DUAL BACTERIAL INTERACTIONS BETWEEN UROPATHOGENS CO-ISOLATED FROM "DOUBLE J" CATHETER.

ARROYO EGEA, JULIAN; VILLEGAS, JOSEFINA M.; RAPISARDA, VIVIANA ANDREA; FARIZANO, JUAN VICENTE; GRILLO PUERTAS, MARIANA

Mendoza

Congreso; LVIII SAIB Meeting; 2022

SAIB

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 morbidity, such as dysuria, hematuria, and lumbar or suprapubic pain. Furthermore, internal ureteral stents also offer an ideal surface for bacterial colonization and biofilm formation. Bacterial colonization with biofilm formation on the stent plays an essential role in the pathogenesis of stent associated infections. We previously carried out a phenotypic characterization of uropathogens (UP) isolates obtained from DJ catheters removed from patients without primary symptoms of urinary tract infection (UTI). Here, we investigated co-cultures and mixed biofilms formed in vitro by the UP co-isolated from DJ stents. We selected five co-isolated pairs considering those isolated simultaneously from the same catheter sample. Co-isolate pairs are E. faecalis EC2/E. coli EC3, E. faecalis EC9/B.pumilus EC10, S. epidermidis EC15/B. subtilis EC16, S. epidermidis EC18/B. subtilis EC17 and K. pneumoniae EC24/B. megaterium EC27. To investigate how co-isolated pairs coexist and interact with each other, we studied interaction by colony proximity in BHI agar plates and growth competition in static and shaked liquid medium. In the colony interaction assay, after 72 h of incubation, EC2 and EC9 of pairs 2/3, 9/10 show a repulsion-like effect with respect to 3 and 10, respectively, evidenced as growth stimulation away from the interaction zone. In pairs 15/16 and 17/18, the presence of Bacillus spp seems to inhibits growth of S. epidermidis in the zone close to the interaction. Regarding biofilm formation, although there is a decrease or increase in the total biomass of the biofilm in the co-cultures (specific pair) with respect to single species cultures, the number of cells obtained from those biofilm does not have a direct relationship. Note that when pairs were grown on plates with specific dyes labeling extracellular matrix components, results show higher extracellular matrix production under those conditions where the polymicrobial biofilm was higher than its single-species counterpart. In addition, to visualize bacterial interactions in surface or colony biofilms, SEM was performed. The interactions studied in static or agitated liquid medium showed variable results according to the pair under study, for example, for pairs 15/16 and 17/18, a lower number of S.epidermidis cells was observed in the co-culture in relation to the axenic culture, while its pair (B. subtilis), increased the number of cells in the 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.