Association of respiratory virus types with clinical features in bronchiolitis: Implications for virus testing strategies. A systematic review and meta-analysis.

BACKGROUND: Bronchiolitis is a leading cause of infant hospitalization, linked to respiratory syncytial virus (RSV) and rhinovirus (RV). Guidelines lack specific viral testing for bronchiolitis management. To establish effective management strategies, it is crucial to assess whether specific respiratory virus types are correlated with distinct examination features. METHODS: Through a systematic search of three databases, 21 studies were qualitatively analyzed, with 18 used for meta-analysis. Various outcomes like wheezing on auscultation, fever, atopic traits, and infection severity were evaluated. RESULTS: RSV-positive bronchiolitis was associated with a higher need for oxygen supplementation (OR 1.78, 95% CI 1.04-3.02) in 5 studies, while RV-positive bronchiolitis was more frequently linked to personal history of eczema (OR 0.60, 95% CI 0.41-0.88) in 6 studies. No significant differences were observed in the other outcomes examined. CONCLUSIONS: Bronchiolitis caused by RSV or RV presents with similar clinical features. Despite the associations between RSV-positive bronchiolitis and need for oxygen supplementation, and RV-positive bronchiolitis and a history of eczema, our study shows that viral etiology of bronchiolitis cannot be determined solely based on clinical presentation. Tailored management strategies, informed by accurate viral testing, seem crucial in clinical practice for enhancing patient outcomes in severe bronchiolitis.

High TSLP responses in the human infant airways are associated with pre-activated airway epithelial IFN antiviral immunity.

Thymic stromal lymphopoietin (TSLP) is a primarily epithelial-derived cytokine that drives type 2 allergic immune responses. Early life viral respiratory infections elicit high TSLP production, which leads to the development of type 2 inflammation and airway hyperreactivity. The goal of this study was to examine in vivo and in vitro the human airway epithelial responses leading to high TSLP production during viral respiratory infections in early infancy. A total of 129 infants (<1-24 m, median age 10 m) with severe viral respiratory infections were enrolled for in vivo (n = 113), and in vitro studies (n = 16). Infants were classified as 'high TSLP' or 'low TSLP' for values above or below the 50th percentile. High versus low TSLP groups were compared in terms of type I-III IFN responses and production of chemokines promoting antiviral (CXCL10), neutrophilic (CXCL1, CXCL5, CXCL8), and type 2 responses (CCL11, CCL17, CCL22). Human infant airway epithelial cell (AEC) cultures were used to define the transcriptomic (RNAseq) profile leading to high versus low TSLP responses in vitro in the absence (baseline) or presence (stimulated) of a viral mimic (poly I:C). Infants in the high TSLP group had greater in vivo type III IFN airway production (median type III IFN in high TSLP 183.2 pg/mL vs. 63.4 pg/mL in low TSLP group, p = 0.007) and increased in vitro type I-III IFN AEC responses after stimulation with a viral mimic (poly I:C). At baseline, our RNAseq data showed that infants in the high TSLP group had significant upregulation of IFN signature genes (e.g., IFIT2, IFI6, MX1) and pro-inflammatory chemokine genes before stimulation. Infants in the high TSLP group also showed a baseline AEC pro-inflammatory state characterized by increased production of all the chemokines assayed (e.g., CXCL10, CXCL8). High TSLP responses in the human infant airways are associated with pre-activated airway epithelial IFN antiviral immunity and increased baseline AEC production of pro-inflammatory chemokines. These findings present a new paradigm underlying the production of TSLP in the human infant airway epithelium following early life viral exposure and shed light on the long-term impact of viral respiratory illnesses during early infancy and beyond childhood.

Respiratory Comorbidities Associated with Bronchiectasis in Patients with Common Variable Immunodeficiency in the USIDNET Registry.

BACKGROUND: Bronchiectasis is a major respiratory complication in patients with common variable immunodeficiency (CVID) and is associated with recurrent pulmonary infections. However, it is unclear whether other infections or non-infectious respiratory conditions are related to its development. OBJECTIVE: To identify respiratory comorbidities associated with bronchiectasis in patients with CVID. METHODS: A total of 1470 CVID patients enrolled in the USIDNET registry were included in a cross-sectional analysis. The primary outcome of our study was to determine the clinical characteristics and other respiratory conditions associated with respiratory comorbidities and physician-reported bronchiectasis. RESULTS: One hundred ninety-seven CVID patients were noted to have bronchiectasis (13.4%). Affected patients were significantly older than patients without bronchiectasis (median age 54 years vs. 49 years, p = 0.0004). These patients also had lower serum IgA (13 mg/dL IQR 60 mg/dL vs. 28.4 mg/dL IQR 66 mg/dL, p = 0.000). Notably, chronic rhinosinusitis (OR = 1.69 95%CI 1.05-2.75), sinusitis (OR = 2.06 95%CI 1.38-3.09), pneumonia (OR = 2.70 95%CI 1.88-3.88), COPD (OR = 2.66 95%CI 1.51-4.67), and interstitial lung disease (OR = 2.34 95%CI 1.41-3.91) were independently associated with the development of bronchiectasis in this population. CONCLUSION: These data suggest that lower and upper respiratory infections, chronic lower airway disease, and interstitial lung diseases are independently associated with bronchiectasis in CVID patients. Further study into predisposing conditions related to the development of bronchiectasis in CVID patients may allow prediction and early intervention strategies to prevent the development of this complication.

The lung in inborn errors of immunity: From clinical disease patterns to molecular pathogenesis.

In addition to being a vital organ for gas exchange, the lung is a crucial immune organ continuously exposed to the external environment. Genetic defects that impair immune function, called inborn errors of immunity (IEI), often have lung disease as the initial and/or primary manifestation. Common types of lung disease seen in IEI include infectious complications and a diverse group of diffuse interstitial lung diseases. Although lung damage in IEI has been historically ascribed to recurrent infections, contributions from potentially targetable autoimmune and inflammatory pathways are now increasingly recognized. This article provides a practical guide to identifying the diverse pulmonary disease patterns in IEI based on lung imaging and respiratory manifestations, and integrates this clinical information with molecular mechanisms of disease and diagnostic assessments in IEI. We cover the entire IEI spectrum, including immunodeficiencies and immune dysregulation with monogenic autoimmunity and autoinflammation, as well as recently described IEI with pulmonary manifestations. Although the pulmonary manifestations of IEI are highly relevant for all age groups, special emphasis is placed on the pediatric population, because initial presentations often occur during childhood. We also highlight the pivotal role of genetic testing in the diagnosis of IEI involving the lungs and the critical need to develop multidisciplinary teams for the challenging evaluation of these rare but potentially life-threatening disorders.

Defining Age-related OSA Features in Robin Sequence Using Polysomnographic-based Analyses of Respiratory Arousal Responses and Gas-exchange Parameters.

INTRODUCTION: Robin sequence (RS) is a leading cause of obstructive sleep apnea (OSA) in newborns. Most studies have focused on understanding anatomic factors leading to OSA and changes in apnea-hypopnea index (AHI) on polysomnography (PSG) beyond the neonatal period. This study aims to define age-related OSA features between patients with RS, without RS and healthy controls using PSG-based analyses of respiratory arousal responses and gas-exchange parameters. DESIGN: Retrospective comparison of PSG features in a total of 48 children encompassing three groups: (a) infants with RS (n = 24, <1-year old), (b) non-RS older children (1-2 years old) with severe OSA (obstructive AHI (OAHI) of ≥10 events; n = 12), and (c) control infants and children (0-2 years old) without sleep apnea (OAHI ≤1.5/h, n = 12). We examined OSA sleep-stage specific and position-specific indexes, and the relationship between OSA severity and respiratory arousal indexes (OAHI/respiratory arousal indexes). RESULTS: OSA sleep-stage specific indexes (rapid eye movement [REM] vs non-REM[NREM]) as well as position-specific indexes (supine vs nonsupine) were similar in individuals with and without RS. Relative to the non-RS groups, infants with RS have more sustained hypoxemia (time with SpO2 < 90%) and reduced arousal responses to OSA demonstrated by higher OAHI/respiratory arousal indexes. OAHI/respiratory arousal indexes significantly correlated with the severity of hypoxemia in infants with RS. CONCLUSION: Infants with RS and OSA show reduced arousal responses to apneic events, which correlates with higher hypoxemia severity. OAHI/respiratory arousal indexes in RS may identify high-risk individuals with upper airway obstruction and reduced arousal protective responses.

Predicting Failure of Non-Invasive Ventilation With RAM Cannula in Bronchiolitis.

INTRODUCTION: In infants hospitalized for bronchiolitis on non-invasive ventilation (NIV) via the RAM cannula nasal interface, variables predicting subsequent intubation, or NIV non-response, are understudied. We sought to identify predictors of NIV non-response. METHODS: We performed a retrospective cohort study in infants admitted for respiratory failure from bronchiolitis placed on NIV in a quaternary children's hospital. We excluded children with concurrent sepsis, critical congenital heart disease, or with preexisting tracheostomy. The primary outcome was NIV non-response defined as intubation after a trial of NIV. Secondary outcomes were vital sign values before and after NIV initiation, duration of NIV and intubation, and mortality. Primary analyses included Chi-square, Wilcoxon rank-sum, student's t test, paired analyses, and adjusted and unadjusted logistic regression assessing heart rate (HR) and respiratory rate (RR) before and after NIV initiation. RESULTS: Of 138 infants studied, 34% were non-responders. There were no differences in baseline characteristics of responders and non-responders. HR decreased after NIV initiation in responders (156 [143-156] to149 [141-158], p < 0.01) compared to non-responders (158 [149-166] to 158 [145-171], p = 0.73). RR decreased in responders (50 [43-58] vs 47 [41-54]) and non-responders (52 [48-58] vs 51 [40-55], both p < 0.01). Concurrent bacterial pneumonia (OR 6.06, 95% CI: 2.54-14.51) and persistently elevated HR (OR: 1.04, 95% CI: 1.01-1.07) were associated with NIV non-response. CONCLUSION: In children with acute bronchiolitis who fail to respond to NIV and require subsequent intubation, we noted associations with persistently elevated HR after NIV initiation and concurrent bacterial pneumonia.

Single-cell characterization of a model of poly I:C-stimulated peripheral blood mononuclear cells in severe asthma.

BACKGROUND: Asthma has been associated with impaired interferon response. Multiple cell types have been implicated in such response impairment and may be responsible for asthma immunopathology. However, existing models to study the immune response in asthma are limited by bulk profiling of cells. Our objective was to Characterize a model of peripheral blood mononuclear cells (PBMCs) of patients with severe asthma (SA) and its response to the TLR3 agonist Poly I:C using two single-cell methods. METHODS: Two complementary single-cell methods, DropSeq for single-cell RNA sequencing (scRNA-Seq) and mass cytometry (CyTOF), were used to profile PBMCs of SA patients and healthy controls (HC). Poly I:C-stimulated and unstimulated cells were analyzed in this study. RESULTS: PBMCs (n = 9414) from five SA (n = 6099) and three HC (n = 3315) were profiled using scRNA-Seq. Six main cell subsets, namely CD4 + T cells, CD8 + T cells, natural killer (NK) cells, B cells, dendritic cells (DCs), and monocytes, were identified. CD4 + T cells were the main cell type in SA and demonstrated a pro-inflammatory profile characterized by increased JAK1 expression. Following Poly I:C stimulation, PBMCs from SA had a robust induction of interferon pathways compared with HC. CyTOF profiling of Poly I:C stimulated and unstimulated PBMCs (n = 160,000) from the same individuals (SA = 5; HC = 3) demonstrated higher CD8 + and CD8 + effector T cells in SA at baseline, followed by a decrease of CD8 + effector T cells after poly I:C stimulation. CONCLUSIONS: Single-cell profiling of an in vitro model using PBMCs in patients with SA identified activation of pro-inflammatory pathways at baseline and strong response to Poly I:C, as well as quantitative changes in CD8 + effector cells. Thus, transcriptomic and cell quantitative changes are associated with immune cell heterogeneity in this model to evaluate interferon responses in severe asthma.

The interplay between airway epithelium and the immune system - A primer for the respiratory clinician.

The respiratory epithelium is one of the primary interfaces between the body's immune system and the external environment. This review discusses the innate and adaptive immunomodulatory effects of the respiratory epithelium, highlighting the physiologic immune responses associated with health and the disease-causing sequelae when these physiologic responses go awry. Airway macrophages, dendritic cells, and innate lymphoid cells are discussed as orchestrators of physiological and pathological innate immune responses and T cells, B cells, mast cells, and granulocytes (eosinophils and neutrophils) as orchestrators of physiologic and pathologic adaptive immune responses. The interplay between the airway epithelium and the varied immune cells as well as the interplay between these immune cells is discussed, highlighting the importance of the dose of noxious stimuli and pathogens in immune programming and the timing of their interaction with the immune cells that determine the pattern of immune responses. Although each cell type has been researched individually, this review highlights the need for simultaneous temporal investigation of immune responses from these varied cells to noxious stimuli and pathogens.

The airway epithelium during infancy and childhood: A complex multicellular immune barrier. Basic review for clinicians.

The airway epithelium is a complex multicellular layer that extends from the nasopharynx to the small airways. It functions as an immune respiratory barrier during early life that develops, matures, and regenerates to adapt to the changes in the environment. While airway epithelial abnormalities have been identified in several clinical disorders, there is increasing interest in understanding its basic regulation and structure in humans. Indeed, recent advances in technology (e.g. single-cell analysis and new human airway epithelial cell models) have allowed us to identify additional cellular subtypes and functions that overall have greatly improved our understanding of the airway epithelium during health and disease. In this review we summarize key features of the airway epithelium including: 1) multilayer structure and cell heterogeneity; 2) adaptability to different environmental and developmental stimuli; 3) innate recognition; and 4) orchestration of immune responses. We discuss these features with a translational and clinical prospective focusing on the development of human respiratory immunity, particularly during early life.

For which infants with viral bronchiolitis could it be deemed appropriate to use albuterol, at least on a therapeutic trial basis?

Although there is increasing evidence showing that infants with viral bronchiolitis exhibit a high degree of heterogeneity, a core uncertainty shared by many clinicians is with regard to understanding which patients are most likely to benefit from bronchodilators such as albuterol. Based on our review, we concluded that older infants with rhinovirus (RV) bronchiolitis, especially those with a nasopharyngeal microbiome dominated by Haemophilus influenzae; those affected during nonpeak months or during non-respiratory syncytial virus (RSV) predominant months; those with wheezing at presentation; those with clinical characteristics such as atopic dermatitis or a family history of asthma in a first-degree relative; and those infants infected with RSV genotypes ON1 and BA, have the greatest likelihood of benefiting from albuterol. Presently, this patient profile could serve as the basis for rational albuterol administration in patients with viral bronchiolitis, at least on a therapeutic trial basis, and it could also be the starting point for future targeted randomized clinical trials (RCTs) on the use of albuterol among a subset of infants with bronchiolitis.

Innate IFN-lambda responses to dsRNA in the human infant airway epithelium and clinical regulatory factors during viral respiratory infections in early life.

INTRODUCTION: IFN lambda (type III-IFN-λ1) is a molecule primarily produced by epithelial cells that provides an important first-line defence against viral respiratory infections and has been linked to the pathogenesis of viral-induced wheezing in early life. The goal of this study was to better understand the regulation of innate IFN-lambda responses in vitro in primary human infant airway epithelial cells (AECs) and in vivo using nasal aspirates during viral respiratory infections. METHODS: IFN-lambda protein levels were quantified: (a) in human infant AECs exposed to (poly(I:C) dsRNA) under different experimental conditions (n = 8 donors); and (b) in nasal aspirates of young children (≤3 years) hospitalized with viral respiratory infection (n = 138) and in uninfected controls (n = 74). In vivo IFN-lambda airway levels during viral infections were correlated with individual characteristics and respiratory disease parameters. RESULTS: Our in vitro experiments showed that the poly(I:C)-induced innate production of IFN lambda in human infant AECs is regulated by (a) p38-MAPK/NF-kB dependent mechanism; and (b) exposure to pro-inflammatory signals such as IL1ß. Our in vivo studies demonstrated that (a) infants (<18 months) had higher virus-induced IFN-lambda airway secretion; (b) subjects with RSV infection showed the highest IFN-lambda airway levels; and (c) individuals with the highest virus-induced IFN-lambda levels (>90th percentile) had higher viral loads and were more likely to have respiratory sick visits within 12 months of discharge (OR = 5.8). CONCLUSION: IFN-lambda responses to dsRNA in the human infant airway epithelium are regulated by p38-MAPK and NF-kB signalling. High in vivo IFN-lambda production is influenced by virus type and associated with recurrent respiratory sick visits in young children.

The impact of viral bronchiolitis phenotyping: Is it time to consider phenotype-specific responses to individualize pharmacological management?

Although recent guidelines recommend a minimalist approach to bronchiolitis, there are several issues with this posture. First, there are concerns about the definition of the disease, the quality of the guidelines, the method of administration of bronchodilators, and the availability of tools to evaluate the response to therapies. Second, for decades it has been assumed that all cases of viral bronchiolitis are the same, but recent evidence has shown that this is not the case. Distinct bronchiolitis phenotypes have been described, with heterogeneity in clinical presentation, molecular immune signatures and clinically relevant outcomes such as respiratory failure and recurrent wheezing. New research is critically needed to refine viral bronchiolitis phenotyping at the molecular and clinical levels as well as to define phenotype-specific responses to different therapeutic options.

Characterization of mucoid and serous middle ear effusions from patients with chronic otitis media: implication of different biological mechanisms?

BACKGROUND: Chronic otitis media with effusion (COME) is characterized by persistent middle ear effusions that are in most cases highly viscous, but some patients present with serous fluid. This study aimed at comprehensively characterizing the macromolecular composition of mucoid vs. serous middle ear effusions (MEEs). METHODS: MEEs from patients with COME were analyzed for proteins by mass spectrometry (MS) and western blot techniques, total DNA quantity, bacterial DNA (16S sequencing), and cytokine content. Proteomics datasets were studied in Ingenuity Pathway Analysis (IPA). RESULTS: Mucoid samples showed a global tendency of increased pro-inflammatory mediators. Interleukin-1ß (IL-1ß) and IL-10 were significantly more abundant in serous samples (p < 0.01). Mucoid samples had higher DNA quantity (p = 0.04), more likely to be positive in MUC5B protein (p = 0.008) and higher peptide counts (12,786 vs. 2225), as well as an overall larger number of identified proteins (331 vs. 177), compared to serous. IPA found the mucoid sample dataset to be related to immune cell function and epithelial remodeling, whereas the serous sample dataset showed acute responses and blood-related proteins. Interestingly, serous samples showed more bacterial DNA than mucoid ones, with less bacterial genera variability. CONCLUSION: This study demonstrates divergent immune responses in children with COME by effusion quality.

Systematic review of instruments aimed at evaluating the severity of bronchiolitis.

OBJECTIVE: No recent studies have performed a systematic review of all available instruments aimed at evaluating the severity of bronchiolitis. The objective of the present study was to perform a systematic review of instruments aimed at evaluating the severity of bronchiolitis and to evaluate their measurement properties. METHODS: A systematic search of the literature was performed in order to identify studies in which an instrument for evaluating the severity of bronchiolitis was described. Instruments were evaluated based on their reliability, validity, utility, endorsement frequency, restrictions in range, comprehension, and lack of ambiguity. RESULTS: A total of 77 articles, describing a total of 32 different instruments were included in the review. The number of items included in the instruments ranged from 2 to 26. Upon analyzing their content, respiratory rate turned out to be the most frequently used item (in 26/32, 81.3% of the instruments), followed by wheezing (in 25/32, 78.1% of the instruments). In 18 (56.3%) instruments, there was a report of at least one of their measurement properties, mainly reliability and utility. Taking into consideration the information contained in the instruments, as well as their measurement properties, one was considered to be the best one available. CONCLUSIONS: Among the 32 instruments aimed at evaluating the severity of bronchiolitis that were identified and systematically examined, one was considered to be the best one available. However, there is an urgent need to develop better instruments and to validate them in a more comprehensive and proper way.

Purification and characterization of microRNAs within middle ear fluid exosomes: implication in otitis media pathophysiology.

BACKGROUND: Otitis media (OM) is characterized by acute infection progressing to chronic middle ear effusion (MEE). Extracellular secretion of microRNAs (miRNAs) in exosomes is a newly discovered mechanism for cells exerting distant cell genetic regulation. Whether MEE contains exosomes with specific miRNAs is unknown. This study aimed to purify and characterize the exosomal and miRNA content of MEE. METHOD: MEEs were subjected to Exoquick exosomal purification and EXOCET exosomal quantification. Extracted vesicles were analyzed by dynamic light scattering (DLS), transmission electron microscopy (TEM), and immunoblotting of HSP-70. NanoString hybridization was performed to profile miRNAs. Exosomal protein content was profiled by Liquid chromatography tandem mass spectrometry (LC-MS/MS). RESULTS: EXOCET assays showed presence of exosomes (0-0.5 × 107/ml) in MEEs. DLS confirmed exosomal size between 10 and 200 nm. Western blot analysis showed presence of HSP-70. Twenty-nine miRNAs were found to be unique to MEEs. The most abundant miRNA was miR-223, a miRNA typically secreted by neutrophils. Proteomics demonstrated typical neutrophil markers as well as common innate immune molecules. CONCLUSION: To our knowledge, this the first report demonstrating the presence of exosomes transporting miRNAs in MEEs. These findings open a broad and novel area of research in OM pathophysiology as driven by miRNA cell communication.

A systematic review of instruments aimed at evaluating metered-dose inhaler administration technique in children.

OBJECTIVE: The objective of the present study was to perform a systematic review of instruments aimed at evaluating pressurized metered-dose inhaler (pMDI) administration technique in children and evaluating the measurement properties of these instruments. METHODS: A systematic search of the literature was performed in order to identify studies in which an instrument (scale, checklist, or questionnaire) for evaluating pMDI administration technique in children was described. Instruments were evaluated based on their reliability, validity, utility, endorsement frequency, restrictions in range, comprehension, lack of ambiguity, and lack of value-laden or offensive content. RESULTS: A total of 24 instruments were identified. The age of the children ranged from 1 month to 18 years, the number of steps or items included in the instruments ranged from 3 to 21, and nearly half of the instruments distinguished between essential and non-essential steps or items. In only 7 of the 24 instruments was there a report of their measurement properties, mainly reliability and utility. Taking into consideration the information contained in the instruments, as well as their measurement properties, we determined four instruments to be the best of the available ones. CONCLUSIONS: Among the 24 instruments for the assessment of pMDI administration technique in children that were identified and systematically examined, four were considered to be the best ones available. However, additional evaluation of their measurement properties should be done before using them in clinical practice and for research purposes.

Preoperative evaluation and comprehensive risk assessment for children with Down syndrome.

Down syndrome is a common chromosome disorder affecting all body systems. This creates unique physiologic concerns that can affect safety during anesthesia and surgery. Little consensus exists, however, on the best way to evaluate children with Down syndrome in preparation for surgery. We review a number of salient topics affecting these children in the perioperative period, including cervical spine instability, cardiovascular abnormalities, pulmonary hypertension, upper airway obstruction, hematologic disturbances, prematurity, low birth weight, and the use of supplements and alternative therapies. Recommendations include obtaining a complete blood count to detect an increased risk for bleeding or stroke, and cardiology evaluation to identify patients with pulmonary hypertension, as well as undiagnosed or residual heart disease. Pediatric cardiac anesthesiologists and intensivists should be involved as needed. The potential for cervical spine instability should be considered, and the anesthesiologist may wish to have several options available both for the medications and equipment used. The child's family should always be asked if he or she is on any nutritional supplements, as some products marketed to families may have secondary effects such as inhibition of platelet function. Using this evaluation in presurgical planning will allow physicians to better consider the individual circumstances for their patients with Down syndrome. Our goal was to optimize patient safety by choosing the most appropriate setting and perioperative personnel, and to mitigate those risk factors amenable to intervention.

Respiratory syncytial virus, adenoviruses, and mixed acute lower respiratory infections in children in a developing country.

There is growing evidence suggesting greater severity and worse outcomes in children with mixed as compared to single respiratory virus infections. However, studies that assess the risk factors that may predispose a child to a mixture of respiratory syncytial virus (RSV) and adenoviral infections, are scarce. In a retrospective cohort study, the study investigated the epidemiology of RSV and adenovirus infections and predictors of mixed RSV-adenoviral infections in young children hospitalized with acute lower respiratory infection in Bogota, Colombia, South America, over a 2-year period 2009-2011. Of a total of 5,539 children admitted with a diagnosis of acute lower respiratory infection, 2,267 (40.9%) who were positive for RSV and/or adenovirus were selected. Out the total number of cases, 1,416 (62.5%) infections occurred during the 3-month period from March to May, the first rainy season of Bogota, Colombia. After controlling for gender, month when the nasopharyngeal sample was taken, and other pre-existing conditions, it was found that an age greater than 6 months (OR:1.74; CI 95%:1.05-2.89; P = 0.030) and malnutrition as a comorbidity (OR:9.92; CI 95%:1.01-100.9; P = 0.049) were independent predictors of mixed RSV-adenoviral infections in the sample of patients. In conclusion, RSV and adenovirus are significant causes of acute lower respiratory infection in infants and young children in Bogota, Colombia, especially during the first rainy season. The identified predictors of mixed RSV-adenoviral infections should be taken into account when planning intervention, in order to reduce the burden of acute lower respiratory infection in young children living in the country.