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

John E Mcginniss,Frederic D Bushman,Dylan A Wadell,Ronald G Collman,Hongzhe Li,Anthony R Lanfranco,David M Dibardino,Aurea Simon-Soro,Joshua M Diamond,Ize Imai,Andrew R Haas,Jason D Christie,Vincent R Knecht,Michael B Sohn,Marisol I Dothard,Laura Frye,Priyanka M Ravindran,Melanie C Brown

doi:10.1371/journal.pone.0217306

Abstract

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.

Highlights

Endobronchial stents are frequently implanted to treat airway complications, with lung transplantation being a common setting for indications including dehiscence, stenosis, and malacia [1,2]
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
One previous study identified Corynebacterium in airway cultures from 4.6% of patients after lung transplantation, and within this population the presence of airway stents was associated with Corynebacterium persistence [33]

Summary

Introduction

Endobronchial stents are frequently implanted to treat airway complications, with lung transplantation being a 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. Bacterial biofilms may contain potential pathogens, and organisms within biofilms are more resistant to host immunity and antimicrobials than free-floating planktonic forms [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. Little is known about biofilms on endobronchial stents,

Objectives

Methods

Results

Conclusion