Simple physical model to study formation and physiology of biofilms on urethral catheters.
Explore the source record for details and available documents.
Bacterial Physiological Phenomena↗
Biomedical subjects
D J Stickler
Publications and source records attributed to D J Stickler.
The effect of urease inhibitors on the encrustation of urethral catheters.
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.
Benzamides↗
Encrustation of indwelling urethral catheters by Proteus mirabilis biofilms growing in human urine.
The encrustation and blockage of four types of urinary catheters was studied in a simple laboratory model of the catheterized bladder. Pooled human urine was supplied to the bladder chamber at 0.5 mL/min. The bladder urine was inoculated with a clinical strain of Proteus 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. All catheters blocked rapidly, the mean times to blockage ranging from 17.7 h (silver-coated latex), 34 h (hydrogel-coated latex), 38 h (silicone-coated latex) to 47 h (all silicone). The internal diameters of the latex catheters were only 1.5 mm compared to the 2.5 mm of the all-silicone catheters. The calcium and magnesium salts were deposited on the lumenal surfaces along the full length of catheters but occurred most extensively just below the eye-holes. There is clearly a need to develop catheter surfaces which resist encrustation by crystalline biofilms of P. mirabilis.
Bacteriuria↗
Biofilms on indwelling urethral catheters produce quorum-sensing signal molecules in situ and in vitro.
Acylated homoserine lactones (AHLs) are chemical signals that mediate population density-dependent (quorum-sensing) gene expression in numerous gram-negative bacteria. In this study, gram-negative bacilli isolated from catheters were screened for AHL production by a cross-feeding assay utilizing an AHL-responsive Agrobacterium tumefaciens reporter strain. Positive reactions were obtained from 14 isolates of Pseudomonas aeruginosa; negative or weakly positive reactions were recorded for isolates of five other species. P. aeruginosa biofilms were then produced on catheters in a physical model of the bladder. Sections of colonized all-silicone catheters gave positive reactions for the quorum-sensing signal molecules as did sections that had been cleaned of biofilm and autoclaved. Control sections of unused catheters were negative in the tests. Sections from four of nine catheters that had been freshly removed from patients gave positive reactions for AHLs. Cleaned autoclaved sections of three of these catheters also gave strongly positive reactions for AHLs. These results demonstrate that AHLs are produced by biofilms as they develop on the catheters both in vitro in the model and in vivo in the patient's bladder. They represent the first demonstration of AHL production by biofilms in a clinical setting.
4-Butyrolactone↗
Evidence of autoinducer activity in naturally occurring biofilms.
N-Acyl homoserine lactone (AHL) molecules have been shown to act as mediators of population density-dependent (quorum-sensing) gene expression in numerous Gram-negative bacteria. Functions associated with AHL include light production in Vibrio fischeri, expression of virulence factors in Pseudomonas aeruginosa, and conjugation in Agrobacterium tumefaciens. In nature, bacteria often grow as surface-adherent biofilm communities. As biofilms typically contain high concentrations of cells, AHL activity and quorum-sensing gene expression have been proposed as essential components of biofilm physiology. However, proof of AHL production within biofilms has heretofore been lacking. In this study we have employed a cross-feeding assay, using A, tumefaciens A136 (traI::lacZ) as an AHL-responsive reporter strain, to show the presence of naturally occurring AHL production in aquatic biofilms growing on submerged stones. AHL was detected in living biofilms and biofilm extracts, but was not present in rocks lacking a biofilm. This represents the first report of AHL activity in naturally occurring biofilms.
4-Butyrolactone↗
Which indwelling urethral catheters resist encrustation by Proteus mirabilis biofilms?
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.
Biofilms↗
An assessment of the ability of a silver-releasing device to prevent bacterial contamination of urethral catheter drainage systems.
OBJECTIVE: To investigate the ability of a silver-releasing device to protect the catheterized bladder from infection by blocking the ascending migration of bacteria from contaminated urine-drainage bags. MATERIALS AND METHODS: A simple physical model of the catheterized bladder and drainage system was used with the device located in the drainage-tube just below the sampling port. Urine was supplied to the model at 1.0 mL/min and the drainage bag was contaminated with Pseudomonas aeruginosa, Escherichia coli and Proteus mirabilis. Over 10 days, urine from the bag, catheter sampling-port and bladder were examined for contamination. RESULTS: Bacteriological analysis showed that the mean time for test organisms to reach the sampling ports of four different control bag systems ranged from 5.7 to 7.7 days. Urine from the sampling ports of the test systems incorporating the silver device remained sterile for 10 days. The device also prevented the growth of the large populations of bacteria (10(8) colony-forming units per mL) that occurred in the control bags. While scanning electron microscopy showed the formation of bacterial biofilm throughout the control drainage systems, no bacterial colonization was visible on the surfaces of the test systems. Chemical analysis established that the devices consistently generated concentrations of silver in urine ranging from 1.0 to 2.0 micrograms/mL. CONCLUSION: The incorporation of the silver-releasing device into the drainage systems produced an antibacterial barrier which protected the catheterized bladder from intraluminal contamination for at least 10 days. These in vitro tests suggest a useful role for the device in controlling infection in patients undergoing short-term indwelling bladder catheterization.
Bacterial Infections↗
Bladder management and urinary tract infections in Danish hospitals, nursing homes, and home care: a national prevalence study.
OBJECTIVE: To establish the prevalence of urinary tract infection in patients undergoing various forms of bladder management. DESIGN: A nationwide descriptive point-prevalence survey with logistic regression analysis of the data relating infection to bladder management. SETTING: Fifteen hospitals, 21 nursing homes, and 13 home care districts throughout Denmark. PATIENTS: Information was collected on 3,665 patients. On the day of the study, 349 patients had indwelling catheters and 1,150 were using external urine drainage systems (condoms or diapers) for bladder management. RESULTS: The prevalence of urinary tract infections in catheterized patients and those using external drainage systems was 13.2% and 8.1%, respectively. The prevalence of hospital-acquired urinary tract infection (4.2%) had not changed from that reported in 1978. The proportion of these infections related to the indwelling catheter, however, had reduced from 66% to 30%. Logistic regression analysis confirmed that, when corrected for the patient-related confounders (female gender, age > 60 years, incontinence, immobility, and stay in hospital for longer than 15 days), condoms (odds ratio [OR], 5.94; 95% confidence interval [CI95], 2.8 to 12.5), indwelling catheters (OR, 3.3; CI95, 2.3 to 4.8), and diapers (OR, 1.5; CI95, 1.1 to 2.1) were significantly (P < .001, P < .001, and P = .008, respectively) related to infection. CONCLUSIONS: Prevalence surveys have revealed that over the period 1978 to 1991, during which efforts have been made to restrict the use of indwelling catheters and to encourage the care of catheterized patients according to guidelines recommended by the Danish National Centre for Hospital Hygiene, the percentage of hospital-acquired urinary tract infections associated with indwelling catheters has been halved. External urine drainage systems, however, have emerged as significant risk factors for urinary tract infection.
Aged↗
The management of urinary catheters: compliance of practice in Danish hospitals, nursing homes and home care to national guidelines.
The compliance of practice to national guidelines on urethral catheter care has been examined. Questionnaires on the practices used with patients under their care were sent to 1350 nursing staff. Replies were received from 1153 individuals, 692 from hospitals, 345 from nursing homes and 116 from home care. While national guidelines stress the importance of maintaining a closed urine drainage system, the results revealed that 25.4% of respondents opened the drainage system to collect samples of urine for analysis, 57.9% to perform bladder washouts and 76% to change urine bags. 26% of respondents reported that they collected urine samples for routine bacteriological surveillance, a procedure considered unnecessary in the guidelines. 83% of staff reported that they washed their hands after emptying urine bags. Staff awareness of written guidelines for various aspects of catheter care ranged from 25-68% in hospitals, 27-45% in nursing homes and 7-17% in home care. A marginal costs analysis was performed to estimate the economic consequences of non-compliance to the national guidelines.
Anti-Bacterial Agents↗
Ultrasound-enhanced latex agglutination for the detection of bacterial antigens in urine.
An ultrasound-enhanced latex agglutination technique has been applied to the detection of bacteria in urine. The approach combines the use of ultrasound, the dilution of latex to allow agglutination with low levels of antigen, and microscopy. Using commercially available latex coated with antibody to Esch. coli O157 or K1, ultrasound enhanced the detection of Esch. coli strains carrying these antigens by x512 and x2048 respectively, compared with the standard test card procedure. The latex particles in the commercial kits were 0.4-1.0 micron in diameter. As larger particles are more effectively manipulated in a sound field, particles of 2.8 microns diameter were coated with antiserum against a urinary tract isolate of Esch. coli (SP3112). The application of ultrasound with these particles facilitated the detection of 6 x 10(3) cells/mL of Esch. coli SP3112 within 2 min, a > 10,000-fold increase in sensitivity compared with the normal agglutination procedure. The possible exploitation of this technique in the clinical laboratory for the rapid, sensitive detection of bacterial antigens in urine is discussed.
Antigens, Bacterial↗
Complications of urinary tract infections associated with devices used for long-term bladder management.
The long-term indwelling urethral catheter continues to be a major cause of morbidity in patients in hospitals, nursing homes and home care. Many authorities have recommended that wherever possible, alternative techniques should be considered for the management of patients with urinary retention or incontinence. This article considers the complications that develop from the urinary tract infections associated with long-term indwelling catheterization and reviews the evidence that the other options for bladder management pose less serious threats to health.
Bacteremia↗
Blockage of urethral catheters by bacterial biofilms.
We report the case of a 63-year-old woman whose indwelling urethral catheter became blocked regularly at 4-5 day intervals over a period of 10 weeks. 'Worm-like' structures 25-30 cm in length were found either in the catheter, completely occluding the lumen, or in the drainage tube thereby blocking the valve of the drainage bag. Electron microscopy showed that these structures were composed of bacteria, while culture revealed them to be mixed communities of Pseudomonas aeruginosa, Escherichia coli, Enterococcus faecalis and Proteus mirabilis. Following treatment with ciprofloxacin, catheter drainage continued freely for a further period of 10 weeks.
Catheters, Indwelling↗
Management of urinary bladder function in Danish hospitals, nursing homes and home care.
The purpose of this study was to determine the prevalence of the various devices used for bladder function management in Denmark and to assess the scope for the use of alternatives to the indwelling urethral catheter. Data were collected on 1581 hospital patients, 1341 nursing home residents and 743 patients receiving home care. The sample populations were characterized by age, sex and independence in the activities of daily living. The prevalence of indwelling catheters in the three groups of patients was 13.2%, 4.9% and 3.9%, respectively. The equivalent figures for condom drainage systems were 1.5%, 0.8% and 1.2%, and for napkins 10.1%, 52.1% and 34.1%. Comparison of the results from this survey with earlier data indicates that over the period 1980-1991 (during which efforts have been made in Denmark to restrict indwelling bladder catheterization and encourage the use of alternative devices) there has been a reduction in the prevalence of indwelling catheters in hospital medical wards from 13.7% to 6.6%. Examination of the reasons for catheterization revealed that the proportions of patients catheterized because of incontinence were 14% in hospitals, 31% in nursing homes and 33% in home care. There is clearly a need to continue the educational efforts to inform staff of the infection risks and complications associated with indwelling catheters and persuade them of the advantages of the alternative techniques for care of the incontinent patient.
Activities of Daily Living↗
The effect of repeated instillations of antiseptics on catheter-associated urinary tract infections: a study in a physical model of the catheterized bladder.
The activity of three antiseptic bladder washout solutions was examined in a physical model of the catheterized bladder. Tests were performed against cultures of four common urinary tract pathogens that had established themselves in the model and colonized the surfaces with biofilm. Double instillations of chlorhexidine (0.02% w/v) at 6-h intervals failed to eliminate Pseudomonas aeruginosa, Proteus mirabilis, and Providencia stuartii from the bladder model. Escherichia coli, however, was susceptible to a second instillation provided that it was performed within 12 h. Supplementing chlorhexidine with EDTA and TRIS potentiated its activity against E. coli. Mandelic acid (1.0% w/v) was the most effective of the agents, double instillations eliminating all but Pr. mirabilis infections.
Administration, Intravesical↗
N-nitrosamine generation by urinary tract infections in spine injured patients.
Urine was collected from 33 patients resident at the Welsh Spinal Injuries Unit and analysed for volatile N-nitrosamines by gas chromatography. N-nitrosodime-thylamine, N-nitrosopiperidine or N-nitrosopyrrolidine was detected in 32 of the samples. Thirty-one of the samples were infected by one or more microbial species. Nitrate and N-nitrosamines were not found in the sterile urines of a group of 10 control individuals exposed to the same dietary and environmental influences as the spinal patients. Although N-nitrosamines were found in some of the catheter drainage system products, they did not elute into urine on 24-h exposure. In addition, 6 of the nitrosamine-containing urines had no contact with drainage systems as they were collected from spinal patients who were capable of independent voiding. It was concluded that the nitrosamines detected in the urines arose from the bacterial nitrosation of urinary amines. These results support the hypothesis that chronic urinary tract infection may have a role in the aetiology of bladder cancer in spine injured patients.
Humans↗
An assessment of antiseptic bladder washout solutions using a physical model of the catheterized bladder.
The antibacterial activity of six antiseptic solutions formulated for use in bladder washout procedures has been examined in a simple model of the catheterized bladder. The experiments were carried out under conditions which examined the efficacy of the formulations against organisms that had recently contaminated the bladder urine. At cell densities of 10(4) cfu ml-1 all the solutions tested proved effective in eliminating bacteria from the bladder urine. Under conditions simulating heavy contamination (10(7)-10(8) cfu ml-1) however, only mandelic acid (1% w/v) eliminated the range of bacterial species commonly responsible for catheter-associated urinary tract infection.
Administration, Intravesical↗
Increased urinary nitrosamine excretion in paraplegic patients.
An increased risk of bladder cancer is a recognized complication in spine-injured patients undergoing long-term urethral catheterization to preserve renal function. Aerobic cultures from 28 of 30 paraplegic patients showed complex bacterial flora containing nitrate-reducing organisms (Escherichia coli, Proteus and Klebsiella spp.). Urine samples from 29 paraplegic patients were also found to contain volatile nitrosamines. Mean N-nitrosamine excretion levels were 0.65 +/- 0.69 micrograms/day N-nitrosodimethylamine, 0.25 +/- 0.44 micrograms/day N-nitrosopiperidine and 0.39 +/- 0.50 micrograms/day N-nitrosopyrrolidine. A mean urinary nitrite excretion of 10.4 +/- 13.2 mg/day was found in 24 out of 30 paraplegic patients. In the sterile urine of control volunteers (medical staff attending the paraplegic patients and in-patients from other wards of the hospital), no urinary excretion of volatile N-nitrosamines and nitrite was found. The results clearly demonstrate a bacterially mediated in vivo formation of N-nitroso compounds in the urinary tracts of paraplegic patients which may be an important etiological risk factor for bladder cancer in this patient group.
Amines↗
The role of antiseptics in the management of patients undergoing short-term indwelling bladder catheterization.
Explore the source record for details and available documents.
Administration, Intravesical↗