Study on Concretions Developed around Urinary Catheters and Mechanisms of Renal Calculi Development

Abstract

Aims: To study the structure and composition of encrustation and concretions developed on urinary catheters to better understand their formation mechanism to be able to prevent them. Methods: The surface of catheters was studied by direct and scanning electron microscopy observation. In vitro formation of encrustations was performed in synthetic urine. Results: The surface of catheters was covered by a continuous layer of organic matter, on which a thin scale consisting of crystals of calcium oxalate monohydrate (COM), uric acid anhydrous or calcium phosphate developed. Encrustations observed on catheters generally exhibited the same composition as the previously developed renal calculi. In catheters collected from patients without previous episodes of renal calculi or with previous episodes of infected renal calculi in which infection was afterwards eradicated, on the first organic layer, in that case plate-like COM crystals forming a columnar layer were observed. In vitro experiments demonstrated that COM columnar structures were only formed when normocalciuric urine containing organic matter was used, and the presence of crystallization inhibitors, as phytate, notably delayed their formation. Conclusion: Calcium oxalate was the main crystalline phase developed on catheters inserted in patients, specially in the absence of urinary infection or urinary pH values <5.5 and high urinary uric acid levels. Thus, prophylaxis of encrustations may consist of preventive measures usually applied in cases of recurrent idiopathic calcium oxalate urolithiasis.

Assessment of Encrustations on Polyurethane Ureteral Stents

“…However, the presence of bacteria is not the only cause for the formation of mineral salts. 10,11 In the literature, there are conflicting reports concerning the sensitivity of urine or stent cultures and bacterial biofilm observation by SEM. 17,18 It is possible to estimate the bacterial biofilm with SEM with the same sensitivity as urine or the more sophisticated stent cultures.…”

“…10,17,19,20 Calcium oxalate solids in all three hydrated forms were identified on the stents as follows: COM in seven stents, COD in four, and COT in three. The principal crystalline component of the encrustation on the stents in which oxalate deposits were absent were struvite in one, apatite in four, and uric acid in six cases.…”

“…The extent of encrustation did not correlate with the age and sex of the patient or the duration of insertion. 10,12 In nine stone formers in whom it was possible to analyze their stones, they were found-except in one case-to consist of the same material as the corresponding stent encrustation. 10 Urine cultures were positive for Escherichia coli in two cases and for Candida albicans, Proteus mirabilis, and Enterococcus in one case each.…”

“…[5][6][7] Also, several reports are concerned with bacterial encrustation, 8 although the encrustation process occurs under sterile conditions as well. 9,10 The purpose of the present work was to identify the most common encrustation deposits encountered on indwelling ureteral stents of polyurethane, mainly in sterile urine. 6 The deposited materials were identified and characterized using instrumental methods including Fourier-transform infrared (FT?R) spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDX).…”

Eficácia in vivo do sumo de Kalanchoe gastonis-bonnieri no controle do biofilme bacteriano e cálculo dentário de cães

“…Além disso, outro mecanismo de ação da Kalanchoe gastonis-bonnieri que se pode supor, segundo Fairbrother e Heasman (2000) e Grases et al (2009), seria a presença de inibidores da cristalização prevenindo ou retardando a formação da fase mineral do cálculo dentário, de acordo com o mecanismo de formação de cálculo sugerido por Mandel (1995), Grases, Costa e Garci (1998), Grases et al (2001).…”