Scanning Electron Microscopic Features of Extubated Monoka Stents

Purpose: The aim of this study was to examine the presence of surface and intraluminal biofilms and physical deposits on the extubated Monoka stents. Methods: A prospective interventional study was performed on consecutive patients who underwent Monoka stents placement for varied indications. The patient samples were retrieved either at 6 weeks or 3 months after the surgery based on the indication for stent use. None of the patients had any clinical evidence of postoperative infection. The intraluminal portions studied include the distal cut ends as well as the entire intraluminal surface. The analysis was performed using the standard protocols of scanning electron microscopy. The external and internal surfaces were compared against sterile stents which acted as controls. Results: A total of 12 stents were studied. Ten were consecutive patient samples and 2 were sterile stents. The external surfaces, cut ends as well as intraluminal surfaces of all the patient stents demonstrated evidence of biofilm formation and physical deposits. The most preferential site of the deposits was the ampullary portion of the stent head. The biofilms and deposits were more extensive in stents retained for 3 months as compared with 6 weeks. Intraluminal surfaces, all through showed clumps of physical deposits and bacterial biofilms with intervening skip areas. Conclusions: All surfaces of Monoka stents harbor physical deposits and biofilms. Lumen-less Monoka stents may prevent the lumens from acting as additional biofilm nidus.