J Med Microbiol 55 (2006), 489-494; DOI: 10.1099/jmm.0.46404-0
© 2006 Society for General Microbiology
ISSN 1473-5644
Modulation of crystalline Proteus mirabilis biofilm development on urinary catheters
David J. Stickler and
Sheridan D. Morgan
Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3TL, UK
Correspondence
David J. Stickler
stickler{at}cardiff.ac.uk
Received 7 November 2005
Accepted 10 January 2006
The crystalline biofilms formed by Proteus mirabilis can seriously complicate the care of patients undergoing long-term bladder catheterization. The generation of alkaline urine by the bacterial urease causes calcium and magnesium phosphates to precipitate from urine and accumulate in the catheter biofilm, blocking the flow of urine from the bladder. The pH at which these salts crystallize from a urine sample, the nucleation pH (pHn), can be elevated by diluting the urine and by increasing its citrate content. The aim of this study was to examine whether manipulation of pHn in these ways modulated the rate at which crystalline biofilm developed. Experiments in laboratory models of the catheterized bladder infected with P. mirabilis showed that when the bladder was supplied with a concentrated urine (pHn 6·7) at a low fluid output (720 ml per 24 h), catheters blocked at 1931 h. Diluting this urine 1 : 4 increased the pHn to 7·5 and models supplied with this urine at 2880 ml per 24 h took 110137 h to block. When models were supplied with urine containing citrate at 1·5 mg ml1 or above (pHn 8·39·1), the catheters drained freely for the full 7 day experimental period. Scanning electron microscopy revealed that the catheter biofilms that developed in urine with high pHn values were devoid of crystalline formations. These observations should encourage a clinical trial to examine the effect of increasing a patient's fluid intake with citrate-containing drinks on the encrustation and blockage of catheters.
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S. M. Jacobsen, D. J. Stickler, H. L. T. Mobley, and M. E. Shirtliff
Complicated Catheter-Associated Urinary Tract Infections Due to Escherichia coli and Proteus mirabilis
Clin. Microbiol. Rev.,
January 1, 2008;
21(1):
26 - 59.
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