P-1297. Nocardia Infections in Oncology Patients: Risk Factors and Patterns of Resistance

Abstract Background Nocardia can lead to disseminated disease with high mortality in immunocompromised patients. Though Nocardia has been well documented in solid organ transplant recipients, its impact on patients with malignancies without bone marrow transplantation is less characterized. Nocardia species exhibit varying susceptibility to antibiotics and treatment requires prolonged courses of multiple antibiotics [1-3]. As our cancer population continues to grow, we are seeing increased cases of nocardiosis, urging the need for better treatment strategies. We investigated the epidemiology, risk factors, antimicrobial susceptibility, and outcomes of oncology patients with proven nocardiosis over a 15-year period.Nocardia speciesHeat Mapdescription of the varying identified species and their susceptibilites Methods This retrospective single-center cohort study reviewed all patients with nocardiosis from 2010 to 2025. In total, 40 patients were identified. Demographics, comorbidities, clinical presentations, epidemiology, susceptibility patterns, and outcomes were evaluated and described.Nocardia susceptibilitiesRisk Factors and 30 Day Mortaility Results By 30 days after positive culture, 12/40 (30%) patients had died. No association was found between sex, age, type of malignancy, degree of dissemination, initial antimicrobial regimen or medical comorbidities evaluated. In total, 16 unique Nocardia species were identified, most frequent were N. farcinica , N. cyriacigeorgica , and N. nova. All organisms exhibited susceptibility to linezolid and trimethoprim-sulfamethoxazole (TMP-SMX); of those tested for imipenem, 14/20 isolates (70%) demonstrated resistance. Conclusion Our findings demonstrate the diversity of pathogenic Nocardia species, antibiotic resistance patterns, and the high 30-day mortality rate (30%) from these infections. All species were susceptible to linezolid and TMP-SMX, while a sizable portion were resistant to imipenem. Empiric regimens may consider linezolid or TMP-SMX, while the role of imipenem may need to be further evaluated. Disclosures All Authors: No reported disclosures