Detection of microbial biofilms inside the lumen of ureteral stents: two case reports

Abstract

Background: We report large biofilm structures that covered almost the entirety of the lumen and surface of double-J stents in two postrenal transplant patients, with no development of urinary tract infection. Biofilm bacteria of one patient were integrated by coccus in a net structure, whereas overlapping cells of bacilli were present in the other patient. To the best of our knowledge, this is the first time that high-quality images of the architecture of noncrystalline biofilms have been found inside double-J stents from long-term stenting in renal transplant recipients.

Case presentation: Two renal transplant recipients, a 34-year-old male and a 39-year-old female of Mexican-Mestizo origin, who underwent a first renal transplant and lost it due to allograft failure, had a second transplant. Two months after the surgical procedure, double-J stents were removed and analyzed using scanning electron microscopy (SEM). None of the patients had an antecedent of UTI, and none developed UTI after urinary device removal. There were no reports of injuries, encrustation, or discomfort caused by these devices.

Conclusion: The bacterial biofilm inside the J stent from long-term stenting in renal transplant recipients was mainly concentrated on unique bacteria. Biofilm structures from the outside and inside of stents do not have crystalline phases. Internal biofilms may represent a high number of bacteria in the double-J stent, in the absence of crystals.

Keywords: Biofilm; Case report; Double J stent; Renal transplant; Scanning electron microscopy (SEM).

Fig. 1

Timeline of interventions and outcomes

Fig. 2

Scanning electron microscopy (SEM) of the biofilm from the external surface of the J stent from male patient. a External surface of the J stent, 80×. b–d Biofilm formation on external surface of J stent. The bacterial cells are shown embedded on extracellular matrix as flat-layered structures. b 5000×, c 5000×, and d 10,000× magnification. No crystalline material was deposited in the bacterial biofilm. Arrows show the bacilli bacteria

Fig. 3

Scanning electron microscopy (SEM) of the biofilm from the external surface of the J stent from female patient. a–d External surface of the J stent. Heap-shaped, patchy bacterial colonies are shown. Most of the bacteria were embedded on the extracellular matrix. a 5000×, b 10,000×, c 12,000×, and d 12,000× magnification, respectively. Arrows show rod-shaped bacteria. No crystalline material was deposited in the bacterial biofilm

Fig. 4

Scanning electron microscopy (SEM) lumen of the J stent from male patient, colonized by coccus bacteria. a Luminal surface of a double-J stent cut longitudinally covered by the biofilm. b 500× magnification. c Aggregation of cells, 3000×. d Biofilm architecture, constituted by a net of bacterial cells connected by polysaccharides. No crystalline material was deposited in the bacterial biofilm

Fig. 5

Scanning electron microscopy (SEM) from the lumen of the stent from the female patient, colonized by bacillus bacteria. a Luminal surface of a double-J stent cut longitudinally covered by the biofilm. b Biofilm architecture, constituted by multi-layered plaques of bacterial cells, 1000× magnification. c Aggregation of bacterial cells, 3000×. d Rod-shaped cells, 10,000×. No crystalline material was deposited in the bacterial biofilm