title: Does the valve regulated release of urine from the bladder decrease encrustation and blockage of indwelling catheters by crystalline proteus mirabilis biofilms?
abstract: OBJECTIVE
  We tested whether valve regulated, intermittent flow of urine from catheterized bladders decreases catheter encrustation.
  
  
  METHODS
  Laboratory models of the catheterized bladder were infected with Proteus mirabilis. Urine was allowed to drain continuously through the catheters or regulated by valves to drain intermittently at predetermined intervals. The time that catheters required to become blocked was recorded and encrustation was visualized by scanning electron microscopy.
  
  
  RESULTS
  When a manual valve was used to drain urine from the bladder at 2-hour intervals 4 times during the day, catheters required significantly longer to become blocked than those on continuous drainage (mean 62.6 vs 35.9 hours, p = 0.039). A similar 1.7-fold increase occurred when urine was drained at 4-hour intervals 3 times daily. Experiments with an automatic valve in which urine was released at 2 or 4-hour intervals through the day and night also showed a significant increase in mean time to blockage compared with continuous drainage (p = 0.001). Scanning electron microscopy confirmed that crystalline biofilm was less extensive on valve regulated catheters.
  
  
  CONCLUSIONS
  Valve regulated, intermittent flow of urine through catheters increases the time that catheters require to become blocked with crystalline biofilm. The most beneficial effect was recorded when urine was released from the bladder at 4-hour intervals throughout the day and night by an automatic valve.
authors.affiliation: Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3TL, Wales, United Kingdom. Sabbuba@cardiff.ac.uk
authors.forename: N A
authors.initials: NA
authors.lastname: Sabbuba
authors.forename: D J
authors.initials: DJ
authors.lastname: Stickler
authors.forename: M J
authors.initials: MJ
authors.lastname: Long
authors.forename: Z
authors.initials: Z
authors.lastname: Dong
authors.forename: T D
authors.initials: TD
authors.lastname: Short
authors.forename: R J C
authors.initials: RJ
authors.lastname: Feneley
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D002408:Catheters, Indwelling / Q000382:microbiology*; D004322:Drainage; D004866:Equipment Contamination; D011513:Proteus mirabilis; D001743:Urinary Bladder / Q000502:physiology*; D014546:Urinary Catheterization; D014556:Urine