Airway inflammation and etiology of acute exacerbations of chronic bronchitis

STUDY OBJECTIVES: The etiologic role of bacterial pathogens isolated from sputum culture in 40 to 50% of acute exacerbations of chronic bronchitis (AECB) is controversial. If bacterial pathogens cause these AECB, they should be associated with greater neutrophilic airway inflammation than pathogen-negative exacerbations. DESIGN: This hypothesis was tested by comparing levels of interleukin (IL)-8, tumor necrosis factor (TNF)-alpha, and neutrophil elastase (NE) in 81 sputum samples obtained from 45 patients with AECB. Four groups were compared. In the first three groups, nontypable Haemophilus influenzae (n = 20), Haemophilus parainfluenzae (n = 27), and Moraxella catarrhalis (n = 14) were isolated as sole pathogens, respectively. In the fourth group, only normal flora was isolated (n = 20). Paired samples, obtained from individual patients at different times, that differed in their culture results were also compared. SETTING: An outpatient research clinic at a Veterans Affairs Medical Center. PATIENTS: These patients were participating in a prospective, longitudinal study of the dynamics of bacterial infection in chronic bronchitis, for which they were seen in the study clinic on a monthly basis as well as when they were experiencing symptoms suggestive of AECB. INTERVENTIONS: None. Measurements and results: H influenzae exacerbations were associated with significantly higher sputum IL-8, TNF-alpha, and NE. M catarrhalis exacerbations demonstrated significantly higher sputum TNF-alpha and NE when compared to pathogen-negative exacerbations. H parainfluenzae-associated exacerbations had an inflammatory profile similar to pathogen-negative exacerbations. Sputum elastase level distinguished bacterial from nonbacterial AECB and correlated with clinical severity of the AECB. CONCLUSIONS: Increased airway inflammation associated with isolation of H influenzae and M catarrhalis supports an etiologic role of these pathogens in AECB.     

Clinical significance of the infection-free interval in the management of acute bacterial exacerbations of chronic bronchitis

Rational and appropriate antibiotic use for patients with acute exacerbation of chronic bronchitis (AECB) is a major concern, as approximately half of these patients do not have a bacterial infection. Typically, the result of antimicrobial therapy for patients with acute bacterial exacerbation of chronic bronchitis (ABECB) is not eradication of the pathogen but resolution of the acute symptoms. However, the length of time before the next bacterial exacerbation can be another important variable, as the frequency of exacerbations will affect the overall health of the patient and the rate of lung deterioration over time. Clinical trials comparing antimicrobial therapies commonly measure resolution of symptoms in AECB patients as the primary end point, regardless of whether the exacerbation is documented as bacterial in nature. Ideally, the scientific approach to assessing the efficacy of antibiotic therapy for ABECB should include a measurement of acute bacterial eradication rates in patients with documented bronchial bacterial infection followed by measurement of the infection-free interval (IFI), ie, the time to the next ABECB. The use of these variables can provide a standard for comparing various antimicrobial therapies. As we learn more about how antibiotics can affect the IFI, treatment decisions should be adapted to ensure optimal management of ABECB for the long-term.     

The workplace impact of acute exacerbations of chronic bronchitis (AECB); A literature review

Acute exacerbations of chronic bronchitis (AECB) are known to have a substantial economic burden in terms of medical care costs. The objective of this study was to assess workplace-based costs associated with AECB, including absenteeism and decreased productivity, based on a review of published literature. A secondary goal was to identify factors related to workplace-based costs in AECB. A literature search was conducted to identify relevant articles assessing one or more aspects of work loss or workplace costs among patients with chronic bronchitis. A review of the identified literature indicates that patients with chronic bronchitis had more days off work; patients whose exacerbations were treated were less likely to have additional exacerbations and had comparatively less work loss. Findings suggest that clinical outcomes and workplace costs are related. While this relationship is clearer in terms of work loss, further exploration is needed to assess decreased productivity and to evaluate this relationship using objective indicators of absenteeism and productivity rather than recall.     

Antibiotic therapy of exacerbations of chronic bronchitis

The role of antibiotics in acute exacerbations of chronic bronchitis (AECB) remains controversial because patients commonly harbor the same bacteria in their sputum at times of stability and at times of acute illness. However, prospective randomized controlled trials do show a benefit for the use of antibiotics, compared with placebo, in AECB, particularly if patients have at least 2 of the following 3 symptoms: increased dyspnea, increased sputum volume, increased sputum purulence. In this setting, antibiotics have value, leading to a more rapid resolution of symptoms and a more rapid return of peak flow rate, compared with placebo. In addition, antibiotics may prevent some patients from developing secondary pneumonia and may prolong the time between exacerbations. When antibiotics are used, a variety of factors must be considered in choosing an agent. These include the likelihood of antibiotic-resistant bacteria, a factor that relates to defining subsets of patients. Patients can fall into 1 of 3 categories, each with a different suggested therapy. These categories include simple AECB, complicated AECB, and AECB at risk for infection with P. aeruginosa. In addition, an antibiotic should be chosen with pharmacokinetics and pharmacodynamic behavior in mind. In the future, research will need to confirm that careful selection of specific agents for specific patients can lead to improved patient outcomes, but already some preliminary data are supporting this concept.     

Antibiotic therapy in acute exacerbations of chronic bronchitis

Chronic obstructive pulmonary disease (COPD) comprises a spectrum of conditions including chronic bronchitis, emphysema, asthma, and bronchiectasis. It has a prevalence in the United States of 5.1% to 5.4% in the middle-aged to elderly population, with a lower rate in nonsmoking individuals. Moreover, COPD is complicated by frequent and recurring acute exacerbations of chronic bronchitis (AECB). Overall, COPD represents the fourth leading cause of mortality in the United States and is the second leading cause of work disability. This condition is also associated with high morbidity and health care expenditures. Despite the controversy over the need to prescribe antibiotics for patients with AECB, high-risk patients have been identified who will benefit from this therapy.These include, patients with a history of repeated infections (>4 per year), comorbid illnesses (such as diabetes, asthma, coronary heart disease), or marked airway obstruction. Furthermore, a bacterial cause is shown in approximately 50% of AECB episodes, and primarily includes Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae. Additionally, resistance among community-acquired respiratory pathogens in the United States has risen dramatically, with beta-lactamase production evident in 40% of H. influenzae and greater than 95% of M. catarrhalis isolates, and with approximately 10% of pneumococci highly resistant to penicillin and simultaneously resistant to macrolide antibiotics. The criteria used to make choices for antibiotic use in patients with AECB should include knowledge of the frequencies of pathogen resistance and patients' clinical characteristics. An effective antibiotic, however, must be able to rapidly resolve the acute infection with the least patient morbidity and need for hospitalization. Although there remains controversy as to when to initiate antibiotic therapy in patients with AECB, several guidelines have been published.     

A review of guidelines for antibacterial use in acute exacerbations of chronic bronchitis

Acute exacerbations of chronic bronchitis (AECB) affect a significant proportion of the adult population worldwide and are associated with a substantial socioeconomic burden. The majority of episodes of AECB are bacterial in aetiology and patients are generally treated empirically with orally administered antibacterial agents. Guidelines for the management of AECB have been developed by a number of national health authorities and international organisations, with the aim of promoting rational selection of antibacterial therapy to minimise the risk of treatment failure and subsequent hospitalisation while containing the development and spread of antibacterial resistance. This paper reviews a number of recently published or updated AECB treatment guidelines, focusing on patient stratification strategies, antibacterial treatment recommendations, and newer antibacterial treatment options, including respiratory fluoroquinolones and the ketolide telithromycin, which have recently been added to a number of national treatment guidelines.     

Treatment of acute exacerbations of chronic bronchitis: antibiotic therapy

Acute exacerbation of chronic bronchitis (AECB) is a condition associated with increased morbidity and mortality. Bacterial infections are the most frequent cause of exacerbations. The most common bacterial etiologies include Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumonia. The diagnosis of AECB is often based on the clinical presentation, but microbiological assessment, including Gram stain and sputum culture should be done. Antibiotic therapy should be used in patients with the following characteristics: underlying lung disease, frequent exacerbations, and comorbid conditions. Penicillins, erythromycin, beta-lactamase inhibitors, and trimethoprim-sulfamethoxazole have been the preferred antibiotics. However, because of the increasing prevalence of resistance among respiratory pathogens, mainly the production of beta-lactamase by H. influenzae and M. catarrhalis, and the emergence of multidrug-resistant S. pneumonia, new generation macrolides and fluoroquinolones should be the first line of treatment in selected patients. These drugs have increased efficacy and safety.     

The role of antimicrobial therapy in acute exacerbations of chronic bronchitis.

Acute exacerbations of chronic bronchitis (AECB) result in increased morbidity and mortality. The role of bacteria in AECB, the importance of antimicrobial therapy, and the choice of antimicrobial agents have been debated for decades. Fortunately, within the past few years, a number of studies and one consensus statement have been reported that have increased the understanding of the role of bacteria in AECB and suggest approaches in selecting antimicrobial therapy. This article will review these studies and present an empiric approach in treating AECB based upon the patient's presenting findings, related risk factors, and potential antimicrobial resistance patterns that may be encountered.     

Introduction: the role of bacterial infection in chronic bronchitis

Acute exacerbations of chronic bronchitis reflect increased airway inflammation and are characterised by one or more symptoms of increased sputum production, sputum purulence, and breathlessness. The causes are multifactorial, and bacterial infection is involved in about half of cases. A proportion of patients also have chronic colonization of the bronchial tree between exacerbations, and this may act as a stimulant of airway inflammation. Colonization represents a balance in which compromised host defences limit bacterial numbers but do not eradicate them.The balance is upset during an exacerbation, often due to extraneous factors such as a viral infection or air pollution, leading to increased bacterial numbers and consequently more inflammation. In patients with severe airway damage, infective exacerbations are more likely to occur, and serious consequences may result if baseline lung function is impaired or there are comorbid conditions. In these circumstances, the exacerbation is less likely to resolve spontaneously. Antibiotic treatment benefits patients by achieving bacterial eradication and resolution of the inflammatory response. However, since superficial mucosal infections may resolve spontaneously, there are serious concerns about widespread antibiotic use in patients with more trivial illness. Future studies should include better definition of the type of patients enrolled, improved techniques to determine bacteriological response, and better outcome measures.     

Infection in acute exacerbations of chronic bronchitis: a clinical perspective

Acute exacerbations of chronic bronchitis (AECB) is an important cause of death and morbidity in developed countries and also has significant economic impact. The disease is characterized by increased dyspnoea, sputum volume and sputum purulence; the most commonly associated pathogens are Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis. H. influenzae and S. pneumoniae express virulence determinants that directly and indirectly impair mucociliary clearance and incite other consequences that are permissive to microbial persistence. Regarding the use of antibiotics, there is currently a lack of large-scale clinical trials that are sufficiently powerful to provide good evidence-based information. Nonetheless, antimicrobial chemotherapy has repeatedly been shown to confer benefit in patients with moderately severe features of AECB. Simple clinical criteria can be used to identify patients in whom there is a higher likelihood of treatment failure or mortality during AECB. These include significant cardiopulmonary co-morbidity, frequent exacerbations, advanced decline in lung function, malnutrition or other generalized debility, advanced age (>70 years) and concurrent treatment with corticosteroids. In such patients, an aggressive antimicrobial approach to AECB may be warranted in order to prevent clinical failure or representation. From a clinical perspective, appropriate drugs include those that are stable to beta-lactamases, are bactericidal against causative pathogens, penetrate diseased lung tissue in high concentrations and have a good safety profile.     

Factors associated with relapse after ambulatory treatment of acute exacerbations of chronic bronchitis. DAFNE Study Group.

This study aimed to identify the risk factors for relapse after ambulatory treatment of acute exacerbations of chronic bronchitis (AECB) that can easily be used in a primary care setting. Data were prospectively collected on 2,414 ambulatory patients with AECB from 268 general practices located throughout Spain. A multivariate model to identify risk factors independently associated with failures was developed and validated from the information recorded at the inclusion visit and at 30-days follow-up visit. A total of 507 patients relapsed (21%); of these, 84 required admission (16.5%). The multivariate model for prediction of the risk of relapse included 2,414 cases: 1,689 for the developmental sample and 725 in the validation sample. The model obtained contained three readily-obtainable variables: ischaemic heart disease (odds ratio (OR)=1.63; 95% confidence interval (CI)=1.07-2.47), degree of dyspnoea (OR = 1.31; 1.14-1.50) and number of visits to the general practitioner the previous year (OR = 1.07; 1.04-1.10). The model calibrated well in developmental and validation samples (goodness-of-fit tests: p = 0.295 and p = 0.637, respectively). Severity of the exacerbation was not associated with increased risk of relapse in either univariate or multivariate analysis. The present results suggest that baseline characteristics of the patients such as degree of dyspnoea, coexisting ischaemic heart disease and number of previous visits to the general practitioner for respiratory problems are strongly associated with increased risk of relapse after ambulatory treatment of acute exacerbations of chronic bronchitis. In contrast, exacerbation severity was not associated with clinical failure. Guidelines for management of acute exacerbations of chronic bronchitis should consider such risk factors and advocate intensive broad spectrum treatment and closer follow-up of patients exhibiting them.     

Evidence of bacterial infection in acute exacerbations of chronic bronchitis

The frequency with which bacterial infection causes exacerbations of chronic obstructive pulmonary disease (COPD) may depend on the dominant pathology present; patients with chronic bronchitis are more susceptible to bacterial bronchial infections than those at the emphysema or asthma ends of the spectrum. However, impairment in respiratory function may be very important in governing the outcome of an exacerbation. Placebo-controlled trials have provided conflicting evidence of the efficacy of antibiotics in acute exacerbations. Overall, there is a significant benefit, particularly in certain patient groups, defined by symptoms and past history. Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis are the species most commonly isolated during exacerbations, and the same species may colonize the bronchial mucosa when the patient is in a stable state. Evidence is accumulating that bacteria are an independent stimulus of mucus hypersecretion and bronchial inflammation, and that they interact with other stimuli such as viral infection, atmospheric pollution, and tobacco smoke. New approaches are being used to investigate the importance of bacterial infection in patients with COPD.There are several good reasons why new more potent antibiotics might be expected to be superior to older standard compounds in the management of patients with problematic COPD. However, future studies should aim to confirm that bacteriologic superiority translates into improved clinical outcomes, and seek to measure the level of benefit.     

Antibiotic therapy for exacerbation

Bacterial infections are involved in approximately 50% of acute exacerbations of chronic bronchitis (AECB). Pneumococci, Haemophilus influenzae and Moraxella catarrhalis are the main pathogens. Studies using quantitative cultures and molecular typing suggest a causal relationship between bacterial infection and exacerbation. Furthermore, an association between infection and bronchial inflammation has been demonstrated. In contrast to steroid therapy and non-invasive ventilation, the benefits of antibiotic treatment are not well established. Current guidelines recommend antimicrobial therapy for AECB in type I exacerbations, for patients needing ventilatory support and for patients with cardiac comorbidity. Bacterial eradication is able to prolong the infection free interval.     

Antibiotikatherapie bei Exazerbation

Bacterial infections are involved in approximately 50% of acute exacerbations of chronic bronchitis (AECB). Pneumococci, Haemophilus influenzae and Moraxella catarrhalis are the main pathogens. Studies using quantitative cultures and molecular typing suggest a causal relationship between bacterial infection and exacerbation. Furthermore, an association between infection and bronchial inflammation has been demonstrated. In contrast to steroid therapy and non-invasive ventilation, the benefits of antibiotic treatment are not well established. Current guidelines recommend antimicrobial therapy for AECB in type I exacerbations, for patients needing ventilatory support and for patients with cardiac comorbidity. Bacterial eradication is able to prolong the infection free interval.     

Prophylactic treatment of chronic bronchitis

Exacerbations of chronic bronchitis may be caused by a variety of bacterial and viral agents. There is ample documentation of a role for Hemophilus influenza, Streptococcus pneumonia, Mycoplasma pneumoniae, influenza A and B viruses, and several other respiratory viruses in causing these exacerbations. Because of the lack of frequency of exacerbations (once every 20 to 78 weeks) and the wide range of pathogens, trials of prophylaxis with antibiotics have been difficult to conduct. Controlled trials conducted since the 1950s have shown mixed results, some demonstrating a reduction in the number of exacerbations and others failing to show efficacy. Of the antibiotics used, tetracycline seemed the most effective. Both the pneumococcal polysaccharide and killed influenza virus vaccines have been suggested for patients with chronic bronchitis. The antiviral drug amantadine has been recommended when vaccine cannot be used. This reviewer concludes that prophylactic antibiotics should be used in selected patients with one or more exacerbations yearly using a drug such as tetracycline. A one-time dose of pneumococcal vaccine and the annual use of killed influenza vaccine are also reasonable. During an influenza A epidemic, amantadine should be considered for unvaccinated patients. Future studies should study intermittent v chronic prophylaxis with cheap but appropriate antibiotics (chosen for their microbial spectrum), and should test newer antiviral vaccines and antiviral drugs as they become available.     

The safety and efficacy of short course (5-day) moxifloxacin vs. azithromycin in the treatment of patients with acute exacerbation of chronic bronchitis

Chronic bronchitis is common among adults and infectious exacerbations contribute considerably to morbidity and mortality. We aimed to compare the safety and efficacy of moxifloxacin to azithromycin for the treatment of patients with acute exacerbations of chronic bronchitis (AECB) of suspected bacterial origin. Between October 1998 and April 1999, 567 patients with AECB were enrolled at 37 centers across the United States and Canada of which 280 (49%) had acute bacterial exacerbation of chronic bronchitis (i.e. pretherapy pathogen). Patients were randomized to either oral moxifloxacin 400 mg administered once daily for 5 days or azithromycin for 5 days (500 mg qd x 1, then 250 mg qd x 4). For the purpose of study blinding, all patients received encapsulated tablets. The main outcome measure was clinical response at the test-of-cure visit (14-21 days post-therapy). Secondary measures included bacteriologic response and a time-course of bacteriological eradication (one center only). Three patient populations were analysed for efficacy: clinically-valid, microbiologically-valid (i.e. those with a pretherapy pathogen), and intent-to-treat (i.e. received at least one dose of study drug). For the efficacy-valid group, clinical response at the test-of-cure visit was 88% for patients in each treatment group. In 237 microbiologically-valid patients, corresponding clinical resolution rates were 88% for 5-day moxifloxacin vs. 86% for 5-day azithromycin. Bacteriological eradication rates at the end of therapy were 95% for 5-day moxifloxacin and 94% for the azithromycin group. Corresponding eradication rates at the test-of-cure visit were 89% and 86%, respectively. Of note, eradication rates at test-of-cure for Haem. philos influenzae and H. parainfluenzae for moxifloxacin were 97% and 88% compared to 83% and 62% respectively for azithromycin. Among 567 intent-to-treat patients (283 moxifloxacin and 284 azithromycin), drug-related events were reported for 22% and 17%, respectively. Diarrhea and nausea were the most common drug-related events reported in each treatment group. Moxifloxacin 400 mg once daily for 5 days was found to be clinically and bacteriologically equivalent to 5-day azithromycin for the treatment of AECB of proven bacterial etiology. Given its excellent in-vitro activity, especially against antibiotic-resistant respiratory pathogens, and its acceptable safety profile, moxifloxacin should be considered an effective alternative therapy for patients with AECB of suspected bacterial origin.     

Quality of life in acute exacerbation of chronic bronchitis: results from a German population study

This study reports on data from a study conducted in the Federal Republic of Germany examining the quality of life (QoL) of patients with chronic bronchitis (CB) and its acute exacerbations (AECB). Data from 320 patients were collected at AECB and subsequently during a stable phase (non-AECB) utilizing the St George's Respiratory Questionnaire (SGRQ) and the Nottingham Health Profile (NHP). As expected, the QoL of CB patients was poor, even at non-AECB, with patients reporting lower scores than patients with other chronic conditions. Patients reported significantly poorer QoL at AECB than at non-AECB. After adjusting for the severity of the underlying condition, poorer QoL at AECB was significantly and independently associated with older age, unemployment, increasing BMI, increasing number of prior AECBs, and Anthonisen AECB grade.While younger subjects reported significantly greater deterioration in QoL at AECB, the factors most consistently and independently associated with relative QoL deterioration at AECB were the number of prior AECBs and exposure to air pollution at home. In conclusion, this study highlights the detrimental effect of CB, and in particular AECB, on QoL.The association between QoL and patient reports of previous AECB number and air pollution are consistent with reports from other studies.     

Acute exacerbation of chronic bronchitis: need for an evidence-based approach

Acute exacerbations of chronic bronchitis (AECB) can be classified into three levels according to severity: (1) home treatment sufficient; (2) hospitalisation required; (3) hospitalisation in the presence of respiratory failure. This evidence-based classification is useful in ranking the clinical relevance of the episode and its outcome, and makes it possible to define the clinical history, clinical evaluation and diagnostic procedures of an exacerbation. Treatment guidelines vary according to severity, but they are essentially based on appropriate bronchodilator therapy (beta(2) agonists and/or anticholinergics, corticosteroids and antibiotics selected according to the local bacterial resistance pattern). It is important that cases requiring management in an intermediate/special respiratory care unit or intensive care unit (ICU) be identified. This is the stage where oxygen therapy and ventilatory support become particularly important. As first choice, they should be non-invasive, saving intubation and invasive ventilatory support for most severe cases characterised by severe acidemia and hypercapnia. We identify the optimal criteria for hospital discharge and follow-up of patients with AECB. In view of the chronic nature of the underlying disease, a correct follow-up is essential to avoid frequent and repeated relapses.     

Changes in bronchial inflammation during acute exacerbations of chronic bronchitis.

There are little data describing noncellular changes in bronchial inflammation during exacerbations of chronic bronchitis. The relationship between sputum colour and airway inflammation at presentation has been assessed during an exacerbation in patients with chronic bronchitis and a primary care diagnosis of chronic obstructive pulmonary disease. Sputum myeloperoxidase, neutrophil elastase, leukotriene B4 (LTB4), interleukin-8 (IL-8), sol:serum albumin ratio and serum C-reactive protein were measured in patients presenting with an exacerbation and mucoid (n = 27) or purulent sputum (n = 42). Mucoid exacerbations were associated with little bronchial or systemic inflammation at presentation, and sputum bacteriology was similar to that obtained in the stable state. Purulent exacerbations were associated with marked bronchial and systemic inflammation (p < 0.025 for all features) and positive sputum cultures (90%). Resolution was related to a significant reduction in LTB4 (p < 0.01), but no change in IL-8, suggesting that LTB4 may be more important in neutrophil recruitment in these mild, purulent exacerbations. In the stable state, IL-8 remained higher in patients who had experienced a purulent exacerbation (2p < 0.02). The presented results indicate that exacerbations of chronic bronchitis, defined by sputum colour, differ in the degree of bronchial and systemic inflammation. Purulent exacerbations are related to bacterial infection, and are associated with increased neutrophilic inflammation and increased leukotriene B4 concentrations.     

Role of infection in chronic bronchitis.

Twenty-five patients with chronic bronchitis were studied intensively from 1968 to 1972. Viral, bacteriologic, mycologic, and mycoplasmal studies, both serologic and cultural, were carried out in an attempt to determine the role these agents play in exacerbations. All of the usual viral agents associated with exacerbations and 2 members of the coronavirus group, 229E and OC43, were detected. One third (33.6 per cent) of the 116 exacerbations observed could be related to viral infection or Mycoplasma pneumoniae (1 exacerbation). Viral infection was also noted to occur during periods of remission but was more commonly associated with periods of exacerbation(P less than 0.001). No interrelationship between viral and bacterial infection was apparent and neither Streptococcus pneumoniae nor Haemophilus influenzae was present more frequently in the sputum of patients in exacerbation. However, the number of S. pneumoniae organisms present in the sputum was significantly greater (P=0.04) during exacerbation than during remission and their presence was significatnly correlated with increases sputum purulence (P LESS THAN 0.01). This was not true of H. influenzae. Ampicillin was effective in clearing the sputum of S. pneumoniae but not of H. influenzae; the reverse was true of tetracycline.