[Infective endocarditis by Rhizobium radiobacter. A case report]

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.