aadA2 (SSu) or a pse-1 (ASu) cassette (SGI1-C and SGI1-B, respectively); (iii) an integron consisting of the SGI1-C MDR region plus an orf513/dfrA10 region as in SGI1-A (SGI1-D; ASSuTm; ampicillin resistance due to a TEM beta-lactamase); and (iv) an integron related to that in SGI1 but which contains a 10-kb inversion between two copies of IS6100, one which is inserted in floR (SGI1-E; ASSuT). We hypothesize that the MDR of SGI1 is subject to recombinational events that lead to the various resistance phenotypes in the Salmonella strains in which it is found.
已发现多重耐药性肠炎沙门氏菌鼠伤寒血清型DT104（DT104）菌株和肠炎沙门氏菌阿哥纳血清型（阿哥纳）菌株携带沙门氏菌基因组岛1（SGI1），这是一个43千碱基的基因组区域，包含许多耐药基因。这类菌株对氨苄青霉素（pse-1）、氯霉素/氟苯尼考（floR）、链霉素/壮观霉素（aadA2）、磺胺类药物（sul1）和四环素[tet(G)]具有抗性（通常称为ACSSuT表型）。所有五个耐药基因都存在于一个13千碱基的多重耐药（MDR）区域，该区域由一个与In4相关的不寻常的I类整合子结构组成。我们检测了表现出其他抗性表型的DT104和阿哥纳菌株，以确定耐药基因是否与变异的SGI1 MDR区域相关。通过Southern杂交、PCR定位和测序相结合的方法，发现所有菌株都携带变异的SGI1样元件。发现变异的SGI1样元件具有以下MDR区域：（i）一个整合子，由SGI1 MDR区域加上一个包含推定转座酶基因（orf513）和位于重复的qacEDelta1/sulI基因之间的dfrA10的区域组成（SGI1-A；ACSSuTTm）；（ii）一个带有aadA2（SSu）或pse-1（ASu）盒式结构的整合子（分别为SGI1-C和SGI1-B）；（iii）一个由SGI1-C MDR区域加上如SGI1-A中的orf
