Single- and dual-species biofilms of Klebsiella pneumoniae and Escherichia coli clinical isolates from patients with catheter-associated urinary tract infections

GALVAN, ESTELA M.; IELPI, LUIS

Puerto Varas

Congreso; XII PABMB Congress; 2013

Urinary tract infections associated with long-term catheterization are polymicrobial, and biofilms constitute a bacterial strategy for persistence on catheter surfaces. In a retrospective study performed at a public hospital from Ciudad Autónoma de Buenos Aires, we found K. pneumoniae and E. coli frequently co-isolated from patients with polymicrobial bacteriuria. We studied the ability of these K. pneumoniae and E. coli clinical strains to form single- and dual- species biofilms. Biofilm quantification was performed through total biomass quantification by crystal violet staining. From the analysis of single-species biofilms, it was evident that K. pneumoniae biofilms developed faster and had a higher total biomass than those of E. coli. Moreover, the number of cultivable cells being recovered from K. pneumoniae biofilms was 3-times higher than for E. coli biofilms at all the time-points assayed (from 2 to 72 h). In dual-species biofilms, development of total biomass was similar to that observed for K. pneumoniae in single-specie biofilms. Cultivability assays using selective media evidenced that K. pneumoniae constituted more than 90 % of the biofilm population after 24 h. Moreover, a decrease in E. coli cultivability in dual-species biofilms, compared to single-specie biofilms, was observed. Our findings suggest that the interaction between K. pneumoniae and E. coli in dual-species biofilms resulted in a detrimental effect over E. coli.