PHENOTYPIC CHARACTERIZATION AND BACTERIAL INTERACTIONS OF THE COMPLEX MICROBIAL POPULATION IN URINARY DOUBLE-J CATHETERS

Abstract

Catheter-associated urinary tract infections (CAUTIs) are a major cause of morbidity in healthcare settings, often linked to the colonization of catheters by diverse bacterial species. This study aimed to characterize 27 clinical uropathogenic isolates obtained from double-J catheters through phenotypic and genotypic assays. The isolated species included, Staphylococcus spp., Enterococcus faecalis, Klebsiella pneumoniae, Escherichia coli and Bacillus spp. These isolates were evaluated for biofilm formation, production of extracellular components such as cellulose and amyloid-like fibers, motility, hemolytic capacity, siderophore production, stress tolerance, and antibiotic resistance profiles. The findings revealed that E. coli, S. aureus, B. subtilis isolates exhibited strong biofilm formation and robust extracellular matrix production, features that contribute to their persistence in catheter environments. Acid pH and oxidative stress tolerance results indicated a differential strain response even within the same genus. Additionally, multidrug resistance (MDR) was observed in several isolates, especially in K. pneumonia and E. faecalis, correlating with their biofilm-forming capacities. Co-cultures studies demonstrated synergistic interactions between the co-isolated pair, particularly with Bacillus spp. enhancing biofilm formation in static condition. The interaction results indicate the importance of investigating the potential clinical relevance of Bacillus spp., even though they are not traditionally considered human pathogens. These results provide critical insights into the pathogenic mechanisms and survival strategies of several uropathogens in CAUTI, emphasizing the need for targeted therapeutic interventions to prevent recurrent infections and manage antibiotic resistance. ImportanceCatheter-associated urinary tract infections (CAUTIs) are a persistent challenge in healthcare due to their association with biofilm-forming bacteria that resist treatments. To investigate the complexity of microbial population of CAUTI, we provide an in-depth analysis of the diverse range of bacterial strains isolates from the devices. This study highlights the role of both well-known pathogens and less traditionally recognized species, such as Bacillus spp., in these infections. By revealing that bacterial interactions analyzed here enhance biofilm formation, this research underscores the need to reconsider the clinical importance of Bacillus spp. in polymicrobial settings. This knowledge is critical for designing more effective therapeutic interventions to mitigate biofilm-related complications in medical devices.