Klebsiella pneumoniae type 3 pili facilitate adherence and biofilm formation on abiotic surfaces

The role of type I and type 3 pili in mediating Klebsiella pneumoniae colonization of inert surfaces was assessed by analysis of 26 clinical, 7 water distribution system and four reference strains. Amongst the 33 wild type strains tested, 57.6% expressed type 1 pili, 54.5% expressed type 3 pili, 42.4% were highly hydrophobic, 69.7% were highly adherent to both glass and polypropylene surfaces, and 48.5% were efficient biofilm-forming strains on polystyrene dishes. High adherence and biofilm formation were positively correlated with bacterial surface hydrophobicity, type 3 fimbriae expression but not with type I pili expression and were not dependent upon the strain's origin. The K. pneumoniae CF3051 reference strain expressing only type I fimbriae adhered slightly to glass and polypropylene and did not form biofilm on polystyrene. K. pneumoniae IA565 and CF3097 reference strains producing type I and type 3 fimbriae showed efficient adherence to both glass and polypropylene and biofilm formation on polystyrene. Moreover, transformation of the afimbriated, weakly-adherent CF3172 strain with the recombinant pFK10 plasmid carrying the mrk gene cluster resulted in type 3 fimbriae expression, increased surface hydrophobicity, increased adherence to abiotic surfaces and biofilm formation. Thus, type 3 pili constitute the main K. pneumoniae adhesive factor, facilitating adherence and biofilm formation on abiotic surfaces of strains of different origins. (C) 2002 Editions scientifiques et medicales Elsevier SAS. All rights reserved.