Catheter Blockage Time K-2199 Background: Infection by Proteus mirabilis can complicate patient care with long-term indwelling bladder catheters. These urease-producing bacilli elevate urinary pH, colonize catheters and produce crystalline biofilms that can block the flow of urine from the bladder. NovaBay has developed a non- antibiotic, anti-infective compound (NVC-422; N,N-dichloro-2,2-dimethyltaurine), a stable analog of the natural antimicrobial N-chlorotaurine that exhibits potent broad spectrum antimicrobial activity with an excellent safety profile. Here we investigated the potential use of NVC-422 in an instillation solution for the control of catheter blockage by P. mirabilis biofilm. Methods: Experiments were performed in laboratory models of the catheterized bladder fed artificial urine and inoculated with P. mirabilis. NVC-422 or saline was instilled daily into the catheterized bladder chambers following protocols to simulate clinical bladder washout regimens. The experiments were run for 144 h or until catheters blocked. The pH of the effluent urine and the times to catheter blockage were measured. Biofilm formation was observed with scanning electron microscopy. Results: In control models (saline) catheters blocked at 46 h. Electron microscopy confirmed that catheter blockage was due to the accumulation of crystalline biofilm in the lumen and around the eyeholes. In these control models, the pH of urine increased from 6 to 9. The catheters treated with 0.2% NVC-422 in saline formulated at pH 4 drained freely for the 144 h experimental period, the urinary pH remained at 6, and no biofilm was visible. Conclusions: Instillations of NVC-422 were effective in preventing crystalline P. mirabilis biofilms on catheters in an in vitro test system. These results suggest that a bladder washout regime using solutions of NVC-422 could be used to manage catheter encrustation that complicates the care of patients undergoing long-term bladder catheterization. Catheterized Bladder Model Abstract Introduction Materials & Methods Efficacy of NVC-422, a Novel Derivative of N-Chlorotaurine, in Controlling Crystalline Proteus mirabilis Biofilm Formation on Urinary Catheters S. A. Rani, C. Celeri, D. Debabov, R. Najafi, M. Anderson NovaBay Pharmaceuticals, Inc., Emeryville, CA 5980 Horton Street, Suite 550 Emeryville, CA 94608 Phone (510) 899-8800 FAX (510) 280-8730 [email protected] Conclusions Stereo Zoom and SEM Imaging Acknowledgements Patients with long-term indwelling bladder catheters often face bacterial colonization causing encrustation and subsequent catheter blockage. Among the many urinary pathogens, urease-positive Proteus mirabilis is the most common culprit. These urease-producing bacilli catalyze the hydrolysis of urea to ammonia, thus creating alkaline conditions. As the urinary pH elevates, calcium and magnesium phosphates precipitate out of solution as struvite and hydroxyapatite crystals respectively (1). The continued formation of crystalline biofilms blocks the normal flow of urine from the bladder, leading to incontinence (2) and increased risks of developing bacteriuria, pyelonephritis, bacteremia, and sepsis (3). Currently, there are no successful treatment protocols for controlling catheter encrustation and blockage (2). In the present study, we utilized an in vitro catheterized bladder model that closely mimics the crystalline biofilm growth conditions in the catheterized bladders. Experiments were performed in laboratory models, where catheterized bladders were fed with artificial urine and inoculated with P. mirabilis. NVC-422 or placebo (control) was instilled into the catheterized bladder model following protocols to simulate clinical bladder instillation and drainage regimens. The catheterized bladder biofilm model was used to simulate crystalline biofilms in patients with long- term indwelling catheters (Figure 1). The model was adapted from Stickler et al. (4) with the following modifications. Irrigation solutions were instilled through the catheter into the bladder as per schematic in Figure 2. The vessel containing artificial urine was infected either in a single inoculation or on a daily basis (see Table 1). Artificial urine composition (0.65 g/L calcium chloride, 0.65 g/L magnesium chloride hexahydrate, 4.6 g/L sodium chloride, 2.3 g/L sodium sulfate, 0.65 g/L sodium citrate dihydrate, 0.2g/L sodium oxalate, 2.8 g/L potassium dihydrogen phosphate,1.6 g/L potassium chloride, 2 g/L ammonium chloride, 12 g/L urea, 1.1 g/L creatinine). Following blockage of catheter or on day 7, the assembly was dismantled and the catheter was removed from the glass vessel. The pH of the effluent urine and the times to catheter blockage were recorded. The catheter was sectioned and analyzed for viable cell counts. Biofilm formation was observed with Scanning Electron Microscopy (SEM) and Stereo Zoom imaging. Table 1. Catheter blockage time. Catheters irrigated with control solutions (saline and acetate saline) blocked between 2-4 days and the pH of artificial urine shifted from 6 to 9. Increase of urinary pH indicates continued formation of crystalline biofilm. The catheters treated with NVC-422 remained patent throughout the 7 day experimental period. The pH of artificial urine remained between 6-7. Catheters treated with Renacidin® (6.6% citric acid, 0.2% glucono delta-lactone, and 3.4% magnesium carbonate) blocked on day 3. Crystalline biofilm partially dissolved immediately after irrigation with Renacidin®, however, biofilm encrustation developed the next day. The authors would like to thank Nick Wayham for assistance in solutions preparation and Dr. Lisa Friedman for scientific contributions. References 1. S. Mathur, M. T. E. Suller, D. J. Stickler, and R. C. L. Feneley (2006) Prospective study of individuals with long-term urinary catheters colonized with Proteus species. BJU. Int. 97:121-128 2. R. J. Broomfield, S. D. Morgan, A. Khan, and D. J. Stickler (2009) Crystalline bacterial biofilm formation on urinary catheters by urease-producing urinary tract pathogens: a simple method of control. J. Med. Microbiol. 58: 1367-1375 3. C. M. Kunin, S. Douthitt, J. Dancing, J. Anderson, and M. Moeschberger (1992) The association between the use of urinary catheters and morbidity and mortality among elderly patients in nursing homes. Am. J. Epidemiol. 135: 291-301 4. D. J. Stickler, N. S. Morris, and C. Winters (1999) Simple physical model to study formation and physiology of biofilms on urethral catheters. Meth. Enyzm. 310: 494-501 Treatment with 0.2% NVC-422 maintained catheter patency for greater than 7 days Treatment with 0.2% NVC-422 greatly reduced P. mirabilis cell counts after each irrigation Treatment with 0.2% NVC-422 reduced crystalline encrustation in the biofilm model Urinary pH remained between 6-7 in NVC-422 treated catheters Treatment with 0.2% NVC-422 maintained catheter patency in the catheterized bladder model within 7 days. Crystalline material was evident in catheter treated with control solutions (saline). Fig. 1. Catheterized bladder model. Schematic of the in vitro catheterized bladder model. The model consists of a size 14 Foley catheter (all silicone) inserted into the bottom of a glass vessel simulating a human bladder. The catheter was held in place by inflating the retention balloon with 10 mL of sterile water. As artificial urine is pumped into the catheterized bladder, the urine drains through the eye-hole into a waste bag with minimal residual urine collecting in the glass vessel. Fig. 3. Efficacy of NVC-422 irrigation. NVC-422 was effective in reducing bacterial counts to the limit of detection and lowering urinary pH immediately after each irrigation during the 7 day experimental period. (I) Urinary effluent pH and (II) viable cell counts measured during the inoculation and irrigation regimen. Fig. 5. Scanning electron microscopy images of NVC-422 treated and saline treated (control) catheters colonized by P. mirabilis biofilm. (V) Section analyzed after daily treatment with NVC-422 in saline. (VI) Sectioned analyzed after control (saline) catheter blocked on day 3. Photo shows a crystal embedded in P. mirabilis biofilm. V VI III IV Fig. 4. Stereo Zoom images of NVC-422 treated and 10 mM acetate saline treated (control) catheters removed from P. mirabilis infected bladder models. (III) Cross section of the eyehole lumen of an unblocked NVC-422 treated catheter draining freely at 7 days. (IV) Cross section of the eyehole of a control treated catheter after blockage on day 3. Fig. 2. Catheter bladder irrigation regimen for daily inoculation and every other day irrigation. On day 1, vessels were inoculated for 1 hr and received bladder irrigations twice. On day 2, 4, and 6, vessels were inoculated for 30 min and did not receive any irrigation. On day 3, 5, and 7, vessels were inoculated for 30 min and received bladder irrigations twice. On day 7 (or after catheter blockage), vessels were taken apart and catheters were removed for analysis. Inoculate with P. mirabilis for 1 hr (day 1) or 30 min (day 3, 5, 7) Day 1, 3, 5, 7 Urine flow for 30 min Bladder instillation for 15 min Urine flow for 30 min Urine flow for 24 hr (30 min on day 7) Bladder instillation for 15 min Inoculate with P. mirabilis for 30 min Day 2, 4, 6 Urine flow for 24 hr Vessel disassembly (day 7) A E D B C F A B Inoculate with P. mirabilis for 1 hr (day 1) or 30 min (day 3, 5, 7) Day 1, 3, 5, 7 Urine flow for 30 min Bladder instillation for 15 min Urine flow for 30 min Urine flow for 24 hr (30 min on day 7) Bladder instillation for 15 min Inoculate with P. mirabilis for 30 min Day 2, 4, 6 Urine flow for 24 hr Vessel disassembly (day 7) A E D B C F A B *0.2% NVC-422 was selected based on our previous in vitro and in vivo studies Log 10 CFU/mL in Catheter Irrigated with 0.2% NVC-422 in 10 mM Acetate Saline pH 4 2 3 4 5 6 7 8 9 10 ABCDEFABABCDEFABABCDEFABABCDEF Catheter Irrigation Regimen Log 10 CFU/mL Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7 Urinary pH Shift in Catheter Irrigated with 0.2% NVC-422 in 10 mM Acetate Saline pH 4 1 2 3 4 5 6 7 8 9 10 ABCDEFABABCDEFABABCDEFABABCDEF Catheter Irrigation Regimen pH Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7 II I Inoculation Treatment Irrigation Solution Time to block (day) Single Daily (excluding day 7) Saline pH 4 (n=3) 2 Single Daily (excluding day 7) 0.2% NVC-422 in Saline pH 4 (n=4) >7 Daily Every other day 10 mM Acetate Saline pH 4 (n=4) 3 Daily Every other day 20 mM Acetate Saline pH 4 (n=1) 4 Daily Every other day 0.2% NVC-422 in 10 mM Acetate Saline pH 4 (n=4) >7 Daily Every other day 0.2% NVC-422 in 20 mM Acetate Saline pH 4 (n=1) >7 Daily Every other day Renacidin® Irrigation (n=2) 3 Artificial Urine, pH 6 Flow Break Waste Foley Catheter Pump Urine Flow (0.5 mL/min) Treatment & Inoculation Site Treatment & Inoculation Flow Glass vessel Foley Catheter Balloon ° Artificial Urine, pH 6 Flow Break Waste Foley Catheter Artificial Urine, pH 6 Flow Break Waste Foley Catheter Pump Pump Urine Flow (0.5 mL/min) Treatment & Inoculation Site Treatment & Inoculation Flow Glass vessel Foley Catheter Balloon ° ° °
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Catheter Blockage Time
K-2199
Background: Infection by Proteus mirabilis can complicate patient care with long-term indwellingbladder catheters. These urease-producing bacilli elevate urinary pH, colonize catheters and producecrystalline biofilms that can block the flow of urine from the bladder. NovaBay has developed a non-antibiotic, anti-infective compound (NVC-422; N,N-dichloro-2,2-dimethyltaurine), a stable analog ofthe natural antimicrobial N-chlorotaurine that exhibits potent broad spectrum antimicrobial activitywith an excellent safety profile. Here we investigated the potential use of NVC-422 in an instillationsolution for the control of catheter blockage by P. mirabilis biofilm. Methods: Experiments wereperformed in laboratory models of the catheterized bladder fed artificial urine and inoculated with P.mirabilis. NVC-422 or saline was instilled daily into the catheterized bladder chambers followingprotocols to simulate clinical bladder washout regimens. The experiments were run for 144 h or untilcatheters blocked. The pH of the effluent urine and the times to catheter blockage were measured.Biofilm formation was observed with scanning electron microscopy. Results: In control models(saline) catheters blocked at 46 h. Electron microscopy confirmed that catheter blockage was due tothe accumulation of crystalline biofilm in the lumen and around the eyeholes. In these control models,the pH of urine increased from 6 to 9. The catheters treated with 0.2% NVC-422 in saline formulatedat pH 4 drained freely for the 144 h experimental period, the urinary pH remained at 6, and no biofilmwas visible. Conclusions: Instillations of NVC-422 were effective in preventing crystalline P. mirabilisbiofilms on catheters in an in vitro test system. These results suggest that a bladder washout regimeusing solutions of NVC-422 could be used to manage catheter encrustation that complicates the careof patients undergoing long-term bladder catheterization.
Catheterized Bladder ModelAbstract
Introduction
Materials & Methods
Efficacy of NVC-422, a Novel Derivative of N-Chlorotaurine, in Controlling Crystalline Proteus mirabilis Biofilm Formation on Urinary Catheters
S. A. Rani, C. Celeri, D. Debabov, R. Najafi, M. AndersonNovaBay Pharmaceuticals, Inc., Emeryville, CA
5980 Horton Street, Suite 550Emeryville, CA 94608
Phone (510) 899-8800FAX (510) 280-8730
Conclusions
Stereo Zoom and SEM Imaging
Acknowledgements
Patients with long-term indwelling bladder catheters often face bacterial colonization causingencrustation and subsequent catheter blockage. Among the many urinary pathogens, urease-positiveProteus mirabilis is the most common culprit. These urease-producing bacilli catalyze the hydrolysisof urea to ammonia, thus creating alkaline conditions. As the urinary pH elevates, calcium andmagnesium phosphates precipitate out of solution as struvite and hydroxyapatite crystals respectively(1). The continued formation of crystalline biofilms blocks the normal flow of urine from the bladder,leading to incontinence (2) and increased risks of developing bacteriuria, pyelonephritis, bacteremia,and sepsis (3). Currently, there are no successful treatment protocols for controlling catheterencrustation and blockage (2).
In the present study, we utilized an in vitro catheterized bladder model that closely mimics thecrystalline biofilm growth conditions in the catheterized bladders. Experiments were performed inlaboratory models, where catheterized bladders were fed with artificial urine and inoculated with P.mirabilis. NVC-422 or placebo (control) was instilled into the catheterized bladder model followingprotocols to simulate clinical bladder instillation and drainage regimens.
The catheterized bladder biofilm model was used to simulate crystalline biofilms in patients with long-term indwelling catheters (Figure 1). The model was adapted from Stickler et al. (4) with the followingmodifications. Irrigation solutions were instilled through the catheter into the bladder as per schematicin Figure 2. The vessel containing artificial urine was infected either in a single inoculation or on adaily basis (see Table 1). Artificial urine composition (0.65 g/L calcium chloride, 0.65 g/L magnesiumchloride hexahydrate, 4.6 g/L sodium chloride, 2.3 g/L sodium sulfate, 0.65 g/L sodium citratedihydrate, 0.2g/L sodium oxalate, 2.8 g/L potassium dihydrogen phosphate,1.6 g/L potassiumchloride, 2 g/L ammonium chloride, 12 g/L urea, 1.1 g/L creatinine).
Following blockage of catheter or on day 7, the assembly was dismantled and the catheter wasremoved from the glass vessel. The pH of the effluent urine and the times to catheter blockage wererecorded. The catheter was sectioned and analyzed for viable cell counts. Biofilm formation wasobserved with Scanning Electron Microscopy (SEM) and Stereo Zoom imaging.
Table 1. Catheter blockage time. Catheters irrigated with control solutions (saline and acetatesaline) blocked between 2-4 days and the pH of artificial urine shifted from 6 to 9. Increase of urinarypH indicates continued formation of crystalline biofilm. The catheters treated with NVC-422 remainedpatent throughout the 7 day experimental period. The pH of artificial urine remained between 6-7.
Catheters treated with Renacidin® (6.6% citric acid, 0.2% glucono delta-lactone, and 3.4%magnesium carbonate) blocked on day 3. Crystalline biofilm partially dissolved immediately afterirrigation with Renacidin®, however, biofilm encrustation developed the next day.
The authors would like to thank Nick Wayham for assistance in solutions preparation and Dr. LisaFriedman for scientific contributions.
References
1. S. Mathur, M. T. E. Suller, D. J. Stickler, and R. C. L. Feneley (2006) Prospective study ofindividuals with long-term urinary catheters colonized with Proteus species. BJU. Int. 97:121-128
2. R. J. Broomfield, S. D. Morgan, A. Khan, and D. J. Stickler (2009) Crystalline bacterial biofilmformation on urinary catheters by urease-producing urinary tract pathogens: a simple method ofcontrol. J. Med. Microbiol. 58: 1367-1375
3. C. M. Kunin, S. Douthitt, J. Dancing, J. Anderson, and M. Moeschberger (1992) The associationbetween the use of urinary catheters and morbidity and mortality among elderly patients in nursinghomes. Am. J. Epidemiol. 135: 291-301
4. D. J. Stickler, N. S. Morris, and C. Winters (1999) Simple physical model to study formation andphysiology of biofilms on urethral catheters. Meth. Enyzm. 310: 494-501
Treatment with 0.2% NVC-422 maintained catheter patency for greater than 7 days
Treatment with 0.2% NVC-422 greatly reduced P. mirabilis cell counts after each irrigation
Treatment with 0.2% NVC-422 reduced crystalline encrustation in the biofilm model
Urinary pH remained between 6-7 in NVC-422 treated cathetersTreatment with 0.2% NVC-422 maintained catheter patency in the catheterized bladder model within 7 days. Crystalline material was evident in catheter treated with control solutions (saline).
Fig. 1. Catheterized bladder model. Schematic of the in vitrocatheterized bladder model. The model consists of a size 14Foley catheter (all silicone) inserted into the bottom of a glassvessel simulating a human bladder. The catheter was held inplace by inflating the retention balloon with 10 mL of sterilewater. As artificial urine is pumped into the catheterized bladder,the urine drains through the eye-hole into a waste bag withminimal residual urine collecting in the glass vessel.
Fig. 3. Efficacy of NVC-422 irrigation. NVC-422 was effectivein reducing bacterial counts to the limit of detection and loweringurinary pH immediately after each irrigation during the 7 dayexperimental period. (I) Urinary effluent pH and (II) viable cellcounts measured during the inoculation and irrigation regimen.
Fig. 5. Scanning electron microscopy images of NVC-422 treated and saline treated(control) catheters colonized by P. mirabilis biofilm. (V) Section analyzed after dailytreatment with NVC-422 in saline. (VI) Sectioned analyzed after control (saline) catheterblocked on day 3. Photo shows a crystal embedded in P. mirabilis biofilm.
V VIIII IV
Fig. 4. Stereo Zoom images of NVC-422 treated and 10 mM acetate saline treated(control) catheters removed from P. mirabilis infected bladder models. (III) Crosssection of the eyehole lumen of an unblocked NVC-422 treated catheter draining freely at 7days. (IV) Cross section of the eyehole of a control treated catheter after blockage on day 3.
Fig. 2. Catheter bladder irrigation regimen for dailyinoculation and every other day irrigation. On day 1, vesselswere inoculated for 1 hr and received bladder irrigations twice.On day 2, 4, and 6, vessels were inoculated for 30 min and didnot receive any irrigation. On day 3, 5, and 7, vessels wereinoculated for 30 min and received bladder irrigations twice. Onday 7 (or after catheter blockage), vessels were taken apart andcatheters were removed for analysis.
Inoculate with P. mirabilis for 1 hr (day 1) or 30 min (day 3, 5, 7)
Day 1, 3, 5, 7
Urine flow for 30 min
Bladder instillation for 15 min
Urine flow for 30 min
Urine flow for 24 hr (30 min on day 7)
Bladder instillation for 15 min
Inoculate with P. mirabilis for 30 min
Day 2, 4, 6
Urine flow for 24 hr
Vessel disassembly (day 7)
A
E
D
B
C
F
A
B
Inoculate with P. mirabilis for 1 hr (day 1) or 30 min (day 3, 5, 7)
Day 1, 3, 5, 7
Urine flow for 30 min
Bladder instillation for 15 min
Urine flow for 30 min
Urine flow for 24 hr (30 min on day 7)
Bladder instillation for 15 min
Inoculate with P. mirabilis for 30 min
Day 2, 4, 6
Urine flow for 24 hr
Vessel disassembly (day 7)
A
E
D
B
C
F
A
B
*0.2% NVC-422 was selected based on our previous in vitro and in vivo studies
Log10 CFU/mL in Catheter Irrigated with 0.2% NVC-422in 10 mM Acetate Saline pH 4
2
34
56
7
89
10
A B C D E F A B A B C D E F A B A B C D E F A B A B C D E F
Catheter Irrigation Regimen
Log 1
0 CFU
/mL
Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7
Urinary pH Shift in Catheter Irrigated with 0.2% NVC-422 in 10 mM Acetate Saline pH 4
123456789
10
A B C D E F A B A B C D E F A B A B C D E F A B A B C D E F
Catheter Irrigation Regimen
pH
Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7
II
I Inoculation Treatment Irrigation Solution Time to block (day)
Single Daily (excluding day 7) Saline pH 4 (n=3) 2
Single Daily (excluding day 7) 0.2% NVC-422 in Saline pH 4 (n=4) >7
Daily Every other day 10 mM Acetate Saline pH 4 (n=4) 3
Daily Every other day 20 mM Acetate Saline pH 4 (n=1) 4
Daily Every other day 0.2% NVC-422 in 10 mM Acetate Saline pH 4 (n=4) >7
Daily Every other day 0.2% NVC-422 in 20 mM Acetate Saline pH 4 (n=1) >7
Daily Every other day Renacidin® Irrigation (n=2) 3
Artificial Urine, pH 6
Flow Break
Waste
Foley Catheter
Pump
Urine Flow(0.5 mL/min)
Treatment & Inoculation Site
Treatment & Inoculation Flow
Glass vessel
Foley Catheter Balloon°
Artificial Urine, pH 6
Flow Break
Waste
Foley Catheter
Artificial Urine, pH 6
Flow Break
Waste
Foley Catheter
PumpPump
Urine Flow(0.5 mL/min)
Treatment & Inoculation Site
Treatment & Inoculation Flow
Glass vessel
Foley Catheter Balloon°°°
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