Concurrent Severe Pneumocystis and Histoplasma Pneumonia in a Renal and Stem Cell Transplant Recipient: A Conundrum in Empiric Management and Bronchoscopic Evaluation

Document Type

Conference Proceeding

Publication Date

10-2025

Publication Title

Chest

Abstract

INTRODUCTION: Pneumocystis and Histoplasma coinfection is rare, with a 4.2% incidence in DNA samples from 289 patients at a tertiary care center. However, Histoplasma was cultured in only 4/16 of these cases. The distinct pathological effects of these fungi enable coinfection: Histoplasma targets macrophages, while Pneumocystis affects alveolar epithelial cells. Coinfection is most commonly observed in immunocompromised individuals, particularly HIV patients. Solid and hematological transplant recipients are also at risk for Pneumocystis pneumonia (PCP), with Bactrim prophylaxis recommended for at least six months post-transplant. Histoplasma capsulatum is a known complication in allogeneic stem cell transplant recipients. CASE PRESENTATION: A 53-year old female with a history of IgA nephropathy requiring three renal transplants, complicated by CNS lymphoma secondary to post-transplant lymphoproliferative disorder, underwent stem cell transplant one year prior. Her medical history also included coronary artery disease, chronic CMV viremia, and adrenal insufficiency. She presented to the emergency department with fever and dysuria, diagnosed with a complicated UTI due to Vancomycin-resistant Enterococcus, and started on IV Daptomycin. Initial CT chest, abdomen, and pelvis with contrast revealed left-sided perinephric and peripelvic fat stranding, along with thrombocytopenia, metabolic acidosis, and patchy ground-glass opacities in bilateral lower lung lobes. Despite Daptomycin therapy, she continued to have fevers up to 103◦F and nausea. Nasopharyngeal testing was positive for rhinovirus, and she had completed Bactrim prophylaxis two weeks prior. A repeat CT chest on Day 2 confirmed persistent bilateral ground-glass opacities, and Fungitell was positive at 171 pg/mL. Given her immunocompromised status, bronchoscopy with bronchoalveolar lavage (BAL) was performed, revealing Pneumocystis jirovecii and Histoplasma antigens. A brain MRI ruled out recurrent CNS lymphoma. She was started on oral Bactrim, switched to IV Bactrim due to nausea. On Day 8, a chest xray showed worsening bilateral consolidations. On Day 9, she developed hypoxia, worsening thrombocytopenia, and was started on itraconazole, valacyclovir, and cefepime. Her oxygen requirements increased to 13 L on cold flow, necessitating MICU transfer for IV diuresis, which reduced her oxygen needs. She underwent repeat bronchoscopy but remained intubated. After 48 hours, she was extubated but continued to require positive pressure ventilation. The infectious disease team switched her to IV Clindamycin and Primaquine. Repeat BAL was positive for Histoplasma. She developed recurrent unstable SVT and atrial fibrillation, unresponsive to treatment. The family chose comfort care, and she passed away later that day. DISCUSSION: Our patient presented a diagnostic challenge with no pneumonia symptoms, only hypoxia documented on vital monitoring. Steroids are recommended for hypoxic patients with SpO2< 90% and A-a gradient >35. Balancing steroids and anti-infectives was challenging due to her multiple transplants—steroids can inhibit graft-versus-tumor effects, while TMP-SMX and valganciclovir may affect the transplanted kidney. We prioritized confirming PCP and ruling out recurrent CNS lymphoma with a brain MRI before starting treatment. There are no guidelines for managing PCP with Histoplasma coinfection due to potential cross-reactivity. Itraconazole was given for 3 days, showing PCP clearance but persistent Histoplasma positivity, suggesting prolonged itraconazole may be beneficial. CONCLUSIONS: Itraconazole and Iv steroids should be initiated early in this cohort.

Volume

168

Issue

4S

First Page

1914A

Comments

American College of Chest Physicians CHEST Annual Meeting, October 19-22, 2025, Chicago, IL

Last Page

1915A

DOI

10.1016/j.chest.2025.07.1085

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