Daly M, Fanning S
Molecular Diagnostics Unit, Cork Institute of Technology, Bishopstown, Cork, Ireland.
Appl Environ Microbiol. 2000 Nov;66(11):4842-8. doi: 10.1128/AEM.66.11.4842-4848.2000.
Two hundred and twenty-six Salmonella enterica serotype Typhimurium isolates were examined for the presence of integron-associated gene cassettes. All but two of the non-DT104 isolates, together with DT104 isolates, contained gene cassettes. Amplicons of 1.5 kbp each were found in two non-DT104 isolates, encoding a dhfrI gene (trimethoprim resistance) linked to an aadA gene (streptomycin and spectinomycin resistance), by site-specific recombination. DT104 isolates of resistance (R) type ACSSuT possessed the recently described 1.0- and 1.2-kbp gene cassettes. Macrorestriction analysis with XbaI and DNA probing mapped ant(3")-1a, bla(PSE-1), and dhfrI genes to large multiresistant gene clusters in a DT170a isolate and a DT193 isolate. In contrast, all DT104 isolates (R-type ACSSuT) possessed a conserved 10-kbp Xba1 DNA fragment. Our study highlights the occurrence of integrons (and antimicrobial resistance determinants) among serotype Typhimurium isolates other than DT104. Larger and previously unrecognized multiresistance gene clusters were identified in these isolates by DNA probing.
对226株肠炎沙门氏菌鼠伤寒血清型菌株进行了整合子相关基因盒的检测。除两株非DT104菌株外，所有非DT104菌株以及DT104菌株均含有基因盒。在两株非DT104菌株中发现了大小均为1.5 kbp的扩增子，通过位点特异性重组编码与aadA基因（链霉素和壮观霉素抗性）相连的dhfrI基因（甲氧苄啶抗性）。抗性（R）型为ACSSuT的DT104菌株拥有最近描述的1.0 kbp和1.2 kbp基因盒。用XbaI进行的宏观限制性分析和DNA探针杂交将ant(3")-1a、bla(PSE-1)和dhfrI基因定位到一株DT170a菌株和一株DT193菌株中的大型多抗性基因簇上。相比之下，所有DT104菌株（R型ACSSuT）都拥有一个保守的10 kbp Xba1 DNA片段。我们的研究突出了在除DT104之外的鼠伤寒血清型菌株中整合子（以及抗菌抗性决定簇）的存在。通过DNA探针杂交在这些菌株中鉴定出了更大的、以前未被识别的多抗性基因簇。
