Scavone P, Iribarnegaray V, Caetano A, Schlapp G, Hartel S, & Zunino P
Pathogens and Disease: 74(5). pii: ftw033. doi: 10.1093/femspd/ftw033. Epub 2016 Apr 17.

Proteus mirabilis is one of the most common etiological agent of complicated urinary tract infections, especially those associated to catheterization. This is related to the ability of P. mirabilis to form biofilms on different surfaces. This pathogen encodes 17 putative fimbrial operons, the highest amount found in any sequenced bacterial species so far. The present study analyzed the role of 4 P. mirabilis fimbriae (MR/P, UCA, ATF and PMF) in biofilm formation using isogenic mutants. Experimental approaches included migration over catheter, swimming and swarming motility, the semiquantitative assay based on adhesion and crystal violet staining and biofilm development by immunofluorescence and confocal microscopy. Different assays were performed using LB or artificial urine. Results indicated that the different fimbriae contribute to the formation of a stable and functional biofilm. Fimbriae revealed particular associated roles. First, all the mutants showed a significantly reduced ability to migrate across urinary catheters sections but neither swimming nor swarming motility were affected. However some mutants formed smaller biofilms compared with the wild type (MRP and ATF) while others formed significantly larger biofilms (UCA and PMF) showing different bioarchitecture features. It can be concluded that P. mirabilis fimbriae have distinguishable roles in the generation of biofilms, particularly associated to catheters.