Type 1 Fimbriae Contribute to Catheter-Associated Urinary Tract Infections Caused by Escherichia coli

Abstract

Biofilm formation on catheters is thought to contribute to persistence of catheter-associated urinary tract infections (CAUTI), which represent the most frequent nosocomial infections. Knowledge of genetic factors for catheter colonization is limited, since their role has not been assessed using physicochemical conditions prevailing in a catheterized human bladder. The current study aimed to combine data from a dynamic catheterized bladder model in vitro with in vivo expression analysis for understanding molecular factors relevant for CAUTI caused by Escherichia coli. By application of the in vitro model that mirrors the physicochemical environment during human infection, we found that an E. coli K-12 mutant defective in type 1 fimbriae, but not isogenic mutants lacking flagella or antigen 43, was outcompeted by the wild-type strain during prolonged catheter colonization. The importance of type 1 fimbriae for catheter colonization was verified using a fimA mutant of uropathogenic E. coli strain CFT073 with human and artificial urine. Orientation of the invertible element (IE) controlling type 1 fimbrial expression in bacterial populations harvested from the colonized catheterized bladder in vitro suggested that the vast majority of catheter-colonizing cells (up to 88%) express type 1 fimbriae. Analysis of IE orientation in E. coli populations harvested from patient catheters revealed that a median level of ϳ73% of cells from nine samples have switched on type 1 fimbrial expression. This study supports the utility of the dynamic catheterized bladder model for analyzing catheter colonization factors and highlights a role for type 1 fimbriae during CAUTI.

Biofilm Producing Uropathogens and Drug Resistance: Dual Foe for Patients on Urinary Catheter

“…This finding correlated with few other previous studies (Hassin 1991;Niveditha et al, 2012;Sayal et al, 2014). The presence and expression of various virulence factors like, adhesions (e.g., type 1 and P. fimbriae) and toxins (e.g., haemolysin) are responsible for uropathogenic E. coli to be the most common cause of UTI (Bien et al, 2012;Reisner et al, 2014).…”

Presence of Virulence-Associated Genes and Ability to Form Biofilm among Clinical Isolates of <i>Escherichia coli</i> Causing Urinary Infection in Domestic Animals

“…Alternatively, urinary infections in animals might be less dependent on biofilm formation than in humans. Since the genes encoding for proteins associated with biofilm formation in UPEC such as type I fimbria, flagellum and Ag43 [6] have been previously identified, future study may look for the expression of those genes in animal UPEC's.…”

“…UPEC is capable of causing infection because it contains the necessary genetic tools. For example, the type I fimbria, flagellum and pili have been associated in many studies with the ability to infect the urinary tract [2] [6]. Genes encoding for proteins that successfully compete for iron in the urinary tract environment have been also demonstrated to be important for the fitness in the site [13] [14].…”

“…The ability to form biofilm is very important for the establishment of urinary tract infection in humans [6] [12]. We explored the question about the importance to form biofilm in animal UTI.…”

“…UPEC normally inhabits the intestinal tract and transition by contaminating the uroepithelial mucosa of the urethra. The bacteria then need to attach to the epithelial surface, a step depending on the presence of virulence factors, such as P adhesin and Type 1 fimbria [6] [7]. Once attached, the microorganism can migrate upwards towards the bladder and kidneys.…”