Role of bacteria in acute exacerbations of chronic obstructive pulmonary disease

Trends in the Bacterial Prevalence and Antibiotic Resistance Patterns in the Acute Exacerbation of Chronic Obstructive Pulmonary Disease in Hospitalized Patients in South India

Exacerbation due to antimicrobial-drug-resistant bacteria among chronic obstructive pulmonary disease (AECOPD) patients contributes to mortality and morbidity. We examined the prevalence of the bacterial organisms and trends in drug resistance in AECOPD. In this retrospective study, between January 2016 to December 2020, among 3027 AECOPD patients, 432 (14.3%) had bacteria isolated. The regression and generalized estimating equations (GEE) were used for trends in the resistance patterns over five years, adjusting for age, gender, and comorbidities. Klebsiella pneumoniae (32.4%), Pseudomonas aeruginosa (17.8%), Acinetobacter baumannii (14.4%), Escherichia coli (10.4%), and Staphylococcus aureus (2.5%) were common. We observed high levels of drug resistance in AECOPD patients admitted to ICU (87.8%) and non-ICU (86.5%). A Cox proportional hazard analysis, observed infection with Acinetobacter baumannii and female sex as independent predictors of mortality. Acinetobacter baumannii had 2.64 (95% confidence interval (CI): 1.08−6.43) higher odds of death, compared to Klebsiella pneumoniae. Females had 2.89 (95% CI: 1.47−5.70) higher odds of death, compared to males. A high proportion of bacterial AECOPD was due to drug-resistant bacteria. An increasing trend in drug resistance was observed among females.

Combination antibiotic therapy versus monotherapy in the treatment of acute exacerbations of chronic obstructive pulmonary disease: an open-label randomized trial

Background

The role of antibiotics in the treatment of chronic obstructive pulmonary disease (COPD) exacerbations and their effectiveness in combination have not been clearly established. To determine whether using a combination of fluoroquinolones and beta-lactams improves the clinical and microbiological efficacy of antibiotics on day 20 of treatment, we conducted an open-label randomized trial based on clinical outcomes, microbiological clearance, spirometry tests, and signs of systemic inflammation in patients hospitalized with acute exacerbations of COPD.

Methods

We enrolled 139 subjects with COPD exacerbations, defined as acute worsening of respiratory symptoms leading to additional treatment. Patients were divided randomly into two groups: 79 patients using beta-lactam antibiotics alone and 60 using beta-lactam antibiotics plus fluoroquinolones. Clinical and microbiological responses, spirometry tests, symptom scores, and serum C-reactive protein (CRP) levels were evaluated.

Results

Clinical success, lung function, and symptoms were similar in patients with or without fluoroquinolone administration on days 10 and 20. Combination therapy was superior in terms of microbiological outcomes and reduction in serum CRP value. Although equivalent to monotherapy in terms of clinical success, the combination showed superiority in terms of microbiological success and a decrease in CRP. The combination therapy group had a higher microbiological success rate with gram-negative bacteria than the monotherapy group with Pseudomonas aeruginosa (100% vs. 33.3%, respectively) and Acinetobacter baumanii (100% vs. 20%, respectively) (P < 0.05).

Conclusions

Concomitant use of fluoroquinolone and beta-lactam antibiotics for bacterial infections during COPD exacerbations caused by gram-negative bacteria appear to be effective and should be applied in clinical practice.

Population Pharmacokinetics and Dose Optimization of Ceftazidime and Imipenem in Patients with Acute Exacerbations of Chronic Obstructive Pulmonary Disease

Background: Ceftazidime and imipenem have been increasingly used to treat Acute Exacerbations of Chronic Obstructive Pulmonary Disease (AECOPD) due to their extended-spectrum covering Pseudomonas aeruginosa. This study aims to describe the population pharmacokinetic (PK) and pharmacodynamic (PD) target attainment for ceftazidime and imipenem in patients with AECOPD. Methods: We conducted a prospective PK study at Bach Mai Hospital (Viet Nam). A total of 50 (ceftazidime) and 44 (imipenem) patients with AECOPD were enrolled. Population PK analysis was performed using Monolix 2019R1 and Monte Carlo simulations were conducted to determine the optimal dose regimen with respect to the attainment of 60% and 40% fT>MIC for ceftazidime and imipenem, respectively. A dosing algorithm was developed to identify optimal treatment doses. Results: Ceftazidime and imipenem PK was best described by a one-compartment population model with a volume of distribution and clearance of 23.7 L and 8.74 L/h for ceftazidime and 15.1 L and 7.88 L/h for imipenem, respectively. Cockcroft–Gault creatinine clearance represented a significant covariate affecting the clearance of both drugs. Increased doses with prolonged infusion were found to cover pathogens with reduced susceptibility. Conclusions: This study describes a novel and versatile three-level dosing algorithm based on patients’ renal function and characteristic of the infective pathogen to explore ceftazidime and imipenem optimal regimen for AECOPD.

Bacterial infections in acute exacerbation of chronic obstructive pulmonary disease: a systematic review and meta-analysis

OBJECTIVE

Due to the importance of Chronic obstructive pulmonary disease (COPD) as the fourth cause of mortality worldwide and the lack of studies evaluating the prevalence of bacterial infections in disease exacerbation, this systematic review and meta-analysis was performed to determine the prevalence rate of bacterial infections in COPD patients.

METHODS

PubMed, ISI Web of Science, and Scopus databases were systematically searched for population-based prevalence studies (1980-2018). MeSH terms for "Bacterial infections" and "AECOPD" were used as search keywords. The selected studies were filtered according to the inclusion and exclusion criteria. Fixed and random-effects models were used for estimation of summary effect sizes. Between-study heterogeneity, as well as publication bias, were calculated.

RESULTS

Finally, 118 out of 31,440 studies were selected. The overall estimation of the prevalence of bacterial infection was 49.59% [95% confidence interval (CI) 0.4418-0.55]. The heterogeneity in estimating the pooled prevalence of bacterial infections was shown in the studies (Cochran Q test: 6615, P < 0.0001, I² = 98.23%). In addition, S. pneumoniae, H. influenzae, M. catarrhalis, A. baumannii, P. aeruginosa, and S. aureus were the most prevalent reported bacteria.

CONCLUSIONS

Our results as the first meta-analysis for the issue demonstrated that bacterial infections are an important risk factor for AECOPD. Further studies must be performed for understanding the exact role of bacterial agents in AECOPD and help physicians for more applicable preventive and therapeutic measurements.

Neutrophil elastase as a biomarker for bacterial infection in COPD

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is predominantly associated with neutrophilic inflammation. Active neutrophil elastase (NE) is a serine proteinase, secreted by neutrophils, in response to inflammation and pathogen invasion. We sought to investigate if NE could be used as a biomarker for bacterial infection in patients with COPD.

METHODS

NE was quantified using ProteaseTag® Active NE Immunoassay (ProAxsis, Belfast) from the sputum of COPD subjects at stable state, exacerbation and 2 weeks post treatment visit.

RESULTS

NE was measured in 90 samples from 30 COPD subjects (18 males) with a mean (range) age of 65 (45-81) years and mean (SD) FEV₁ of 47% (18). The geometric mean (95%CI) of NE at stable state was 2454 ng/mL (1460 to 4125 ng/mL). There was a significant increase in NE levels at an exacerbation (p = 0.003), and NE levels were higher in a bacterial-associated exacerbation (NE log difference 3.873, 95% CI of log difference 1.396 to 10.740, p = 0.011). NE was an accurate predictor of a bacteria-associated exacerbation (area (95%CI) under the receiver operator characteristic curve 0.812 (0.657 to 0.968).

CONCLUSION

NE is elevated during exacerbations of COPD. NE may be a viable biomarker for distinguishing a bacterial exacerbation in patients with COPD.

TRIAL REGISTRATION

Leicestershire, Northamptonshire and Rutland ethics committee (reference number: 07/H0406/157).

New therapeutic targets for the prevention of infectious acute exacerbations of COPD: role of epithelial adhesion molecules and inflammatory pathways

Chronic respiratory diseases are among the leading causes of mortality worldwide, with the major contributor, chronic obstructive pulmonary disease (COPD) accounting for approximately 3 million deaths annually. Frequent acute exacerbations (AEs) of COPD (AECOPD) drive clinical and functional decline in COPD and are associated with accelerated loss of lung function, increased mortality, decreased health-related quality of life and significant economic costs. Infections with a small subgroup of pathogens precipitate the majority of AEs and consequently constitute a significant comorbidity in COPD. However, current pharmacological interventions are ineffective in preventing infectious exacerbations and their treatment is compromised by the rapid development of antibiotic resistance. Thus, alternative preventative therapies need to be considered. Pathogen adherence to the pulmonary epithelium through host receptors is the prerequisite step for invasion and subsequent infection of surrounding structures. Thus, disruption of bacterial-host cell interactions with receptor antagonists or modulation of the ensuing inflammatory profile present attractive avenues for therapeutic development. This review explores key mediators of pathogen-host interactions that may offer new therapeutic targets with the potential to prevent viral/bacterial-mediated AECOPD. There are several conceptual and methodological hurdles hampering the development of new therapies that require further research and resolution.

Metabolomics and transcriptomics pathway approach reveals outcome-specific perturbations in COPD

Chronic obstructive pulmonary disease (COPD) comprises multiple phenotypes such as airflow obstruction, emphysema, and frequent episodes of acute worsening of respiratory symptoms, known as exacerbations. The goal of this pilot study was to test the usefulness of unbiased metabolomics and transcriptomics approaches to delineate biological pathways associated with COPD phenotypes and outcomes. Blood was collected from 149 current or former smokers with or without COPD and separated into peripheral blood mononuclear cells (PBMC) and plasma. PBMCs and plasma were analyzed using microarray and liquid chromatography mass spectrometry, respectively. Statistically significant transcripts and compounds were mapped to pathways using IMPaLA. Results showed that glycerophospholipid metabolism was associated with worse airflow obstruction and more COPD exacerbations. Sphingolipid metabolism was associated with worse lung function outcomes and exacerbation severity requiring hospitalizations. The strongest associations between a pathway and a certain COPD outcome were: fat digestion and absorption and T cell receptor signaling with lung function outcomes; antigen processing with exacerbation frequency; arginine and proline metabolism with exacerbation severity; and oxidative phosphorylation with emphysema. Overlaying transcriptomic and metabolomics datasets across pathways enabled outcome and phenotypic differences to be determined. Findings are relevant for identifying molecular targets for animal intervention studies and early intervention markers in human cohorts.

Proteases and Their Inhibitors in Chronic Obstructive Pulmonary Disease

In the context of respiratory disease, chronic obstructive pulmonary disease (COPD) is the leading cause of mortality worldwide. Despite much development in the area of drug development, currently there are no effective medicines available for the treatment of this disease. An imbalance in the protease: Antiprotease ratio in the COPD lung remains an important aspect of COPD pathophysiology and several studies have shown the efficacy of antiprotease therapy in both in vitro and in vivo COPD models. However more in-depth studies will be required to validate the efficacy of lead drug molecules targeting these proteases. This review discusses the current status of protease-directed drugs used for treating COPD and explores the future prospects of utilizing the potential of antiprotease-based therapeutics as a treatment for this disease.

Evaluation of Systemic Corticosteroids in Patients With an Acute Exacerbation of COPD and a Diagnosis of Pneumonia

Background: Chronic obstructive pulmonary disease (COPD) and pneumonia are leading causes of morbidity and mortality and are frequently comorbid. Studies of systemic corticosteroids in pneumonia have shown conflicting outcomes, whereas studies in acute exacerbations of COPD (AECOPD) have shown significant benefits. No studies have evaluated systemic corticosteroids in patients with both an AECOPD and pneumonia. Purpose: To evaluate the use of systemic corticosteroids in patients with both an AECOPD and pneumonia. Patients and Methods: Patients with a diagnosis of both COPD or obstructive chronic bronchitis with exacerbation and pneumonia admitted to the University of Colorado Hospital between July 1, 2012 and May 20, 2016 were retrospectively evaluated. Patients who received systemic corticosteroids were compared to those that did not. The primary outcome was length of hospital stay (LOHS). Secondary outcomes were in-hospital treatment failure, a composite of intensive care unit (ICU) admission, ventilation, and escalation of steroid therapy, 30-day AECOPD or pneumonia readmission, and 30-day mortality. Results: A total of 138 patients were included-- 89 in the steroid group and 49 in the non-steroid group. No significant differences in baseline characteristic were noted. No difference was seen in mean LOHS (4.7±3.2 versus 4.2±2.1 days, p=0.27), in-hospital treatment failure (7% versus 4%, p=0.72), 30-day readmission or 30-day mortality between the steroid and non-steroid groups, respectively. There was a difference in mean LOHS for patients with severe pneumonia between the steroid and non-steroid groups (6.0±4.0 versus 4.3±1.8; p=0.03). Conclusions: This study suggests that systemic corticosteroids may not provide a clinical benefit to patients with an AECOPD and pneumonia.

Sputum microbiome temporal variability and dysbiosis in chronic obstructive pulmonary disease exacerbations: an analysis of the COPDMAP study

Background

Recent studies suggest that lung microbiome dysbiosis, the disease associated disruption of the lung microbial community, might play a key role in chronic obstructive pulmonary disease (COPD) exacerbations. However, characterising temporal variability of the microbiome from large longitudinal COPD cohorts is needed to better understand this phenomenon.

Methods

We performed a 16S ribosomal RNA survey of microbiome on 716 sputum samples collected longitudinally at baseline and exacerbations from 281 subjects with COPD at three UK clinical centres as part of the COPDMAP consortium.

Results

The microbiome composition was similar among centres and between stable and exacerbations except for a small significant decrease of Veillonella at exacerbations. The abundance of Moraxella was negatively associated with bacterial alpha diversity. Microbiomes were distinct between exacerbations associated with bacteria versus eosinophilic airway inflammation. Dysbiosis at exacerbations, measured as significant within subject deviation of microbial composition relative to baseline, was present in 41% of exacerbations. Dysbiosis was associated with increased exacerbation severity indicated by a greater fall in forced expiratory volume in one second, forced vital capacity and a greater increase in CAT score, particularly in exacerbations with concurrent eosinophilic inflammation. There was a significant difference of temporal variability of microbial alpha and beta diversity among centres. The variation of beta diversity significantly decreased in those subjects with frequent historical exacerbations.

Conclusions

Microbial dysbiosis is a feature of some exacerbations and its presence, especially in concert with eosinophilic inflammation, is associated with more severe exacerbations indicated by a greater fall in lung function.

Trial registration number

Results, NCT01620645.

A Prospective Study of Bacteriological Etiology in Hospitalized Acute Exacerbation of COPD Patients: Relationship with Lung Function and Respiratory Failure

OBJECTIVES

Bacterial infections are the major cause of acute exacerbation of COPD (AE-COPD). The relationship between lung functions and respiratory failure (arterial blood gas parameters) with the etiology of AE-COPD has not been clearly understood. We conducted this study to determine the bacterial profile in AE-COPD and to identify the associated risk factors and drug sensitivity pattern.

MATERIAL AND METHODS

Seventy-two patients hospitalized for AE-COPD were prospectively evaluated. Quantitative sputum culture, blood gas analysis, and drug sensitivity testing were performed at the time of admission, and pulmonary function testing was performed 6 weeks after discharge as per standard guidelines.

RESULTS

Bacterial pathogens were isolated in 34 (47.22%) cases. Pathogens isolated were Pseudomonas aeruginosa (38.23%), Klebsiella pneumoniae (29.41%), Staphylococcus aureus (23.53%), Streptococcus pneumoniae (5.88%), and Acinetobacter spp. (2.94%). Isolation of bacterial pathogen was observed in patients with advancing age (p=0.02), frequent exacerbations (p<0.001), systemic steroid use (p=0.005), and deranged lung function (p=0.02). Binary logistic regression analysis revealed that higher partial pressure of carbon dioxide (PaCO2) was independently associated with isolation of K. pneumoniae (p=0.025) and P. aeruginosa (p=0.001). Additional independent factors that favor isolation of K. pneumoniae were age >55 years (p=0.017) and systemic steroid use (p=0.017). Antibiotic sensitivity testing showed that ciprofloxacin and piperacillin/tazobactum were effective in 27/34 (79.41%) of isolates followed by gentamycin in 26/34 (76%).

CONCLUSION

Hypercapnic respiratory failure is an independent risk factor for isolation of K. pneumoniae and P. aeruginosa in addition to advanced age and systemic steroid use. These findings may be an important adjunct in deciding the initial antibiotic therapy.

Chryseobacterium indolegenes infection in a patient with chronic obstructive pulmonary disease

Chryseobacterium indolegenes is a rare pathogen that causes a variety of infections in inviduals who are mostly hospitalized with severe underlying diseases. Here we present a case of C. indolegenes in a 69-year-old male with chronic obstructive pulonary disease (COPD) who was admitted to the chest disease outpatient clinic with symptoms like cough, fever and sputum production and followed up on a suspicion of pneumonia. Despite the fact that our patient did not have any history of hospitalization for at least one year, pneumonia cause was due to C. indolegenes. Clinicians should pay attention to the rare pathogens such as C. indologenes while managing COPD patients without prior hospitalization history.

Investigating the role of pentraxin 3 as a biomarker for bacterial infection in subjects with COPD

Background

Pentraxin 3 (PTX3) is an acute phase protein, involved in antibacterial resistance. Recent studies have shown PTX3 levels to be elevated in the presence of a bacterial infection and in a murine sepsis model.

Objective

We aim to investigate if sputum PTX3 can be used as a biomarker for bacterial infection in subjects with COPD.

Materials and methods

Sputum samples from 142 COPD patients (102 men) with a mean (range) age of 69 years (45–85) and mean (SD) post-bronchodilator percentage predicted forced expiratory volume in 1 second (FEV₁) of 50% (19) were analyzed for PTX3, using a commercial assay at stable state and during an exacerbation. Association with bacteria, from culture, quantitative real-time polymerase chain reaction (qPCR) and colony-forming units (CFU) was investigated.

Results

The geometric mean (95% CI) PTX3 level at stable state was 50.5 ng/mL (41.4–61.7). PTX3 levels correlated with absolute neutrophil count in sputum (r=0.37; P<0.01), but not FEV₁ or health status. There was a weak correlation between PTX3 and bacterial load (CFU: r=0.29, P<0.01; 16S qPCR: r=0.18, P=0.05). PTX3 was a poor predictor of bacterial colonization (defined as >10⁵ CFU/mL at stable state) with a receiver-operating characteristic (ROC) area under the curve (AUC) of 0.59 and 95% confidence interval (CI) 0.43–0.76 (P=0.21). During an exacerbation, there was a modest increase in PTX3 (fold difference 0.15, 95% of difference 0.02–0.29; P=0.02), and PTX3 fared better at identifying a bacteria-associated exacerbation (ROC AUC 0.65, 95% CI 0.52–0.78, P=0.03).

Conclusion

PTX3 is associated with bacterial infection in patients with COPD, but its utility as a biomarker for identifying a bacteria-associated exacerbation warrants further studies.

Impact of micro-environmental changes on respiratory tract infections with intracellular bacteria

Community-acquired pneumonia is caused by intra- and extracellular bacteria, with some of these bacteria also being linked to the pathogenesis of chronic lung diseases, including asthma and chronic obstructive pulmonary disease. Chlamydia pneumoniae is an obligate intracellular pathogen that is highly sensitive to micro-environmental conditions controlling both pathogen growth and host immune responses. The availability of nutrients, as well as changes in oxygen, pH and interferon-γ levels, have been shown to directly influence the chlamydial life cycle and clearance. Although the lung has been traditionally regarded as a sterile environment, sequencing approaches have enabled the identification of a large number of bacteria in healthy and diseased lungs. The influence of the lung microbiota on respiratory infections has not been extensively studied so far and data on chlamydial infections are currently unavailable. In the present study, we speculate on how lung microbiota might interfere with acute and chronic infections by focusing exemplarily on the obligate intracellular C. pneumoniae. Furthermore, we consider changes in the gut microbiota as an additional player in the control of lung infections, especially in view the increasing evidence suggesting the involvement of the gut microbiota in various immunological processes throughout the human body.

TLR9 expression is required for the development of cigarette smoke-induced emphysema in mice

The expression of Toll-like receptor (TLR)-9, a pathogen recognition receptor that recognizes unmethylated CpG sequences in microbial DNA molecules, is linked to the pathogenesis of several lung diseases. TLR9 expression and signaling was investigated in animal and cell models of chronic obstructive pulmonary disease (COPD). We observed enhanced TLR9 expression in mouse lungs following exposure to cigarette smoke. Tlr9(-/-) mice were resistant to cigarette smoke-induced loss of lung function as determined by mean linear intercept, total lung capacity, lung compliance, and tissue elastance analysis. Tlr9 expression also regulated smoke-mediated immune cell recruitment to the lung; apoptosis; expression of granulocyte-colony stimulating factor (G-CSF), the CXCL5 protein, and matrix metalloproteinase-2 (MMP-2); and protein tyrosine phosphatase 1B (PTP1B) activity in the lung. PTP1B, a phosphatase with anti-inflammatory abilities, was identified as binding to TLR9. In vivo delivery of a TLR9 agonist enhanced TLR9 binding to PTP1B, which inactivated PTP1B. Ptp1b(-/-) mice had elevated lung concentrations of G-CSF, CXCL5, and MMP-2, and tissue expression of type-1 interferon following TLR9 agonist administration, compared with wild-type mice. TLR9 responses were further determined in fully differentiated normal human bronchial epithelial (NHBE) cells isolated from nonsmoker, smoker, and COPD donors, and then cultured at air liquid interface. NHBE cells from smokers and patients with COPD expressed more TLR9 and secreted greater levels of G-CSF, IL-6, CXCL5, IL-1β, and MMP-2 upon TLR9 ligand stimulation compared with cells from nonsmoker donors. Although TLR9 combats infection, our results indicate that TLR9 induction can affect lung function by inactivating PTP1B and upregulating expression of proinflammatory cytokines.

Lung microbiome dynamics in COPD exacerbations

Increasing evidence suggests that the lung microbiome plays an important role in chronic obstructive pulmonary disease (COPD) severity. However, the dynamics of the lung microbiome during COPD exacerbations and its potential role in disease aetiology remain poorly understood.We completed a longitudinal 16S ribosomal RNA survey of the lung microbiome on 476 sputum samples collected from 87 subjects with COPD at four visits defined as stable state, exacerbation, 2 weeks post-therapy and 6 weeks recovery.Our analysis revealed a dynamic lung microbiota where changes appeared to be associated with exacerbation events and indicative of specific exacerbation phenotypes. Antibiotic and steroid treatments appear to have differential effects on the lung microbiome. We depict a microbial interaction network for the lung microbiome and suggest that perturbation of a few bacterial operational taxonomic units, in particular Haemophilus spp., could greatly impact the overall microbial community structure. Furthermore, several serum and sputum biomarkers, in particular sputum interleukin-8, appear to be highly correlated with the structure and diversity of the microbiome.Our study furthers the understanding of lung microbiome dynamics in COPD patients and highlights its potential as a biomarker, and possibly a target, for future respiratory therapeutics.

Effects of Mycotoxins on mucosal microbial infection and related pathogenesis

Mycotoxins are fungal secondary metabolites detected in many agricultural commodities and water-damaged indoor environments. Susceptibility to mucosal infectious diseases is closely associated with immune dysfunction caused by mycotoxin exposure in humans and other animals. Many mycotoxins suppress immune function by decreasing the proliferation of activated lymphocytes, impairing phagocytic function of macrophages, and suppressing cytokine production, but some induce hypersensitive responses in different dose regimes. The present review describes various mycotoxin responses to infectious pathogens that trigger mucosa-associated diseases in the gastrointestinal and respiratory tracts of humans and other animals. In particular, it focuses on the effects of mycotoxin exposure on invasion, pathogen clearance, the production of cytokines and immunoglobulins, and the prognostic implications of interactions between infectious pathogens and mycotoxin exposure.

Housing conditions modulate the severity of Mycoplasma pulmonis infection in mice deficient in class A scavenger receptor

Mycoplasmosis is a frequent causative microbial agent of community-acquired pneumonia and has been linked to exacerbation of chronic obstructive pulmonary disease. The macrophage class A scavenger receptor (SRA) facilitates the clearance of noxious particles, oxidants, and infectious organisms by alveolar macrophages. We examined wildtype and SRA(-/-) mice, housed in either individually ventilated or static filter-top cages that were cycled with fresh bedding every 14 d, as a model of gene-environment interaction on the outcome of pulmonary Mycoplasma pulmonis infection. Intracage NH3 gas measurements were recorded daily prior to infection. Mice were intranasally infected with 1 × 10(7) cfu M. pulmonis UAB CT and evaluated at 3, 7, and 14 d after inoculation. Wildtype mice cleared 99.5% of pulmonary M. pulmonis by 3 d after infection but remained chronically infected through the study. SRA (-/-) mice were chronically infected with 40-fold higher mycoplasma numbers than were wildtype mice. M. pulmonis caused a chronic mixed inflammatory response that was accompanied with high levels of IL1β, KC, MCP1, and TNFα in SRA(-/-) mice, whereas pulmonary inflammation in WT mice was represented by a monocytosis with elevation of IL1β. Housing had a prominent influence on the severity and persistence of mycoplasmosis in SRA(-/-) mice. SRA(-/-) mice housed in static cages had an improved recovery and significant changes in surfactant proteins SPA and SPD compared with baseline levels. These results indicate that SRA is required to prevent chronic mycoplasma infection of the lung. Furthermore, environmental conditions may exacerbate chronic inflammation in M. pulmonis-infected SRA(-/-) mice.

Airway epithelial platelet-activating factor receptor expression is markedly upregulated in chronic obstructive pulmonary disease

BACKGROUND

We recently published that platelet-activating factor receptor (PAFr) is upregulated on the epithelium of the proximal airways of current smokers and also in bronchial epithelial cells exposed to cigarette smoke extract. These treated cells also showed upregulation of Streptococcus pneumoniae adhesion. Bacterial wall phosphorylcholine specifically binds to PAFr expressed on airway epithelium, thus facilitating adherence and tissue invasion, which may be relevant to chronic obstructive pulmonary disease (COPD). Moreover, the use of inhaled corticosteroids (ICS) in COPD patients is associated with an increased risk of invasive respiratory pneumococcal infections.

OBJECTIVE

In this study, we have investigated whether PAFr expression is especially upregulated in airway epithelium in COPD patients and whether this expression may be modulated by ICS therapy.

METHODS

We cross-sectionally evaluated PAFr expression in bronchial biopsies from 15 COPD patients who were current smokers (COPD-smokers) and 12 COPD-ex-smokers, and we compared these to biopsies from 16 smokers with normal lung function. We assessed immunostaining with anti-PAFr monoclonal antibody. We also used material from a previous double-blinded randomized placebo-controlled 6-month ICS intervention study in COPD patients to explore the effect of ICS on PAFr expression. We employed computer-aided image analysis to quantify the percentage of epithelium stained for PAFr.

RESULTS

Markedly enhanced expression of PAFr was found in both COPD-smokers (P<0.005) and COPD-ex-smokers (P<0.002) compared to smokers with normal lung function. There was little evidence that PAFr expression was affected by ICS therapy over 6 months.

CONCLUSION

Epithelial PAFr expression is upregulated in smokers, especially in those with COPD, and is not obviously affected by ICS therapy.

Detection of microorganisms in exhaled breath condensate during acute exacerbations of COPD

BACKGROUND AND OBJECTIVE

One hallmark of COPD is colonization and infection of the lung. Acute exacerbations of COPD (AECOPD) are acute deteriorations of the chronic disease and are associated with a change of the pulmonary microbial balance. The collection of exhaled breath condensate (EBC) can be used to non-invasively determine markers of lung disease. The aim of the present study was to compare the results of assays based on the detection of microbial nucleic acids from EBC and from spontaneous sputum in patients with AECOPD.

METHODS

EBC and sputa of 29 adults with AECOPD were obtained. Isolated DNA or RNA were used as starting material for the PCR assays to detect Staphylococcus aureus, Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pneumoniae, Legionella pneumophila, Mycoplasma pneumoniae, Chlamydia pneumoniae, influenza viruses (AH 1, AH 3) and respiratory syncytial virus.

RESULTS

Bacterial or viral nucleic acids were identified in 14 EBC and 21 sputa from 29 patients. Results from EBC did not correlate well with those from sputum. Viral and S. pneumoniae nucleic acids were detected only in sputum, whereas L. pneumophila DNA was only found in EBC. In three EBC and 10 sputa nucleic acids of more than one microorganism was detected.

CONCLUSIONS

Bacterial nucleic acids can be identified in EBC of COPD patients with exacerbations. The results obtained from EBC and sputum did not correlate well.

Guidelines for the management of adult lower respiratory tract infections--full version

This document is an update of Guidelines published in 2005 and now includes scientific publications through to May 2010. It provides evidence-based recommendations for the most common management questions occurring in routine clinical practice in the management of adult patients with LRTI. Topics include management outside hospital, management inside hospital (including community-acquired pneumonia (CAP), acute exacerbations of COPD (AECOPD), acute exacerbations of bronchiectasis) and prevention. Background sections and graded evidence tables are also included. The target audience for the Guideline is thus all those whose routine practice includes the management of adult LRTI.

Oral hygiene, periodontal health and chronic obstructive pulmonary disease exacerbations

AIM

To assess the associations of oral hygiene and periodontal health with chronic obstructive pulmonary disease (COPD) exacerbations.

MATERIAL AND METHODS

In total, 392 COPD patients were divided into frequent and infrequent exacerbation (≥2 times and <2 times in last 12 months) groups. Their lung function and periodontal status were examined. Information on oral hygiene behaviours was obtained by interview.

RESULTS

In the univariate analysis, fewer remaining teeth, high plaque index (PLI) scores, low tooth brushing times, and low regular supra-gingival scaling were significantly associated with COPD exacerbations (all p-values <0.05). After adjustment for age, gender, body mass index, COPD severity and dyspnoea severity, the associations with fewer remaining teeth (p = 0.02), high PLI scores (p = 0.02) and low tooth brushing times (p = 0.008) remained statistically significant. When stratified by smoking, fewer remaining teeth (OR = 2.05, 95% CI: 1.04-4.02) and low tooth brushing times (OR = 4.90, 95% CI: 1.26-19.1) among past smokers and high PLI scores (OR = 3.43, 95% CI: 1.19-9.94) among never smokers were significantly associated with COPD exacerbations.

CONCLUSIONS

Fewer remaining teeth, high PLI scores, and low tooth brushing times are significant correlates of COPD exacerbations, indicating that improving periodontal health and oral hygiene may be a potentially preventive strategy against COPD exacerbations.

Management of bacterial infections in children with asthma

Respiratory viruses are the single most common causes of asthma exacerbations in children. Rhinovirus-induced wheezing is a risk factor for chronic asthma, but its mechanism has remained unknown. Human bocavirus is a common finding in wheezing children, but its role as a respiratory pathogen is still unclear. Mycoplasma pneumoniae may, like viruses, induce wheezing and asthma exacerbation. Chlamydia pneumoniae and, in recent studies, Chlamydia trachomatis, may not only induce asthma exacerbations but may also be involved in the pathogenesis of chronic asthma. Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis are often involved in respiratory infections associated with wheezing, but there is no evidence for their active role in asthma pathogenesis or exacerbation. This review summarizes current knowledge on the association between respiratory infections and asthma in children, with a special focus on the role of antibiotics in incipient asthma, asthma exacerbation and chronic stable asthma.