A case of septic pulmonary embolization due to rapidly growing mycobacteria during chemotherapy for acute lymphoblastic leukemia

Abstract

We report a case of septic pulmonary embolization due to Mycobacterium mucogenicum. A 6-year-old boy was diagnosed B precursor cell type acute lymphoblastic leukemia a year ago, and thereafter he had been receiving chemotherapy. During the 6^th chemotherapy treatment, he had fever and blood culture was positive. The Gram staining of his blood culture sample did not show any bacteria but Ziehl-Neelsen staining showed bacteria. We did a rapid identification test using mass spectrometer, which proved that the results were highly positive for Mycobacterium phocaicum. Computed tomography of his chest revealed multiple small nodules images, so we diagnosed his infection as a septic pulmonary embolization due to rapidly growing mycobacteria. We removed the central venous catheter in an early stage and started multiple antibiotic agents. After that his fever rapidly subsided. The pathogen was finally identified as M. mucogenicum by gene analysis. M. mucogenicum is one of the rapidly growing mycobacteria which could be found in water and soil. It causes opportunistic infectious disease including abscess in lung and skin. In the case of immunocompromised patient with positive blood culture and negative Gram staining, we should consider the possibility of bloodstream infection due to rapidly growing mycobacteria.