Progression of nasopharyngeal and tracheal bacterial microbiotas of feedlot cattle during development of bovine respiratory disease

It is generally accepted that as bovine respiratory disease (BRD) develops, bacterial pathogens first proliferate in the nasopharynx and then colonize the lungs, leading to bronchopneumonia. However, such temporal changes have never been definitively demonstrated. Therefore, the objective was to describe the progression of the nasopharyngeal and tracheal bacterial microbiotas of feedlot cattle during development of BRD. Nasopharyngeal swabs and tracheal wash samples were collected from 24 heifers over 20 d after arrival at a feedlot. Heifers were assessed daily and sampled based on reticulo-rumen/rectal temperatures and development of clinical signs of BRD. The study end point for each heifer was either at BRD treatment (BRD group; n = 15) or day 20 if the heifer remained healthy or did not meet BRD treatment criteria (TOL group; n = 9). Total DNA was extracted from each sample and the 16S rRNA gene (V3-V4) sequenced. Alpha and beta diversity were compared between BRD-TOL groups and sampling locations over time. There were no common patterns of change over time in composition or diversity of either the nasopharyngeal or tracheal bacterial microbiotas of cattle that developed BRD. Health status affected bacterial composition (R² = 0.043; < 0.001), though this effect was low compared to variation among individual animals (R² = 0.335; < 0.001) and effects of days on feed (R² = 0.082; < 0.001). Specific bacterial taxa (Moraxella and Mycoplasma dispar) nevertheless appeared to have a potential role in respiratory health.

Randomised study of the immunomodulatory effects of azithromycin in severely asthmatic horses

Neutrophilic inflammation is believed to contribute to the airway obstruction and remodelling in equine asthma. Azithromycin, an antibiotic with immunomodulatory properties, reduces pulmonary neutrophilia and hyper-responsiveness in human asthmatics and decreases airway remodelling in rodent models of asthma. It was therefore hypothesised that azithromycin would improve lung function, mucus accumulation and central airway remodelling by decreasing luminal neutrophilia in severe equine asthma. The effects of a 10-day treatment with either azithromycin or ceftiofur, an antimicrobial without immune-modulating activity, were assessed using a blind, randomised, crossover design with six severe asthmatic horses in clinical exacerbation. Lung function, tracheal mucus accumulation, tracheal wash bacteriology, bronchial remodelling, airway neutrophilia and mRNA expression of proinflammatory cytokines (interleukin (IL)-8, IL-17A, IL-1β, tumour necrosis factor-α) in bronchoalveolar lavage fluid were evaluated. Azithromycin decreased the expression of IL-8 (P=0.03, one-tailed) and IL-1β (P=0.047, one-tailed) but failed to improve the other variables evaluated. Ceftiofur had no effect on any parameter. The reduction of neutrophilic chemoattractants (IL-8, IL-1β) justifies further efforts to investigate the effects of a prolonged treatment with macrolides on airway neutrophilia and remodelling. The lack of efficacy of ceftiofur suggests that severe equine asthma should not be treated with antibiotics at first-line therapy.

Economic evaluation alongside the Probiotics to Prevent Severe Pneumonia and Endotracheal Colonization Trial (E-PROSPECT): study protocol

INTRODUCTION

Ventilator-associated pneumonia (VAP) is a common healthcare-associated infection in the intensive care unit (ICU). Probiotics are defined as live microorganisms that may confer health benefits when ingested. Prior randomised trials suggest that probiotics may prevent infections such as VAP and Clostridioides difficile-associated diarrhoea (CDAD). PROSPECT (Probiotics to Prevent Severe Pneumonia and Endotracheal Colonization Trial) is a multicentre, double-blinded, randomised controlled trial comparing the efficacy of the probiotic Lactobacillus rhamnosus GG with usual care versus usual care without probiotics in preventing VAP and other clinically important outcomes in critically ill patients admitted to the ICU.

METHODS AND ANALYSIS

The objective of E-PROSPECT is to determine the incremental cost-effectiveness of L. rhamnosus GG plus usual care versus usual care without probiotics in critically ill patients. E-PROSPECT will be performed from the public healthcare payer's perspective over a time horizon from ICU admission to hospital discharge.We will determine probabilities of in-ICU and in-hospital events from all patients alongside PROSPECT. We will retrieve unit costs for each resource use item using jurisdiction-specific public databases, supplemented by individual site unit costs if such databases are unavailable. Direct costs will include medications, personnel costs, radiology/laboratory testing, operative/non-operative procedures and per-day hospital 'hoteling' costs not otherwise encompassed. The primary outcome is the incremental cost per VAP prevented between the two treatment groups. Other clinical events such as CDAD, antibiotic-associated diarrhoea and in-hospital mortality will be included as secondary outcomes. We will perform pre-specified subgroup analyses (medical/surgical/trauma; age; frailty status; antibiotic use; prevalent vs no prevalent pneumonia) and probabilistic sensitivity analyses for VAP, then generate confidence intervals using the non-parametric bootstrapping approach.

ETHICS AND DISSEMINATION

Study approval for E-PROSPECT was granted by the Hamilton Integrated Research Ethics Board of McMaster University on 29 July 2019. Informed consent was obtained from the patient or substitute decision-maker in PROSPECT. The findings of this study will be published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT01782755; Pre-results.

Respiratory and Gut Microbiota in Commercial Turkey Flocks with Disparate Weight Gain Trajectories Display Differential Compositional Dynamics

Communities of gut bacteria (microbiota) are known to play roles in resistance to pathogen infection and optimal weight gain in turkey flocks. However, knowledge of turkey respiratory microbiota and its link to gut microbiota is lacking. This study presents a 16S rRNA gene-based census of the turkey respiratory microbiota (nasal cavity and trachea) alongside gut microbiota (cecum and ileum) in two identical commercial Hybrid Converter turkey flocks raised in parallel under typical field commercial conditions. The flocks were housed in adjacent barns during the brood stage and in geographically separated farms during the grow-out stage. Several bacterial taxa, primarily Staphylococcus, that were acquired in the respiratory tract at the beginning of the brood stage persisted throughout the flock cycle. Late-emerging predominant taxa in the respiratory tract included Deinococcus and Corynebacterium Tracheal and nasal microbiota of turkeys were identifiably distinct from one another and from gut microbiota. Nevertheless, gut and respiratory microbiota changed in parallel over time and appeared to share many taxa. During the brood stage, the two flocks generally acquired similar gut and respiratory microbiota, and their average body weights were comparable. However, there were qualitative and quantitative differences in microbial profiles and body weight gain trajectories after the flocks were transferred to geographically separated grow-out farms. Lower weight gain corresponded to the emergence of Deinococcus and Ornithobacterium in the respiratory tract and Fusobacterium and Parasutterella in gut. This study provides an overview of turkey microbiota under field conditions and suggests several hypotheses concerning the respiratory microbiome.IMPORTANCE Turkey meat is an important source of animal protein, and the industry around its production contributes significantly to the agricultural economy. The microorganisms present in the gut of turkeys are known to impact bird health and flock performance. However, the respiratory microbiota in turkeys is entirely unexplored. This study has elucidated the microbiota of respiratory tracts of turkeys from two commercial flocks raised in parallel throughout a normal flock cycle. Further, the study suggests that bacteria originating in the gut or in poultry house environments influence respiratory communities; consequently, they induce poor performance, either directly or indirectly. Future attempts to develop microbiome-based interventions for turkey health should delimit the contributions of respiratory microbiota and aim to limit disturbances to those communities.

Bovine Respiratory Syncytial Virus Decreased Pasteurella multocida Adherence by Downregulating the Expression of Intercellular Adhesion Molecule-1 on the Surface of Upper Respiratory Epithelial Cells

The synergistic infection of bovine respiratory syncytial virus (BRSV) and Pasteurella multocida (PM) may predispose cattle to develop severe pneumonia. Previously, we reported that BRSV infection significantly decreased PM adherence to the upper respiratory epithelial cells. It may allow bacteria to invade into the lower respiratory tract and lead to severe pneumonia. To investigate whether BRSV infection regulates the cell surface adherence receptor on bovine trachea epithelial cells (bTECs), we performed proteomic and functional analyses. BRSV infection decreased the expression of intercellular adhesion molecule-1 (ICAM1) on bTECs. Inhibition and knockdown experiments using anti-ICAM1 antibody and siRNAs targeting ICAM1 indicated that PM adherence to bTECs was dependent on ICAM1 expression. These data suggest that under normal conditions bTECs may capture PM in the upper respiratory tract, while BRSV infection reverses this mechanism. The proposed gateway function of bTECs is disrupted by BRSV infection that may facilitate bacterial invasion into the lower respiratory tract and lead to secondary or more severe respiratory infection.

The association between the microbes in the tracheobronchial aspirate fluid and bronchopulmonary dysplasia in preterm infants

OBJECTIVE

The study aimed to evaluate the association between microbes in the lower respiratory tract (LRT) and the srisk for severe bronchopulmonary dysplasia (sBPD) in premature infants.

METHODS

We conducted a retrospective, single-center study of preterm infants who were admitted to the neonatal intensive care unit (NICU) of Southern Medical University Affiliated Maternal & Child Health Hospital of Foshan, China, between January 2015 and December 2017. The microbes in the LRT were screened by using tracheobronchial aspirate fluid (TAF) culture.

RESULTS

One hundred and fifty-five infants were included in the analysis. Among 155 infants, 41 were diagnosed with sBPD, and 114 were diagnosed without sBPD. There were significant differences between infants with and without sBPD in regard to birth weight (BW), gestational age (GA), the duration of endotracheal ventilation and supplemental oxygen. The incidence of retinopathy (ROP) and sepsis was higher in the sBPD infants than in the infants without sBPD. There was a difference in the detection rate of Gram-negative bacteria (GNB) between the two groups. Stenotrophomonas maltophilia and Klebsiella pneumoniae were mainly detected in TAF.

CONCLUSIONS

The LRT microbes were different between infants with and without sBPD, and GNB is more frequently detected in sBPD infants.

Differential Response of the Chicken Trachea to Chronic Infection with Virulent Mycoplasma gallisepticum Strain Ap3AS and Vaxsafe MG (Strain ts-304): a Transcriptional Profile

Mycoplasma gallisepticum is the primary etiological agent of chronic respiratory disease in chickens. Live attenuated vaccines are most commonly used in the field to control the disease, but current vaccines have some limitations. Vaxsafe MG (strain ts-304) is a new vaccine candidate that is efficacious at a lower dose than the current commercial vaccine strain ts-11, from which it is derived. In this study, the transcriptional profiles of the trachea of unvaccinated chickens and chickens vaccinated with strain ts-304 were compared 2 weeks after challenge with M. gallisepticum strain Ap3AS during the chronic stage of infection. After challenge, genes, gene ontologies, pathways, and protein classes involved in inflammation, cytokine production and signaling, and cell proliferation were upregulated, while those involved in formation and motor movement of cilia, formation of intercellular junctional complexes, and formation of the cytoskeleton were downregulated in the unvaccinated birds compared to the vaccinated birds, reflecting immune dysregulation and the pathological changes induced in the trachea by infection with M. gallisepticum Vaccination appears to protect the structural and functional integrity of the tracheal mucosa 2 weeks after infection with M. gallisepticum.

Integrative study of the upper and lower airway microbiome and transcriptome in asthma

Relatively little is known about interactions between the airway microbiome and airway host transcriptome in asthma. Since asthma affects and is affected by the entire airway, studying the upper (e.g., nasal) and lower (e.g., bronchial) airways together represents a powerful approach to understanding asthma. Here, we performed a systematic, integrative study of the nasal and bronchial microbiomes and nasal and bronchial host transcriptomes of children with severe persistent asthma and healthy controls. We found that (a) the microbiomes and host transcriptomes of asthmatic children are each distinct by site (nasal versus bronchial); (b) among asthmatic children, Moraxella and Alloiococcus are hub genera in the nasal microbiome, while there are no hubs among bronchial genera; (c) bronchial Actinomyces is negatively associated with bronchial genes for inflammation, suggesting Actinomyces may be protective; (d) compared with healthy children, asthmatic children express more nasal genes for ciliary function and harbor more nasal Streptococcus; and (e) nasal genera such as Corynebacterium are negatively associated with significantly more nasal genes for inflammation in healthy versus asthmatic children, suggesting a potentially stronger protective role for such nasal genera in healthy versus asthmatic children. Our systematic, integrative study provides a window into host-microbiome associations in asthma.

A Novel AAV-mediated Gene Delivery System Corrects CFTR Function in Pigs

Cystic fibrosis is an autosomal-recessive disease that is caused by a mutant CFTR (cystic fibrosis transmembrane conductance regulator) gene and is characterized by chronic bacterial lung infections and inflammation. Complementation with functional CFTR normalizes anion transport across the airway surface. Adeno-associated virus (AAV) is a useful vector for gene therapy because of its low immunogenicity and ability to persist for months to years. However, because its episomal expression may decrease after cell division, readministration of the AAV vector may be required. To overcome this, we designed an integrating AAV-based CFTR-expressing vector, termed piggyBac (PB)/AAV, carrying CFTR flanked by the terminal repeats of the piggyBac transposon. With codelivery of the piggyBac transposase, PB/AAV can integrate into the host genome. Because of the packaging constraints of AAV, careful consideration was required to ensure that the vector would package and express its CFTR cDNA cargo. In this short-term study, PB/AAV-CFTR was aerosolized to the airways of CF pigs in the absence of the transposase. Two weeks later, transepithelial Cl- current was restored in freshly excised tracheal and bronchial tissue. Additionally, we observed an increase in tracheal airway surface liquid pH and bacterial killing in comparison with untreated CF pigs. Airway surface liquid from primary airway cells cultured from treated CF pigs exhibited increased pH correlating with decreased viscosity. Together, these results show that complementing CFTR in CF pigs with PB/AAV rescues the anion transport defect in a large-animal CF model. Delivery of this integrating viral vector system to airway progenitor cells could lead to persistent, life-long expression in vivo.

The microbiome of the upper respiratory tract in health and disease

The human upper respiratory tract (URT) offers a variety of niches for microbial colonization. Local microbial communities are shaped by the different characteristics of the specific location within the URT, but also by the interaction with both external and intrinsic factors, such as ageing, diseases, immune responses, olfactory function, and lifestyle habits such as smoking. We summarize here the current knowledge about the URT microbiome in health and disease, discuss methodological issues, and consider the potential of the nasal microbiome to be used for medical diagnostics and as a target for therapy.

Comparison of the sensitivity of laryngeal swabs and deep tracheal catheters for detection of Mycoplasma hyopneumoniae in experimentally and naturally infected pigs early and late after infection

Detection of Mycoplasma hyopneumoniae infection in live pigs is a critical component to measure the success of disease control or elimination strategies. However, in vivo diagnosis of M. hyopneumoniae is difficult and the imperfect sensitivity of diagnostic tools has been deemed as one of the main challenges. Here, the sensitivity of laryngeal swabs and deep tracheal catheters for detection of M. hyopneumoniae early and late after infection was determined using inoculation status as a gold standard in experimentally infected pigs and a Bayesian approach in naturally infected pigs. Three-hundred and twenty 8-week old seeder pigs were intra-tracheally inoculated with M. hyopneumoniae strain 232 and immediately placed with 1920 contact pigs to achieve a 1:6 seeder-to-contact ratio. A subset of seeders and contacts were longitudinally sampled at 7, 28, 97, and 113 days post-inoculation (dpi) and at 28, 56, 84, and 113 days post-exposure (dpe), respectively, using laryngeal swabs and deep tracheal catheters. Samples were tested for M. hyopneumoniae by a species-specific real-time PCR. The sensitivity of deep tracheal catheters was higher than the one obtained in laryngeal swabs at all samplings (seeders: 36% higher than laryngeal swabs at 7 dpi, 29% higher at 97 dpi, and 44% higher at 113 dpi; contacts: 51% higher at 56 dpe, 42% higher at 84 dpe, and 32% higher at 113 dpe). Our study indicates that deep tracheal catheters were a more sensitive sample than laryngeal swabs. The sensitivity of both sample types varied over time and by exposure method, and these factors should be considered when designing diagnostic strategies.

In vitro activity of ceftolozane-tazobactam and ceftazidime-avibactam against clinical isolates of meropenem-non-susceptible Pseudomonas aeruginosa: A two-centre study

OBJECTIVES

This study aimed to compare the activity of ceftazidime-avibactam (C/A), ceftolozane-tazobactam (C/T) and three anti-pseudomonal β-lactams (piperacillin-tazobactam, ceftazidime and cefepime) against a collection of meropenem-non-susceptible Pseudomonas aeruginosa (P. aeruginosa) clinical isolates recovered from two centres in Turkey.

METHODS

A total of 102 unique patient isolates of meropenem-non-susceptible P. aeruginosa were included in the study. MICs of antimicrobials were determined by the gradient diffusion method.

RESULTS

Overall susceptibility rates for C/A and C/T were 83.3% and 82.4%, respectively. Both C/A and C/T had better activity than any one of the three anti-pseudomonal β-lactams. According to the MIC₅₀ values, C/T was the most potent agent against isolates. Although the susceptibility rates of isolates to C/T and C/A were similar, C/T (MIC₅₀, 1 μg/mL) was four-fold more potent than C/A (MIC₅₀, 4 μg/mL). The MIC₅₀ values of C/A and C/T for the isolates that were non-susceptible to three β-lactams were significantly higher than those for isolates that were non-susceptible to zero, one or two β-lactams. Also, the C/A MIC₅₀ value for the isolates that were non-susceptible to two β-lactams was higher than that for isolates which were non-susceptible to one β-lactam.

CONCLUSIONS

C/A and C/T showed good activity against meropenem-non-susceptible P. aeruginosa isolates. However, resistance to these agents was not uncommon among these isolates. The overall β-lactam susceptibility profile of isolates seems to have an effect on the probability of susceptibility to C/A and C/T. Antimicrobial susceptibility testing should be performed for C/A and C/T if these agents are considered for treatment of infections caused by meropenem-non-susceptible P. aeruginosa.

Intranasal Inoculation of Cryptococcus neoformans in Mice Produces Nasal Infection with Rapid Brain Dissemination

Cryptococcus neoformans is an important fungal pathogen, causing life-threatening pneumonia and meningoencephalitis. Brain dissemination of C. neoformans is thought to be a consequence of an active infection in the lung which then extravasates to other sites. Brain invasion results from dissemination via either transport by free yeast cells in the bloodstream or Trojan horse transport within mononuclear phagocytes. We assessed brain dissemination in three mouse models of infection: intravenous, intratracheal, and intranasal models. All three modes of infection resulted in dissemination of C. neoformans to the brain in less than 3 h. Further, C. neoformans was detected in the entirety of the upper respiratory tract and the ear canals of mice. In recent years, intranasal infection has become a popular mechanism to induce pulmonary infection because it avoids surgery, but our findings show that instillation of C. neoformans produces cryptococcal nasal infection. These findings imply that immunological studies using intranasal infection should assume that the initial sites of infection of infection are brain, lung, and upper respiratory tract, including the nasal airways.IMPORTANCECryptococcus neoformans causes an estimated 181, 000 deaths each year, mostly associated with untreated HIV/AIDS. C. neoformans has a ubiquitous worldwide distribution. Humans become infected from exposure to environmental sources, after which the fungus lays dormant within the human body. Upon AIDS-induced immunosuppression or therapy-induced immunosuppression (required for organ transplant recipients or those suffering from autoimmune disorders), cryptococcal disease reactivates and causes life-threatening meningitis and pneumonia. This study showed that upon contact with the host, C. neoformans can quickly (a few hours) reach the host brain and also colonizes the nose of infected animals. Therefore, this work paves the way to better knowledge of how C. neoformans travels through the host body. Understanding how C. neoformans infects, disseminates, and survives within the host is critically required so that we can prevent infections and the disease caused by this deadly fungus.

Increased Serum Sedimentation and Positive Tuberculosis Antibody Combined Left Lung Consolidation in Chest CT Scan in an Adult Patient Firstly Misdiagnosed as Tuberculosis Proved as Foreign Body Aspiration in the Left Main Stem Bronchus by Bronchoscopy: a Case Report and Literature Review

BACKGROUND

Foreign body aspiration is a rare entity in adults. We presented an adult case with recurrent pulmonary infection firstly misdiagnosed as tuberculosis, which proved as foreign body aspiration in the left main stem bronchus by bronchoscopy.

METHODS

Appropriate laboratory tests are carried out. The chest CT scan and bronchoscopy were performed for diagnosis.

RESULTS

Serum sedimentation was increased and tuberculosis antibody was positive. The chest CT scan showed left lung consolidation and small pleural exudate on the left side. Significant calcification can be seen near the left main bronchus. The bronchoscopy demonstrated plenty of yellow sputum in left main bronchus and a peanut shell completely obstructed the left main bronchus and peripheral granulation tissue hyperplasia. The peanut shell was removed and the left main trachea was unobstructed.

CONCLUSIONS

When a patient has recurrent pulmonary infection, especially at the same site, physicians should pay attention to airway obstruction caused by foreign body, cancer and other causes of airway stenosis. Bronchoscopy is crucial for the ultimate diagnosis.

Identification of respiratory microbiota markers in ventilator-associated pneumonia

PURPOSE

To compare bacteria recovered by standard cultures and metataxonomics, particularly with regard to ventilator-associated pneumonia (VAP) pathogens, and to determine if the presence of particular bacteria or microbiota in tracheal and oropharyngeal secretions during the course of intubation was associated with the development of VAP.

METHODS

In this case-control study, oropharyngeal secretions and endotracheal aspirate were collected daily in mechanically ventilated patients. Culture and metataxonomics (16S rRNA gene-based taxonomic profiling of bacterial communities) were performed on serial upper respiratory samples from patients with late-onset definite VAP and their respective controls.

RESULTS

Metataxonomic analyses showed that a low relative abundance of Bacilli at the time of intubation in the oropharyngeal secretions was strongly associated with the subsequent development of VAP. On the day of VAP, the quantity of human and bacterial DNA in both tracheal and oropharyngeal secretions was significantly higher in patients with VAP than in matched controls with similar ventilation times. Molecular techniques identified the pathogen(s) of VAP found by culture, but also many more bacteria, classically difficult to culture, such as Mycoplasma spp. and anaerobes.

CONCLUSIONS

Molecular analyses of respiratory specimens identified markers associated with the development of VAP, as well as important differences in the taxa abundance between VAP and controls. Further prospective trials are needed to test the predictive value of these markers, as well as the relevance of uncultured bacteria in the pathogenesis of VAP.

Co-infection of epithelial cells established from the upper and lower bovine respiratory tract with bovine respiratory syncytial virus and bacteria

Bovine respiratory disease complex is a major disease affecting the global cattle industry. Multiple infections by viruses and bacteria increase disease severity. Previously, we reported that bovine respiratory syncytial virus (BRSV) infection increases adherence of Pasteurella multocida to human respiratory and bovine kidney epithelial cells. To examine the interaction between the virus and bacteria in bovine respiratory cells, we generated respiratory epithelial cell lines from bovine trachea (bTEC), bronchus (bBEC), and lung (bLEC). Although all established cell lines were infected by BRSV and P. multocida susceptibility differed according to site of origin. The cells derived from the lower respiratory tract (bBEC and bLEC) were significantly more susceptible to BRSV than those derived from the upper respiratory tract (bTEC). Pre-infection of bBEC and bLEC with BRSV increased adherence of P. multocida; this was not the case for bTEC. These results indicate that BRSV may reproduce better in the lower respiratory tract and encourage adherence of bacteria. Thus, we identify one possible mechanism underlying severe pneumonia.

Prenatal complications are associated with the postnatal airway host response and microbiota in intubated preterm infants

PURPOSE

To prospectively examine the relationship between prenatal events, postnatal airway host response and microbiota, and clinical outcomes.

MATERIALS AND METHODS

Tracheal aspirates collected at seven days of age from 71 mechanically ventilated infants (median gestational age (GA), 25 weeks [range 23-28]) were simultaneously processed for a 12-plex protein assay and bacterial identification by 16S rRNA sequencing. Phenotypes were determined by unsupervised clustering of the protein analytes. Subject characteristics, microbial communities and clinical factors and outcomes were compared across the phenotype groups.

RESULTS

Three clusters were identified: 1 (high protein levels), 2 (high proinflammatory proteins and low anti-inflammatory proteins), and 3 (low protein levels), respectively. Antenatal hemorrhage was most common in cluster 1, while chorioamnionitis characterized cluster 2 and preeclampsia was most prevalent in cluster 3, which was characterized by a predominance of Staphylococcus and relative absence of Ureaplasma. There were higher rates of adverse clinical outcomes in cluster 1.

CONCLUSIONS

Airway protein profiles in seven days old mechanically ventilated preterm infants are associated with important antenatal events and unique airway microbial communities. These relationships may reveal new mechanisms by which antenatal events impact the course and outcomes of preterm infants.

Laryngotracheal Microbiota in Adult Laryngotracheal Stenosis

Laryngotracheal stenosis is an obstructive respiratory disease that leads to voicing difficulties and dyspnea with potential life-threatening consequences. The majority of incidences are due to iatrogenic etiology from endotracheal tube intubation; however, airway scarring also has idiopathic causes. While recent evidence suggests a microbial contribution to mucosal inflammation, the microbiota associated with different types of stenosis has not been characterized. High-throughput sequencing of the V4 region of the16S rRNA gene was performed to characterize the microbial communities of 61 swab samples from 17 iatrogenic and 10 adult idiopathic stenosis patients. Nonscar swabs from stenosis patients were internal controls, and eight swabs from four patients without stenosis represented external controls. Significant differences in diversity were observed between scar and nonscar samples and among sample sites, with decreased diversity detected in scar samples and the glottis region. Permutational analysis of variance (PERMANOVA) results revealed significant differences in community composition for scar versus nonscar samples, etiology type, sample site, groups (iatrogenic, idiopathic, and internal and external controls), and individual patients. Pairwise Spearman's correlation revealed a strong inverse correlation between Prevotella and Streptococcus among all samples. Finally, bacteria in the family Moraxellaceae were found to be distinctly associated with idiopathic stenosis samples in comparison with external controls. Our findings suggest that specific microbiota and community shifts are present with laryngotracheal stenosis in adults, with members of the family Moraxellaceae, including the known pathogens Moraxella and Acinetobacter, identified in idiopathic scar. Further work is warranted to elucidate the contributing role of bacteria on the pathogenesis of laryngotracheal stenosis.IMPORTANCE The laryngotracheal region resides at the intersection between the heavily studied nasal cavity and lungs; however, examination of the microbiome in chronic inflammatory conditions of the subglottis and trachea remains scarce. To date, studies have focused on the microbiota of the vocal folds, or the glottis, for laryngeal carcinoma, as well as healthy larynges, benign vocal fold lesions, and larynges exposed to smoking and refluxate. In this study, we seek to examine the structure and composition of the microbial community in adult laryngotracheal stenosis of various etiologies. Due to the heterogeneity among the underlying pathogenesis mechanisms and clinical outcomes seen in laryngotracheal stenosis disease, we hypothesized that different microbial profiles will be detected among various stenosis etiology types. Understanding differences in the microbiota for subglottic stenosis subtypes may shed light upon etiology-specific biomarker identification and offer novel insights into management approaches for this debilitating disease.

Characterization of an intratracheal aerosol challenge model of Brucella melitensis in guinea pigs

B. melitensis is considered the most virulent of the Brucella species, and a need exists for an improved laboratory animal model of infection that mimics natural transmission and disease. Guinea pigs are highly susceptible to infection with Brucella spp. and develop a disease syndrome that mimics natural disease after aerosol inoculation. Intratracheal inoculation is a targeted means of generating aerosols that offer advantages over aerosol chamber delivery. To establish this delivery method, female, Hartley guinea pigs were infected via intratracheal inoculation with PBS or 16M B. melitensis at low dose (101 to 103) or high dose (106 to 108) and monitored for 30 days for signs of disease. Guinea pigs in the high dose groups developed fever between 12-17 days post-inoculation. Bacteria were recovered from the spleen, liver, lymph nodes, lung, and uterus at 30-days post-inoculation and demonstrated dose dependent mean increases in colonization and pathologic changes consistent with human brucellosis. To study the kinetics of extrapulmonary dissemination, guinea pigs were inoculated with 107 CFU and euthanized at 2-hours post inoculation and at weekly intervals for 3 weeks. 5.8x105 to 4.2x106 CFU were recovered from the lung 2 hours post-inoculation indicating intratracheal inoculation is an efficient means of infecting guinea pigs. Starting at 1-week post inoculation bacteria were recovered from the aforementioned organs with time dependent mean increases in colonization. This data demonstrates that guinea pigs develop a disease syndrome that models the human manifestation of brucellosis, which makes the guinea pig a valuable model for pathogenesis studies.

Pertussis epidemiology in Tunisian infants and children and characterization of Bordetella pertussis isolates: results of a 9-year surveillance study, 2007 to 2016

PURPOSE

Pertussis remains a public health concern in most countries. Our study aimed to prospectively explore the epidemiology of pertussis in the Tunis area of Tunisia between 2007 and 2016, and to characterize the virulence-associated genes of the collected Bordetella pertussis isolates.

METHODOLOGY

Infants and children hospitalized at the Children's Hospital of Tunis, Tunisia, between 2007 and 2016 for suspicion of pertussis were enrolled in the study. Culture and real-time PCR (qPCR) assays targeting IS481, IS1001, recA, H-IS1001 and ptxP were used to confirm the pertussis diagnosis. Phenotypic and genotypic characterization of recovered isolates was performed.Results/Key findings. A total of 1844 children were included in the study. Overall, 306 children (16.6 %) with Bordetella infection were confirmed by qPCR. Among them, 265 (86.6 %) were confirmed as having B. pertussis (IS481+, ptxP+, H-IS1001-), 18 (5.9 %) as having Bordetella parapertussis (IS481-, IS1001+) and 11 (3.6 %) as having Bordetella spp. (IS481+, ptxP-, H-IS1001-). No Bordetella holmesii (IS481+, IS1001-, H-IS1001+) was identified. The estimated pertussis incidence in the Tunis area was 134/100 000 in children aged less than 5 years. Two epidemic peaks were observed in 2009 and 2014. Ten B. pertussis isolates were cultured and characterized. Deficiency in pertactin expression was not observed, and genotyping of the isolates revealed a predominant allelic profile: ptxP3-ptxA1-prn2-fim2-1-fim3-2.

CONCLUSION

This study demonstrated that pertussis is still present as a cyclical disease in Tunisia, despite high primo-vaccination coverage with a pertussis whole-cell vaccine. The predominant genotype of Tunisian B. pertussis isolates is similar to isolates circulating in countries using the acellular vaccine.

Mechanical ventilator as a major cause of infection and drug resistance in intensive care unit

Ventilator-associated pneumonia (VAP) is the most frequent infection in intensive care units (ICU). It is associated with high rates of long morbidity and mortality. Management of a case of VAP is often said to add $40,000 to hospital costs USA. All these data directed our interest to study the etiology, risk factors, and antibiotic susceptibility patterns of VAP in ICU of Tanta University Hospital. This study included 36 cases of VAP. Endotracheal aspirates were obtained from all cases and microbiologically analyzed. Samples were collected over 1 year. Forty-two strains were isolated from 28 cases, while eight cases showed no bacterial growth. The most frequent organism was Staphylococcus aureus (30.95%), followed by Acinetobacter baumannii and Pseudomonas aeruginosa (21.43% for each), and the least common was Staphylococcus epidermidis (2.38%). Multi-drug resistance was detected in (50%) of the isolated bacteria in this study. Imipenem, amikacin, linezolid, vancomycin, and levofloxacin are recommended to be the most effective drugs in management of VAP. VAP is a serious problem in ICU carrying many risks for the patient live. Regimens of empirical treatment should take in consideration the update in the bacterial etiology and antibiotic susceptibility patterns of VAP.

The Role of Presepsin Obtained from Tracheal Aspirates in the Diagnosis of Early Onset Pneumonia in Intubated Newborns

OBJECTIVES

To investigate the role of presepsin obtained from tracheal aspirate of intubated newborns in the diagnosis of early neonatal pneumonia.

METHODS

A cross-sectional observational study was performed on 60 intubated newborns during the two-year period. Tracheal aspirate for examination was taken in aseptic conditions in usual toilets, by lavage with 2 ml of 0.9% NaCl in Mucus suction set. On the same day, presepsin (blood) was measured.

RESULTS

There were 34 newborns in the examined group (with pneumonia) and 26 in the control group. Patient groups were similar regarding demographic characteristics related to gender and Apgar score. The coefficients of simple linear correlation revealed the statistically significant connection between presepsin (from tracheal aspirate) and birth body weight, presepsin (plasma), maternal infection and pneumonia. Significant differences in the values of presepsin (from tracheal aspirate) (p < 0.001) and birth body weight (p = 0.036) were found.

CONCLUSIONS

In intubated newborns, measurements of presepsin obtained from tracheal aspirate suggested that it can be used as a complementary marker in diagnosing early onset neonatal pneumonia.

Clinical features, bacteriology of endotracheal aspirates and treatment outcomes of patients with chronic obstructive pulmonary disease and community-acquired pneumonia in an intensive care unit in Taiwan with an emphasis on eosinophilia versus non-eosinophilia: a retrospective case-control study

OBJECTIVES

The clinical implications of blood eosinophil level in patients with chronic obstructive pulmonary disease (COPD) and community-acquired pneumonia (CAP) requiring invasive mechanical ventilation (IMV) and intensive care unit (ICU) admission are still unknown. Thus, this study aimed to compare the features of such patients with and without blood eosinophilia.

DESIGN

This was a retrospective case-control study.

SETTING

An ICU of a medical centre in central Taiwan.

PARTICIPANTS

A total of 262 patients with COPD and CAP requiring IMV and ICU admission.

RESULTS

Of all participants (n=262), 32 (12.2%) had an eosinophil percentage (EP) >2% and 169 (64.5%) had an absolute eosinophil count (AEC) >300 cells/µL. Regardless of whether 2% or 300 cells/µL was used as a cut-off value, the eosinophilia group were slightly older (years) (82.9±5.4 vs 78.1±9.1, p=0.000 and 79.2±8.4 vs 77.6±9.6, p=0.246, respectively), and had a higher forced expiratory volume in 1 s/forced vital capacity (%) (56.0±8.0 vs 51.3±11.6, p=0.005 and 53.1±11.2 vs 49.5±11.2, p=0.013, respectively), less severe spirometric classification (p=0.008 and p=0.001, respectively), and lower white cell count 109/L (8.8±3.2 vs 11.1±4.9, p=0.009 and 10.3±4.4 vs 11.8±5.3, p=0.017, respectively) than the non-eosinophilia group. The bacteriology of endotracheal aspirates showed that Pseudomonas aeruginosa and other gram-negative bacilli were the most common organisms in all study groups. Participants with an EP >2% had a shorter ICU length of stay (OR=12.13, p=0.001) than those with an EP ≤2%, while an AEC >300 cells/µL was not associated with any in-ICUoutcomes.

CONCLUSIONS

The results of this study have significant clinical implications and should be considered when making treatment decisions for the management of patients with COPD and CAP requiring IMV and ICU admission.

Hospital-acquired colonization and infections in a Vietnamese intensive care unit

Data concerning intensive care unit (ICU)-acquired bacterial colonization and infections are scarce from low and middle-income countries (LMICs). ICU patients in these settings are at high risk of becoming colonized and infected with antimicrobial-resistant organisms (AROs). We conducted a prospective observational study at the Ho Chi Minh City Hospital for Tropical Diseases, Vietnam from November 2014 to January 2016 to assess the ICU-acquired colonization and infections, focusing on the five major pathogens in our setting: Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Klebsiella spp., Pseudomonas spp. and Acinetobacter spp., among adult patients with more than 48 hours of ICU stay. We found that 61.3% (223/364) of ICU patients became colonized with AROs: 44.2% (161/364) with rectal ESBL-producing E. coli and Klebsiella spp.; 30.8% (40/130) with endotracheal carbapenemase-producing Acinetobacter spp.; and 14.3% (52/364) with nasal methicillin-resistant S. aureus. The incidence rate of ICU patients becoming colonized with AROs was 9.8 (223/2,276) per 100 patient days. Significant risk factor for AROs colonization was the Charlson Comorbidity Index score. The proportion of ICU patients with HAIs was 23.4% (85/364), and the incidence rate of ICU patients contracting HAIs was 2.3 (85/3,701) per 100 patient days. The vascular catheterization (central venous, arterial and hemofiltration catheter) was significantly associated with hospital-acquired bloodstream infection. Of the 77 patients who developed ICU-acquired infections with one of the five specified bacteria, 44 (57.1%) had prior colonization with the same organism. Vietnamese ICU patients have a high colonization rate with AROs and a high risk of subsequent infections. Future research should focus on monitoring colonization and the development of preventive measures that may halt spread of AROs in ICU settings.