Bacterial infection and risk factors in outpatients with acute exacerbation of chronic obstructive pulmonary disease: a 2-year prospective study

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.

Acute Moraxella catarrhalis Airway Infection of Chronically Smoke-Exposed Mice Increases Mechanisms of Emphysema Development: A Pilot Study

In chronic obstructive pulmonary disease (COPD), acute exacerbations and emphysema development are characteristics for disease pathology. COPD is complicated by infectious exacerbations with acute worsening of respiratory symptoms with Moraxella catarrhalis as one of the most frequent pathogens. Although cigarette smoke (CS) is the primary risk factor, additional molecular mechanisms for emphysema development induced by bacterial infections are incompletely understood. We investigated the impact of M. catarrhalis on emphysema development in CS exposed mice and asked whether an additional infection would induce a solubilization of pro-apoptotic and pro-inflammatory endothelial monocyte-activating-protein-2 (EMAPII) to exert its activities in the pulmonary microvas-culature and other parts of the lungs not exposed directly to CS.

Mice were exposed to smoke (6 or 9 months) and/or infected with M. catarrhalis. Lungs, bronchoalveolar lavage fluid (BALF), and plasma were analyzed.

CS exposure reduced ciliated area, caused rarefaction of the lungs, and induced apoptosis. EMAPII was increased independent of prior smoke exposure in BALF of infected mice. Importantly, acute M. catarrhalis infection increased release of matrixmetalloproteases-9 and -12, which are involved in emphysema development and comprise a mechanism of EMAPII release.

Our data suggest that acute M. catarrhalis infection represents an independent risk factor for emphysema development in smoke-exposed mice.

Moraxella catarrhalis induces an immune response in the murine lung that is independent of human CEACAM5 expression and long-term smoke exposure

In patients with chronic obstructive pulmonary disease (COPD), Moraxella catarrhalis infection of the lower airways is associated with chronic colonization and inflammation during stable disease and acute exacerbations. Chronic smoke exposure induces chronic inflammation and impairs mucociliary clearance, thus contributing to bacterial colonization of the lower airways in COPD patients. The human-specific carcinoembryonic antigen-related cell adhesion molecule (CEACAM) 5, expressed in human airways, has been shown to contribute to epithelial colonization of CEACAM-binding pathogens. To investigate the impact of CEACAM5 expression on pulmonary M. catarrhalis colonization, we infected mice transgenic for human CEACAM5 (hCEACAM5) and wild type mice intratracheally with M. catarrhalis with or without preceding smoke exposure and analyzed bacterial colonization and local and systemic inflammation. Our results show that airway infection with M. catarrhalis accelerated acute local but not systemic inflammation, albeit independent of hCEACAM5 expression. Long-term smoke exposure alone or prior to M. catarrhalis infection did not contribute to increased local or systemic inflammation. No difference was found in pulmonary clearance of M. catarrhalis in hCEACAM5-transgenic mice compared with wild-type mice. Smoke exposure neither altered time nor extent of persistence of M. catarrhalis in the lungs of both genotypes. In conclusion, M. catarrhalis induced a local acute immune response in murine airways. Neither hCEACAM5 expression nor chronic smoke exposure nor a combination of both was sufficient as prerequisites for the establishment of chronic M. catarrhalis colonization. Our results demonstrate the difficulties in mirroring conditions of chronic airways colonization of M. catarrhalis in a murine model.

Microbial communities in the upper respiratory tract of patients with asthma and chronic obstructive pulmonary disease

Respiratory infections are well-known triggers of chronic respiratory diseases. Recently, culture-independent tools have indicated that lower airway microbiota may contribute to pathophysiologic processes associated with asthma and chronic obstructive pulmonary disease (COPD). However, the relationship between upper airway microbiota and chronic respiratory diseases remains unclear. This study was undertaken to define differences of microbiota in the oropharynx of asthma and COPD patients relative to those in healthy individuals. To account for the qualitative and quantitative diversity of the 16S rRNA gene in the oropharynx, the microbiomes of 18 asthma patients, 17 COPD patients, and 12 normal individuals were assessed using a high-throughput next-generation sequencing analysis. In the 259,572 total sequence reads, α and β diversity measurements and a generalized linear model revealed that the oropharynx microbiota are diverse, but no significant differences were observed between asthma and COPD patients. Pseudomonas spp. of Proteobacteria and Lactobacillus spp. of Firmicutes were highly abundant in asthma and COPD. By contrast, Streptococcus, Veillonella, Prevotella, and Neisseria of Bacteroidetes dominated in the healthy oropharynx. These findings are consistent with previous studies conducted in the lower airways and suggest that oropharyngeal airway microbiota are important for understanding the relationships between the various parts of the respiratory tract with regard to bacterial colonization and comprehensive assessment of asthma and COPD.

Molecular characterization of clinical isolates of Moraxella catarrhalis by randomly amplified polymorphic DNA fingerprinting

Moraxella catarrhalis, a less virulent microorganism that colonizes the upper respiratory tract, has recently been associated with lower respiratory disease, especially in HIV-positive immunocompromised individuals and children. Here, we correlated the DNA clustering pattern of 24 clinical isolates of M. catarrhalis for β-lactamase production and drug resistance, from different disease groups using three different arbitrarily selected primers, P1 (5'-TCACGATGCA-3'), P14 (5'-GATCAAGTCC-3') and P17 (5'-GATCTGACAC-3'). M. catarrhalis revealed three distinct banding patterns with primer P1, four with P14 and P17. 71% (n = 17) of the isolates revealed pattern 2 with primer P1, which discriminated majority (12/21) of the isolates grouped under the major branch of the dendrogram. The minor branch had only three isolates. Separation of M. catarrhalis into two subpopulations (major and minor clusters) with primer P1 is suggestive of diverse genetic lineage. A high level of concordance between RAPD and antibiotic profile was observed. Clustering of M. catarrhalis recovered from different disease groups reflect the identical clinical background or the common geographical/temporal factors. The presence or absence of β-lactamase in a cluster confirmed their single source of origin.

Guidelines for the management of adult lower respiratory tract infections--summary

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. The target audience for the Guideline is thus all those whose routine practice includes the management of adult LRTI.

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.

Chronic wounds and the medical biofilm paradigm

There is a growing recognition that biofilms are the principal cause of wound chronicity. The development of treatments for wound biofilms raises the prospect that chronic wounds can be treated, potentially saving many patients' lives.

Association between paraoxonase-1 Q192R polymorphism and lung function among Saskatchewan grain handlers

Introduction: Paraoxonase-1 (PON1) is a high-density, lipoprotein-associated, multifunctional antioxidant enzyme that is detected in nonciliated bronchiolar epithelial cells, although its role in the lung has not yet been clarified. We therefore investigated the association between the PON1 Q192R polymorphism and lung function. Patients & Methods: A total of 216 male Saskatchewan grain handlers provided demographic, occupational and respiratory-symptom information by means of questionnaires, and thereafter underwent PON1 Q192R genotyping and lung-function testing. Results: Mean lung-function values did not differ among the Q192R genotypes. However, current smokers with the Q/Q genotype had a higher mean percent predicted forced expiratory volume in the first second (FEV1), and absolute and percent predicted FEV1 per forced vital capacity (FVC) compared with current smokers with at least one 192R allele (100.9 ± 11.2% vs 92.0 ± 15.1%, p = 0.01; 78.0 ± 5.9% vs 74.1 ± 6.8%, p = 0.03; and 96.8 ± 7.1% vs 92.1 ± 8.3%, p = 0.03; respectively). The incidence of subjects with FEV1/FVC less than 70% was significantly higher in current smokers with at least one 192R allele than in nonsmokers with the Q/Q genotype (odds ratio: 5.0; 95% confidence interval: 1.5–17.4). The protective effect of the Q/Q genotype was not found in nonsmokers. The FVC was not influenced by either PON1 genotype or smoking status. Conclusion: The results obtained from grain handlers suggest that PON1 may play some role in the protection of the airways against the toxicity of cigarette smoke, and the 192R allele may be a novel genetic risk factor for airway injury.