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Sean P. Gorman - One of the best experts on this subject based on the ideXlab platform.
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validation of the cdc biofilm reactor as a dynamic model for assessment of Encrustation formation on urological device materials
Journal of Biomedical Materials Research Part B, 2010Co-Authors: Brendan Gilmore, David S. Jones, Turlough M Hamill, Sean P. GormanAbstract:Contemporary medical science is reliant upon the rational selection and utilization of devices, and therefore, an increasing need has developed for in vitro systems aimed at replicating the conditions to which urological devices will be subjected to during their use in vivo. We report the development and validation of a novel continuous flow Encrustation model based on the commercially available CDC biofilm reactor. Proteus mirabilis-induced Encrustation formation on test biomaterial sections under varying experimental parameters was analyzed by X-ray diffraction, infrared- and Raman spectroscopy and by scanning electron microscopy. The model system produced encrusted deposits similar to those observed in archived clinical samples. Results obtained for the system are highly reproducible with Encrustation being rapidly deposited on test biomaterial sections. This model will have utility in the rapid screening of Encrustation behavior of biomaterials for use in urological applications.
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Models for the assessment of biofilm and Encrustation formation on urological materials
Biomaterials and Tissue Engineering in Urology, 2009Co-Authors: Brendan Gilmore, Sean P. Gorman, David S. Jones, Howard CeriAbstract:Abstract Medical devices of the urinary tract are in commonplace usage in modern urology and are likely to remain the cornerstone of many surgical interventions in the field. This is despite the fact that their effective use is still drastically hindered by the formation of biofilm and Encrustation which can cause obstruction and blockage of the device, as well as significant morbidity in the patient. This chapter examines the in vitro Encrustation models available for evaluation and preliminary assessment of new biomaterials, coatings and drug-eluting devices for use in the urinary tract, aimed at resisting surface Encrustation and microbial biofilm formation.
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Characterization and optimization of experimental variables within a reproducible bladder Encrustation model and in vitro evaluation of the efficacy of urease inhibitors for the prevention of medical device-related Encrustation.
Journal of biomedical materials research. Part B Applied biomaterials, 2006Co-Authors: David S. Jones, Jasmina Djokic, Sean P. GormanAbstract:This study presents a reproducible, cost-effective in vitro Encrustation model and, furthermore, describes the effects of components of the artificial urine and the presence of agents that modify the action of urease on Encrustation on commercially available ureteral stents. The Encrustation model involved the use of small-volume reactors (700 mL) containing artificial urine and employing an orbital incubator (at 37°C) to ensure controlled stirring. The artificial urine contained sources of calcium and magnesium (both as chlorides), albumin and urease. Alteration of the ratio (% w/w) of calcium salt to magnesium salt affected the mass of Encrustation, with the greatest Encrustation noted whenever magnesium was excluded from the artificial urine. Increasing the concentration of albumin, designed to mimic the presence of protein in urine, significantly decreased the mass of both calcium and magnesium Encrustation until a plateau was observed. Finally, exclusion of urease from the artificial urine significantly reduced Encrustation due to the indirect effects of this enzyme on pH. Inclusion of the urease inhibitor, acetohydroxamic acid, or urease substrates (methylurea or ethylurea) into the artificial medium markedly reduced Encrustation on ureteral stents. In conclusion, this study has described the design of a reproducible, cost-effective in vitro Encrustation model. Encrustation was markedly reduced on biomaterials by the inclusion of agents that modify the action of urease. These agents may, therefore, offer a novel clinical approach to the control of Encrustation on urological medical devices. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
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design and validation of a dynamic flow model simulating Encrustation of biomaterials in the urinary tract
Journal of Pharmacy and Pharmacology, 2003Co-Authors: Sean P. Gorman, Clare P Garvin, Fergus Quigley, David S. JonesAbstract:A number of models exist for assessing Encrustation on biomaterials employed as devices in the urinary tract. However, static urine models are suitable only for assessment of biomaterials residing in the bladder and the dynamic models available suffer from a number of disadvantages, notably their complexity and limitation to short-term assessment. The dynamic model described herein is a relatively simple design incorporating the ability to assess a large number of biomaterials in replicate fashion and over long periods of time. The biomaterials tested in the dynamic model conform to the urethral catheter and ureteral stent devices that experience urine flow within the urinary tract. The model was initially validated using Percuflex as a test biomaterial. The mass of calcium and magnesium, representing hydroxyapatite and struvite Encrustation, respectively, on Percuflex was detected by atomic absorption spectrometry. No significant differences in Encrustation levels were detected either between vessels or between biomaterial positions on any mandrel within the vessels, indicating the suitability of the dynamic model for reproducible determination of biomaterial Encrustation. The dynamic model was then used to compare the Encrustation of biomaterials commonly employed in urinary-tract devices, namely polyurethane, Percuflex and silicone. Calcium and magnesium levels on polyurethane and Percuflex were shown to be statistically similar, whereas silicone exhibited significantly reduced Encrustation. When, subsequently, comparisons were made of biomaterial Encrustation between the dynamic model and a static model, calcium and magnesium levels arising from the latter model were significantly higher on each of the biomaterials. However, the same rank order of Encrustation resistance was observed for the biomaterials in both models, with silicone performing better than polyurethane or Percuflex. The prediction of in-vivo performance based on in-vitro models of Encrustation is often difficult, although the model described provides a more accurate method for assessing the potential of novel and existing biomaterials for use in urinary medical devices requiring flow of urine.
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poly e caprolactone and poly e caprolactone polyvinylpyrrolidone iodine blends as ureteral biomaterials characterisation of mechanical and surface properties degradation and resistance to Encrustation in vitro
Biomaterials, 2002Co-Authors: David S. Jones, Jasmina Djokic, Colin P Mccoy, Sean P. GormanAbstract:This study describes the physicochemical properties and in vitro resistance to Encrustation of solvent cast films composed of either poly(e-caprolactone) (PCL), prepared using different ratios of high (50,000) to low (4000) (molecular weight) m.wt., or blends of PCL and the polymeric antimicrobial complex, poly(vinylpyrrolidone)-iodine (PVP-I). The incorporation of PVP-I offered antimicrobial activity to the biomaterials. Films were characterised in terms of mechanical (tensile analysis, dynamic mechanical thermal analysis) and surface properties (dynamic contact angle analysis, scanning electron microscopy), whereas degradation (at 37°C in PBS at pH 7.4) was determined gravimetrically. The resistance of the films to Encrustation was evaluated using an in vitro Encrustation model. Reductions in the ratio of high:low-m.wt. PCL significantly reduced the ultimate tensile strength, % elongation at break and the advancing contact angle of the films. These effects were attributed to alterations in the amorphous content and the more hydrophilic nature of the films. Conversely, there were no alterations in Young's modulus, the viscoelastic properties and glass-transition temperature. Incorporation of PVP-I did not affect the mechanical or rheological properties of the films, indicative of a limited interaction between the two polymers in the solid state. Manipulation of the high:low m.wt. ratio of PCL significantly altered the degradation of the films, most notably following longer immersion periods, and resistance to Encrustation. Accordingly, maximum degradation and resistance to Encrustation was observed with the biomaterial composed of 40:60 high:low m.wt. ratios of PCL; however, the mechanical properties of this system were considered inappropriate for clinical application. Films composed of either 50:50 or 60:40 ratio of high:low m.wt. PCL offered an appropriate compromise between physicochemical properties and resistance to Encrustation. This study has highlighted the important usefulness of degradable polymer systems as ureteral biomaterials.
David S. Jones - One of the best experts on this subject based on the ideXlab platform.
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validation of the cdc biofilm reactor as a dynamic model for assessment of Encrustation formation on urological device materials
Journal of Biomedical Materials Research Part B, 2010Co-Authors: Brendan Gilmore, David S. Jones, Turlough M Hamill, Sean P. GormanAbstract:Contemporary medical science is reliant upon the rational selection and utilization of devices, and therefore, an increasing need has developed for in vitro systems aimed at replicating the conditions to which urological devices will be subjected to during their use in vivo. We report the development and validation of a novel continuous flow Encrustation model based on the commercially available CDC biofilm reactor. Proteus mirabilis-induced Encrustation formation on test biomaterial sections under varying experimental parameters was analyzed by X-ray diffraction, infrared- and Raman spectroscopy and by scanning electron microscopy. The model system produced encrusted deposits similar to those observed in archived clinical samples. Results obtained for the system are highly reproducible with Encrustation being rapidly deposited on test biomaterial sections. This model will have utility in the rapid screening of Encrustation behavior of biomaterials for use in urological applications.
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Models for the assessment of biofilm and Encrustation formation on urological materials
Biomaterials and Tissue Engineering in Urology, 2009Co-Authors: Brendan Gilmore, Sean P. Gorman, David S. Jones, Howard CeriAbstract:Abstract Medical devices of the urinary tract are in commonplace usage in modern urology and are likely to remain the cornerstone of many surgical interventions in the field. This is despite the fact that their effective use is still drastically hindered by the formation of biofilm and Encrustation which can cause obstruction and blockage of the device, as well as significant morbidity in the patient. This chapter examines the in vitro Encrustation models available for evaluation and preliminary assessment of new biomaterials, coatings and drug-eluting devices for use in the urinary tract, aimed at resisting surface Encrustation and microbial biofilm formation.
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Characterization and optimization of experimental variables within a reproducible bladder Encrustation model and in vitro evaluation of the efficacy of urease inhibitors for the prevention of medical device-related Encrustation.
Journal of biomedical materials research. Part B Applied biomaterials, 2006Co-Authors: David S. Jones, Jasmina Djokic, Sean P. GormanAbstract:This study presents a reproducible, cost-effective in vitro Encrustation model and, furthermore, describes the effects of components of the artificial urine and the presence of agents that modify the action of urease on Encrustation on commercially available ureteral stents. The Encrustation model involved the use of small-volume reactors (700 mL) containing artificial urine and employing an orbital incubator (at 37°C) to ensure controlled stirring. The artificial urine contained sources of calcium and magnesium (both as chlorides), albumin and urease. Alteration of the ratio (% w/w) of calcium salt to magnesium salt affected the mass of Encrustation, with the greatest Encrustation noted whenever magnesium was excluded from the artificial urine. Increasing the concentration of albumin, designed to mimic the presence of protein in urine, significantly decreased the mass of both calcium and magnesium Encrustation until a plateau was observed. Finally, exclusion of urease from the artificial urine significantly reduced Encrustation due to the indirect effects of this enzyme on pH. Inclusion of the urease inhibitor, acetohydroxamic acid, or urease substrates (methylurea or ethylurea) into the artificial medium markedly reduced Encrustation on ureteral stents. In conclusion, this study has described the design of a reproducible, cost-effective in vitro Encrustation model. Encrustation was markedly reduced on biomaterials by the inclusion of agents that modify the action of urease. These agents may, therefore, offer a novel clinical approach to the control of Encrustation on urological medical devices. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
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design and validation of a dynamic flow model simulating Encrustation of biomaterials in the urinary tract
Journal of Pharmacy and Pharmacology, 2003Co-Authors: Sean P. Gorman, Clare P Garvin, Fergus Quigley, David S. JonesAbstract:A number of models exist for assessing Encrustation on biomaterials employed as devices in the urinary tract. However, static urine models are suitable only for assessment of biomaterials residing in the bladder and the dynamic models available suffer from a number of disadvantages, notably their complexity and limitation to short-term assessment. The dynamic model described herein is a relatively simple design incorporating the ability to assess a large number of biomaterials in replicate fashion and over long periods of time. The biomaterials tested in the dynamic model conform to the urethral catheter and ureteral stent devices that experience urine flow within the urinary tract. The model was initially validated using Percuflex as a test biomaterial. The mass of calcium and magnesium, representing hydroxyapatite and struvite Encrustation, respectively, on Percuflex was detected by atomic absorption spectrometry. No significant differences in Encrustation levels were detected either between vessels or between biomaterial positions on any mandrel within the vessels, indicating the suitability of the dynamic model for reproducible determination of biomaterial Encrustation. The dynamic model was then used to compare the Encrustation of biomaterials commonly employed in urinary-tract devices, namely polyurethane, Percuflex and silicone. Calcium and magnesium levels on polyurethane and Percuflex were shown to be statistically similar, whereas silicone exhibited significantly reduced Encrustation. When, subsequently, comparisons were made of biomaterial Encrustation between the dynamic model and a static model, calcium and magnesium levels arising from the latter model were significantly higher on each of the biomaterials. However, the same rank order of Encrustation resistance was observed for the biomaterials in both models, with silicone performing better than polyurethane or Percuflex. The prediction of in-vivo performance based on in-vitro models of Encrustation is often difficult, although the model described provides a more accurate method for assessing the potential of novel and existing biomaterials for use in urinary medical devices requiring flow of urine.
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poly e caprolactone and poly e caprolactone polyvinylpyrrolidone iodine blends as ureteral biomaterials characterisation of mechanical and surface properties degradation and resistance to Encrustation in vitro
Biomaterials, 2002Co-Authors: David S. Jones, Jasmina Djokic, Colin P Mccoy, Sean P. GormanAbstract:This study describes the physicochemical properties and in vitro resistance to Encrustation of solvent cast films composed of either poly(e-caprolactone) (PCL), prepared using different ratios of high (50,000) to low (4000) (molecular weight) m.wt., or blends of PCL and the polymeric antimicrobial complex, poly(vinylpyrrolidone)-iodine (PVP-I). The incorporation of PVP-I offered antimicrobial activity to the biomaterials. Films were characterised in terms of mechanical (tensile analysis, dynamic mechanical thermal analysis) and surface properties (dynamic contact angle analysis, scanning electron microscopy), whereas degradation (at 37°C in PBS at pH 7.4) was determined gravimetrically. The resistance of the films to Encrustation was evaluated using an in vitro Encrustation model. Reductions in the ratio of high:low-m.wt. PCL significantly reduced the ultimate tensile strength, % elongation at break and the advancing contact angle of the films. These effects were attributed to alterations in the amorphous content and the more hydrophilic nature of the films. Conversely, there were no alterations in Young's modulus, the viscoelastic properties and glass-transition temperature. Incorporation of PVP-I did not affect the mechanical or rheological properties of the films, indicative of a limited interaction between the two polymers in the solid state. Manipulation of the high:low m.wt. ratio of PCL significantly altered the degradation of the films, most notably following longer immersion periods, and resistance to Encrustation. Accordingly, maximum degradation and resistance to Encrustation was observed with the biomaterial composed of 40:60 high:low m.wt. ratios of PCL; however, the mechanical properties of this system were considered inappropriate for clinical application. Films composed of either 50:50 or 60:40 ratio of high:low m.wt. PCL offered an appropriate compromise between physicochemical properties and resistance to Encrustation. This study has highlighted the important usefulness of degradable polymer systems as ureteral biomaterials.
Olivier Traxer - One of the best experts on this subject based on the ideXlab platform.
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Silicone-hydrocoated ureteral stents Encrustation and biofilm formation after 3-week dwell time: results of a prospective randomized multicenter clinical study
World Journal of Urology, 2021Co-Authors: Yazeed Barghouthy, Michel Daudon, Oliver Wiseman, Eugenio Ventimiglia, Julien Letendre, Jonathan Cloutier, Francois Kleinclauss, Steeve Doizi, Mariela Corrales, Olivier TraxerAbstract:Objective To explore the risk of Encrustation and biofilm formation for silicone ureteral stents compared to percuflex polymer stents, through a randomized multicenter study. Patients and methods Design, setting and participants: A Multicenter, prospective, randomized, single blind, comparative study of hydrocoated silicone stent (Coloplast Imajin^® hydro) versus Percuflex™ Plus stent (Boston Scientific), in 141 patients treated by flexible URS for a kidney stone. The study had ethical committee approval in the respective hospitals. Outcome measurements and statistical analysis: Endpoints related to Encrustation were biofilm formation and mineral Encrustation after a period of 3-week indwelling time. They were evaluated at removal through a scoring scale of ureteral stents Encrustation, infrared spectroscopy and optical microscopy of inner and outer surfaces of tips, angles and along the stent’s body. Comparison was performed using ANOVA. Results 119 stents were available after removal for analysis, 56 in the silicone and 63 in the Percuflex TM Plus group. Mean dwelling duration was 21.8 days for silicone, 22.1 days for PercuflexTM Plus. There was significantly more biofilm on Percuflex™ Plus compared to silicone (1.24 ± 0.08 vs 0.93 ± 0.09, p = 0.0021), and more mineral Encrustation (1.22 ± 0.10 vs 0.78 ± 0.11, p = 0.0048), respectively. Conclusions This multicenter randomized study shows that silicone-hydrocoated stents are less prone to Encrustation than PercuflexTM Plus after a 3-week dwelling period and confirms the low Encrustation potential of silicone.
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can ureteral stent Encrustation analysis predict urinary stone composition
Urology, 2005Co-Authors: Morgan Roupret, Michel Daudon, Vincent Hupertan, Bernard Gattegno, Philippe Thibault, Olivier TraxerAbstract:Abstract Objectives To determine the value of mid-infrared spectroscopy (MIRS) of ureteral stent Encrustations in predicting urinary stone composition. Methods A retrospective study analyzed the composition of stent Encrustations and urinary stones by MIRS in patients who had had a stent for ureteral obstruction between 2001 and 2003. The overall correlation was evaluated. The correlation coefficient kappa for agreement between the proportions of each component was calculated. Results A total of 72 stents and 72 stones from 72 patients were analyzed. The mean stent indwelling time was 55.5 days (range 14 to 102). The stents had been placed for fever (52 cases, 72%), pain refractory to analgesics (15 cases, 21%), and impairment of kidney function (5 cases, 7%). The overall correlation between stone composition and stent Encrustation was 71.4%, excluding biofilm analysis. The kappa value was 0.78 for the main component (n = 72; P P P Conclusions MIRS analysis of stent Encrustations is a reliable method of predicting stone composition when the stone cannot be retrieved. Systematic MIRS analysis of stent Encrustations is not recommended but can be very useful in clinical situations in which no stone is available.
Michael M. Tunney - One of the best experts on this subject based on the ideXlab platform.
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Assessment of Encrustation Behaviour on Urinary Tract Biomaterials
Journal of biomaterials applications, 1997Co-Authors: Sean P. Gorman, Michael M. TunneyAbstract:The effective clinical use of biomaterials within the urinary tract is often hindered by the associated problems of bacterial biofilm formation and Encrustation which may cause obstruction or blockage of urethral catheters and ureteral stents. Methods for assessing Encrustation formation on these devices are reviewed and novel urinary tract biomaterials which may be more effective at resisting Encrustation are discussed.
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Development of a model for assessment of biomaterial Encrustation in the upper urinary tract.
Biomaterials, 1996Co-Authors: Michael M. Tunney, Patrick F. Keane, M.c. Bonner, Sean P. GormanAbstract:Abstract A need exists for ureteral stent materials capable of preventing or reducing Encrustation. The aim of this study, therefore, was to develop an in vitro model producing biomaterial Encrustation similar to that on stents in vivo . Three models were designed and evaluated. Polyurethane stent sections were immersed in human urine (37 °C, 5% CO 2 ): (1) with and (2) without crushed human kidney stone and (3) in an artificial urine (37 °C, 5% CO 2 ). Encrustation of similar composition, as determined by infrared spectroscopy, X-ray diffraction and energy dispersive X-ray analysis, formed on stent materials in vivo , in artificial urine and in human urine with crushed kidney stone. Magnesium ammonium phosphate (struvite) and calcium phosphate (hydroxyapatite) predominated in all Encrustations. The reproducibility and ease of use of the artificial urine model provided optimum Encrustation assessment of materials presently used in ureteral stents and evaluation of novel biomaterials.
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Comparative assessment of ureteral stent biomaterial Encrustation
Biomaterials, 1996Co-Authors: Michael M. Tunney, Patrick F. Keane, David S. Jones, Sean P. GormanAbstract:Long-term use of ureteral stents is hindered by the inherent problem of biomaterial Encrustation which may lead to stone formation and attendant problems. The wide variety of polymeric biomaterials currently used for stent fabrication suggests that no single material is significantly superior to the others at resisting Encrustation. A model representing upper urinary tract conditions was employed to compare the long-term struvite and hydroxyapatite Encrustation of five materials currently used in the fabrication of ureteral stents. Silicone was least prone to struvite Encrustation, followed by polyurethane, silitek, percuflex and hydrogel-coated polyurethane, in rank order. Similarly, silicone was least prone to hydroxyapatite Encrustation, followed by silitek, polyurethane, percuflex and hydrogel-coated polyurethane. This study has shown that the problem of Encrustation may limit the long-term use of ureteral stent biomaterials and suggests directions for improvement of biomaterials in this regard.
David J Stickler - One of the best experts on this subject based on the ideXlab platform.
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the effect of edta instillations on the rate of development of Encrustation and biofilms in foley catheters
Urological Research, 2009Co-Authors: Nora Sabbuba, Steven L Percival, Peter Kite, David J SticklerAbstract:The aim of this research was to examine whether a daily instillation of tetra sodium ethylenediaminetetraacetic acid (EDTA) solution could reduce the rate at which Encrustation by crystalline Proteus mirabilis biofilms blocks urinary catheters. Sets of three bladder models were fitted with size 14 all-silicone catheters. Tetra sodium EDTA solution was instilled into the catheter following biofilm development. Catheters were examined by digital photography and scanning electron microscopy for evidence of Encrustation. The results showed that the mean time to blockage of the control catheters was 45 h for saline, 57 h for water and 67 h for those exposed to daily instillations of the EDTA solution. Statistical analysis confirmed that the mean Encrustation rate on the EDTA-treated catheters was significantly lower than on the control-treated devices (P = 0.047). This in vitro study indicates that EDTA may have beneficial effects in reducing the complication of catheter Encrustation and blockage by crystalline biofilms.
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A clinical assessment of the performance of a sensor to detect crystalline biofilm formation on indwelling bladder catheters
BJU international, 2006Co-Authors: David J Stickler, Steven M. Jones, Gabriel Opoku Adusei, Mark Waters, Jenny Cloete, Sunil Mathur, R. C. L. FeneleyAbstract:OBJECTIVES To test the ability of a sensor developed to signal infection by the organisms that generate the crystalline biofilms that encrust catheters, to give an early warning that Encrustation was occurring on patients’ catheters, as the care of many patients undergoing long-term bladder catheterization is complicated by the Encrustation and blockage of their catheters PATIENTS AND METHODS Twenty patients were followed prospectively for the lifetime of one of their catheters. Sensors based on cellulose acetate/bromothymol blue were placed in the urine-collection bags, which were changed as usual at weekly intervals. The bacteriology was assessed and pH determined weekly on urine samples. Photographic records were made of the sensors twice weekly. On removal, each catheter was examined for Encrustation and blockage. RESULTS Proteus mirabilis was not isolated from five patients and in these cases the sensor colour remained golden-yellow to brown. The catheters drained for the scheduled period and showed no signs of Encrustation. By contrast, the sensors turned dark blue/black in the urine of all 15 patients infected with P. mirabilis. All these patients’ catheters were encrusted and in 12 the catheters blocked. The mean interval between the sensor signalling and the catheter blocking was 12 days. CONCLUSION The cellulose acetate/bromothymol blue sensors placed in the urine collection bags are capable of signalling infection by P. mirabilis. They also signal the early stages of catheter Encrustation and allow catheter replacement in ample time to avoid the clinical crises and emergency referrals caused by catheter blockage.
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The effect of urease inhibitors on the Encrustation of urethral catheters
Urological research, 1998Co-Authors: Nicola S Morris, David J SticklerAbstract:Encrustation and blockage of indwelling urethral catheters is primarily brought about by infection of the urinary tract by Proteus mirabilis or other urease-producing species. The bacteria colonise the catheter forming a biofilm community within a polysaccharide matrix. The activity of the urease drives up the urinary pH and causes the crystallisation of calcium and magnesium phosphates in the biofilm. We have used a simple physical model of the catheterised bladder to investigate the ability of urease inhibitors to control Encrustation. It was observed that acetohydroxamic acid (1.0 mg/ml) and fluorofamide (1.0 microg/ml) restricted the increase in pH of P. mirabilis-infected urine from 9.1 to 7.6. Significant reductions in the deposition of calcium and magnesium salts were also recorded on the silicone catheters. Electron microscopy confirmed that Encrustation and occlusion of the catheter lumen was minimal in the presence of the urease inhibitors. The data from this in vitro study suggests that urease inhibitors, particularly fluorofamide, could have clinical applications in the prevention of catheter Encrustation and blockage.
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which indwelling urethral catheters resist Encrustation by proteus mirabilis biofilms
BJUI, 1997Co-Authors: Nicola S Morris, David J Stickler, C WintersAbstract:Objective To test the resistance of currently available types of indwelling urethral catheters to blockage by Encrustation with mineralized Proteus mirabilis biofilms. Materials and methods Encrustation was studied in a simple laboratory model of the catheterized bladder. Artificial urine was supplied to the bladder chamber at 0.5 mL/min. The bladder urine was inoculated with a clinical strain of P. mirabilis that had been isolated from an encrusted catheter. The models were operated until the catheters blocked and atomic absorption spectrometry was used to assess the amounts of calcium and magnesium deposited on the catheters. Scanning electron microscopy was also used to locate and assess the degree of Encrustation. Results The mean times to blockage ranged from 21 h for the Bard hydrogel/silver-coated latex catheter to 56 h for the Eschmann Folatex S all-silicone catheter. The calcium and magnesium salts were mainly deposited on the 10 cm below the eye-holes of the catheters, complete blockage generally occurring in the 2 cm immediately below the eye-hole. Conclusion None of the 18 types of catheter tested, including those coated with hydrogel or silver, were capable of resisting Encrustation by P. mirabilis biofilm.
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Proteus mirabilis biofilms and the Encrustation of urethral catheters
Urological research, 1993Co-Authors: David J Stickler, L. Ganderton, J.b. King, J. Nettleton, C WintersAbstract:Bacterial biofilms were observed on 69 of 75 catheters taken from patients undergoing long-term bladder management. Ten catheters were colonized by pure cultures of Proteus mirabilis. In each of these cases the bacteria formed layers on the catheter surface, underlying Encrustations of struvite and hydroxyapatite which partially or completely occluded the catheter lumen. Encrustation was also apparent on catheters colonized by P. mirabilis plus other species, but was rarely seen on catheters colonized by non-urease-producing species. These observations support the hypothesis that catheter Encrustation is brought about by the activity of urease-producing biofilms and confirms that the main target in the control of catheter Encrustation should be P. mirabilis.