title: A clinical assessment of the performance of a sensor to detect crystalline biofilm formation on indwelling bladder catheters.
abstract: OBJECTIVE
  To test the ability of a sensor developed to signal infection by the organisms that generate the crystalline biofilms that encrust catheters, to give an early warning that encrustation was occurring on patients' catheters, as the care of many patients undergoing long-term bladder catheterization is complicated by the encrustation and blockage of their catheters.
  
  
  METHODS
  Twenty patients were followed prospectively for the lifetime of one of their catheters. Sensors based on cellulose acetate/bromothymol blue were placed in the urine-collection bags, which were changed as usual at weekly intervals. The bacteriology was assessed and pH determined weekly on urine samples. Photographic records were made of the sensors twice weekly. On removal, each catheter was examined for encrustation and blockage.
  
  
  RESULTS
  Proteus mirabilis was not isolated from five patients and in these cases the sensor colour remained golden-yellow to brown. The catheters drained for the scheduled period and showed no signs of encrustation. By contrast, the sensors turned dark blue/black in the urine of all 15 patients infected with P. mirabilis. All these patients' catheters were encrusted and in 12 the catheters blocked. The mean interval between the sensor signalling and the catheter blocking was 12 days.
  
  
  CONCLUSIONS
  The cellulose acetate/bromothymol blue sensors placed in the urine collection bags are capable of signalling infection by P. mirabilis. They also signal the early stages of catheter encrustation and allow catheter replacement in ample time to avoid the clinical crises and emergency referrals caused by catheter blockage.
authors.affiliation: Cardiff School of Dentistry, Cardiff University, Cardiff, Wales, UK. stickler@cardiff.ac.uk
authors.forename: David J
authors.initials: DJ
authors.lastname: Stickler
authors.forename: Steven M
authors.initials: SM
authors.lastname: Jones
authors.forename: Gabriel O
authors.initials: GO
authors.lastname: Adusei
authors.forename: Mark G
authors.initials: MG
authors.lastname: Waters
authors.forename: Jenny
authors.initials: J
authors.lastname: Cloete
authors.forename: Sunil
authors.initials: S
authors.lastname: Mathur
authors.forename: Roger C L
authors.initials: RC
authors.lastname: Feneley
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D002408:Catheters, Indwelling / Q000009:adverse effects / Q000382:microbiology*; D003460:Crystallization; D004866:Equipment Contamination / Q000517:prevention & control*; D004867:Equipment Design; D006801:Humans; D008855:Microscopy, Electron, Scanning; D011446:Prospective Studies; D011511:Proteus / Q000502:physiology; D011512:Proteus Infections / Q000517:prevention & control*; D011513:Proteus mirabilis / Q000502:physiology; D014546:Urinary Catheterization / Q000295:instrumentation*; D014549:Urinary Incontinence / Q000628:therapy