Stenotrophomonas maltophilia of clinical origin display higher temperature tolerance comparing with environmental isolates

Stenotrophomonas maltophilia is a gram-negative, multidrug-resistant, opportunistic human pathogen responsible for hard-to-treat infections in immunocompromised individuals. Besides being recognized as an important clinical pathogen, S. maltophilia is also widespread in the natural environment, with knowledge of the pathogenic potential of the environmental S. maltophilia pool still lacking. In this study, we aimed to identify the differences in virulence-related traits between clinical and environmental S. maltophilia isolates by assessing their genotypic and phenotypic features. For this purpose, 40 S. maltophilia isolates from natural environment and 34 clinical isolates obtained from patients were analysed. We observed a high degree of genotypic diversity among the isolates irrespective of their origin. Although antibiotic resistance- and virulence-related genes were more prevalent in the clinical isolates, the majority of the analysed genes were also present in the environmental isolates. Most importantly, the phenotypic features, specifically the ability to form biofilms and display twitching motility at human body temperature were predominantly characteristic to the clinical isolates. Our study indicates that adaptation to endure human body temperature is a feature strongly linked to S. maltophilia strains of clinical origin, and is significant when differentiating harmless environmental bacteria from pathogenic S. maltophilia isolates.