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Which indwelling urethral catheters resist encrustation by Proteus mirabilis biofilms?
N S Morris1, D J Stickler, C Winters
1School of Pure and Applied Biology, University of Wales Cardiff, UK.
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.
Insights
No current indwelling urethral catheters, even those with hydrogel or silver coatings, can resist blockage by mineralized Proteus mirabilis biofilms. Mineral deposits primarily form below the catheter eye-holes, leading to blockage.
Area of Science:
- Urology
- Biomaterials Science
- Microbiology
Background:
- Indwelling urethral catheters are prone to encrustation by mineralized biofilms, particularly those formed by Proteus mirabilis.
- This encrustation can lead to catheter blockage, patient discomfort, and potential complications.
Purpose of the Study:
- To evaluate the resistance of various commercially available indwelling urethral catheters to encrustation by mineralized Proteus mirabilis biofilms.
- To identify if catheter material or coatings (hydrogel, silver) offer protection against biofilm formation and encrustation.
Main Methods:
- A laboratory model simulating the catheterized bladder environment was used.
- Artificial urine inoculated with a clinical strain of P. mirabilis was circulated through different catheter types until blockage occurred.
- Atomic absorption spectrometry and scanning electron microscopy were employed to quantify mineral deposition and assess encrustation severity.
Main Results:
- Catheter blockage times varied, ranging from 21 hours for hydrogel/silver-coated latex to 56 hours for all-silicone catheters.
- Calcium and magnesium salt deposition was concentrated below the catheter eye-holes, with complete blockage occurring in the immediate vicinity.
- No significant resistance to encrustation was observed across the 18 tested catheter types.
Conclusions:
- None of the tested indwelling urethral catheter types demonstrated resistance to encrustation by P. mirabilis biofilms.
- Current catheter materials and coatings are insufficient to prevent mineralized biofilm formation and subsequent blockage.