Crystalline bacterial biofilm formation on urinary catheters by urease-producing urinary tract pathogens: a simple method of control

Abstract

The problem of catheter encrustation stems from infection by urease-producing bacteria. These organisms generate ammonia from urea, elevate the pH of urine and cause crystals of calcium and magnesium phosphates to form in the urine and the biofilm that develops on the catheter. In this study, a laboratory model was used to compare the ability of 12 urease-positive species of urinary tract pathogens to encrust and block catheters. Proteus mirabilis, Proteus vulgaris and Providencia rettgeri were able to raise the urinary pH above 8.3 and produce catheter-blocking crystalline biofilms within 40 h. Morganella morganii and Staphylococcus aureus elevated the pH of urine to 7.4 and 6.9, respectively, and caused some crystal deposition in the biofilms but did not block catheters in the 96 h experimental period. Isolates of Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter cloacae, Serratia marcescens, Pseudomonas aeruginosa and Providencia stuartii were only capable of raising the pH of urine to a maximum of 6.4 and failed to cause crystal deposition in the biofilm. The most effective way to prevent catheter encrustation was shown to be diluting urine and increasing its citrate concentration. This strategy raises the nucleation pH (pH n ) at which calcium and magnesium phosphates crystallize from urine. Increasing the fluid intake of a healthy volunteer with citrated drinks resulted in urine with a pH n of .8.0 in which catheter encrustation was inhibited. It is suggested that this dietary strategy will be an effective means of controlling catheter encrustation, whichever bacterial species is causing the problem.

Detection of Urer and Urec Among Proteus Mirabilis

“…A suspected bacterial isolates that showed swarming phenomenon was further identified depending on conventional methods according to MacFaddin (2000) and molecular technique using 16SrRNA gene by polymerase chain reaction (PCR) technique [8].…”

“…This multimeric nickel-metalloenzyme is encoded by urea-inducible urease gene cluster (ureDABCEFG) [8]. Urease operon transcription is positively activated by ureR a dimer of identical 293 amino acid polypeptides that bind urea resulting in the binding of protein avidly to both ureR and ureD promoters, then RNA polymerase is activated by ureR and thus will initiate transcription [9].…”

The encrustation and blockage of long-term indwelling bladder catheters: a way forward in prevention and control

“…1,2 All available catheter types are vulnerable to this problem and currently no effective methods are available for its prevention or control. [3][4][5] In many cases, the replacement catheters block repeatedly and the patients are classified as 'blockers'. 6 Up to 50% of the patients undergoing long-term catheterization will experience catheter encrustation and blockage.…”

“…15 Experimental study in laboratory models of the catheterized bladder demonstrated that species such as M. morganii, K. pneumoniae and P. aeruginosa failed to produce alkaline urine and generate appreciable encrustation on catheters. 5,16 The only species capable of producing alkaline urine and causing extensive encrustation were P. mirabilis, P. vulgaris and Providencia rettgeri. The latter two organisms are only found in about 5-10% of catheter biofilms.…”

Xanthogranulomatous pyelonephritis with nephrocutaneous fistula due to Providencia rettgeri infection

“…Proteus species and Escherichia coli are the organisms most commonly isolated in XGP (Korkes et al, 2008). Even though Providencia rettgeri has been isolated from nosocomial urinary tract infection (O'Hara et al, 2000) and was found to form crystalline bacterial biofilms on urinary catheters (Broomfield et al, 2009), it has not been reported in XGP cases. Herein, we report an unusual case of XGP with nephrocutaneous fistula due to Providencia rettgeri infection that was genetically confirmed by 16S rRNA gene sequencing in both renal tissue and culture from fistulous discharge.…”