Bacterial biofilms and catheters in experimental urinary tract infection

Employing in vitro and in vivo models of catheter-associated infection, bio film formation of Pseudomonas aeruginosa in artificial urine and bactericid al activity of several classes alone or in combination with a macrolide ant ibiotic were investigated. In the course of continuous urine flow, bacteria adherent to a Teflon catheter formed microcolonies at 6 h and a biofilm at 24 h. Following 24 h of urine flow, the thickness and the density of the b iofilm increased to about 20 mu m and 10(8) cfu/mm(3), respectively. Of the antibiotics examined, the fluoroquinolones showed the most potent bacteric idal activity against the P. aeruginosa biofilms. However, those antibiotic s were not always potentiated by the combination with a macrolide antibioti c. (C) 1999 Elsevier Science B.V. All rights reserved.