动物源qnr基因阳性肠杆菌I类整合子的研究

【目的】研究I类整合子在qnr基因阳性的动物源肠杆菌中的流行情况，探讨qnr基因与I类整合子之间的流行相关性。【方法】PCR测序检测从526株动物源肠杆菌中筛选到的14株qnr基因阳性株的I类整合酶，并对I类整合酶阳性菌的基因盒进行长片段PCR测序。【结果】14株qnr基因阳性动物源肠杆菌均携带I类整合子，且每个基因盒至少携带两个耐药基因。在所发现的基因盒中二氢叶酸还原酶（dfrA）和氨基糖苷腺苷酰转移酶（aadA）的检出率最高。本研究还检测到了1个携带林可胺核苷酸转移酶（linF）和2个携带利福平核糖基转移酶（arr-3）的基因盒子。2株aac(6')-Ib-cr基因阳性菌的aac(6')-Ib-cr基因也位于基因盒中，且均位于一空基因盒的下游。在本研究检测到的基因盒中，dfrA27-aadA2、dfrA12-orfF-aadA2和dfrA17-aadA5为检出率最高的基因盒排列。【结论】qnr 基因与I类整合子具有明显的流行相关性。

Study of Class I Integrons in qnr-positive Enterobacteriaceae Isolates from Animals

【Objective】The objective of this study is to investigate the prevalence of class 1 integrons in qnr-positive enterobacteriaceae isolates from animals.【Method】 Fourteen qnr-positive strains of Enterobacteriaceae from animals were screened for class 1 integrase gene intI by PCR and sequencing.Gene cassettes of the detected class 1 integrons were studied by PCR using LA Taq enzyme and sequencing.【Result】intI1 was detected in all the 14 qnr positive strains tested.And more than two resistance genes were found in each cassette.The genes most commonly found in integrons were dihydrofolate reductase(dfr) gene for trimethoprim resistance and adenylvltransferase(aadA) gene for amino glycoside resistance.Lincosamide nucleotidyltransferase linF gene and ribosyl transferase arr-3 gene for rifampin resistance were also detected in this study.Plasmid-mediated quinolone resistance aac(6’)-Ib-cr was found following an empty cassette.dfrA27-aadA2,dfrA12-orfF-aadA2 and dfrA17-aadA5 were the major arrays.【Conclusion】It seems that the class 1 integrons are extensively existed in qnr positive strains.