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

## TL;DR

The study examines Nocardia infections in cancer patients, finding high mortality and resistance patterns, with linezolid and TMP-SMX showing consistent effectiveness.

## Contribution

The study provides new insights into Nocardia species diversity and resistance patterns in oncology patients, highlighting treatment implications.

## Key findings

- 30% of patients with nocardiosis died within 30 days of diagnosis.
- N. farcinica, N. cyriacigeorgica, and N. nova were the most frequently identified species.
- 70% of isolates tested showed resistance to imipenem, while all were susceptible to linezolid and TMP-SMX.

## Abstract

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

Nocardia species

Heat Map

description of the varying identified species and their susceptibilites

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

Nocardia susceptibilities

Risk Factors and 30 Day Mortaility

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.

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.

All Authors: No reported disclosures