Colicins prevent colonization of urinary catheters

Abstract

Objectives: Natural microbial defence systems, such as bacteriocins, may be a novel means to prevent catheter-associated urinary tract infection. We investigated in vitro whether a colicin-expressing strain of Escherichia coli could prevent urinary catheter colonization by a colicin-susceptible, uropathgenic strain of E. coli.

Methods: Segments of urinary catheter were inoculated with colicin-producing E. coli K-12 and then exposed to either colicin-susceptible E. coli (a uropathogenic clinical isolate) or colicin-resistant E. coli (derived from the susceptible clinical isolate). Catheters were then incubated overnight, rinsed and sonicated.

Results: The presence of colicin-producing E. coli K-12 on the catheter surface completely prevented catheter colonization by colicin-susceptible E. coli but not by resistant E. coli. The colicin-susceptible strain but not the colicin-resistant strain also disappeared from broth cultures in the presence of colicin-producing E. coli K-12.

Conclusions: The observed inhibition of catheter colonization by the uropathogenic clinical isolate of E. coli can be attributed to the presence of a colicin-producing strain of E. coli on the catheter surface. Bacteriocin production by a non-pathogenic organism may have clinical applicability as a means to prevent catheter-associated urinary tract infection.

Figure 1

Recovery of challenge E. coli from treated catheters. The paired bars represent the medians of six, two and two experiments, respectively. No colicin-susceptible organisms were recovered from catheters pre-coated with the colicin producing strain in any of the six trials. The difference in the cfu/cm of Col^S and Col^R recovered from catheters coated with colicin-producing E. coli K-12 was statistically significant (P = 0.009, Wilcoxon Rank Sum test).