Relationship between airway stents and airway microorganisms: a literature review

Abstract

Background and Objective

Airway stent placement is widely used for the management of airway stenosis; however, it can be associated with complications such as granulation, stent migration, and infection, all of which affect patient outcomes. Among these complications, infection is a major concern, yet the relationship between airway stents and microbial colonization remains insufficiently studied. This review aims to summarize the current evidence on the effects of airway stents on the airway microbiome and to discuss their potential clinical implications.

Methods

A literature search was conducted in PubMed for relevant studies published from database inception to December 31, 2025. Search terms included “airway stent”, “tracheal stent”, “bronchial stent”, “airway microbiome”, “biofilm”, and “respiratory infection”. Relevant studies were screened according to predefined criteria, and the available evidence was narratively synthesized.

Key Content and Findings

Available evidence suggests that airway stents can alter the airway microenvironment and facilitate microbial colonization, most commonly involving Pseudomonas aeruginosa (P. aeruginosa), Staphylococcus aureus (S. aureus), and Klebsiella pneumoniae (K. pneumoniae). Both metallic and silicone stents lead to similar microbial profiles, dominated by P. aeruginosa and S. aureus. Although microbial colonization frequently occurs after stent implantation, colonization does not necessarily reflect clinically significant infection, and microbiological findings should be interpreted in the clinical context. Most clinical studies report an increased risk of respiratory infection following airway stent placement. In certain specific clinical situations, such as patients with tracheoesophageal fistula, infection rates may decrease after stenting due to restoration of airway integrity. Conventional culture-based methods remain adequate for detecting common respiratory pathogens, while emerging techniques such as metagenomic next-generation sequencing (mNGS) enable broader characterization of airway microbial communities.

Conclusions

Airway stents appear to alter the airway’s microbial environment by promoting the growth of potentially pathogenic microorganisms. Different stent materials, including silicone stents and self-expanding metallic stents (SEMS), seem to affect the biofilm formation on the stents’ surface, which may influence microbial colonization. More studies with larger sample sizes, standardized methodologies, and advanced techniques like metagenomic sequencing are needed to further clarify the microbial changes and improve clinical management.

Introduction

Background

In recent years, airway stents have been widely used to treat airway stenosis caused by various factors. Airway stents effectively alleviate symptoms related to airway obstruction, such as dyspnea, shortness of breath, decreased activity endurance, and thus have become an important treatment option for airway stenosis (1,2).

Rationale and knowledge gap

However, airway stenting may be accompanied by complications like sputum retention, stent displacement, granulation, and infection (3-5). Stent-associated infections are closely related to the prognosis of patients (6), so attention should be paid to them. Since the airway is a channel that communicates with the outside world, many microorganisms survive in the airway for a long time, and the host immune system maintains a balance with microorganisms (7). In healthy populations, several key factors determine the lung microbiome: (I) the immigration of microbial species into the airway, such as microaspiration and mucosal transmission; (II) microbial species clearance from the airway such as cough, mucociliary clearance, innate and adaptive host defense; (III) relative reproductive rates of different microbial members (often referring to species or genera) within the community. This relative growth is finely regulated by local environmental gradients (e.g., pH, temperature, oxygen partial pressure) and complex microbe-microbe/host interactions (8). However, in severe lung diseases, this regulatory balance is disrupted. The compositional shift of the microbiota becomes predominantly driven by altered growth conditions in the diseased niche, which may include extreme changes in the aforementioned gradients (e.g., pH, oxygenation), nutritional conditions, and dysregulated host responses (e.g., excessive inflammation, epithelial damage). These changes may selectively favor the expansion of specific pathogens, leading to a loss of microbial diversity and ecosystem stability (9). Therefore, it is unclear whether the placement of the stent will change the growth environmental conditions of microorganisms in the airway, and whether this change is one of the causes of infection.

Objective

Therefore, this review summarizes the recent studies on the effects of airway stents on the microbial environment in the airway. We present this article in accordance with the Narrative Review reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-1-2649/rc).

Methods

A literature search was conducted in PubMed from database inception to December 31, 2025. The search strategy combined MeSH terms and free-text terms related to airway stents, airway microorganisms and infection. The main search terms included “airway stent”, “tracheal stent”, “bronchial stent”, “endobronchial stent”, “tracheobronchial stent”, “microbiome”, “microbiota”, “microbial colonization”, “biofilm”, and “respiratory infection”. Boolean operators (AND/OR) were used to combine terms appropriately. The search strategy summary is presented in Table 1.

Table 1. The search strategy summary.

Items	Specification
Date of search	Initial search: September 1, 2025; final update: February 15, 2026
Databases and other sources searched	PubMed. In addition, the reference lists of relevant articles were manually screened to identify potentially eligible studies
Search terms used	The search strategy combined MeSH terms and free-text terms related to airway stents and airway microorganisms/infection, including “airway stent”, “tracheal stent”, “bronchial stent”, “endobronchial stent”, “tracheobronchial stent”, “microbiome”, “microbiota”, “microbial colonization”, “biofilm”, and “respiratory infection”. Relevant MeSH terms included Stents, Microbiota, Biofilms, Respiratory Tract Infections, and Prosthesis-Related Infections. Boolean operators (AND/OR) were used to combine search terms (the detailed PubMed search strategy is provided in Table S1)
Timeframe	From database inception to December 31, 2025
Inclusion and exclusion criteria	Inclusion criteria: studies related to airway stent placement and reporting findings on microbial colonization, airway microbiota, biofilm formation, or respiratory infection after stent implantation; original clinical studies, observational studies and microbiological studies were considered
	Exclusion criteria: studies not directly related to airway stents or airway microbial outcomes; editorials, commentaries, conference abstracts, duplicate publications, and non-English articles
Selection process	The titles and abstracts of retrieved records were screened independently by X.C. and S.P. Full texts of potentially relevant articles were then reviewed independently for eligibility. Any disagreements regarding study selection were resolved through discussion and, when necessary, consultation with C.T.
Any additional considerations	Given the heterogeneity in study design, patient populations, stent types, microbiological methods, and reported outcomes, the evidence was synthesized narratively rather than quantitatively

The influence of the stent on the microbial environment in the airway

Studies have shown that the microbial environment in the respiratory tract of healthy non-smokers is different from that of chronic respiratory diseases such as chronic obstructive pulmonary disease (COPD) and cystic fibrosis. The upper respiratory tract includes the nasal cavity, paranasal sinus, pharynx, and larynx, mainly colonized by Staphylococcus, Haemophilus, and Streptococcus. Regarding the lower respiratory tract, composed of the trachea and lung, Prevotella, Veillonella, Haemophilus, and Neisseria are the main microbial communities that mainly come from the mouth (10,11). The lung microbiota can influence not only the susceptibility or severity of respiratory diseases but also the activity and treatment (12).

The invention and application of the Montgomery T-tube in 1956 (13) and the Dumon stent in 1987 (14) ushered in the era of airway stents. The placement of airway stents has become one of the most popular topics in interventional pulmonology. Tao et al. analyzed the pathogens in the airways of 100 patients with esophageal cancer complicated with esophagopharyngeal fistula before and after stenting and found that the overall infection rate of the patients decreased from 83.0% to 53.0%. A total of 79 pathogenic microorganisms were detected, among which Pseudomonas aeruginosa (P. aeruginosa), methicillin-resistant Staphylococcus aureus (S. aureus) (MRSA), and Pseudomonas pseudomallei were the main pathogens (15). Grosu et al. retrospectively analyzed 72 patients with malignant airway stenosis and found that stents were associated with an increased risk of infection [hazard ratio (HR), 3.76; 95% confidence interval (CI): 1.57–8.99; P=0.003], indicating that stent placement will increase the risk of respiratory infection in patients with malignant airway diseases, mainly P. aeruginosa, followed by Actinomyces, Hemolytic streptococcus, and individually detected Aspergillus, Legionella, S. aureus, Cytomegalovirus and Klebsiella pneumoniae (K. pneumoniae) (16). Noppen et al. prospectively studied 14 patients with central airway stenosis implanted with airway stents and found that 7 new patients had positive culture results after stent placement. Four potential pathogens were identified, including P. aeruginosa (n=4), S. aureus (n=3), Streptococcus pneumoniae (n=1), and K. pneumoniae (n=1) (17). While some studies have reported reduced infection rates in selected patients with pre-existing airway fistulas following stenting, this finding is likely related to restoration of airway integrity. In addition, the potential influence of concomitant antibiotic therapy cannot be excluded. It should also be noted that the available evidence is derived primarily from a single-center retrospective study, which limits the generalizability of these conclusions (15). Regardless of the type of primary disease, pathogens such as P. aeruginosa, S. aureus, and K. pneumoniae can be cultured when stent-associated infection occurs (15-17). Overall, current evidence suggests that airway stent placement is generally associated with increased microbial colonization of the airway and may be accompanied by a higher risk of respiratory infection, although the magnitude of this risk varies across clinical contexts.

Other studies have shown that rigid bronchoscopic treatments without stent placement, such as balloon dilation, cryoablation, and laser therapy, have little effect on airway microbes (18).

Nowadays, there are a variety of stent types and stent materials to choose from, and the most commonly used ones are metallic stents and silicone stents (1). Studies have shown that different types of stents have different types of biofilm on their surfaces (19), suggesting that stents made of different materials may have different impacts on the microbial environment in the airway.

Taken together, current evidence suggests that airway stents modify the airway microenvironment primarily through mechanical alteration of airway structure, impairment of mucociliary clearance, and promotion of biofilm formation, thereby facilitating microbial colonization.

Metallic stents

Metallic stents are divided into two categories according to whether they are coated: covered metallic stents and uncovered metallic stents. Although they are easy to operate, they are prone to complications such as granulation, coughing, hemoptysis, and perforation. They are suitable for short-term placement and are often used for malignant central airway stenosis (3). Notably, fully covered self-expandable metallic stents (SEMS) may also be used in selected patients with benign airway diseases. In some cases, the stents are generally intended for temporary placement and can be removed endoscopically if the implantation duration is limited. Clinical studies have shown that covered SEMS can be successfully removed in a substantial proportion of patients and may serve as a bridging or short-term therapeutic option for complex benign airway stenosis, although careful patient selection and close follow-up are required because of the risk of complications (20-22). Izhakian et al. retrospectively studied 57 lung transplant patients who had received SEMS placement during 2002–2018 and matched 57 patients without stent placement as a control group out of a total of 582 lung transplant patients. The airway microbial colonization in both groups was evaluated by bronchoalveolar lavage (BAL) culture. In the implanted group, there were mainly Pseudomonas (86% vs. 35%, P<0.001), Acinetobacter (21% vs. 7%, P=0.05), Klebsiella (21% vs. 5%, P=0.02), and Staphylococcus (11% vs. 0%, P=0.02) in the airway (23). Liu et al. reported that covered metallic stents were more prone to stent-associated infections than bare stents, which might be related to the effect of covered metallic stents on ciliary activity and mucous clearance function of the respiratory tract, as well as the placement time (24). However, no relevant reports have been found on whether there are differences in the effects of the two on airway microorganisms.

Silicone stent

Silicone stent, mainly the Dumon stent, is suitable for benign central airway stenosis. Although it needs to be implanted through rigid bronchoscopy under general anesthesia, it has high histocompatibility and can be placed for a long time (4). Importantly, before the widespread adoption of SEMS, silicone stents were the most commonly used airway stents for the palliation of malignant central airway obstruction and tracheoesophageal fistula. Even in the current era, silicone stents remain an important therapeutic option for selected malignant cases, particularly when temporary stenting or future stent removal is anticipated. This historical and current clinical positioning highlights the complementary roles of silicone and metallic stents in both benign and malignant airway diseases (25). Wang et al. retrospectively analyzed 34 cases of central airway stenosis undergoing silicone stent placement. The main diseases included airway invasion caused by lung or esophageal cancer, airway scar stenosis after tracheotomy or tuberculosis, and idiopathic subglottic tracheal stenosis. They found that 19 cases (55.88%) developed lower respiratory tract infections (88.46% pneumonia) within 100 days after stent implantation. There were mainly Gram-negative bacteria (P. aeruginosa, n=5, 69.23%), followed by Acinetobacter baumannii (n=3), Aspergillus species (n=3), MRSA (n=1), K. pneumoniae (n=1), and unknown pathogens (n=13) (26). Another common silicone stent is the Montgomery T-shaped tube. It is primarily indicated for laryngotracheal and upper tracheal stenosis of various etiologies, including post-intubation stenosis, post-tracheostomy stenosis, inflammatory disease-related stenosis, traumatic airway injury, and postoperative airway reconstruction (27,28). It functions both as a tracheostomy tube and as an intraluminal airway stent, allowing maintenance of airway patency while preserving phonation and physiological airflow (29). Although it provides effective airway support and relatively low mucosal irritation, retention of airway secretions and sputum crust formation may occur during long-term placement, which can contribute to subsequent airway infection if airway care is inadequate (6,30). Therefore, post-placement care of airway secretions is very important after T-tube placement. Fusconi et al. found Staphylococcus epidermidis and Candida albicans from the T-tube surface biofilm after placement for 15 and 90 days. They have shown that microbial colonization on the T-tube is a major cause of T-tube treatment failure (31).

After placement of metallic stents and silicone stents, the main pathogenic bacteria in the airways were similar in composition, with Gram-negative bacteria including P. aeruginosa, as well as Acinetobacter baumannii, and K. pneumoniae, and Gram-positive bacteria such as S. aureus. Nevertheless, this does not mean that different stent materials have no effect on airway microbial composition. Some studies have reported that compared with silicone stents, metallic stents are more prone to infection after operation (32). This may be because metallic stents are often used in patients with malignant airway stenosis, who have impaired immunity due to long-term radiotherapy and immunosuppressive therapy, leading to increased susceptibility to infection (6). However, the potential impact of stent material on airway microbial load cannot be excluded. At present, few studies have examined the effect of stent materials on the airway microbial environment, and the relationship between the stent material and microbial changes requires further investigation. Understanding this relationship is significant for the development of antibacterial materials and the improvement of stent design to reduce the incidence of stent-associated infections.

Overall, in both malignant and benign airway stenosis, airway stents may affect the original airway microbiological environment. In general, colonization of potentially pathogenic microorganisms occurs in the airways of most treated patients within 3±4 weeks after airway stenting (18). Wang et al. found that the relative abundance and composition of the microbiota may change at different stages after stent implantation (33). This may be due to the alteration of the airway structure by the airway stent, resulting in impaired ciliary motility, hemodynamic disorder, and stent-stimulated granulomatous growths blocking the airway and preventing sputum expulsion (34,35). Increased mucus production promotes microbial colonization, and after microbial colonization, it will lead to increased release of microbial immune regulation products, such as short-chain fatty acids (SCFAs), stimulating host immune response. In addition, an imbalance of T helper type 1 (Th1) and T helper type 2 (Th2) cell, a T helper type 17 (Th17) response, and secretion of pro-inflammatory cytokines lead to neutrophil activation, which in turn triggers inflammation, increased regulatory T-cell responses, and impaired immune surveillance. These changes ultimately lead to increased bacterial loads (36), thereby promoting secondary infections. Therefore, changes in the microbial environment in the airway will play an important role in the occurrence of infection after stent placement. In addition, airway microbial colonization may be related to restenosis. One study found that the presence of granulation after stent placement altered the composition of the airway microbial community compared to that before stent placement, as evidenced by a significant increase in the abundance of the airway microbiota when granulation tissue proliferated after stent implantation (33). In addition, Nouraei et al. found that colonization by S. aureus and P. aeruginosa was significantly associated with and a risk factor for granulomatous proliferation after stent placement (37).

Main existing problems and prospects

Many previous studies have focused primarily on infection occurring after stent placement. For example, Zhang et al. (38) and Agrafiotis et al. (6) both investigated the pathogens isolated from the airways of infected patients following stent implantation, with S. aureus and P. aeruginosa identified as the predominant organisms. Other pathogens, including C. albicans, Proteus mirabilis, and Streptococcus species, have also been isolated. Due to the lack of studies on the microbial environment in the airway without stent-associated infection, comparative analyses remain difficult, and it is still unclear whether stents alter the airway microbial environment. Moreover, the sample sizes in these studies were small, and the sample types and detection methods were heterogeneous, which may not accurately reflect the overall airway microbial environment. In addition, although many studies identified similar types of pathogens, their quantitative data were not reported consistently, and incidence rates varied. Therefore, larger sample sizes, standardized standards, and more accurate detection methods are needed to assess the airway microbial environment.

Detection accuracy

Most of these studies have taken sputum, protected specimen brush (PSB), and BAL for culture, the most common clinical test methods, to obtain results that reflect the microbial environment in the airway. However, because culture is only suitable for common pathogenic bacteria, it is not the best choice for rare and harsh microorganisms, and it takes a long time, especially in the case of acid-fast and fungal cultures. In recent years, a new detection method has emerged, metagenomic next-generation sequencing (mNGS), also known as high-throughput or large-scale parallel sequencing, which is a technique that directly uses thousands to billions of DNA fragments in a specimen to independently sequence them simultaneously. It can extract all nucleic acid results in samples and sequence them to obtain the sequences of hosts and microorganisms, and provide pathogen-related information through specific biological information analysis software (39). Qin et al. subjected both BAL and PSB test specimens to mNGS and pathogenicity culture and found that in the mNGS group, there was no statistically significant difference between the two specimens in terms of the results and the detection rate, while the detection rate of the mNGS group was higher than that of the culture group. In addition to the common pathogens such as P. aeruginosa, Stenotrophomonas maltophilia, C. albicans, and Candida tropicalis, the mNGS also detected Corynebacterium striatum and Human herpesvirus type 4, which were not found in the culture group (40). Compared with culture, mNGS can obtain more accurate and comprehensive information, overcoming the limitations of culture, including its time-consuming nature, narrow pathogen spectrum and low positive rate. It has been a popular detection method in recent years, but it also has disadvantages, which are more expensive and not widely used in clinical applications.

Specimen diversity

According to previous studies and clinical experience, common specimens are sputum, PSB, and BAL. In addition to the specimens mentioned above, biofilms have also been gradually discovered. In the human body, stents, central venous catheters, cardiac devices, and orthopedic devices are foreign bodies, and biofilms are easily formed on their surfaces (41). Understanding the nature of the biofilm on the surface of the implanted device allows the evaluation of the therapeutic outcome of the device, which can lead to the optimization of such devices. However, there are few studies on biofilms on endobronchial stents. In this study, which primarily involved post-lung transplant patients, molecular analysis was performed on the biofilms of 46 airway stents. Stent biofilms may also contain potential pathogens, and the results showed that the biofilm composition was significantly associated with stent material: the biofilm on the surface of the covered metallic stents is mainly Staphylococcus, while the silicone stent is mainly Corynebacterium-dominated biofilm. In contrast, the biofilm on the surface of the uncovered metallic stent exhibited a polymicrobial composition, including genera such as Pseudomonas, Streptococcus, and Prevotella. Compared to free-floating microorganisms, organisms within biofilms are more resistant to host immunity and antimicrobial drugs because they have fixed sites to grow and multiply (19). Therefore, studying the microorganisms in biofilms on the surface of airway stents can provide more accurate pathogenetic information for infections that have already occurred so that effective treatment can be taken. In addition, the stent can also be improved according to the biofilm formation conditions. Due to the principle of targeted sampling, patients with airway stenosis generally select the main stenosis site for sampling (42). Dickson et al. conducted PSB and bilateral BAL on seven different parts of eight healthy volunteers, including the trachea and the left and right main bronchus, and analyzed the microbial environment in the lung by metagenomic sequencing. They found that the microbial composition of the trachea was most similar to that of the oral cavity compared with other parts, likely due to oral-to-pulmonary bacterial migration. This finding indicates that sampling from gravity-dependent proximal tracheobronchial surfaces, such as bronchial bifurcations, should be avoided during PSB to reduce contamination (43).

New types of stents

According to the characteristics of the airway microbial environment, an increasing number of novel stents have been designed to reduce stent-associated infection rates. Dong et al. developed a microinjection-molded biopolymer airway stent with antibacterial and anti-proliferative properties. The hydrophilic surface of this airway stent inhibits mucus blockage, and its silver nanoparticles and cisplatin loading provide antibacterial and anti-proliferative effects. This is a biodegradable airway stent that reduces the number of secondary resections and solves common problems associated with mucus blockage, bacterial infection, and granulomatous hyperplasia (44). Similarly, a recent study evaluated silver-coated silicone stents in both in vitro and clinical settings. The silver coating significantly reduced the adhesion and viability of common pathogenic bacteria, including P. aeruginosa and S. aureus, with bacterial mortality reaching 88–96% for P. aeruginosa, indicating strong antibacterial activity and potential for preventing stent-associated infections (45). The nano-silver co-cisplatin-eluting electrostatically spun fiber-coated stent developed by Li et al. operates on a similar principle. They prepared nano-silver co-cisplatin-eluted fiber-coated airway stents by electrostatic spinning technology, which have better physical and chemical stability and could significantly inhibit the growth of common pathogens such as S. aureus, P. aeruginosa, and C. albicans, and therefore reduce microbial colonization after airway stent placement (46). Liu et al. designed and fabricated a new reticulated bioabsorbable stent with polycaprolactone (PCL) as the skeleton. PCL is a semi-crystalline polymer with a low melting point (59–64 °C), and it shows good flexibility at room temperature and 37 °C, which is also non-toxic and compatible with tissues, so it can eventually be absorbed by the body. The new PCL stent demonstrated good safety and biocompatibility in a rabbit trachea model (47). Li et al. developed airway stents coated with polylactic acid (PLA) and silver nanoparticles (AgNPs) fiber membrane, showing potential clinical utility for patients with tracheal stenosis. According to animal experiments, the PLA/AgNPs membrane suppressed the activity of S. aureus and P. aeruginosa. The stent reduced bacterial overgrowth, alleviated tracheal inflammation, and suppressed tracheal granulation tissue proliferation (46). Zhao et al. developed airway stents composed of vancomycin (VA)-loaded PCL composite nanofiber films (PVNF) through electrospinning. These stents possess a network structure and hydrophobicity, capable of sustained VA release. These stents exhibited excellent antibacterial activity against MRSA and S. pneumoniae. In addition, they also reduced granulation tissue thickness and collagen density by inhibiting the expression of inflammatory factors such as tumor necrosis factor-alpha (TNF-α), interleukin-1 (IL-1), and interleukin-6 (IL-6) (48). From the current research, the new stents are safe and effective, have high histocompatibility, and have a promising application in the treatment of airway stenosis, but most of them are in the experimental stage, and there are few related clinical studies or randomized controlled studies with large samples. The ideal stent now being pursued should be safe and convenient in both placement and removal, which needs to be further proved by a large number of basic and clinical trials.

Conclusions

In summary, airway stent placement profoundly influences the airway microbial ecosystem and contributes to the development of stent-associated infections. Airway stenting alters airway structure and impairs mucociliary clearance, resulting in ciliary dysfunction, sputum retention, and disruption of microbial homeostasis, which promotes colonization of the airway by pathogenic microorganisms and increases the risk of infection. Common pathogens include P. aeruginosa, S. aureus, and C. albicans. These microbial alterations may represent a key mechanistic link between stent implantation and subsequent infectious complications.

Although current studies suggest an association between airway stenting and microbial colonization, the causal relationship between stent implantation, microbiome alteration, and clinically significant infection remains incompletely understood. Current studies focus on the post-implantation lower airway microbiome, while longitudinal comparative studies evaluating microbial changes before and after stent placement are lacking. The microbial environment without infection after stent placement in the absence of overt infection is often overlooked. In addition, comparative analyses of other factors, such as different materials of stents and different primary diseases, are also rare. Current evidence is further constrained by predominantly retrospective study designs and limited sample sizes.

From a clinical perspective, a better understanding of airway microbiome changes following stent implantation may facilitate early identification of high-risk patients, optimization of stent selection, and development of targeted preventive strategies, including surveillance protocols and individualized antimicrobial approaches. With the emergence and popularization of new detection technologies like mNGS, future large-scale prospective studies using standardized methodologies are expected to provide more scientific methods to guide the prevention and treatment of clinical airway stent-associated infections.

Supplementary

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Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.