Clinical Characteristics, Outcomes, and Antimicrobial Resistance of Non-aeruginosa Pseudomonas Infection in Adult Cancer Patients

Abstract Background Non-aeruginosa Pseudomonas (NAP) species, historically considered environmental contaminants, are increasingly recognized as clinically significant pathogens, particularly in immunocompromised patients. While Pseudomonas aeruginosa is well-studied, less is known about the epidemiology and resistance patterns of NAP species. Methods We conducted a retrospective review of culture-confirmed NAP infections in adult inpatients at a cancer center from 2012 to 2022. Data on demographics, infection sites, malignancy types, and antimicrobial susceptibilities were extracted from electronic medical records. Results Among 104 infections, the most common species were Pseudomonas putida (63.5%), P. fluorescens (25%), P. stutzeri (7%), and P. mendocina (4%). Urinary and respiratory infections predominated, frequently linked to indwelling devices. P. fluorescens infections had the highest 30-day mortality (19%) versus P. putida (7%). Polymicrobial infections were common. Fluoroquinolone susceptibility was high across all species (85%–100%). Discussion NAP species are emerging as relevant pathogens in oncology patients, especially those with hematologic malignancies. Species-level differences in clinical impact and resistance underscore the need for targeted diagnostics and stewardship strategies.