多重耐药德尔卑沙门菌临床株耐药基因的研究

目的检测临床分离的多重耐药德尔卑沙门菌对抗菌药物的敏感性及其耐药机制。方法选取8株多重耐药的德尔卑沙门菌,用微量肉汤稀释法检测对12种抗菌药物的敏感性。质粒指纹图谱分析耐药质粒分布。聚合酶链反应(PCR)检测TEM、CTX-M型β内酰胺酶基因、I型整合子相关的整合酶intI基因和qacEΔ12sul1耐消毒剂和磺胺基因,染色体和质粒介导喹诺酮耐药基因gyrA,parC,qnrA/qnrB/qnrC/qnrS,aac(6')-Ⅰb-cr,oqxAB等12种耐药基因。结果8株多重耐药菌对氨苄西林、哌拉西林、头孢呋辛、头孢西丁、卡那霉素、庆大霉素、复方磺胺甲唑、四环素及氯霉素等9种抗菌药物全部耐药,2株对头孢曲松耐药。所有菌株对亚胺培南、头孢哌酮/舒巴坦、哌拉西林/他唑巴坦、头孢吡肟敏感。质粒电泳显示,8株菌均携带1~4种大小不等质粒,其中约182kb大小质粒可发现于3株菌中。所有8株菌都携带TEM编码基因,intI和qacEΔ12sul1、aac(6')-Ⅰb-cr基因。有2株菌携CTX-M-14型耐药基因。在喹诺酮耐药相关基因中,5株菌的GyrA发生了D87S的氨基酸突变,5株菌的ParC发生了T57S的氨基酸突变。5株菌携带oqxAB基因,4株菌携带qnrS基因。所有菌株都未携带qnrA/qnrB/qnrC耐药基因。结论多重耐药沙门菌同时存在多种耐药基因,耐药质粒与I型整合子系统共存是导致菌株同时对多种结构各异的抗菌药物耐药的原因。

Research of the resistant genes in clinical isolates of multi-drug resistant Salmonella derby

Objective To identify the antimicrobial susceptibility of clinical isolates of multi-drug resistant Salmonella derby and to detect its resistant genes. Methods Eight clinical MDR isolates of Salmonella derby strains were randomly selected. Antibiotic susceptibility of Salmonella derby to 14 different antibiotics was tested using the microdillution method. The β-1actamase gene of TEM and CTX-M type, integron I-relative genes such as intI gene, acEA12sull genes , fluoroquinolone-resistant genes such as gyrA and parC,qnrA／qnrB／ qnrC／ qnrS gene, aac（6＇ ）- Ⅰ b-cr gene, and oqxAB gene were all detected by PCR. Results Eight multi-drug resistant strains were resistant to ampicillin, piperacillin, cefuroxime, kanamycin, entamicin, trimesulf and chloramphenicol, two out of eight isolates were resistant to ceftriaxone .Whereas all were sensitive to imipenem, cefoperazone/sulbactam, piperacillin/tazobactam and cefepime. All eight MDR isolates carried TEM encoding gene, intI gene and qacEAl2sull gene, aac （6＇）- Ⅰ b-cr gene. Two out of eight isolates carried the CTX-M-14 type gene. For the fluoroquinolone-resistant genes, GyrA mutation of D87N was found in five isolates and ParC mutation of T57S was found in six isolates. Five isolates carried oqxAB gene, and four carried qnrS gene. None of all the eight strains was found to carry qnrMqnrB/qnrC gene.Conclusion The multi-drug resistant Salmonella derby strains contained an array of drug resistant genes, leading to the resistance to different antibiotics.