JAC Advance Access originally published online on December 9, 2005
Journal of Antimicrobial Chemotherapy 2006 57(2):266-272; doi:10.1093/jac/dki447
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Effect of triclosan on the development of bacterial biofilms by urinary tract pathogens on urinary catheters
Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3TL, Wales, UK
* Corresponding author. Tel: +44-29-20874311; Fax: +44-29-20874305; E-mail: stickler{at}cardiff.ac.uk
Received 24 May 2005; returned 4 September 2005; revised 5 October 2005; accepted 12 November 2005
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Abstract |
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Objectives: To examine (i) the effect of triclosan on the formation of catheter biofilms by urinary tract pathogens and (ii) the diffusion of triclosan through the retention balloons of urinary catheters.
Methods: Models of the catheterized bladder were infected with eight different urinary tract pathogens and the effect of triclosan on biofilm formation was assessed by determining the numbers of viable cells colonizing the catheters and by scanning electron microscopy. HPLC was used to determine the triclosan concentration in urine draining from models that had been fitted with triclosan-inflated silicone catheters.
Results: When catheters were inflated with triclosan (10 g/L) the formation of catheter biofilm by Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus and Proteus mirabilis was prevented. The numbers of Enterococcus faecalis and Providencia stuartii cells colonizing catheters were also significantly reduced (P < 0.05). Serratia marcescens, Morganella morganii and Pseudomonas aeruginosa, however, were able to produce extensive catheter biofilms in the presence of triclosan. Only P. mirabilis produced alkaline urine and encrusted the catheters. Concentrations of 0.02–0.16 mg/L of the biocide were detected in urine draining from the model over the 48 h experimental period.
Conclusions: Triclosan diffused through silicone catheter balloons and produced urinary concentrations that prevented catheter encrustation by P. mirabilis and biofilm formation by several other common pathogens of the catheterized urinary tract. It had little effect on urease-producing P. aeruginosa, S. marcescens or M. morganii but these species did not produce alkaline urine or crystalline biofilms.
Keywords: urinary tract infections , Proteus mirabilis , antibacterials , uropathogenic strains
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Introduction |
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The indwelling urinary catheter is the most commonly deployed prosthetic medical device.1 It constitutes a convenient way to drain urine from the bladder but unfortunately, also provides a conduit along which bacteria can pass from a heavily contaminated external skin site to infect a vulnerable body cavity. The risk of infection is related to the length of time the catheter is in place and for the many patients catheterized for periods longer than 4 weeks, it is inevitable that bacterial communities will establish themselves in the bladder.2 A variety of organisms commonly colonize the catheterized urinary tract, including Enterococcus faecalis, Escherichia coli, Providencia stuartii, Pseudomonas aeruginosa, Proteus mirabilis, Morganella morganii and Klebsiella pneumoniae.3,4
While the catheter is in situ the infections are notoriously difficult to eradicate with antibiotics. It is normal practice to resort to treatment only when there is evidence that the infection has reached the kidneys or the bloodstream. In patients undergoing long-term bladder management, a common regimen is to change catheters at 10–12 week intervals. In these circumstances infected urine thus flows through catheters for up to 3 months at a time. The catheters are manufactured from silicone or from latex, which is then coated in either silicone or hydrogel. These materials provide attractive, unprotected sites for bacterial attachment. In addition the irregular surfaces left by the manufacturing process, particularly around the eye-holes, can trap cells as the infected urine flows through the catheter.5 Attached to a surface, bathed in a constant gentle flow of a nutrient-rich medium, the bacterial populations thrive. Within days extensive biofilms develop, particularly on the luminal surfaces of the catheter.6
The biofilms produced by urease-positive bacteria such as P. mirabilis, pose particular threats to the health of catheterized patients. The urease generates ammonia and creates alkaline conditions under which calcium and magnesium phosphates crystallize in the urine and the biofilm. These unique crystalline biofilms develop rapidly and can completely block the flow of urine from the bladder. If this situation is not detected and the catheter changed, it can lead to urinary retention, painful distension of the bladder, reflux of infected urine to the kidneys, triggering pyelonephritis and septicaemia.7
Conceptually, the simplest way to prevent the biofilm formation is to impregnate catheters with a broad-spectrum antimicrobial agent that elutes into the surrounding environment. In this way planktonic bacteria in the vicinity of the device could be attacked before they colonize the surface and adopt the biofilm-resistant phenotype.8 However, difficulties in delivering effective concentrations of antimicrobial agents from catheters for prolonged periods have limited the usefulness of antimicrobial catheters in patients undergoing long-term bladder management. Bibby et al.9 suggested that large amounts of an antibacterial agent could be loaded into the catheter retention balloon, and that the membrane of the balloon might provide a diffusion barrier to control the release of the agent into the bladder urine over protracted periods.
In a previous study we used this strategy to deliver the biocide triclosan to the catheterized bladder.10 In a laboratory model infected with P. mirabilis, we confirmed that triclosan can diffuse through the balloons of all-silicone catheters and inhibit the formation of crystalline P. mirabilis biofilm. In the present study we have examined the effect of triclosan on the formation of catheter biofilms by a range of urinary tract pathogens and determined the concentrations of triclosan released from the retention balloon.
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Materials and methods |
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Bacterial strains
The bacteria used in this study were clinical isolates from the indwelling catheters of patients undergoing long-term catheterization. The uropathogenic species tested were P. mirabilis, P. aeruginosa, E. coli, K. pneumoniae, M. morganii, P. stuartii, Serratia marcescens, Staphylococcus aureus and E. faecalis.
Media
The media used in this study were purchased from Oxoid Ltd (Basingstoke, UK). Cysteine-lactose electrolyte deficient agar was used to culture the range of urinary pathogens and was used for the enumeration of all bacterial strains except K. pneumoniae. Nutrient agar was used for viable cell counting of K. pneumoniae cultures. Tryptone Soya agar (TSA) was used for determining the MICs of triclosan for the test organisms. A nutrient agar containing 2% (v/w) urea was used to check for the production of the urease enzyme. Tryptone Soya broth (TSB) was used to grow cultures for experimental purposes. The artificial urine used in this study was based on that devised by Griffith et al.;11 the composition and method of sterilization have been described previously.12 The pH of the urine supplied to the model was 6.1. The neutralizer used for triclosan contained 1.5% (w/v) lecithin (Sigma, Poole, UK) and 5% Tween 80 (v/v) (Sigma).13
MIC determinations
Stock solutions of triclosan (Ciba, Basle, Switzerland) were prepared in dimethyl sulphoxide (DMSO) (Fisher Scientific Ltd, Loughborough, UK) and were added to molten TSA to produce plates containing different triclosan concentrations. Plates containing TSA alone and TSA containing the maximum DMSO concentration were used as controls. Aliquots (1 µL) of overnight cultures of test organisms in TSB (10 mL) were applied to the agar plates using the Denley multipoint inoculator (Denley instruments Ltd, Billinghurst, UK). Each strain was inoculated onto three plates for each concentration of triclosan and control plates. The plates were incubated at 37°C for 18 h and examined for growth the following day.
Bladder model
The bladder model has been described previously.12 It consists of a glass chamber maintained at 37°C by a water jacket. Each model was sterilized by autoclaving and then a size 14 Ch all-silicone catheter (Bard Ltd, Crawley, UK) was inserted into the chamber through an outlet at the base. The catheter retention balloons were inflated with 10 mL of water or 10 g/L of triclosan in 5% (w/v) polyethylene glycol (PEG) (Sigma). To prepare the triclosan mixture it was stirred overnight with heating to 70°C to produce a stable white colloidal suspension. The catheters were connected to drainage bags in the normal way. Sterile artificial urine was pumped into the chambers at 0.5 mL/min, so that residual volumes collected below the catheter eye-holes before flowing through the drainage tube to the collecting bags.
Experimental protocol
Pairs of models were assembled and supplied with artificial urine up to the level of the catheter eye-holes. Control models were fitted with catheters inflated with water, test models were fitted with catheters inflated with triclosan. The urine supply was then switched off and 10 mL of the artificial urine was removed from the bladder chamber and replaced with a 4 h artificial urine culture (10 mL) of one of the test organisms. The mean values for the numbers of viable cells of each test organism in the inocula ranged from 106 to 107 cfu/mL. After the organisms had been left for an hour to establish in the bladder urine, the urine supply to the models was resumed for a total of 48 h or until catheter blockage. The time taken for the catheters to block was recorded. The urinary pH and the numbers of viable cells in the residual bladder urine at 48 h or blockage were also determined.
Enumeration of viable bacterial cells in the attached biofilm
To determine the number of cells attached onto the catheter, the catheters were removed from the models and the balloons of the triclosan catheters were flushed out 10 times with fresh sterile water. The catheter balloons were removed and the top of the catheters taken from 5 cm below the balloon was cut into 1 cm sections. These sections were placed into neutralizer (10 mL), vortexed for 2 min and sonicated at 35 kHz in a sonic cleaning bath for 5 min. Viable cell counts on the resulting cell suspensions were then performed to determine the numbers of bacteria that had been colonizing the catheter sections.
Neutralizer efficacy and toxicity
The efficacy of the neutralizer was confirmed using a method based on that described by Langsrud and Sundheim.14 Incubation mixtures were prepared containing the neutralizer (8 mL), triclosan (100 µL of a 10 mg/mL of solution in DMSO) and sterile deionized water (900 µL). Inocula of P. mirabilis cells (1 mL of overnight TSB cultures grown at 37°C) were added to the triclosan and neutralizer mixtures. After 5 min contact time at ambient temperature, samples were removed to enumerate the numbers of viable cells. As controls, sterile deionized water was added to the incubation mixture instead of (i) the triclosan solution, and (ii) the neutralizer. When the P. mirabilis cells were exposed to the triclosan without the neutralizer, no viable cells were detected in the sample after the 5 min incubation period. There was no significant difference (P = 0.919) between the viable cell count of the test cultures (exposed to triclosan and the neutralizer) and the positive control where water was added instead triclosan. This confirmed that 5% Tween 80 and 1.5% lecithin could effectively quench bactericidal activity of triclosan at 100 mg/L.
To examine the possible toxicity of the neutralizer, tests based on the method by Messager et al.15 were performed. Overnight TSB cultures (1 mL) grown at 37°C were added to the neutralizer (9 mL), following a 15 min contact time viable counts were performed. Controls using 9 mL of sterile deionized water instead of the neutralizer enabled the bacterial reduction to be calculated. This test was carried out on all strains that came into contact with the neutralizer. There were no significant differences (P > 0.05) between the viable cell counts from the control and the neutralizer-treated cultures, confirming that the neutralizer was non-toxic to all the strains tested.
Low vacuum scanning electron microscopy
At the end of the experimental period the catheters were removed from the models. Two sections (1 cm in length) were cut from each catheter, one included the eye-hole and the second was taken from immediately below the eye-hole. These sections were viewed directly in a JEOL 5200 scanning electron microscope (Jeol Ltd, Tokyo, Japan) using the low vacuum setting.
Triclosan extraction from artificial urine and chemical analysis
The chemicals used for this test were AnalaR grade chemicals (BDH Chemicals Ltd, Poole, UK). Artificial urine samples (50 mL) were acidified with 250 µL of concentrated hydrochloric acid, and they were then extracted twice with 10 mL of dichloromethane using a separating funnel. The organic phase was dried over anhydrous sodium sulphate, decanted into a 50 mL round bottom flask and the solvent removed in a rotary evaporator. Two artificial urine samples, which were spiked with triclosan to a level of 1 mg/L, were processed to determine recovery. All samples were re-dissolved in 70% acetonitrile for subsequent analysis by HPLC. The HPLC system comprised a gradient pump system (Dionex, AGP), autosampler (SpectraPhysics AS 3500) and UV detector (SpectraPhysics 100). Samples (20 µL) were subjected to chromatography on a 250 x 4 mm column packed with 5 µm of LiChrospher RP8e (Phenomenex) at 1 mL/min of 70% acetonitrile isocratically. Chromatographs were recorded at 279 nm, the data were processed with HPLC Technologies Prime chromatography software and quantified against an external standard of 10 mg/L of triclosan in absolute ethanol. The efficiency of the extraction procedure was found to be 81%. This figure was used to correct the concentration of triclosan recovered from each urine sample.
Statistical analysis
One-way ANOVA carried out at 95% confidence interval was the statistical test of choice for all the experiments. This was carried out using Minitab® release 13 software (Minitab, Inc., PA, USA). If the assumptions required to perform ANOVA were violated, the Kruskal-Wallis test was performed at 95% confidence interval. Where appropriate the standard error of the mean was indicated.
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Susceptibility of urinary tract pathogens to triclosan
The MICs of triclosan for isolates of eight species that had been recovered from patient's catheters are presented in Table 1. The maximum triclosan concentration used in the MIC tests was 100 mg/L, as this is the limit of its solubility in agar. Table 1 also indicates the isolates that were found to produce urease.
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Ability of urinary tract pathogens to form biofilms on catheters and the effect of triclosan on their development
Control and test models were set-up, infected with a test organism and supplied with artificial urine for up to 48 h. The experiments were repeated four times for each species. The pHs of the residual urine in the models at 48 h (or at the time of catheter blockage in the case of P. mirabilis B2) were measured and the mean results are presented in Figure 1. The mean numbers of viable cells recovered from these urines are presented in Table 2. In three of the replicates the extent of biofilm was assessed by determining the number of viable cells attached to the top 10 cm of each catheter (Table 3). In the fourth replicate, catheter biofilm formation was visualized by scanning electron microscopy. Micrographs of the biofilms found on control and triclosan catheters in models infected with P. mirabilis are presented in Figure 2.
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Detection of triclosan in the urine of the catheterized bladder
To determine the concentration of triclosan diffusing from the catheter balloon into the urine, bladder models were fitted with catheters inflated with water or triclosan and supplied with artificial urine for 48 h. The models were not inoculated. The urine in the drainage bags of the model fitted with the triclosan catheter was collected at intervals over 48 h. Samples of freshly prepared urine and urine collected from the bags fitted to control catheters were also taken. Triclosan was extracted from all the samples and assayed by HPLC. The results from duplicate experiments are summarized in Figure 3. No triclosan was detected in the freshly prepared urine or in the samples taken from the control models fitted with catheters inflated with sterile water.
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Using a simple in vitro model, Bibby et al.9 showed that the antibacterial agent mandelic acid could diffuse through the retention balloon of all-silicone catheters producing concentrations of
0.1 mg/mL in the surrounding fluid. Although mandelic acid had been used in bladder instillations intended to clear bacteriuria in catheterized patients, its activity against the important pathogen of the catheterized urinary tract P. mirabilis is poor.16 The biocide triclosan, however, has been shown to be highly active against P. mirabilis, the MICs for isolates from encrusted catheters were found to be <0.5 mg/L.17 Using a laboratory model of the catheterized bladder supplied with an artificial urine and infected with P. mirabilis, we have previously shown that triclosan can diffuse through the balloons of all-silicone catheters and inhibit crystalline biofilm formation.10 In these tests, control catheters inflated with water became blocked by crystalline material within 24 h, whereas the test catheters with balloons inflated with triclosan [10 g/L in 5% (w/v) PEG] drained freely for at least 7 days when the experiment was terminated. The triclosan maintained the pH of the urine <7 and also impregnated the whole length of the catheter. In contrast the pH in the control models rose rapidly to 8.4. The results presented in Table 1 show that the isolates of E. coli, P. stuartii, K. pneumoniae and S. aureus are all very susceptible to triclosan. E. faecalis has an intermediate susceptibility (MIC 7.0 mg/L), whereas the highest test concentration (100 mg/L) failed to inhibit the growth of S. marcescens, M. morganii and P. aeruginosa. Models of the catheterized bladder fitted with all-silicone catheters were used to test the ability of these commonly isolated urinary tract pathogens to form biofilms, and to examine the effect of introducing triclosan into the bladder on their development. In addition to testing the eight different uropathogens, control and test models inoculated with P. mirabilis B2 were also included. The results presented in Figure 1 show that as expected the growth of P. mirabilis in the control models resulted in the characteristic increase in mean urinary pH (from 6.1 to 8.2), whereas the urine in the triclosan test models remained acidic for the duration of the experiment. The control catheters blocked with crystalline biofilm in a mean time of 29 h. The test catheters drained freely for the 48 h duration of the experiment, and little encrustation was seen on the catheter even when the incubation was continued for 7 days (Figure 2). Preliminary experiments had established that when catheters inflated with water or PEG (5%, w/v) were fitted into models infected with P. mirabilis there was no significant difference in the numbers of viable cells per mL of urine at 48 h, and in both cases the pH of the urine rose to mean values >8.5. The activity of the formulation of the agent in PEG is thus due to the triclosan.
The control and test catheters inoculated with the eight other uropathogenic species drained freely for the duration of the experiment. The pH of the residual urine of the control and test models inoculated with each of the uropathogens remained acidic throughout the experiments (Figure 1). The results of the viable cell counts of each organism in the residual urine of the bladder models (Table 2) show that the numbers of P. mirabilis, P. stuartii, E. coli, S. aureus, E. faecalis and K. pneumoniae were significantly reduced by triclosan (P < 0.05). However, there was little reduction in the numbers of S. marcescens, M. morganii or P. aeruginosa. A similar pattern of results was observed when the numbers of cells colonizing the catheters was determined (Table 3). It can be seen that triclosan completely inhibited the formation of biofilm by E. coli, K. pneumoniae, S. aureus and P. mirabilis. It also produced a significant (P < 0.05) reduction in the numbers of viable E. faecalis and P. stuartii cells that colonized catheters. S. marcescens, M. morganii and P. aeruginosa, however, were able to produce extensive catheter biofilms in the presence of triclosan.
Scanning electron microscopy showed that in contrast to the catheters from models infected with P. mirabilis (Figure 2) none of the catheters removed from models infected with the other species were colonized by crystalline biofilm. Catheters from models inoculated with E. coli, for example, showed signs of a biofilm around the eye-hole of the control catheter, but there was little colonization on the triclosan test catheter. In the case of P. aeruginosa, mucoid, non-crystalline biofilm was apparent around the eye-holes and luminal surfaces of both the control and test catheters, confirming the inability of triclosan to inhibit biofilm formation by this species. These observations together with the data presented in Figure 1 provide further evidence that despite being capable of producing urease in standard bacteriological identification tests, S. marcescens, S. aureus, K. pneumoniae, P. aeruginosa and M. morganii are not capable of generating the alkaline conditions in urine necessary for the production of a crystalline catheter biofilm.
The findings that P. mirabilis rapidly elevates the urinary pH and forms crystalline biofilms, whereas other urease producers fail to do so correlates well with earlier clinical observations. For example, Mobley and Warren3 found a significant association between catheter obstruction and the presence of P. mirabilis in the urine, but not between any other urease-positive species. Bacteriological analysis of catheters removed from patients undergoing long-term bladder management revealed that while catheters colonized with P. mirabilis formed crystalline biofilms, significant crystalline material was absent in non-Proteus biofilms.18
Concerns have been expressed over the overexploitation of triclosan.19,20 It is possible that its widespread use could result in the selection of triclosan-resistant species such as P. aeruginosa or generate triclosan-resistant mutants of normally susceptible species such as E. coli. Triclosan has been used extensively in many antibacterial preparations for over 30 years and while there have been reports of the development of triclosan-resistant strains in the laboratory, there has been little sign that the clinical or domestic use of this agent has led to the generation of resistant organisms.21–23 An important aspect of any clinical trial or subsequent clinical use of the triclosan strategy to control the catheter encrustation problem is the careful monitoring of the urine to check for changes in the bacterial flora and its susceptibility to triclosan and antibiotics.
The data presented in Table 2 indicate that in models fitted with catheters that had been inflated with triclosan, the urinary populations of all the triclosan-susceptible species were reduced compared with controls. In the case of P. mirabilis the increase in pH of the residual urine in the bladder chamber was prevented. These observations suggest that the antibacterial agent is passing from the catheter balloon and exerting its effect in the urine. It is also possible of course that the triclosan impregnated in the silicone of the catheter might have an additional effect in reducing the viability of any susceptible organisms that adhere to the catheters.
In an attempt to predict the persistence of the antibacterial activity, the concentration of triclosan achieved in the urine was determined by chemical estimation. The results presented in Figure 3 show that concentrations ranging from 0.02 to 0.16 mg/L were detected in the urine samples taken over the 48 h period. The results from the first samples suggest that there is a short delay before appreciable diffusion through the catheter balloon occurs. Assuming a release rate of triclosan from the balloon which achieves concentrations of 0.16 mg/L at a flow rate of urine through the bladder of 0.5 mL/min, 115 µg of triclosan would be released from the catheter daily. Given that the balloon is inflated with 10 mL of a 10 mg/mL of triclosan solution, if this release rate was maintained, the triclosan would last for well over the 84 days of the normal maximum placement period. It is interesting that the urinary concentrations of triclosan were below the MICs recorded in agar (Table 1). It is probably that at these concentrations, triclosan slows the growth rate of the cells and leads to washout of the culture in the continuous flow system of the catheterized bladder.
In conclusion, we have been able to demonstrate the loading of the retention balloons with triclosan (10 g/L in 5% PEG) can achieve concentrations of up to 0.16 mg/L of the biocide in urine. At this concentration, the antibacterial activity should last for at least the current maximum life-span of 12 weeks for long-term catheters. The strategy prevents catheter encrustation by P. mirabilis and biofilm formation by several other common pathogens of the catheterized urinary tract. While it has little effect on the urease-producing strains of P. aeruginosa, S. marcescens or M. morganii, these species do not seem to be capable of producing alkaline urine and crystalline biofilms.
Currently there are no effective methods for controlling the problem of catheter blockage by encrustation. If the triclosan strategy can be transferred successfully from the laboratory to the clinic, it could bring major improvements in the bladder management of many elderly and disabled patients.
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None to declare.
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It is the policy of this journal not to include a deceased contributor in the author list if they have died prior to signing a submission form. We would therefore like to acknowledge the contribution of Professor Denver Russell, who sadly died in September 2004, for his invaluable contribution to our work. We thank Cardiff University for financial support in the form of a postgraduate studentship for Gwennan Jones.
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1. Darouiche RO. Device-associated infections: a macroproblem that starts with microadherence. Clin Infect Dis 2002; 33: 1567–72.
2. Stickler DJ, Zimakoff J. Complications of urinary tract infections associated with devices used for long-term bladder management. J Hosp Infect 1994; 28: 177–94.[CrossRef][Web of Science][Medline]
3.
Mobley HL, Warren JW. Urease-positive bacteriuria and obstruction of long-term urinary catheters. J Clin Microbiol 1987; 25: 2216–17.
4. Kunin CM. Blockage of urinary catheters: role of microorganisms and constituents of the urine on formation of encrustations. J Clin Epidemiol 1989; 42: 835–42.[CrossRef][Web of Science][Medline]
5. Stickler D, Young R, Jones G et al. Why are Foley catheters so vulnerable to encrustation and blockage by crystalline bacterial biofilm? Urol Res 2003; 31: 306–11.[CrossRef][Web of Science][Medline]
6. Ganderton L, Chawla J, Winters C et al. Scanning electron microscopy of bacterial biofilms on indwelling bladder catheters. Eur J Clin Microbiol Infect Dis 1992; 11: 789–96.[CrossRef][Web of Science][Medline]
7. Kunin CM. Urinary Tract Infections: Detection, Prevention and Management, 5th edn. Baltimore: Williams and Wilkins, 1997.
8. Danese PN. Antibiofilm approaches: prevention of catheter colonization. Chem Biol 2002; 9: 873–80.[CrossRef][Web of Science][Medline]
9. Bibby JM, Cox AJ, Hukins DW. Feasibility of preventing encrustation of urinary catheters. Cells Materials 1995; 2: 183–95.
10. Stickler DJ, Jones GL, Russell AD. Control of encrustation and blockage of Foley catheters. Lancet 2003; 361: 1435–37.[CrossRef][Web of Science][Medline]
11. Griffith DP, Musher DM, Itin C. Urease. The primary cause of infection-induced urinary stones. Invest Urol 1976; 13: 346–50.[Web of Science][Medline]
12. Stickler DJ, Morris NS, Winters C. Simple physical model to study formation and physiology of biofilms on urethral catheters. Methods Enzymol 1999; 310: 494–501.[CrossRef][Web of Science][Medline]
13. Suller MT, Russell AD. Antibiotic and biocide resistance in methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococcus. J Hosp Infect 1999; 43: 281–91.[CrossRef][Web of Science][Medline]
14. Langsrud S, Sundheim G. Factors influencing a suspension test method for antimicrobial activity of disinfectants. J Appl Microbiol 1998; 85: 1006–12.[Medline]
15.
Messager S, Goddard PA, Dettmar PW et al. Determination of the antibacterial efficacy of several antiseptics tested on skin by an ‘ex-vivo’ test. J Med Microbiol 2001; 50: 284–92.
16. King JB, Stickler DJ. The effect of repeated instillations of antiseptics on catheter-associated urinary tract infections: a study in a physical model of the catheterized bladder. Urol Res 1992; 20: 403–7.[CrossRef][Web of Science][Medline]
17. Stickler DJ. Susceptibility of antibiotic-resistant gram-negative bacteria to biocides: a perspective from the study of catheter biofilms. J Appl Microbiol 2002; 92 Suppl 1: 1163–70.
18. Stickler D, Ganderton L, King J et al. Proteus mirabilis biofilms and the encrustation of urethral catheters. Urol Res 1993; 21: 407–11.[CrossRef][Web of Science][Medline]
19. Levy SB. Antibacterial household products: cause for concern. Emerg Infect Dis 2001; 7: 512–15.[Web of Science][Medline]
20. Schweizer HP. Triclosan: a widely used biocide and its link to antibiotics. FEMS Microbiol Lett 2001; 202: 1–7.[CrossRef][Web of Science][Medline]
21. Sreenivasan P, Gaffar A. Antiplaque biocides and bacterial resistance: a review. J Clin Periodontol 2002; 29: 965–74.[CrossRef][Web of Science][Medline]
22.
McBain AJ, Bartolo RG, Catrenich CE et al. Exposure of sink drain microcosms to triclosan: population dynamics and antimicrobial susceptibility. Appl Environ Microbiol 2003; 69: 5433–42.
23.
Russell AD. Whither triclosan? J Antimicrob Chemother 2004; 53: 693–5.
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