# Concurrent Mold, Mycobacterial, and Viral Infections in a Hematopoietic Stem Cell Transplant Recipient Undergoing Lung Transplantation for Graft-Versus-Host Disease

## TL;DR

A stem cell transplant patient developed multiple rare lung infections, requiring lung transplantation and highlighting the need for personalized care in immunocompromised individuals.

## Contribution

This case study presents a rare and complex clinical scenario of overlapping mold, mycobacterial, and viral infections in a stem cell transplant recipient.

## Key findings

- The patient developed infections with Microascus spp., Mycobacterium chimaera, Aspergillus calidoustus, and RSV after stem cell transplantation.
- Lung transplantation was necessary due to progressive bronchiolitis obliterans despite prolonged antifungal and antimicrobial therapy.
- Post-transplant prophylaxis with multiple antifungal and antimicrobial agents prevented recurrence and ensured clinical stability.

## Abstract

Patients who undergo stem cell transplantation for blood cancers often develop long-term immune system problems that increase their risk of serious infections. Some infections are difficult to diagnose and treat, especially when more than one infection occurs at the same time. We describe a woman who developed multiple rare lung infections years after her stem cell transplant, including fungal and mycobacterial infections, followed by respiratory viral infection. Treating these infections was challenging because of medication side effects, drug interactions, and limited treatment guidance. Despite prolonged therapy, progressive lung damage ultimately required lung transplantation. Examination of the removed lungs confirmed evidence of prior treated infections. With careful long-term antimicrobial prevention and close monitoring, she recovered well after transplantation. This case highlights the complexity of managing overlapping infections in severely immunocompromised patients and emphasizes the importance of individualized, multidisciplinary care and careful medication management.

Hematopoietic stem cell transplant (HSCT) recipients are at high risk for opportunistic infections due to profound immunosuppression and graft-versus-host disease (GvHD). Molds and nontuberculous mycobacteria (NTM) pose diagnostic and therapeutic challenges, especially when infections overlap. A 42-year-old woman with prior allogeneic HSCT for acute myeloid leukemia (AML) developed pulmonary infections with Microascus spp. and Mycobacterium chimaera, later complicated by Aspergillus calidoustus and RSV infection. Initial therapy included voriconazole, amphotericin B, and a macrolide-based multidrug regimen for NTM. Modifications were required for drug resistance and hepatotoxicity. Despite partial response, recurrent fungal infection necessitated prolonged antifungal therapy, including adjunctive inhaled amphotericin B and terbinafine. Ultimately, progressive bronchiolitis obliterans prompted bilateral lung transplantation. Explant pathology revealed necrotizing granulomas positive for NTM and Microascus spp. Post-transplant prophylaxis with voriconazole, rifabutin, azithromycin, and inhaled amikacin prevented recurrence, and the patient remained clinically stable at 6-month follow-up. This case illustrates the complexity of managing overlapping mold and NTM infections in HSCT recipients, highlighting the need for individualized, multidisciplinary care. Therapeutic drug monitoring, careful adjustment for drug–drug interactions, and the use of adjunctive inhaled antifungals were critical to achieving a favorable outcome.