Rhizobium radiobacter Bacteremia in an Immunocompetent Host

1Medical College of Wisconsin, Milwaukee, Wl
2Medical College of Wisconsin, Milwaukee, Wl
3Medical College of Wisconsin, Milwaukee, Wl
4Medical College of Wisconsin, Milwaukee, Wl

Meeting: Hospital Medicine 2009, May 14-17, Chicago, Ill.

Abstract number: 208

Case Presentation:

Rhizobium spp are aerobic gram‐negative bacilli widely distributed in soil and commonly known as tumorigenic plant pathogens. R. radiobacter is an uncommon cause of human infection. Immunocompromised patients with indwelling vascular devices are the most commonly infected human hosts. We present a 47‐year‐old woman with a history of short gut syndrome. She had been on total parenteral nutrition for 6 months and was admitted with chills and burning in her left arm in the area of her PICC. The hospital line sepsis protocol, which included vancomycin and cefepime, was initiated. Her first blood culture grew gram‐variable rods later identified as Rhizobium radiobacter. The organism was sensitive to cefepime and ciprofloxacin. Vancomycin was stopped, and cefepime was continued to the end of her hospitalization. She was discharged on oral ciprofloxacin and had complete symptom resolution.


In the United States, more than 200,000 infections related to indwelling vascular devices occur each year. The microorganisms most commonly associated with central venous catheter (CVC) infection are coagulase‐negative staphylococci, S. aureus, different species of gram‐negative bacilli, and Candida. Hospital protocols for catheter‐acquired infections are based on local epidemiological data. The majority of case reports on Rhizobium radiobacter infection are associated with profound immunosuppression and catheter‐related bloodstream infection (CRBSI). Additionally, cases of peritonitis in patients on peritoneal dialysis, endophthalmitis in patients with intraocular lens implants, pneumonia and prosthetic valve endocarditis have been reported. There has never been a clinical trial to determine optimal therapy for R. radiobacter infection. To date, susceptibility patterns vary, so treatment should be based on individualized antimicrobial sensitivities. A review of the literature suggests that fluoroquinolones, tetracyclines, extended spectrum beta‐lactams and carbapenems have been effective empiric therapies.


This represents the first case report of Rhizobium radiobacter CRBSI in an immunocompetent host. Clinicians should be attentive to unusual pathogens causing CRBSI, especially in centers with high volumes of CVC use and protocol‐driven treatments.

Author Disclosure:

J. N. Wainaina, none; M. Radzienda, none; G. Kumar, none; N. Ledeboer, none.

To cite this abstract:

Wainaina J, Radzienda M, Kumar G, Ledeboer N. Rhizobium radiobacter Bacteremia in an Immunocompetent Host. Abstract published at Hospital Medicine 2009, May 14-17, Chicago, Ill. Abstract 208. Journal of Hospital Medicine. 2009; 4 (suppl 1). https://www.shmabstracts.com/abstract/rhizobium-radiobacter-bacteremia-in-an-immunocompetent-host/. Accessed May 21, 2019.

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