(1222) Evaluation of Diffuse Alveolar Hemorrhage Infectious Causes in Patients With Hematologic Malignancy

Introduction: Diffuse alveolar hemorrhage (DAH) is a recognized pulmonary complication in patients with hematologic malignancy (HM). The etiology of DAH can be multifactorial with both infectious and non-infectious causes. Much of the data describing DAH in patients with HM focuses on non-infectious DAH (NI-DAH). Infection associated diffuse alveolar hemorrhage (I-DAH) in patients with HM is not well described. We sought to evaluate the prevalence of I-DAH in patients with HM and describe common pathogens associated with IAH.

Methods: This was a retrospective cohort study of adult patients with HM who were admitted to Barnes Jewish Hospital between 7/1/2018 to 12/31/2021. Patients were eligible for inclusion if they underwent bronchoscopy with findings consistent with DAH defined as progressively bloodier aliquots with sequential bronchoalveolar lavage samples. Clinical, laboratory, microbiologic, and treatment data were collected. Standard bacterial cultures and a respiratory multiplex polymerase chain reaction (PCR) testing were performed per local standards. The primary outcome was positive microbiologic findings from the bronchoscopy.

Results: A total of 276 patients with HM underwent bronchoscopy during the study period. Bronchoscopy findings of DAH were seen in 32 patients. The most common HM was acute myeloid leukemia (52%) and 56.2% of patients had a history of hematopoietic stem cell transplant. Positive microbiologic data from bronchoscopy were found in 50% of patients (positive viral PCR, 56.3%; positive bacterial culture, 18.7%; both positive bacterial culture and viral PCR,25%). The most common viral pathogens were rhinovirus/enterovirus (N=6), herpes simplex virus (N=4), cytomegalovirus (N=4), and influenza A (N=3). Bacterial pathogens included Staphylococcus aureus (N=2), Klebsiella spp (N=2), Escherichia coli (N=1), Stenotrophomonas maltophilia (N=1), and Moraxella catarrhalis (N=1). In-hospital mortality occurred in 65.6% of patients (12/16 I-DAH vs. 9/16 NI-DAH; p=0.264).

Conclusions: Among patients with HM and DAH, concomitant positive microbiologic findings on bronchoscopy were common with viral pathogens predominating over bacterial pathogens. Our study serves as a basis for further research evaluating the impact of viral respiratory pathogens on DAH development and patient prognosis.