Genotypes and antimicrobial susceptibility of Rhizobium radiobacter isola-ted from pediatric patients with bacteremia / 中国感染控制杂志

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.

Evaluation on laboratory diagnosis of catheter-related bloodstream infec-tion due to Rhizobium radiobacter in pediatric patients / 中国感染控制杂志

Objective To evaluate diagnostic method and infection factors for catheter-related bloodstream infec-tion(CRBSI)due to Rhizobium radiobacter (R.radiobacter)in pediatric patients.Methods Clinical data of 1 014 pediatric patients with central venous catheter(CVC)-related treatment in a hospital from February 2012 to February 2014 were collected,semi-quantitative culturing of catheter,colony forming unit (CFU)ratio of catheter to venous blood,difference in culture time between venous blood and catheter were detected among patients with R.radiobact-er infection;factors for R.radiobacter infection were analyzed.Results Of 1 014 pediatric patients who used CVC, 32 were detected R.radiobacter from catheter blood,28 were detected from venous blood,27 were detected from both catheter and venous blood.Catheter semi-quantitative culture of 27 patients were ≥ 15 CFU,5 were5 days are risk factors for R.radiobacter bloodstream infection.

Endocarditis infecciosa por Rhizobium radiobacter: Reporte de un caso / Infective endocarditis by Rhizobium radiobacter: A case report

Rhizobium radiobacter es una bacteria Gram-negativa, fijadora de nitrógeno que se encuentra principalmente en el suelo. Rara vez causa infecciones en humanos. Ha sido asociada a bacteriemia secundaria a colonización de catéteres intravasculares en pacientes inmunocomprometidos. El objetivo de este trabajo es informar un caso de endocarditis infecciosa por R. radiobacter. Se trata de paciente masculino, de 47 años de edad, con diagnóstico de enfermedad renal crónica estadio 5 en tratamiento sustitutivo con hemodiálisis, quien acude a centro asistencial por presentar fiebre de dos semanas de evolución. Es hospitalizado, se toman muestras de sangre periférica para hemocultivo y se inicia antibioticoterapia empírica con cefotaxime más vancomicina. El ecocardiograma transtorácico revelo vegetación fusiforme en válvula tricúspide con regurgitación grado III-IV/IV. Al séptimo día del inicio de la antibioterapia el paciente presenta mejoría clínica y paraclínica. La bacteria identificada por hemocultivo es Rhizobium radiobacter resistente a ceftriaxona y sensible a imipenem, amikacina, ampicilina y ampicilina/sulbactam. Debido a la mejoría clínica se decide continuar tratamiento con vancomicina y se anexa imipenem. A los 14 días de iniciada la antibioterapia el paciente es dado de alta con tratamiento ambulatorio con imipenen hasta cumplir seis semanas de tratamiento. En el ecocardiograma control se evidencio ausencia de la vegetación en la válvula tricúspide. Este caso sugiere que R. radiobacter puede ser una causa de endocarditis en pacientes portadores de catéteres intravasculares.

Rhizobium radiobacter is a Gram-negative, nitrogen-fixing bacterium, which is found mainly on the ground. It rarely causes infections in humans. It has been associated with bacteremia, secondary to colonization of intravascular catheters, in immunocompromised patients. The aim of this paper was to report the case of an infective endocarditis caused by R. radiobacter, in a 47-year-old male, diagnosed with chronic kidney disease stage 5, on replacement therapy with hemodialysis and who attended the medical center with fever of two weeks duration. The patient was hospitalized and samples of peripheral blood were taken for culture. Empirical antibiotic therapy was started with cefotaxime plus vancomycin. The transthoracic echocardiogram revealed fusiform vegetation on the tricuspid valve, with grade III-IV/IV regurgitation. On the seventh day after the start of antibiotic therapy, the patient had a clinical and paraclinical improvement. The bacterium identified by blood culture was Rhizobium radiobacter, ceftriaxone-resistant and sensitive to imipenem, amikacin, ampicillin and ampicillin/ sulbactam. Because of the clinical improvement, it was decided to continue treatment with vancomycin and additionally, with imipenem. At 14 days after the start of antibiotic therapy, the patient was discharged with outpatient treatment with imipenem up to six weeks of treatment. The control echocardiogram showed the absence of vegetation on the tricuspid valve. This case suggests that R. radiobacter can cause endocarditis in patients with intravascular catheters.

Peritonite por Rhizobium radiobacter / Peritonitis due to Rhizobium radiobacter

Rhizobium radiobacter (Agrobacterium radiobacter) is an aerobic Gram-negative rod belonging to Agrobacterium genus, a group of phytopathogenic bacteria present in the soil that has been implicated in human opportunistic infections. We report a clinical case of bacterial peritonitis in a 5-year-old child with chronic renal disease in peritoneal dialysis, who had a history of direct soil contact identified. The infection was treated with ceftazidime and piperaciline+tazobactam without relapses or the need to remove the peritoneal dialysis catheter.

O Rhizobium radiobacter (Agrobacterium radiobacter) é um microorganismo Gram-negativo aeróbio do gênero Agrobacterium, grupo de bactérias fitopatogénicas presentes no solo, que tem sido implicado em infecções oportunistas nos humanos. Relata-se um caso clínico de peritonite bacteriana em criança de 5 anos com doença renal crônica em diálise peritoneal, que teve um factor epidemiológico de contato direto com o solo identificado. A infecção foi tratada com ceftazidima e piperacilina+tazobactam, sem reinfecções ou necessidade de remoção do cateter de diálise peritoneal.

Catheter associated bloodstream infection caused by R. radiobacter.

Rhizobium radiobacter is a gram negative bacillus that is infrequently recognized in clinical specimens but is emerging as an opportunistic human pathogen. Infections due to Rhizobium radiobacter are strongly related to the presence of foreign plastic material and effective treatment often requires removal of the device. We report a case of R. radiobacter bloodstream infection associated with a central venous catheter which was easily controlled by antimicrobial treatment and did not require removal of intravascular device. To the best of our knowledge, this is the first case report from India implicating R. radiobacter as a cause of human infection.

A Case of Rhizobium Radiobacter Peritonitis Cured without Removal of the PD Catheter in a Patient on CAPD / 대한신장학회지

Rhizobium radiobacter has been recognized as a rare pathogen affecting debilitated patients and usually associated with indwelling foreign body. Rhizobium radiobacter is a rare pathogen of peritonitis in patients on peritoneal dialysis. It is assumed that a cure can hardly be expected without removal of a peritoneal dialysis catheter. We experienced a case of Rhizoboum radiobacter peritonitis in a patient on CAPD successfully cured without removal of the peritoneal dialysis catheter. The patient was 42-year-old male and maintained on CAPD for 2 months. He visited with cloudy peritoneal dialysate effluent and showed mild abdominal tenderness. 650 leucocytes/microL were counted and Rhizobium radiobacter was isolated in the peritoneal dialysate effluent. His peritonitis was completely resolved with 3 weeks course of intraperitoneal ceftazidime and oral ciprofloxacin. He has maintained on CAPD without recurrence of peritonitis for 12 months.

Agrobacterium tumefaciens-mediated transformation of uracil auxotroph Aspergillus fumigatus is an efficient method for target gene knockout / 北京大学学报(医学版)

Objective:To investigate the efficiency of Agrobacterium tumefaciensmediated transfor-mation of Aspergillus fumigatus by using pyrG as a recessive selectable marker.Methods: FAP1 and SHO1 genes target sequences,composed of a selectable marker pyrG and the flanking sequences of the FAP1 and the SHO1 genes,were cloned into a binary plasmid pDHt/sk,respectively.The produced plasmids were transformed into A.tumefaciens.The A.tumefaciens and uracil auxotroph A.fumigatus were cocultured in induction medium without uricil and uridine at 24 ℃ for 48 h.To inhibit growth of A.tumefaciens and to select transformants,the cultures were transferred to 37 ℃ and incubated for another 48 h.Results: In this study,A.tumefaciens-medidated transformation of A.fumigatus produced high homologous recombination rates,which was 44%(7 of 16) for FAP1 and 35%(7 of 20) for SHO1.Conclusion: Our study showed that A.tumefaciens-medidated transformation by using pyrG as a recessive selectable marker is an efficient tool for target gene deletion of A.fumigatus.