Some Observations on the Diffusion of Antimicrobial Agents Through the Retention Balloons of Foley Catheters

Biodegradable ciprofloxacin-incorporated waterborne polyurethane polymers prevent bacterial biofilm formation in vitro

The aim of the present study was to explore whether ciprofloxacin-incorporated waterborne polyurethane (WBPU) polymers have the capacity to inhibit bacterial biofilm formation in vitro. WBPU polymers were incorporated with ciprofloxacin and were cultured with Escherichia coli (E. coli) or Staphylococcus aureus (S. aureus) in media for 2, 4 or 7 days. In another experiment, the WBPU membranes were cultured with Proteus mirabilis (P. mirabilis) in artificial urine for 2, 4 or 7 days. Colony counting, scanning electron microscopy and fluorescence confocal microscopy were utilized to examine bacterial biofilms on the surfaces of membranes. The membranes were further co-cultured with P. mirabilis in a simple model of an artificial catheterized bladder in order to evaluate their ability to control encrustation. The WBPU films with ciprofloxacin effectively inhibited bacterial biofilm formation in the culture medium and in artificial urine. In addition, in artificial urine, the films with ciprofloxacin reduced catheter obstruction. In conclusion, ciprofloxacin-incorporated WBPU polymers are able to effectively inhibit bacterial biofilm formation in vitro.

[Investigation of the use of triclosan in patients with indwelling catheters: a randomized, double blind, multicenter, placebo-controlled clinical study]

BACKGROUND

This article presents the first randomized, double blind, multicenter, placebo-controlled, non-interventional trial with a medical product after approval by the ethical committee of the medical council of North-Rhine. The study investigated the use of the antimicrobial agent triclosan (Farco-fill® Protect) as a liquid for inflation of catheter balloons in patients with chronic indwelling catheters.

PATIENTS AND OBJECTIVES

In this study 84 patients were investigated (43 in the treatment group and 41 in the placebo group) all with a suprapubic catheter and a positive history of catheter incrustation. The catheters were changed after 6 weeks and endpoints were the quantitative analysis of the incrustation, weight of the catheter, pain during catheter change and the number of urinary tract infections. The maintenance of the catheter was a secondary endpoint.

RESULTS

The primary endpoint could not be reached because the study, which was initially planned with 70 patients in each arm, had to be terminated due to logistical and technical problems with the catheter weighing. The maintenance of the catheter as the most important clinical parameter showed statistically significant differences with a longer indwelling time in the triclosan group. Adverse events with respect to the product were not recorded.

CONCLUSIONS

Using the antimicrobial solution triclosan as a fluid for inflation of catheter balloons led to a statistically significant extension in the catheter indwelling time. The reduction of pain during changing the catheter and the reduction of incrustation, although not statistically significant, led to an improvement in the quality of life of these patients.

Bacteriophage-mediated control of a two-species biofilm formed by microorganisms causing catheter-associated urinary tract infections in an in vitro urinary catheter model

Microorganisms from a patient or their environment may colonize indwelling urinary catheters, forming biofilm communities on catheter surfaces and increasing patient morbidity and mortality. This study investigated the effect of pretreating hydrogel-coated silicone catheters with mixtures of Pseudomonas aeruginosa and Proteus mirabilis bacteriophages on the development of single- and two-species biofilms in a multiday continuous-flow in vitro model using artificial urine. Novel phages were purified from sewage, characterized, and screened for their abilities to reduce biofilm development by clinical isolates of their respective hosts. Our screening data showed that artificial urine medium (AUM) is a valid substitute for human urine for the purpose of evaluating uropathogen biofilm control by these bacteriophages. Defined phage cocktails targeting P. aeruginosa and P. mirabilis were designed based on the biofilm inhibition screens. Hydrogel-coated catheters were pretreated with one or both cocktails and challenged with approximately 1×10(3) CFU/ml of the corresponding pathogen(s). The biofilm growth on the catheter surfaces in AUM was monitored over 72 to 96 h. Phage pretreatment reduced P. aeruginosa biofilm counts by 4 log10 CFU/cm2 (P≤0.01) and P. mirabilis biofilm counts by >2 log10 CFU/cm2 (P≤0.01) over 48 h. The presence of P. mirabilis was always associated with an increase in lumen pH from 7.5 to 9.5 and with eventual blockage of the reactor lines. The results of this study suggest that pretreatment of a hydrogel urinary catheter with a phage cocktail can significantly reduce mixed-species biofilm formation by clinically relevant bacteria.

Electrical microcurrent to prevent conditioning film and bacterial adhesion to urological stents

Long-term catheters remain a significant clinical problem in urology due to the high rate of bacterial colonization, infection, and encrustation. Minutes after insertion of a catheter, depositions of host urinary components onto the catheter surface form a conditioning film actively supporting the bacterial adhesion process. We investigated the possibility of reducing or avoiding the buildup of these naturally forming conditioning films and of preventing bacterial adhesion by applying different current densities to platinum electrodes as a possible catheter coating material. In this model we employed a defined environment using artificial urine and Proteus mirabilis. The film formation and desorption was analyzed by highly mass sensitive quartz crystal microbalance and surface sensitive atomic force microscopy. Further, we performed bacterial staining to assess adherence, growth, and survival on the electrodes with different current densities. By applying alternating microcurrent densities on platinum electrodes, we could produce a self regenerative surface which actively removed the conditioning film and significantly reduced bacterial adherence, growth, and survival. The results of this study could easily be adapted to a catheter design for clinical use.

Eliminating biofilm from ureteral stents: the Holy Grail

PURPOSE OF REVIEW

Biofilms continue to be a major limiting factor in the long-term use of ureteral stents, promoting the development of chronic infections and antibiotic resistance and encrustation. Apart from stent removal in conjunction with antibiotic therapy, there is currently no treatment proven successful for completely eradicating a biofilm-related infection, highlighting the need for continued research in this area.

RECENT FINDINGS

Research continues to focus mainly on biofilm prevention, specifically the development of novel coatings comprising antibacterial, antifouling or bacterial signalling compounds. Notably, all three strategies have generated candidate coatings showing recent success both in vitro and in vivo.

SUMMARY

Despite the current lack of a completely biofilm-resistant device, coating or treatment strategy, continued research into the causation of bacterial biofilm formation and the continued development of novel antibacterial, antifouling and antibiofilm compounds is promising. Future work should be aimed at more rigorous testing of candidate coatings from both physical and bacterial challenge standpoints as well as increased in-vivo investigation via clinical trials.

Bacterial biofilms in patients with indwelling urinary catheters

Bacteria have a basic survival strategy: to colonize surfaces and grow as biofilm communities embedded in a gel-like polysaccharide matrix. The catheterized urinary tract provides ideal conditions for the development of enormous biofilm populations. Many bacterial species colonize indwelling catheters as biofilms, inducing complications in patients' care. The most troublesome complications are the crystalline biofilms that can occlude the catheter lumen and trigger episodes of pyelonephritis and septicemia. The crystalline biofilms result from infection by urease-producing bacteria, particularly Proteus mirabilis. Urease raises the urinary pH and drives the formation of calcium phosphate and magnesium phosphate crystals in the biofilm. All types of catheter are vulnerable to encrustation by these biofilms, and clinical prevention strategies are clearly needed, as bacteria growing in the biofilm mode are resistant to antibiotics. Evidence indicates that treatment of symptomatic, catheter-associated urinary tract infection is more effective if biofilm-laden catheters are changed before antibiotic treatment is initiated. Infection with P. mirabilis exposes the many faults of currently available catheters, and plenty of scope exists for improvement in both their design and production; manufacturers should take up the challenge to improve patient outcomes.