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

摘要:

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IFM 10623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。

Abstract:

ObjectiveTo investigate genotypes and antimicrobial susceptibility of Rhizobium radiobacter (R. radiobacter) isolated from pediatric patients with bacteremia.MethodsR. radiobacter strains from blood cultures of pediatric patients 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), antimicrobial susceptibility testing were performed by KirbyBauer disk diffusion method. Results13 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, aztreonam and polymyxin B, but sensitive to cefepime, doripenem, imipenem, meropenem, tobramycin,  netilmicin, ciprofloxacin, levofloxacin, and norfloxacin.  In addition, cefotaxime and ceftriaxone showed larger inhibition zone.ConclusionTherapy of R.radiobacter infection should be based on antimicrobial susceptibility testing results;  cefotaxime and ceftriaxone are better selection for the therapy of R.radiobacter infection in pediatric patients.