3株含qnr基因肺炎克雷伯菌中超广谱β-内酰胺酶的检测

目的了解临床分离含qnr基因,(质粒介导的喹酮类耐药基因)肺炎克雷伯菌中超广谱β-内酰胺酶的基因型别。方法琼脂稀释法测定3株临床分离含qnr基因肺炎克雷伯菌对β-内酰胺类、喹诺酮类抗菌药物的耐药性,NCCLS表型确证试验进行产ESBLs菌株的表型鉴定、采用TEM、SHV、CTX-M-1组、CTX-M-2组、CTX-M-13组、OXA-1组、OXA-2组、OXA-10组、PER-1、VEB-1β-内酰胺酶通用引物以及TEM、CTX-M-13组、OXA-1组全编码基因引物、I类整合酶基因引物进行PCR检测和DNA序列分析;同时对这些菌株进行PFGE检测。结果3株临床分离含qnr基因肺炎克雷伯菌均为产ESBLs菌株,ESBLs基因型别为CTX-M-14,其中2株细菌同时产生TEM-1型广谱β-内酰胺酶、1株同时产生TEM-1和OXA-30型广谱β-内酰胺酶,I类整合酶基因均为阳性;这些菌株对青霉素类、一代、二代、三代头孢菌素(头孢噻肟)以及多种喹诺酮类均显示耐药。3株菌株中有2株的PFGE谱型相同。结论临床分离含qnr基因肺炎克雷伯菌可同时产生CTX-M-14超广谱β-内酰胺酶,引起多重耐药,并存在克隆传播,临床应加强检测。

Detection of extended-spectrum β-lactamases in Klebsiellae pneumoniae isolates with qnr gene

Aim To identify the extended-spectrum β-lactamases(ESBLs) gene in Klebsiellae pneumoniae isolates with qnr gene.Methods Antimicrobial agents susceptibilities were determined with standard agar dilution procedure on Mueller-Hintonagar and 3 isolates with qnr gene were confirmed as ESBLs producing strains by NCCLS Confirmatory Test.The partial blagene of ESBLs producing isolates were detected by PCR using universal primers for TEM,SHV,CTX-M-1group,CTX-M-2 group,CTX-M-13group,OXA-1group,OXA-2 group,OXA-10 group,PER-1 and VEB-1,respectively.At the same time,Class 1 integrase gene was also detected by PCR.The entire blaCTX-M-13group,blaTEM,blaOXA-1group were amplified by PCR using the primers outside the Open Reading Frame(ORF) of these β-lactamases.The PCR products were also directly sequenced and analyzed;the clinical isolates of ESBLs producers were detected by PFGE. Results 3 Klebsiellae pneumoniae isolates with qnr gene were ESBLs producers and they produced CTX-M-14 ESBLs and TEM-1 β-lactamases.1 isolate simultaneously produced OXA-1β-lactamases,and 3 isolates carried class 1 integron.Besides quinolones,ESBL producers were also resistant to most β-lactams,and PFGE patterns of two isolates were same.Conclusion 3 Klebsiellae pneumoniae isolates with qnr gene produced CTX-M-14 ESBLs,which caused their multi-resistance,and clone spread was found in them.More attention should be paid to detect those strains.