Mycetohabitans rhizoxinica bacteremia in the setting of invasive fungal disease in an immunocompromised patient.

BACKGROUND

Mycetohabitans [Burkholderia] rhizoxinica is an endosymbiotic bacteria of Rhizopus microsporus that normally causes rice seedling blight. In our case report, we present one of the first known cases of concomitant bacteremia with M. rhizoxinica and invasive mold infection due to Rhizopus spp. in an immunocompromised child.

CASE SUMMARY: A 3 year old male recently diagnosed with B-cell acute lymphoblastic leukemia developed febrile neutropenia. His workup was significant for invasive fungal sinusitis due to Exserohilum spp. based on histopathology and culture, a right middle lobe infiltrate, and a blood culture positive for gram-negative coccobacilli, later identified as M. rhizoxinica. Additionally, metagenomics next-generation sequencing was positive for R. microsporus as was broad-range fungal PCR testing of a lung biopsy sample. His surgical treatments included sinus debridement and a near total right pneumonectomy, and his antimicrobial treatment included 10 days of cefepime for his bacteremia, 4 weeks of liposomal amphotericin B, 4 weeks of micafungin following his pneumonectomy, and approximately 12 months of posaconazole.

CONCLUSION

This case highlights the association of M. rhizoxinica with Rhizopus spp., wherein the isolation of M. rhizoxinica led to a high index of suspicion of Rhizopus infection in an immunocompromised patient who developed bacteremia with a slow-growing, oxidase positive, gram-negative bacteria not able to be identified by traditional identification methods.