菌血症患儿血培养放射根瘤菌基因型与药敏分析

Genotypes and antimicrobial susceptibility of Rhizobium radiobacter isolated from pediatric patients with bacteremia

目的了解菌血症患儿血培养放射根瘤菌的基因型及药敏情况。方法收集2013年2月—2014年2月某2所医院全部菌血症患儿血培养的放射根瘤菌,应用聚合酶链反应(PCR)扩增其16S rDNA片段,采用脉冲场凝胶电泳(PFGE)鉴定细菌基因型,以及K-B法做药敏试验。结果 12例血培养阳性患儿共检出13株放射根瘤菌,包括3种基因型;其16S r DNA序列与放射根瘤菌IFM10623株同源性达99%。依据临床和实验室标准化协会(CLSI)2013铜绿假单胞菌药敏标准,13株菌对头孢他啶、哌拉西林、替卡西林、哌拉西林/他唑巴坦、替卡西林/克拉维酸、氨曲南与多粘菌素B耐药;而对头孢吡肟、多尼培南、亚胺培南、美罗培南、妥布霉素、奈替米星、环丙沙星、左氧氟沙星和诺氟沙星敏感。此外,13株菌对头孢噻肟和头孢曲松有较大的抑菌圈。结论临床需根据药敏试验结果,选择药物治疗放射根瘤菌感染;其中头孢噻肟和头孢曲松是治疗患儿放射根瘤菌感染的较好选择。

Objective To investigate genotypes and antimicrobial susceptibility of Rhizobium radiobacter （R.radiobact-er）isolated from pediatric patients with bacteremia.Methods R.radiobacter strains from blood cultures of pediatric pa-tients with bacteremia from February 2013 through February 2014 were collected.16S rDNA fragment was amplified by polymerase chain reaction（PCR）,bacterial genotypes were identified by pulsed-field gel electrophoresis （PFGE）,antimi-crobial susceptibility testing were performed by Kirby-Bauer disk diffusion method.Results 13 isolates of R.radiobacter were isolated from 12 children with positive blood culture,which including 3 genotypes,the homology of 16S rDNA fragment and R.radiobacter IFM 10623 was up to 99%.According to CLSI 2003 standard,these 13 R.radiobacter were resistant to ceftazidime,piperacillin,ticarcillin,piperacillin/tazobactam,ticarcillin/clavulanic acid,aztreo-nam and polymyxin B,but sensitive to cefepime,doripenem,imipenem,meropenem,tobramycin,netilmicin,cip-rofloxacin,levofloxacin,and norfloxacin.In addition,cefotaxime and ceftriaxone showed larger inhibition zone. Conclusion Therapy of R.radiobacter infection should be based on antimicrobial susceptibility testing results;cefo-taxime and ceftriaxone are better selection for the therapy of R.radiobacter infection in pediatric patients.