Prospective Study
Copyright ©The Author(s) 2018. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jan 7, 2018; 24(1): 112-123
Published online Jan 7, 2018. doi: 10.3748/wjg.v24.i1.112
Characterization of biofilms in biliary stents and potential factors involved in occlusion
Chetana Vaishnavi, Jayanta Samanta, Rakesh Kochhar
Chetana Vaishnavi, Jayanta Samanta, Rakesh Kochhar, Department of Gastroenterology, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India
Author contributions: Vaishnavi C conceived the original idea and prepared the study design, provided administrative support, supervised the project and collected the data and finalized the manuscript; Kochhar R provided patients’ samples and their clinical details; Samanta J analyzed the data statistically with the help of the department of Biostatistics and wrote the draft manuscript; Kochhar R critically revised the draft manuscript; all authors have directly contributed to the study, reviewed and approved the final manuscript for submission.
Supported by Indian Council of Medical Research, New Delhi, India, No. 5/4/3-4/10-NCD-II.
Institutional review board statement: This study of organisms responsible for biofilm formation in biliary stents and molecular characterization (NKG/704). At this Institute (Postgraduate Institute of Medical Education and Research, Chandigarh), the Institute Ethics committee meeting held on 01-05-2010, the above documents were examined and discussed. After consideration, the committee has approved the project.
Clinical trial registration statement: We have registered our clinical trial with the Indian Council of Medical Research, New Delhi, India, and gave them annual reports of the progress of the project on study of organisms responsible for biofilm formation in biliary stents and their molecular characterization.
Informed consent statement: All study participants provided informed written consent prior to study enrollment.
Conflict-of-interest statement: The authors have no conflict of interest to declare.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Correspondence to: Chetana Vaishnavi, MNAMS, MSc, PhD, Professor, Department of Gastroenterology, Postgraduate Institute of Medical Education and Research, Sector-12, Chandigarh 160012, India.
Telephone: +91-172-2756609 Fax: +91-172-2744401
Received: October 12, 2017
Peer-review started: October 13, 2017
First decision: November 8, 2017
Revised: December 1, 2017
Accepted: December 12, 2017
Article in press: December 12, 2017
Published online: January 7, 2018

To quantify the components in biofilms and analyze the predisposing factors involved in occlusion of biliary stents.


In a prospective study conducted from April 2011 to March 2014 at a tertiary care hospital, all consecutive patients who required endoscopic biliary stent exchange/removal were included. Etiology of the biliary disease was diagnosed by imaging, cytology and on follow-up. Clinical details of patients with biliary stent retrieval were noted. All extracted stents were collected in sterile containers and immediately processed for quantification of biofilm proteins and polysaccharides. Molecular identification of commonly known and unknown bacteria was performed by polymerase chain reaction and density gradient gel electrophoresis methods.


Eighty one patients (41 males) with age range of 20-86 years were studied. The underlying causes for stent insertion were bile duct stones (n = 46; 56.8%) benign stricture (n = 29; 35.8%) and malignancy (n = 6; 7.4%) with cholangitis in 50 (61.7%) patients. The retrieved stent sizes were 7 Fr (n = 62; 76.5%) and 10 Fr (n = 19; 23.5%) with 65 days median insertion duration. Polybacterial consortia were detected in 90.1% of the stents. The most common bacteria identified by polymerase chain reaction alone and/or sequencing were Pseudomonas (n = 38), Citrobacter (n = 23), Klebsiella (n = 22), Staphylococcus (n = 20), Serratia (n = 16), Escherichia coli (n = 14), Streptococcus (n = 13), Enterococcus (n = 13), Aeromonas (n = 12), Proteus (n = 10) and Enterobacter (n = 9). Protein concentration according to gender (0.547 ± 0.242 mg/mL vs 0.458 ± 0.259 mg/mL; P = 0.115) as well as age > 60 years and < 60 years (0.468 ± 0.295 mg/mL vs 0.386 ± 0.238 mg/mL; P = 0.205) was non-significant. However, polysaccharide concentration was significant both according to gender (0.052 ± 0.021 mg/mL vs 0.049 ± 0.016 mg/mL; P < 0.0001) and age (0.051 ± 0.026 mg/mL vs 0.038 ± 0.016 mg/mL; P < 0.011). Protein concentration in the biofilm was significantly higher (0.555 ± 0.225 mg/mL vs 0.419 ± 0.276 mg/mL; P = 0.018) in patients with cholangitis, lower (0.356 ± 0.252 mg/mL vs 0.541 ± 0.238 mg/mL; P = 0.005) in the 10 Fr group than the 7 Fr group, and significantly higher (0.609 ± 0.240 mg/mL vs 0.476 ± 0.251 mg/mL; P = 0.060) in stents of ≥ 6 mo of indwelling time. However presence/absence of cholangitis, size of stent, indication of stent insertion and indwelling time did not affect the quantity of polysaccharide concentration.


Plastic stents retrieved from patients with biliary tract disease showed polymicrobial organisms with higher protein content among patients with cholangitis and those with smaller diameter stents. Longer indwelling duration had more biofilm formation.

Keywords: Biofilm constituents, Polybacterial profile, Predisposing factors, Underlying causes, Biliary stents

Core tip: This prospective study evaluated the components in biofilms of retrieved biliary stents and analyzed predisposing factors involved in the process. A majority of stents showed growth of polymicrobial consortia. Polymerase chain reaction and sequencing helped to detect several microorganisms in most of the stents. Presence of cholangitis, smaller diameter of stents and longer indwelling time of stents were associated with higher chance of biofilm formation. To prevent stent occlusion, longer diameter stents with an indwelling time of 3 to 6 mo should be used.