Early Detection and Identification of Methylobacterium radiotolerans Bacteremia in an Early T-Cell Precursor Acute Lymphoblastic Leukemia Patient: A Rare Infection and Literature Review.

(1) Background: Methylobacterium radiotolerans (M. radiotolerans) is a fastidious, aerobic, Gram-negative bacillus primarily found in environmental sources such as soil and sewage, with rare clinical isolation. Its identification remains challenging due to poor growth with conventional culture methods. (2) Case presentation: A 42-year-old male patient with early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) presented with M. radiotolerans bacteremia during hospitalization. The organism was successfully isolated from peripheral blood using the Myco/F Lytic culture vial (Becton, Dickinson and Company, Lincoln, MT, USA). Comparative analysis demonstrated markedly superior growth of M. radiotolerans in Myco/F Lytic culture vials compared with Plus Aerobic/F Lytic and Lytic/10 Anaerobic/F culture vials (Becton, Dickinson and Company, Lincoln, MT, USA). Antimicrobial susceptibility testing, performed with the epsilometer test (E-test) and Bauer-Kirby disk diffusion (BK) method, guided the selection of an appropriate therapeutic regimen. The patient's infection was ultimately controlled following targeted antimicrobial therapy. (3) Conclusions: M. radiotolerans demonstrates a distinct growth preference for the Myco/F Lytic culture medium. This observation highlights the importance of considering alternative culture media in cases of rare or fastidious bacterial infections that cannot be reliably detected using conventional Plus Aerobic/F Lytic or Lytic/10 Anaerobic/F culture vials, which are typically employed for clinical isolation of aerobic and anaerobic bacteria.