Dual bacterial interactions between uropathogens co-isolated from "double J"catheters

ARROYO EGEA, J; VILLEGAS, JM; RAPISARDA, VA; FARIZANO, JV; GRILLO-PUERTAS, M

Congreso; LVIII Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology Research; 2022

Ureteral double-J (DJ) stents are extensively used in the management of upper urinary tract obstruction and prevention of complications in urological interventions. However, their use is associated with dysuria, hematuria, and lumbar or suprapubic pain. Furthermore, internal ureteral stents also offer an ideal surface for bacterial colonization and biofilm formation, features with an essential role in the pathogenesis of stent associated infections. A phenotypic characterization of uropathogens (UP) isolates obtained from DJ catheters removed from patients without primary symptoms of urinary tract infection (UTI) was previously carried out. Here, mixed planktonic cultures and biofilms derived from UP co-isolated from the DJ stents were investigated. Five co-isolated pairs isolated simultaneously from the same catheter sample were selected: Enterococcus faecalis EC2/Escherichia coli EC3 (pair 2/3), E. faecalis EC9/Bacillus pumilus EC10 (pair 9/10), Staphylococcus epidermidis EC15/B. subtilis EC16 (pair 15/16), S. epidermidis EC18/B. subtilis EC17 (pair 17/18) and Klebsiella pneumoniae EC24/B. megaterium EC27 (pair 24/27). Assays such as colony proximity in BHI agar plates and growth competition in static and shaked liquid medium were carried out to investigate the interaction and coexistence of the co-isolated pairs. In the colony interaction assay, after 72 h of incubation, E. faecalis strains from pairs 2/3 and 9/10 displaced their growth to the opposite periphery from the interaction zone with EC3 and EC10, respectively. In pairs 15/16 and 17/18, the presence of Bacillus spp. seems to inhibit growth of S. epidermidis in the interaction region. In regard to biofilm formation, there is a variation in the total biomass of the co-cultures when compared to single species cultures. No correlation was observed between biomass and number of viable cells in the mixed biofilms. It is worth to mention that a higher extracellular matrix production was observed in the polymicrobial condition compared to its single-species counterpart. In addition, to visualize the mentioned bacterial interactions, SEM was performed. The interactions studied in static or agitated liquid cultures showed variable results according to the pair under study. For instance, a lower number of S. epidermidis cells was observed in the co-culture of pairs 15/16 and 17/18, when compared to the axenic culture, while its pair (B. subtilis) showed a higher number of cells in the mentioned co-culture. The study of the microbial competitions, synergies or interferences between UP in the context of UTI could help to establish the real clinical role of these microorganisms in polymicrobial infections, as well as to gain further insight on how both pathogens interact with each other in the urinary tract.