Observations on the adherence of Proteus mirabilis onto polymer surfaces.

AIMS: Infection of the catheterized urinary tract with Proteus mirabilis causes blockage of the catheter by crystalline bacterial biofilms. The aim of this work is to identify a surface-coating for catheters that is not vulnerable to colonization by Pr. mirabilis. METHODS AND RESULTS: A parallel-plate flow-cell and phase contrast microscopy were used to follow bacterial adhesion onto polymer films. Experiments with a urease-negative mutant of Pr. mirabilis suspended in buffer or urine, identified agarose as a polymer on which biofilm did not form. In tests with wild-type urease-producing cells in urine, no adhesion of cells onto agarose was observed for 3 h but then as the pH rose above 8.2, the surface rapidly became colonized by crystalline biofilm. CONCLUSIONS: In urine at pH below 8.0, Pr. mirabilis does not adhere to agarose-coated surfaces. When the pH rises above 8.2, however, aggregates of crystals and bacteria form in the urine and are deposited on such surfaces. SIGNIFICANCE AND IMPACT OF THE STUDY: Strategies to prevent the formation of crystalline biofilms on urinary catheters will need to consider both the properties of the surface-coatings and the requirement to prevent the alkaline conditions that induce crystal formation in urine.

Does drinking cranberry juice produce urine inhibitory to the development of crystalline, catheter-blocking Proteus mirabilis biofilms?

OBJECTIVE: To test the recommendation that to avoid the complications of long-term indwelling bladder catheterization (e.g. encrustation and blockage by crystalline Proteus mirabilis biofilms) patients should drink cranberry juice. MATERIALS AND METHODS: Urine was collected from groups of volunteers who had drunk up to 2 x 500 mL of cranberry juice or water within an 8-h period. Laboratory models of the catheterized bladder were supplied with urine from these groups and inoculated with P. mirabilis. After incubation for 24 or 48 h, the extent of catheter encrustation was determined by chemical analysis for calcium and magnesium. Encrustation was also visualized by scanning electron microscopy. RESULTS: The amounts of calcium and magnesium recovered from catheters incubated in urine pooled from individuals who had drunk 500 mL of cranberry juice was not significantly different from that on catheters incubated in pooled urine from control subjects who had drunk 500 mL of water. However, there was significantly less encrustation (P = 0.007) on catheters from models receiving urine from volunteers who had drunk 2 x 500 mL of water than on catheters incubated in models supplied with urine from volunteers who had drunk 2 x 500 mL of cranberry juice. The amounts of encrustation on these two groups of catheters were also significantly less than that on catheters incubated in models supplied with urine from volunteers who had not supplemented their normal fluid intake. (P < 0.001). Experiments in the models using artificial urine showed that increasing the low fluid intake (720 mL/24 h) characteristic of many patients undergoing long-term catheterization by factors of three and six, significantly (P < 0.01) reduced the amounts of calcium and magnesium that formed on catheters. At a simulated fluid intake of 720 mL/24 h, catheters blocked with encrustation after a mean of 42.5 h, while those supplied with urine produced from an intake of 4320 mL/24 h, drained freely for > 10 days. CONCLUSION: In this in vitro study, drinking cranberry juice did not produce urine that was inhibitory to the development of crystalline catheter-blocking P. mirabilis biofilms. The important factor in preventing catheter encrustation is a high fluid intake.

Implementation of curriculum guidelines for pharmacology and pharmacotherapeutics in FNP graduate programs: a national survey.

Model Pharmacology and Pharmacotherapeutics Curriculum Guidelines were developed by the National Council of State Boards of Nursing and the National Organization of Nurse Practitioner Faculties and published in 1998. To date, no publication of evaluation of adoption or adherence to these guidelines is available. The purpose of this survey was to determine how family nurse practitioner programs incorporate the guidelines into their curriculum. A mailed self-report questionnaire to 193 schools yielded a 41% response rate. Eighty-five percent (n = 68) of the programs have not yet fully integrated the guidelines into their curriculum. Difficulties addressing the extensive content within a 3-credit course and the challenges of teaching students with varied clinical backgrounds and knowledge levels were frequently cited. Although further study of achievement of the guidelines is necessary, an increase in credit allocation, consideration of a conceptual approach to the topic, and use of varied teaching strategies may make achievement of the guidelines more realistic.

Distal radius fracture in adults: self-reported physical functioning, role functioning, and meaning of injury.

PURPOSE: To identify physical function, role function, and meaning of injury in adults with a distal radius fracture. SAMPLE: Convenience sample of 60 adults with an isolated distal radius fracture. METHOD: Repeated measures of analysis of variance were used to test the relationship of gender, age, education, hand dominance, preinjury physical health, and treatment modality to physical function, role function, and meaning of illness/injury. The independent variable is time and the dependent variables are physical function, role function, and meaning of illness/injury. FINDINGS: Although improvement occurred with time, older adults had significantly lower physical functioning than younger adults while their wrist was immobilized, and middle-age adults had significantly lower role functioning compared to younger and older adults. Physical function was influenced by age, and role function was influenced by both age and education. CONCLUSION: The identified need for additional guidance and physical and emotional support with the standard treatment of distal radius fractures highlights the need for nursing care during the early recovery period.

The development of bacterial biofilms on indwelling urethral catheters.

The biofilm mode of growth has been implicated in the majority of human bacterial infections. In the urinary tract, notable biofilm-associated infections include prostatitis, chronic cystitis, struvite urolithiasis, and catheter-associated infections. Biofilms protect the causative organisms from host defences and antimicrobial therapy. Biofilm formation has traditionally been considered to result from adhesion and capsule formation by adherent microorganisms. Recent work has shown that a large number of genes are activated during this process, some of which have been associated with twitching motility, quorum sensing, and slow growth. In this paper, we review some of the recent work on biofilm biology and highlight its role in urinary tract infections, particularly those associated with urinary catheters.

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.

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.

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.

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.

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.