Research Article: Molecular analysis of the endobronchial stent microbial biofilm reveals bacterial communities that associate with stent material and frequent fungal constituents

Date Published: May 29, 2019

Publisher: Public Library of Science

Author(s): John E. McGinniss, Ize Imai, Aurea Simon-Soro, Melanie C. Brown, Vincent R. Knecht, Laura Frye, Priyanka M. Ravindran, Marisol I. Dothard, Dylan A. Wadell, Michael B. Sohn, Hongzhe Li, Jason D. Christie, Joshua M. Diamond, Andrew R. Haas, Anthony R. Lanfranco, David M. DiBardino, Frederic D. Bushman, Ronald G. Collman, Vishnu Chaturvedi.


Endobronchial stents are increasingly used to treat airway complications in multiple conditions including lung transplantation but little is known about the biofilms that form on these devices. We applied deep sequencing to profile luminal biofilms of 46 endobronchial stents removed from 20 subjects primarily with lung transplantation-associated airway compromise. Microbial communities were analyzed by bacterial 16S rRNA and fungal ITS marker gene sequencing. Corynebacterium was the most common bacterial taxa across biofilm communities. Clustering analysis revealed three bacterial biofilm types: one low diversity and dominated by Corynebacterium; another was polymicrobial and characterized by Staphylococcus; and the third was polymicrobial and associated with Pseudomonas, Streptococcus, and Prevotella. Biofilm type was significantly correlated with stent material: covered metal with the Staphylococcus-type biofilm, silicone with the Corynebacterium-dominated biofilm, and uncovered metal with the polymicrobial biofilm. Subjects with sequential stents had frequent transitions between community types. Fungal analysis found Candida was most prevalent, Aspergillus was common and highly enriched in two of three stents associated with airway anastomotic dehiscence, and fungal taxa not typically considered pathogens were highly enriched in some stents. Thus, molecular analysis revealed a complex and dynamic endobronchial stent biofilm with three bacterial types that associate with stent material, a central role for Corynebacterium, and that both expected and unexpected fungi inhabit this unique niche. The current work provides a foundation for studies to investigate the relationship between stent biofilm composition and clinical outcomes, mechanisms of biofilm establishment, and strategies for improved stent technology and use in airway compromise.

Partial Text

Endobronchial stents are frequently implanted to treat airway complications, with lung transplantation being a particularly common setting for indications including dehiscence, stenosis, and malacia [1,2]. Stents are composed of various materials, including uncovered metal, covered metal, and silicone [3]. Despite their value in treating medical conditions, implanted biomaterials typically become colonized via biofilms. In other biomedical devices, biofilms have been linked to device failure, especially in immunosuppressed and critically ill hosts [4]. Bacterial biofilms may also contain potential pathogens, and organisms within biofilms are more resistant to host immunity and antimicrobials than free-floating planktonic forms [5]. Biofilms on central venous catheters, intra-cardiac devices, and orthopedic devices has been explored extensively [4,5]. Understanding the nature of biofilms that form on implanted devices is an essential first step in assessing biofilm impact on outcome and/or optimizing such devices. Remarkably little is known about biofilms on endobronchial stents, however.

Here we report the first molecular investigation of the airway stent biofilm. In this predominantly post-transplant cohort, we identified three bacterial community types—one low diversity and dominated by Corynebacterium, while the other two have greater diversity and are characterized by Staphylococcus or by a mixed population including Pseudomonas, Prevotella, and Streptococcus. Biofilm type correlated with stent material. When individuals had serial stents, the biofilm communities frequently shifted, suggesting that device-related, procedural and/or contemporaneous clinical factors, but not pre-transplant lung disease, influence biofilm formation. Fungal sequences were frequently detected, sometimes at high read counts.