title: Relationship between urease-producing bacteria, urinary pH and encrustation on indwelling urinary catheters.
abstract: In 11 patients with long-term indwelling catheters the amount of catheter encrustation and urinary pH were measured and the urine regularly cultured over a prolonged period of time (median of 7 periods of 3 weeks). The mean urinary pH was related to the persistent presence of urease-producing micro-organisms (P. mirabilis) and urinary pH governed the precipitation of catheter encrustation. The critical pH appeared to be around 6.8. In patients with a mean urinary pH below this level the encrustation was minute (less than or equal to 2.9 mg phosphate). In patients with a mean urinary pH above 6.8 it was considerable but with a marked interindividual variation (35.5-138.7 mg phosphate). The composition of the encrustation was also strongly pH-related, with a much higher proportion present as magnesium ammonium phosphate in patients with a mean urinary pH above 6.8. The persistent presence of urease producers was not associated with a high pH or a more pronounced precipitation of phosphate in all patients. The amount of encrustation thus appears to depend not only on the presence of urease-producing micro-organisms but also on individual factors such as urinary composition.
authors.affiliation: Department of Urology, Sahlgrenska Sjukhuset, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Hedelin
authors.forename: C G
authors.initials: CG
authors.lastname: Bratt
authors.forename: G
authors.initials: G
authors.lastname: Eckerdal
authors.forename: K
authors.initials: K
authors.lastname: Lincoln
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001419:Bacteria / Q000201:enzymology*; D002408:Catheters, Indwelling; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D011513:Proteus mirabilis / Q000201:enzymology / Q000302:isolation & purification; D013997:Time Factors; D014510:Urease / Q000096:biosynthesis*; D014546:Urinary Catheterization / Q000009:adverse effects*; D014556:Urine / Q000382:microbiology / Q000502:physiology*
chemical_list: D014510:Urease