An in vitro model of catheter-associated urinary tract infections to investigate the role of uncommon bacteria on the Escherichia coli microbial consortium

Abstract

Uncommon bacteria, such as Delftia tusurhatensis have been isolated from CAUTIs in combination with well-established pathogenic bacteria such as Escherichia coli. Nonetheless, the reason why E. coli coexists with other bacteria instead of outcompeting and completely eliminating them is unknown. As such, a flow cell reactor simulating the hydrodynamic conditions found in CAUTIs (shear rate of 15 s −1) was used to characterize the microbial physiology of E. coli and D. tsuruhatensis individually and in consortium, in terms of the growth kinetics and substrate uptake. Single-species biofilms showed that up to 48 h the cultivable cell counts significantly increased for both species (p < 0.05). When in dual-species biofilm, E. coli outnumbered D. tsuruhatensis up to 16 h and then D. tsuruhatensis gained a fitness advantage. However, the assessment of the spatial distribution of the dual-species biofilm by LNA/2 OMe-FISH revealed that E. coli and D. tsuruhatensis coexist and tend to co-aggregate over time, which suggests that both bacteria are able to cooperate synergistically. Substrate uptake measurements revealed that D. tsuruhatensis metabolized citric acid more rapidly, presumably leaving more uric acid available in the medium to be used by E. coli. In conclusion, E. coli and uncommon bacteria seem to cooperate, when sharing the same environment under dynamic conditions, leading to the persistence of both bacteria in a stable microbial community.

Using Lactobacilli to Fight Escherichia coli and Staphylococcus aureus Biofilms on Urinary Tract Devices

“…Both model pathogenic strains confirmed their ability to grow in artificial urine medium, as well as to adhere and form stable biofilms on silicone rubber. The ability of E. coli to form robust biofilms on this surface material was previously reported by our research group [52,53]. Moreover, E. coli biofilms exhibited higher cellular densities than S. aureus (Figure 1), demonstrating its higher propensity to form biofilms on silicone.…”

In vitro dynamic bladder models for studying urinary tract infections: a narrative review

“…Forty-five studies were conducted to explore bacterial biofilm formation in bladder models, which corresponds with the current research focus. A total of 36 studies were performed with comparative experimental designs, mainly consisting of comparisons between various coatings of drugs or different materials, including between static and dynamic models in three studies (20,27,30), the comparative analysis of culture fluids in two studies (56,57), comparisons between multiple interventions in 21 studies (13,14,(17)(18)(19)(20)22,(28)(29)(30)36,38,39,41,43,50,(53)(54)(55)58,64), comparisons between infection vectors in eight studies (37,40,42,44,45,52,53,58), and comparisons between experimental temperature in one study (37).…”

“…In total, only five studies reported a comparative experiment of in vitro bladder models (20,27,30,56,57), which are summarized in Table S1. Among these, Frant et al (20) suggested that biofilm formation was more prevalent in the BioEncrustation dynamic bladder model and that more substances were observed in the urine scale.…”

Microbiology of Catheter Associated Urinary Tract Infection

“…D. tsuruhatensis metabolized citric acid more rapidly leaving more uric acid available in the medium to be used by E. coli for dynamic growth of both organisms. Identification of this organism is not confirmatory with culture, so molecular methods are more reliable [83].…”