致病菌耐药因子分布及特征分析

目的 对临床菌株中的整合子分布及其携带耐药基因盒的结构特征进行分析。方法 应用多重PCR方法检测55株临床菌株中的3类整合酶基因intⅠ。并对intⅠ阳性菌株耐药基因盒进行测序及序列分析。结果 55株临床菌株均为第1类整合酶基因阳性（100％）。耐药基因盒特异PCR扩增发现，27株革兰阳性菌株和22株革兰阴性菌株均得到1913bp的扩增产物，携带基因盒为dhfr、orfF和aadA2；6株革兰阴性菌得到1664bp的产物．携带基因盒为aadA5和dfrl7。aadA2和aadA5均为编码对氨基糖苷类抗生素产生耐药的基因盒。dhfr和dfr17均为编码对磺胺类药物甲氧苄氨嘧啶产生耐药的基因盒；orfF为未知功能的开放阅读框。结论 临床致病革兰阳性菌和革兰阴性菌株均广泛存在着整合子结构．应加强对耐药基因在细菌种属间水平转移的监测工作。

Analysis on distribution and characterization of drug-resistant determinants in clinical bacteria

Objective To investigate the distribution and characterization of integrons in clinical strains.Methods The presence and genetic content of 3 classes integrons among 55 clinical strains were examined by multiple PCR and sequencing.Results 55(100%)strains were positive for intI1 gene.Furthermore,intI1-positive strains were amplified with primers of in-F and in-B which were set for amplifying the region of antibiotics resistance genes.Among 55 strains,an amplicon of 1?913?bp was yielded in 49 isolates,an amplicon of 1?664?bp was yielded in 6 isolates.Sequencing analysis revealed that amplicon 1?913?bp harbored genes of dhfr,orfF and aadA?2,amplicon 1?664?bp harbored genes of aadA5 and dfr?17,adA?2 and aadA?5 showing aminoglycoside resistance;dhfr and dfr?17 conferring resistance to trimethoprim,orfF encoding unknown function.Conclusion Resistance gene(s)mediated by class 1 integron was extensively existed in clinical isolates of both gram-negative and gram-positive bacteria.The result stressed the need for continued surveillance of antibiotic resistance gene(s) horizontal transference among bacteria genus.