Interaction between atypical microorganisms and E. coli in catheter-associated urinary tract biofilms

Abstract

Most biofilms involved in catheter-associated urinary tract infections (CAUTIs) are polymicrobial, with disease causing (eg Escherichia coli) and atypical microorganisms (eg Delftia tsuruhatensis) frequently inhabiting the same catheter. Nevertheless, there is a lack of knowledge about the role of atypical microorganisms. Here, single and dual-species biofilms consisting of E. coli and atypical bacteria (D. tsuruhatensis and Achromobacter xylosoxidans), were evaluated. All species were good biofilm producers (Log 5.84–7.25 CFU cm⁻² at 192 h) in artificial urine. The ability of atypical species to form a biofilm appeared to be hampered by the presence of E. coli. Additionally, when E. coli was added to a pre-formed biofilm of the atypical species, it seemed to take advantage of the first colonizers to accelerate adhesion, even when added at lower concentrations. The results suggest a greater ability of E. coli to form biofilms in conditions mimicking the CAUTIs, whatever the pre-existing microbiota and the inoculum concentration.

Keywords:

• Escherichia coli
• atypical species
• multispecies biofilms
• urinary tract infections
• urinary catheters

Acknowledgements

This work was supported by the Portuguese Science Foundation (FCT), DNA mimics Research Project [Ref. PIC/IC/82815/2007] from the FCT and MCTES; PhD Fellowship [SFRH/BD/82663/2011]; and Postdoctoral Fellowship [SFRH/BPD/74480/2010]. The authors would like to thank to M. Fenice M and A. Steinbüchel for kindly providing the Delftia tsuruhatensis BM90 and Achromobacter xylosoxidans B3 species, respectively.