First case of infective endocarditis caused by Methylobacterium radiotolerans

Methylobacterium radiotolerans has only been identified in blood samples from end-stage renal failure or leukaemia patients in clinic. Here, we report a case of infective endocarditis (IE) caused by M. radiotolerans. 16S rRNA sequencing and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) were used to identify the bacteria isolated from cardiac vegetation. A drug sensitivity test was conducted by disk diffusion on blood Mueller-Hinton agar. This isolate was identified as M. radiotolerans, which was susceptible to aminoglycosides and ciprofloxacin. Our findings also suggest that M. radiotolerans can cause infection in a patient with normal immune function.