Epidemiological and Clinical Characteristics of Stenotrophomonas maltophilia Isolates from Hospitalized Medical Patients; An Emerging Pathogen in the Non-Critically Ill

Until recently, <i>Stenotrophomonas maltophilia</i> was considered a low-virulence pathogen, usually found as an environmental commensal and colonizer of moist abiotic surfaces. Lately, it has increasingly been implicated in invasive infections with high associated morbidity and mortality. Most epidemiological studies involving patients with <i>S. maltophilia</i> infections have recorded risk factors and their associations with outcomes in critically ill patients. The aim of this study was to investigate its epidemiology as a pathogen in patients hospitalized in medical wards and potential factors associated with mortality. For this purpose, <i>S. maltophilia</i>-positive cultures from patients admitted to medical wards from 1 January 2023 to 30 June 2025 were collected, demographics and patient characteristics were recorded and analyzed and associated with clinical outcome. Twenty-nine patients and their first positive <i>S. maltophilia</i> positive culture were included in the study with a direct attributable mortality of 27.6%. Patients with cardiovascular and chronic obstructive pulmonary disease more commonly developed respiratory tract infections. Among the recorded comorbidities, only diabetes was associated with worse outcome. Most of the strains retained sensitivity to co-trimoxazole and levofloxacin and treatment outcome was not affected by the choice of regimen. This study highlights the rise of <i>S. maltophilia</i> to a true pathogen affecting immunocompetent patients; in combination with its antimicrobial resistance, this justifies its recognition as an emerging pathogen of public health concern.