Endofungal Mycetohabitans rhizoxinica Bacteremia Associated with Rhizopus microsporus Respiratory Tract Infection

Abstract

We report Mycetohabitans rhizoxinica bacteremia in a 65-year-old woman in California, USA, who was undergoing chimeric antigen receptor T-cell therapy for multiple myeloma. Acute brain infarction and pneumonia developed; Rhizopus microsporus mold was isolated from tracheal suction. Whole-genome sequencing confirmed bacteria in blood as genetically identical to endofungal bacteria inside the mold.

Keywords: Burkholderia rhizoxinica; Mycetohabitans rhizoxinica; Rhizopus microspores; United States; bacteremia; bacteria; endofungal bacteria; fungi; mucormycosis; respiratory infection.

Figure 1

Imaging studies from a 65-year-old woman with multiple myeloma undergoing chimeric antigen receptor T-cell therapy who was admitted to the hospital for worsening foot and ankle pain, California, USA. A) Chest radiograph image, showing a moderate right-sided pleural effusion and adjacent pulmonary opacities indicative of pneumonia. B) Magnetic resonance imaging of the patient’s brain, showing the infarct involving the left medial parietal lobe.

Figure 2

Whole-genome sequencing analysis of bacterial and fungal isolates (A) in a 65-year-old woman with multiple myeloma undergoing chimeric antigen receptor T-cell therapy, California, USA. The bacteria were identified as Mycetohabitans rhizoxinica with >99% identity in all 3 full-length marker genes compared with the reference organism (B, left side). The mold was identified as Rhizopus microsporus with >99% identity in the ITS gene and the D1–D2 region of the 28S gene compared with a reference organism (B, right side). Whole-genome sequences of the bacteria from blood (C, left side) revealed whole-genome coverage 94.0% and pairwise identity 95.5% with sufficient mean coverage of 298×. Whole-genome sequence of the mold from tracheal aspirate (C, right side) aligned to reference bacterial whole-genome sequence showed whole-genome coverage 94.1% and pairwise identity 95.8%, with sufficient mean coverage of 75×. The bacteria inside the mold from the trachea were genetically identical to the bacteria from the blood, as shown by the SNP analysis (D). ITS, internal transcribed spacer; SNP, single nucleotide polymorphism.