Airborne Pathogens Research Articles

P-249. Diverse populations of viable pathogenic moulds and Candida, including C. auris, are commonly recovered from air samples at two tertiary care hospitals

Abstract Background Airborne fungi are important nosocomial pathogens. However, there are scant data on populations of viable fungi in air from hospital environments.Table 1.Hospitals and units included in air sampling Methods We cultured air samples at least once/month beginning in May 2023 at 2 hospitals separated by 1.5 miles, 1 of which had new building construction [Table 1]. Air was collected with SASS 3100 (36,000 L/2 hrs onto dry filters) and SAS Super 100 (1,000 L directly onto MYE plates) samplers, at the following sites: Outside, lobby, nurse stations (NS) and rooms on units housing immunosuppressed hosts (protected (HEPA filter, positive pressure) and unprotected rooms). Processed filters (sonicated, un-sonicated) and plates were incubated at 30°C, and fungi identified by morphology and ITS sequencing.Table 2.Aspergillus positive air cultures at two hospitalsData from 2 hospitals are combined and presented as % of air samples with a given result. Results There was a hierarchy in air culture positivity for pathogenic moulds, which was similar at the 2 hospitals: outdoor cultures > lobbies > NS > unprotected rooms > protected rooms. The predominant fungus was Aspergillus fumigatus (68% and 6% of outdoor and protected room samples positive, respectively), followed by other Aspergillus spp [Table 2]. Other common moulds were Alternaria (48% outside +), Cladosporium (35% outside +), Fusarium (24% outside +) and Mucorales (17% outside +, including Rhizopus, Syncephalastrum racemosum and Mucor) [Table 3]. Candida was cultured at similar frequencies outside and inside hospitals ((overall + (range): 7% (3%-13%)); in rank order, spp. were C. glabrata (n=8), C. krusei (6), C. albicans (5), C. tropicalis (4), C. parapsilosis (3), C. auris (1). C. auris was recovered from a unit that was not known to house an infected pt.Table 3.Non-Aspergillus positive air cultures at two hospitalsData from 2 hospitals are combined and presented as % of air samples with a given result. Conclusion Potentially pathogenic fungi were commonly cultured from air samples inside and outside 2 hospitals in Pittsburgh, including within rooms housing immunosuppressed pts. Burdens were lower within hospitals than immediately outside. Fungi included moulds like Aspergillus spp., which are well-recognized airborne pathogens, and, surprisingly, Candida spp., which are not typically considered as such. Among the latter was C. auris, which was temporo-spatially distant from pts known to be infected at the hospitals. We are currently studying potential links between fungi recovered during surveillance and invasive fungal infections, including by whole genome sequencing. Disclosures Cornelius J. Clancy, MD, Cidara: Grant/Research Support|Gilead: Honoraria|Merck: Grant/Research Support|Scynexis: Advisor/Consultant|Shionogi: Advisor/Consultant|Venatorx: Advisor/Consultant Alexander Sundermann, DrPH, CIC, FAPIC, OpGen: Honoraria Graham M. Snyder, MD, SM, Infectious Diseases Connect: Advisor/Consultant

Parametric Analysis of the Factors Impacting the Spatial Distribution of Particles in a Bus Environment

This study presents a parametric analysis of the factors impacting particle distribution within a bus environment using computational fluid dynamics (CFD) simulations, with a primary focus on the relative concentration (RC) of particles. The Novel Relative Concentration (RC) metric, which measures the deviation from a return concentration, was used to assess the effects of ventilation rates, the number and spatial arrangement of particle emitters, and thermal conditions. Our investigation reveals that increasing air changes per hour (ACHs) from 5.74 h⁻1 to 28.66 h⁻1 reduces the overall particle concentration by approximately 45%, but localized high concentration zones persist, with maximum RC values observed at 1.57. Scenarios with evenly distributed emitters achieved near-uniform particle distribution, with RC values averaging around 0.95, while clustered emitters resulted in localized high concentrations, with RC values exceeding 2.0. Thermal conditions were found to have a minimal effect on RC, with average values of 1.664 for cooling and 1.588 for heating, showing only a 4.68% difference. The RC metric provided clear insights into the non-uniformity of particle distribution, highlighting areas prone to higher concentrations, with some zones reaching RC values of 2.5, indicating concentrations 2.5 times higher than the well-mixed average. These findings underscore the importance of optimizing ventilation systems for both overall air exchange and uniform air distribution, offering practical implications for improving air quality and reducing the risk of airborne pathogen transmission in public transportation systems. Future research should explore real-time ventilation adjustments based on passenger load, the effects of different particle types, and the development of models incorporating human behavior and movement patterns.

Healthier Indoor Environments for Vulnerable Occupants: Analysis of Light, Air Quality, and Airborne Disease Risk

This study evaluates indoor environmental quality (IEQ) in childcare facilities, focusing on air quality and lighting—key factors affecting children’s health and development. The analysis examines a nursery in Seville, Spain, where continuous monitoring revealed challenges in maintaining suitable indoor conditions. Carbon dioxide (CO2) levels often surpassed Spanish standards (770 ppm) and stricter thresholds (550 ppm) for sensitive groups, peaking at nearly 1900 ppm. These concentrations are linked to possible cognitive impairments and increased airborne pathogen risks, with Attack Rates (ARs) exceeding 70%. Passive ventilation strategies, such as window openings, proved insufficient, emphasizing the need for Controlled Mechanical Ventilation (CMV) systems to ensure consistent air renewal while maintaining thermal comfort. Lighting assessments identified insufficient circadian stimulus during key periods. Excessive lighting during nap times disrupted rest, while morning daylight levels failed to provide adequate circadian stimulation. These findings stress the importance of integrating solar protection and dynamic daylight and electric lighting systems to align with children’s biological rhythms. This research highlights the urgent need for comprehensive IEQ strategies in childcare settings, combining advanced ventilation, hygrothermal management, and circadian-friendly lighting to create safer and healthier environments for young children.

The oxygen level in air directs airway epithelial cell differentiation by controlling mitochondrial citrate export.

Oxygen controls most metazoan metabolism, yet in mammals, tissue O2 levels vary widely. While extensive research has explored cellular responses to hypoxia, understanding how cells respond to physiologically high O2 levels remains uncertain. To address this problem, we investigated respiratory epithelia as their contact with air exposes them to some of the highest O2 levels in the body. We asked how the O2 level in air controls differentiation of airway basal stem cells into the ciliated epithelial cells essential for clearing airborne pathogens from the lung. Through a metabolomics screen and 13C tracing on primary cultures of human airway basal cells, we found that the O2 level in air directs ciliated cell differentiation by increasing mitochondrial citrate export. Unexpectedly, disrupting mitochondrial citrate export elicited hypoxia transcriptional responses independently of HIF1α stabilization and at O2 levels that would be hyperoxic for most tissues. These findings identify mitochondrial citrate export as a cellular mechanism for responding to physiologically high O2 levels.

Open-set deep learning-enabled single-cell Raman spectroscopy for rapid identification of airborne pathogens in real-world environments.

Pathogenic bioaerosols are critical for outbreaks of airborne disease; however, rapidly and accurately identifying pathogens directly from complex air environments remains highly challenging. We present an advanced method that combines open-set deep learning (OSDL) with single-cell Raman spectroscopy to identify pathogens in real-world air containing diverse unknown indigenous bacteria that cannot be fully included in training sets. To test and further enhance identification, we constructed the Raman datasets of aerosolized bacteria. Through optimizing OSDL algorithms and training strategies, Raman-OSDL achieves 93% accuracy for five target airborne pathogens, 84% accuracy for untrained air bacteria, and 36% reduction in false positive rates compared to conventional close-set algorithms. It offers a high detection sensitivity down to 1:1000. When applied to real air containing >4600 bacterial species, our method accurately identifies single or multiple pathogens simultaneously within an hour. This single-cell tool advances rapidly surveilling pathogens in complex environments to prevent infection transmission.

Detection of airborne Coccidioides spores using lightweight portable air samplers affixed to uncrewed aircraft systems in California's Central Valley.

UAS-based air sampling for bioaerosols, including pathogenic Coccidioides spp., opens new possibilities for characterizing the aerosolization and transport of fungal spores and other airborne pathogens.

Coxiellosis in Dogs-A Hitherto Masked Zoonosis in India: An Insight From Seromolecular Investigation and Risk Factor Analysis.

Coxiellaburnetii is an airborne bacterial zoonotic pathogen that causes Q fever/coxiellosis in humans and animals. Although dogs are suspected of transmitting Q fever to humans in past outbreaks, the prevalence of C. burnetii in the Indian dog population and risk factors for infection remain unknown. In this study, 452 dogs from pet clinics in three Indian states were screened for coxiellosis using molecular (Trans-PCR, Com 1-PCR) and serological (IFAT) tests. C. burnetii DNA was detected in 0.44% of blood samples using Trans-PCR, and pathogen-specific antibodies were found in 4.20% of sera using IFAT. Contact with stray dogs and ownership by farmers were identified as risk factors for canine coxiellosis. This study appears to be the first systematic assessment of coxiellosis and associated risk factors among dogs in India. A large-scale assessment of canine coxiellosis and its risk factors is warranted among pets and high-risk occupational groups in India.

Microdroplet Resuspension Off Surfaces.

Understanding the resuspension of droplets from surfaces into air is important for elucidating a range of processes such as disease transmission of airborne pathogens and determining environmental contamination and the effectiveness of cleaning procedures. The resuspension condition is defined as the escape velocity of a droplet from a surface. This study investigated the dynamics of microliter-sized droplet resuspension off surfaces utilizing a novel free-fall device. We studied surfaces with three different wettabilities, three droplet volumes, and substrate velocities ranging from 0 to 3.5 m/s for deionized water and viscous droplets representing a prototype saliva substitute. Experimental results provide quantitative results for the increased propensity for drop resuspension for more hydrophobic surfaces, larger droplet volume, and higher velocity. By using high-speed imaging, we segment the resuspension process into four stages: initial equilibrium, deformation, elongation, and breakage. Experimental results are generalized as a machine-learning-derived decision surface, which predicts resuspension by defining a 2D decision boundary in our 3D parameter space. We present a simple physical model, corroborated by computational fluid dynamics simulations, for the dynamics of resuspension that explains the process and is in good agreement with the experiments.

Rapid In-Field Detection of Airborne Pathogens Using Loop-Mediated Isothermal Amplification (LAMP).

Multiple human and plant pathogens are dispersed and transmitted as bioaerosols (e.g., Mycobacterium tuberculosis, SARS-CoV-2, Legionella pneumophila, Aspergillus fumigatus, Phytophthora spp., and Fusarium graminearum). Rapid, on-site methods to detect airborne pathogens would greatly enhance our ability to monitor exposure and trigger early mitigation measures across different settings. Analysis of air samples for microorganisms in a regulatory context is often based on culture-based methods, which are slow, lack specificity, and are not suitable for detecting viruses. Molecular methods (based on nucleic acids) could overcome these challenges. For example, loop-mediated isothermal amplification (LAMP) is rapid, sensitive, specific, and may detect microbial pathogens from air samples in under 60 min. However, the low biomass in air samples makes recovering sufficient nucleic acids for detection challenging. To overcome this, we present a simple method for concentrating bioaerosols collected through liquid impingement (one of the most common methods for bioaerosol collection). This method paired with LAMP (or other molecular approaches) offers simple, rapid, and sensitive detection of pathogens. We validated this method using three airborne pathogens (Mycobacterium tuberculosis, Legionella pneumophila, and Aspergillus fumigatus), and we were able to detect fewer than five cells in a 15 mL liquid impinger air sample in under 60 min. This simple method offers rapid pathogen detection without the use of specialist equipment, and it can be used across healthcare, education, environmental monitoring, and military settings.

Assessment of bioaerosol composition and public health implications in high-traffic urban areas of Southwest, Nigeria.

Bioaerosols, a significant yet underexplored component of atmospheric particulate matter, pose substantial public health risks, particularly in regions with poor air quality. This study investigates the composition of bioaerosols in public spaces, specifically two interstate motor parks and two marketplaces in Osun State, Nigeria, over six months. Air samples were collected, and bacterial and fungal species were identified, focusing on pathogenic organisms. The results revealed the presence of well-known pathogens, including Staphylococcus aureus, Escherichia coli, Klebsiella sp., Pseudomonas aeruginosa, Aspergillus sp., and Fusarium sp., which are associated with respiratory and gastrointestinal infections, as well as antimicrobial resistance. Site-specific differences in microbial diversity were observed, with higher bacterial diversity in motor parks and greater fungal occurrence in marketplaces influenced by environmental factors such as waste management. The findings highlight the urgent need for microbial air quality monitoring in public spaces, alongside improved sanitation practices. This study provides critical insights into the public health risks posed by bioaerosols and calls for local and global interventions to mitigate the impact of airborne pathogens in urban environments.

Wavelength-specific inactivation mechanisms and efficacies of germicidal UVC for airborne human coronavirus

Ultraviolet germicidal irradiation (UVGI) technology can inhibit the environmental transmission of airborne pathogens, but the dose-response behavior of airborne human coronavirus and wavelength-specific inactivation mechanisms are not well understood. This study investigated three competitive UVC sources for their inactivation efficacy and mechanisms against human coronavirus OC43 (HCoV-OC43). Results showed the following order of inactivation efficacy: 222-nm KrCl excimer lamp > 263-nm UV-LEDs > 254-nm low-pressure mercury lamp. The 222-nm KrCl excimer lamp achieved a 5-log inactivation of aerosolized HCoV-OC43 with a dose of less than 1 mJ/cm², while the 263-nm UV-LEDs had the highest genome damage rate constant at 7.08 ± 0.85 mJ/cm². Although 222-nm Far-UVC caused less genome damage, it affected viral proteins more significantly, specifically the nucleocapsid (N) and spike (S) proteins, which lead to compromising capsid integrity and binding ability to host cells. Capsid integrity RT-qPCR and binding assay RT-qPCR used in this study could better monitor infectivity of airborne coronavirus than standard RT-qPCR. Additionally, significant lipid oxidation of HCoV-OC43 was observed under 222-nm irradiation, potentially impacting overall inactivation efficacy. This study provides detailed evidence on the effects of different UVC wavelengths on airborne HCoV-OC43, contributing to the optimization of UVC irradiation for indoor bioaerosol disinfection.

Decoding lung complexity: single-cell sequencing in lung diseases, regeneration, and drug discovery

The lung is constantly exposed to the external environment, making it highly susceptible to infections and injuries caused by airborne pollutants and pathogens. Understanding the cellular players and molecular mechanisms underlying post-injury lung repair is essential for elucidating the repair processes following injury. Single-Cell Sequencing (sc-seq) offers unprecedented single-cell resolution, enabling researchers to dissect the complex biological profiles that drive diverse lung pathologies and to uncover the signaling pathways crucial for lung regeneration. This review will explore the latest findings in lung diseases and regeneration revealed by sc-seq. Additionally, we will highlight how continuous advancements in sc-seq technology are paving the way for the development of novel drugs aimed at targeting pathways involved in lung regeneration and treating lung diseases. By offering single-cell resolution, recent advancements in sc-seq have enabled researchers to dissect multiple layers of biological profiles underlying diverse lung pathogenesis and uncover signaling pathways critical for lung regeneration. In this review, we will discuss recent sc-seq findings in lung diseases and regeneration. Continuous advancements in sc-seq technology hold great promise for facilitating the development of novel drugs targeting lung regeneration pathways and lung diseases. These repair processes are mediated by resident epithelial stem cells and their niche cells.

The dynamics and assembly patterns of airborne pathogen communities in the municipal food waste treatment system and its risk implications

While municipal solid waste (MSW) provides an ideal habitat for pathogen propagation, the dynamics and assembly of airborne pathogen communities in these environments remain largely unknown. Here, we combined amplicon and metagenomics with spatiotemporal sampling to study inhalable particulate matter-carried potential pathogenic bacteria at full-scale food waste treatment plants (FWTPs), alongside comparisons to urban air in the area. The results showed that pathogenic bacteria constituted a notable portion (64.5 % ± 20.6 %, n = 75) of the total bacterial communities in FWTPs-impacted air, with species and relative abundance 2–4 times higher than that of urban air, and contributed over 50 % of pathogens to the outdoor air. Airborne pathogen community structures were highly shaped by sampling sites (i.e. treatment units), but conserved across seasons (summer vs. winter) and particle sizes (PM2.5vs. PM10). Notably, Acinetobacter johnsonii-dominated pathogens (i.e. biofilm-related species) presented high levels of aerosolization and consistently occupied the upper-representative niches in all neutral models, highlighting their persistent exposure risk. Furthermore, pathogen community assembly was strongly driven by stochastic processes (58.8 %–96.8 %), while environmental variables explained only limited variations (3.4 %–28.7 %). In particular, the relative importance of stochastic processes clearly increased along an outdoor-to-indoor gradient (84.9 %–96.5 % vs. 71.3 %–76 %), which might be related to indoor anthropogenic activities that weaken microbial network stability and environmental filtering effects. This work enhances our knowledge of the dynamic behaviors and risk of airborne pathogen communities in MSW disposal and underscores the role of FWTPs in disseminating airborne pathogens.

Human CFTR deficient iPSC-macrophages reveal impaired functional and transcriptomic response upon Pseudomonas aeruginosa infection.

Cystic fibrosis (CF) is a hereditary autosomal recessive disease driven by deleterious variants of the CFTR gene, leading, among other symptoms, to increased lung infection susceptibility. Mucus accumulation in the CF lung is, as of yet, considered as one important factor contributing to its colonization by opportunistic pathogens such as Pseudomonas aeruginosa. However, in recent years evidence was provided that alveolar macrophages, which form the first line of defense against airborne pathogens, seem to be intrinsically defective with regard to bactericidal functionality in the CF lung. To assess the impact of CFTR deficiency in human macrophages only insufficient systems are available. To address this problem and to evaluate the role of CFTR in human macrophages, we successfully differentiated human induced pluripotent stem cells (iPSC) from a CF p.Phe508del homozygous individual and a healthy donor into primitive macrophages (iMacΔF508 and iMacWT), respectively, and compared the bactericidal functionality in the relevant cell type. iMacΔF508 showed impaired P. aeruginosa clearance and intracellular killing capacity in comparison to iMacWT. Furthermore, iMacΔF508 exhibited a less acidic lysosomal pH, and upon P. aeruginosa infection, there were signs of mitochondrial fragmentation and autophagosome formation together with a hyperinflammatory phenotype and deficient type I interferon response. In summary, we present a defective phenotype in iMacΔF508 upon P. aeruginosa infection, which will constitute an ideal platform to further study the role of macrophages in the context of CF.

Study of the Microbiological Efficiency of a Hospital Ventilation System With Hepa Filtration in the Prevention of Airborne Pathogens

Objective: To evaluate the microbiological efficiency in air conditioning systems with HEPA filtration in an infectious disease hospital. Theoretical Framework: Air conditioning in intensive care units and wards must consider the spread of microorganisms through respiratory pathways, as both patients and healthcare professionals are exposed to infectious agents transmitted by bioaerosols. Due to the possibility of environmental infection, there is a growing recognition that poorly designed air conditioning systems enhance the transmission of pathogens in areas with constant flow of individuals, particularly immunocompromised patients, who are more susceptible to infections. Air conditioning with HEPA filtration is a hospital engineering technique that shows great potential for filtering airborne contaminants, thereby reducing their dispersion in the environment. Method: Air samples were collected using the active impaction method over a 32-week period in the intensive care unit and wards of a reference hospital for infectious diseases. Results and Discussion: In the hospital environment, 67% of fungi and 33% of bacteria were identified, along with their respective subcategories. The colony-forming unit count exceeded the standards established by current regulations. The study highlights that hospital air is a pathway for the transmission and persistence of pathogenic microorganisms. Research Implications: The importance of ensuring a safe and healthy hospital environment is emphasized. Originality/Value: There are few studies addressing pathogens transmitted by bioaerosols. This study contributes to expanding knowledge on this topic and suggests the need for a review of current regulatory standards.

Can we use viral receptor mapping and particle deposition models to predict the clinical severity of novel airborne pathogens?

Can we use viral receptor mapping and particle deposition models to predict the clinical severity of novel airborne pathogens?

Bipolar Ionization Did Not Reduce Airborne Bacteria in a Lecture Hall.

Ionization treatment of indoor air has attracted attention for its potential to inactivate airborne pathogens and reduce disease transmission, yet its real-world effectiveness remains unverified. We evaluated the impact of an in-duct, bipolar ionization system on airborne particles, including culturable bacteria, in a lecture hall. The ionizer was off with variable fan speed for 1 week, on with variable fan speed for a second week, and on with high and constant fan speed for a third week. We measured ion concentrations and aerosol particle concentrations, and we collected bioaerosol samples for analysis of 16S rRNA gene copies representing total bacteria and colony forming units (CFUs) on Tryptic Soy Agar representing culturable bacteria. There were no significant differences in positive, in-room ion concentrations between any weeks; however, negative, in-room ion concentrations were significantly lower when the ionizer was on with constant fan speed. To account for day-to-day variability in total bacteria concentrations, related to occupancy and other factors, we examined the ratio of CFUs to 16S rRNA gene copies (CFU gc-1) and found no significant differences whether the ionizer was on or off. This result indicates that the ionizer was not effective at reducing levels of culturable airborne bacteria in this study.

Quantitative analysis of facial shape in children to support respirator design

The COVID-19 pandemic demonstrated the need for respiratory protection against airborne pathogens. Respirator options for children are limited, and existing designs do not consider differences in facial shape or size. We created a dataset of children's facial images from three cohorts, then used geometric morphometric analyses of dense and sparse facial landmark representations to quantify age, sex and ancestry-related variation in shape. We found facial shape and size in children vary significantly with age from ages 2 to 18, particularly in dimensions relevant to respirator design. Sex differences are small throughout most of the age range of our sample. Ancestry is associated with significant facial shape variation in dimensions that may affect respirator fit. We offer guidance on how to our results can be used for the appropriate design of devices such as respirators for pediatric populations. We also highlight the need to consider ancestry-related variation in facial morphology to promote equitable, inclusive products.

Modifying the Refuse Chute Design to Prevent Infection Spread: Engineering Analysis and Optimization

Considering the presence of airborne viruses, there is a need for renovation in refuse chutes, regarded as the first step in recycling household waste in buildings. This study aimed to revise the design of existing refuse chutes in light of the challenging experiences in waste management and public health during the coronavirus pandemic. This research primarily focused on the risks posed by various types of coronaviruses, such as the novel coronavirus (COVID-19) and acute respiratory syndrome (SARS and SARS-CoV), on stainless steel surfaces, with evidence of their survival under certain conditions. Refuse chutes are manufactured from stainless steel to resist the corrosive effects of waste. In examining the existing studies, it was observed that Casanova et al. and Chowdhury et al. found that the survival time of coronaviruses on stainless steel surfaces decreases as the temperature increases. Based on these studies, mechanical revisions have been made to the sanitation system of the refuse chute, thus increasing the washing water temperature. Additionally, through mechanical improvements, an automatic solution spray entry is provided before the intake doors are opened. Furthermore, to understand airflow and clarify flow parameters related to airborne infection transmission on residential floors in buildings equipped with refuse chutes, a computational fluid dynamics (CFD) analysis was conducted using a sample three-story refuse chute system. Based on the simulation results, a fan motor was integrated into the system to prevent pathogens from affecting users on other floors through airflow. Thus, airborne pathogens were periodically expelled into the atmosphere via a fan shortly before the intake doors were opened, supported by a PLC unit. Additionally, the intake doors were electronically interlocked, ensuring that all other intake doors remained locked while any single door was in use, thereby ensuring user safety. In a sample refuse chute, numerical calculations were performed to evaluate parameters such as the static suitability of the chute body thickness, static compliance of the chute support dimensions, chute diameter, chute thickness, fan airflow rate, ventilation duct diameter, minimum rock wool thickness for human contact safety, and the required number of spare containers. Additionally, a MATLAB code was developed to facilitate these numerical calculations, with values optimized using the Fmincon function. This allowed for the easy calculation of outputs for the new refuse chute systems and enabled the conversion of existing systems, evaluating compatibility with the new design for cost-effective upgrades. This refuse chute design aims to serve as a resource for readers in case of infection risks and contribute to the literature. The new refuse chute design supports the global circular economy (CE) model by enabling waste disinfection under pandemic conditions and ensuring cleaner source separation and collection for recycling. Due to its adaptability to different pandemic conditions including pathogens beyond coronavirus and potential new virus strains, the designed system is intended to contribute to the global health framework. In addition to the health measures described, this study calls for future research on how evolving global health conditions might impact refuse chute design.

Single cell transcriptional analysis of human adenoids identifies molecular features of airway microfold cells.

The nasal, oropharyngeal, and bronchial mucosa are primary contact points for airborne pathogens like Mycobacterium tuberculosis (Mtb), SARS-CoV-2, and influenza virus. While mucosal surfaces can function as both entry points and barriers to infection, mucosa-associated lymphoid tissues (MALT) facilitate early immune responses to mucosal antigens. MALT contains a variety of specialized epithelial cells, including a rare cell type called a microfold cell (M cell) that functions to transport apical antigens to basolateral antigen-presenting cells, a crucial step in the initiation of mucosal immunity. M cells have been extensively characterized in the gastrointestinal (GI) tract in murine and human models. However, the precise development and functions of human airway M cells is unknown. Here, using single-nucleus RNA sequencing (snRNA-seq), we generated an atlas of cells from the human adenoid and identified 16 unique cell types representing basal, club, hillock, and hematopoietic lineages, defined their developmental trajectories, and determined cell-cell relationships. Using trajectory analysis, we found that human airway M cells develop from progenitor club cells and express a gene signature distinct from intestinal M cells. Surprisingly, we also identified a heretofore unknown epithelial cell type demonstrating a robust interferon-stimulated gene signature. Our analysis of human adenoid cells enhances our understanding of mucosal immune responses and the role of M cells in airway immunity. This work also provides a resource for understanding early interactions of pathogens with airway mucosa and a platform for development of mucosal vaccines.