The intrabronchial microbial flora in chronic bronchitis patients: a target for N-acetylcysteine therapy?

Molecular Mechanisms Related to Responses to Oxidative Stress and Antioxidative Therapies in COVID-19: A Systematic Review

The coronavirus disease (COVID-19) pandemic is a leading global health and economic challenge. What defines the disease's progression is not entirely understood, but there are strong indications that oxidative stress and the defense against reactive oxygen species are crucial players. A big influx of immune cells to the site of infection is marked by the increase in reactive oxygen and nitrogen species. Our article aims to highlight the critical role of oxidative stress in the emergence and severity of COVID-19 and, more importantly, to shed light on the underlying molecular and genetic mechanisms. We have reviewed the available literature and clinical trials to extract the relevant genetic variants within the oxidative stress pathway associated with COVID-19 and the anti-oxidative therapies currently evaluated in the clinical trials for COVID-19 treatment, in particular clinical trials on glutathione and N-acetylcysteine.

A Systematic Review and Meta-Analysis of the Prevalence and Impact of Pulmonary Bacterial Colonisation in Stable State Chronic Obstructive Pulmonary Disease (COPD)

Background: Half of acute exacerbations of COPD are due to bacterial infection, and the other half are likely influenced by microbial colonisation. The same organisms commonly cultured during acute exacerbations are often found in the sputum of patients during stability. A robust assessment of the prevalence of potentially pathogenic microorganisms (PPMs) in the sputum of stable COPD patients may help to inform the targeted prevention of exacerbation by these organisms. Methods: A systematic review and meta-analysis was carried out to determine the prevalence of PPMs in patients with COPD in the stable state. Meta-analysis of prevalence was carried out using the Freeman–Tukey double arcsine transformation random effects model, and sub-group analysis was performed for sputum modality. Prevalence of total and individual PPMs was calculated from patient-level data from individual studies. Results: Pooled prevalence of PPMs identified by sputum culture was found to be 41% (95% CI 36–47%). Significant heterogeneity was found across all studies, which can likely be attributed to inconsistent measuring and reporting of PPMs. The most commonly reported organisms were H. influenzae, M catarrhalis, S. pneumoniae, S. aureus, and P. aeruginosa. Declining lung function was weakly correlated with prevalence of PPMs. Conclusion: The airways of patients with COPD are colonised with PPMs during the stable state in almost half of patients. A complex relationship likely exists between the microbiome in the stable state and the phenotype of COPD patients. Targeted microbial therapy for preventing exacerbations of COPD should carefully consider the stable microbiome as well as the exacerbated.

Respiratory

Lung disease rivals the position for the top cause of death worldwide. Causes and pathology of the myriad lung diseases are varied, yet nutrition can either affect the outcome or support treatment in the majority of cases. This chapter explores the modifiable risk factors, from lifestyle changes to dietary intake to specific nutrients, anti-nutrients, and toxins helpful for the nutritionist or dietitian working with lung disease patients. General lung health is discussed, and three major disease states are explored in detail, including alpha-1 antitrypsin deficiency, asthma, and idiopathic pulmonary fibrosis. Although all lung diseases have diverse causes, many integrative and functional medical nutrition therapies are available and are not being utilized in practice today. This chapter begins the path toward better nutrition education for the integrative and functional medicine professional.

Cysteine/Glutathione Deficiency: A Significant and Treatable Corollary of Disease

Glutathione (GSH) deficiency may play a pivotal role in a variety of apparently unrelated clinical conditions and diseases. Orally administered N-acetylcysteine (NAC), which replenishes the cysteine required for GSH synthesis, has been tested in a large number of randomized placebo-controlled trials involving these diseases and conditions. This chapter focused on developing a base of evidence suggesting that NAC administration improves disease by increasing cysteine and/or GSH in a variety of diseases, thereby implying a significant role for GSH deficiency in the clinical basis of many diseases. To develop this base of evidence, we systematically selected studies which considered the hypothesis that the therapeutic efficacy for NAC is an indication that cysteine and/or GSH deficiency is a pathophysiological part of the diseases studied. In this manner we focus this chapter on explaining the biological mechanisms of NAC therapy in a wide variety of disorders and demonstrate its ubiquitous role in improving disease that involves disrupted GSH and/or cysteine metabolism.

Bronchoscopic findings in children with chronic wet cough

OBJECTIVES

Protracted bacterial bronchitis is defined as the presence of more than 4 weeks of chronic wet cough that resolves with appropriate antibiotic therapy, in the absence of alternative diagnoses. The diagnosis of protracted bacterial bronchitis is not readily accepted within the pediatric community, however, and data on the incidence of bacterial bronchitis in children are deficient. The objective of this study was to determine the frequency of bacterial bronchitis in children with chronic wet cough and to analyze their bronchoscopic findings.

METHODS

We performed a retrospective review of charts of children who presented with chronic wet cough, unresponsive to therapy, before referral to the pediatric pulmonary clinic.

RESULTS

A total of 197 charts and bronchoscopy reports were analyzed. Of 109 children who were 0 to 3 years of age, 33 (30.3%) had laryngomalacia and/or tracheomalacia. The bronchoscopy showed purulent bronchitis in 56% (110) cases and nonpurulent bronchitis in 44% (87). The bronchoalveolar lavage bacterial cultures were positive in 46% (91) of the children and showed nontypable Haemophilus influenzae (49%), Streptococcus pneumoniae (20%), Moraxella catarrhalis (17%), Staphylococcus aureus (12%), and Klebsiella pneumoniae in 1 patient. The χ(2) analysis demonstrated that positive bacterial cultures occurred more frequently in children with purulent bronchitis (74, 69.8%) than in children with nonpurulent bronchitis (19, 19.8%) (P < .001).

CONCLUSIONS

Children who present with chronic wet cough are often found to have evidence of purulent bronchitis on bronchoscopy. This finding is often indicative of a bacterial lower airway infection in these children.

Molecular and cellular mechanism of lung injuries due to exposure to sulfur mustard: a review

Sulfur mustard (SM), a potent chemical weapon agent, was used by Iraqi forces against Iranian in the Iraq-Iran war (1981-1989). Chronic obstructive pulmonary disease (COPD) is a late toxic pulmonary consequence after SM exposure. The COPD observed in these patients is unique (described as Mustard Lung) and to some extent different from COPD resulted from other well-known causes. Several mechanisms have been hypothesized to contribute to the pathogenesis of COPD including oxidative stress, disruption of the balance between apoptosis and replenishment, proteinase-antiproteinase imbalance and inflammation. However, it is not obvious which of these pathways are relevant to the pathogenesis of mustard lung. In this paper, we reviewed studies addressing the pathogenicity of mustard lung, and reduced some recent ambiguities in this field. There is ample evidence in favor of crucial role of both oxidative stress and apoptosis as two known mechanisms that are more involved in pathogenesis of mustard lung comparing to COPD. However, according to available evidences there are no such considerable data supporting neither proteolytic activity nor inflammation mechanism as the main underlying pathogenesis in Mustard Lung.

WITHDRAWN: Antibiotics for exacerbations of chronic obstructive pulmonary disease

BACKGROUND

Most patients with an exacerbation of chronic obstructive pulmonary disease (COPD) are treated with antibiotics. However the value of their use remains uncertain. Some controlled trials of antibiotics have shown benefit (Berry 1960; Pines 1972) while others have not (Elmes 1965b; Nicotra 1982).

OBJECTIVES

To conduct a systematic review of the literature estimating the value of antibiotics in the management of acute COPD exacerbations.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2005, issue 4) which contains the Acute Respiratory Infections Group's Specialized Register; MEDLINE (1966 to December 2005); EMBASE (1974 to December 2005); Web of Science (December 2005), and other electronically available databases.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in patients with acute COPD exacerbations comparing antibiotic (for a minimum of five days) and placebo.

DATA COLLECTION AND ANALYSIS

Data were analysed using Review Manager software. Continuous data were analysed using weighted mean differences (WMD) and 95% confidence intervals (CI). Relative risks (RR) (and 95% CI) were calculated for all dichotomous data. Where appropriate, number needed to treat to benefit (NNT) and 95% CI were calculated.

MAIN RESULTS

Eleven trials with 917 patients were included. Ten trials used increased cough, sputum volume and purulence diagnostic criteria for COPD exacerbation. Eight-hundred and fifty-seven patients provided data for outcomes including mortality, treatment failure, increased sputum volume, sputum purulence, PaCO(2), PaO(2), peak flow and adverse events. Antibiotic therapy regardless of antibiotic choice significantly reduced mortality (RR 0.23; 95% CI 0.10 to 0.52 with NNT of 8; 95% CI 6 to 17), treatment failure (RR 0.47; 95% CI 0.36 to 0.62 with NNT of 3; 95% CI 3 to 5) and sputum purulence (RR 0.56; 95% CI 0.41 to 0.77 with NNT of 8; 95% CI 6 to 17). There was a small increase in risk of diarrhoea with antibiotics (RR 2.86; 95% CI 1.06 to 7.76). Antibiotics did not improve arterial blood gases and peak flow.

AUTHORS' CONCLUSIONS

This review shows that in COPD exacerbations with increased cough and sputum purulence antibiotics, regardless of choice, reduce the risk of short-term mortality by 77%, decrease the risk of treatment failure by 53% and the risk of sputum purulence by 44%; with a small increase in the risk of diarrhoea. These results should be interpreted with caution due to the differences in patient selection, antibiotic choice, small number of included trials and lack of control for interventions that influence outcome, such as use of systemic corticosteroids and ventilatory support. Nevertheless, this review supports antibiotics for patients with COPD exacerbations with increased cough and sputum purulence who are moderately or severely ill.

Antibiotics in addition to systemic corticosteroids for acute exacerbations of chronic obstructive pulmonary disease

RATIONALE

The role of antibiotics in acute exacerbations is controversial and their efficacy when added to systemic corticosteroids is unknown.

OBJECTIVES

We conducted a randomized, placebo-controlled trial to determine the effects of doxycycline in addition to corticosteroids on clinical outcome, microbiological outcome, lung function, and systemic inflammation in patients hospitalized with an acute exacerbation of chronic obstructive pulmonary disease.

METHODS

Of 223 patients, we enrolled 265 exacerbations defined on the basis of increased dyspnea and increased sputum volume with or without increased sputum purulence. Patients received 200 mg of oral doxycycline or matching placebo for 7 days in addition to systemic corticosteroids. Clinical and microbiological response, time to treatment failure, lung function, symptom scores, and serum C-reactive protein were assessed.

MEASUREMENTS AND MAIN RESULTS

On Day 30, clinical success was similar in intention-to-treat patients (odds ratio, 1.3; 95% confidence interval, 0.8 to 2.0) and per-protocol patients. Doxycycline showed superiority over placebo in terms of clinical success on Day 10 in intention-to-treat patients (odds ratio, 1.9; 95% confidence interval, 1.1 to 3.2), but not in per-protocol patients. Doxycycline was also superior in terms of clinical cure on Day 10, microbiological outcome, use of open label antibiotics, and symptoms. There was no interaction between the treatment effect and any of the subgroup variables (lung function, type of exacerbation, serum C-reactive protein, and bacterial presence).

CONCLUSIONS

Although equivalent to placebo in terms of clinical success on Day 30, doxycycline showed superiority in terms of clinical success and clinical cure on Day 10, microbiological success, the use of open label antibiotics, and symptoms. Clinical trial registered with www.clinicaltrials.gov (NCT00170222).

Sputum colour reported by patients is not a reliable marker of the presence of bacteria in acute exacerbations of chronic obstructive pulmonary disease

Sputum colour is regarded as a good marker of bacterial involvement in acute exacerbations of chronic obstructive pulmonary disease (COPD) and guides many physicians in deciding on antibiotic treatment. Although most doctors rely on the sputum colour that is reported by patients, it can also be assessed using a validated colour chart. In this study, reported sputum colour and assessed sputum colour were compared as markers of the presence of bacteria, bacterial load, and systemic inflammation. Data on 257 exacerbations in 216 patients hospitalized with an acute exacerbation were analysed (mean age, 72 years; mean forced expiratory volume in 1 s, 44.8% + or - 17.8% (+ or - standard deviation)). Sputum colour was reported by the patients and assessed at the laboratory with a colour chart. Subsequently, quantitative sputum cultures were performed. C-reactive protein was measured as a marker of systemic inflammation. A sputum sample was obtained in 216 exacerbations (84%), of which 177 (82%) were representative. A pathogen was identified in 155 patients (60%). Assessed sputum colour was a better marker of the presence of bacteria (OR 9.8; 95% CI 4.7-20.4; p <0.001) than reported sputum colour (OR 1.7; 95% CI 1.0-3.0; p 0.041). The sensitivity and specificity were 73% and 39% for reported sputum colour, and 90% and 52% for assessed sputum colour. Assessed sputum colour was clearly related to sputum bacterial load and C-reactive protein levels, whereas reported sputum colour was not. It is concluded that sputum colour reported by patients is an unreliable marker of the presence of bacteria in acute exacerbations of COPD. Assessed sputum colour is clearly superior and is also related to bacterial load and systemic inflammation.

Role of mucolytics in the management of COPD

There is, to date, no medical therapy that modifies the decline in lung function that occurs in COPD. As the disease becomes more severe, exacerbations of COPD become increasingly common, affecting patient quality of life and increasing health care costs. Mucolytic agents, through their actions on inflammatory and oxidative pathways, have potential benefits in COPD. This paper reviews the randomized controlled trial (RCT) evidence for the effectiveness of at least 2 months of daily therapy with oral mucolytics in COPD. Based on evidence from 26 RCTs, mucolytics reduce exacerbations by up to 0.8 exacerbations per year, with a greater effect in patients with more severe COPD. This effect appears to be of a similar magnitude to the reduction in exacerbations seen with tiotropium and inhaled corticosteroids (ICS), but RCTs that compared the agents would be required to confirm this. Mucolytics do not affect the rate of lung function decline, but they do not have any significant adverse effects. Mucolytic treatment should be considered in: patients with more severe COPD who have frequent or prolonged exacerbations; those who are repeatedly admitted to hospital; or in those patients with frequent exacerbations who are unable to take tiotropium or ICS.

Stress oxydatif et BPCO. Rôle des infections. Prévention

For the next decade, COPD will become the third cause of mortality in the world. COPD is mainly due to cigarette smoking and presents different levels of severity according to people, probably linked to environmental and genetic factors, which are not well documented. Recent publications pointed out bacterial bronchial colonization and exacerbations of infectious origin as worsening factors through a pro-inflammatory effect and oxidative stress. This should lead to a comprehensive review of anti-infectious prevention tools and to discuss the role of prophylactic antibiotherapy and antioxidants.

Antibiotics for exacerbations of chronic obstructive pulmonary disease

BACKGROUND

Most patients with an exacerbation of chronic obstructive pulmonary disease (COPD) are treated with antibiotics. However the value of their use remains uncertain. Some controlled trials of antibiotics have shown benefit (Berry 1960; Pines 1972) while others have not (Elmes 1965b; Nicotra 1982).

OBJECTIVES

To conduct a systematic review of the literature estimating the value of antibiotics in the management of acute COPD exacerbations.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 4, 2005); MEDLINE (1966 to December 2005); EMBASE (1974 to December 2005); Web of Science (December 2005), and other electronically available databases.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in patients with acute COPD exacerbations comparing antibiotic (for a minimum of five days) and placebo.

DATA COLLECTION AND ANALYSIS

Data were analysed using Review Manager software. Continuous data were analysed using weighted mean differences (WMD) and 95% confidence intervals (CI). Relative risks (RR) (and 95% CI) were calculated for all dichotomous data. Where appropriate, number needed to treat to benefit (NNT) and 95% CI were calculated.

MAIN RESULTS

Eleven trials with 917 patients were included. Ten trials used increased cough, sputum volume and purulence diagnostic criteria for COPD exacerbation. Eight-hundred and fifty-seven patients provided data for outcomes including mortality, treatment failure, increased sputum volume, sputum purulence, PaCO(2), PaO(2), peak flow and adverse events. Antibiotic therapy regardless of antibiotic choice significantly reduced mortality (RR 0.23; 95% CI 0.10 to 0.52 with NNT of 8; 95% CI 6 to 17), treatment failure (RR 0.47; 95% CI 0.36 to 0.62 with NNT of 3; 95% CI 3 to 5) and sputum purulence (RR 0.56; 95% CI 0.41 to 0.77 with NNT of 8; 95% CI 6 to 17). There was a small increase in risk of diarrhoea with antibiotics (RR 2.86; 95% CI 1.06 to 7.76). Antibiotics did not improve arterial blood gases and peak flow.

AUTHORS' CONCLUSIONS

This review shows that in COPD exacerbations with increased cough and sputum purulence antibiotics, regardless of choice, reduce the risk of short-term mortality by 77%, decrease the risk of treatment failure by 53% and the risk of sputum purulence by 44%; with a small increase in the risk of diarrhoea. These results should be interpreted with caution due to the differences in patient selection, antibiotic choice, small number of included trials and lack of control for interventions that influence outcome, such as use of systemic corticosteroids and ventilatory support. Nevertheless, this review supports antibiotics for patients with COPD exacerbations with increased cough and sputum purulence who are moderately or severely ill.

Exacerbations of chronic obstructive pulmonary disease and chronic mucus hypersecretion

Chronic obstructive pulmonary disease (COPD) exacerbations are an important cause of the considerable morbidity and mortality found in COPD. COPD exacerbations increase with increasing severity of COPD, and some patients are prone to frequent exacerbations leading to hospital admission and readmission. These frequent exacerbations may have considerable impact on quality of life and activities of daily living. Factors that increase the risk for COPD exacerbations are associated with increased airway inflammation caused by common pollutants and bacterial and/or viral infections. These inflammatory responses cause mucus hypersecretion and, thereby, airway obstruction and associated exacerbations. While chronic mucus hypersecretion is a significant risk factor for frequent and severe exacerbations, patients with chronic mucus hypersecretion have a lower rate of relapse after initial treatment for acute exacerbation. The benefit of antibiotics for treatment of COPD exacerbations is small but significant. While the mechanisms of actions are not clear, mucolytic agents reduce the number of days of disability in subjects with exacerbations. Reducing mucous cell numbers in small airways could be a useful way to reduce chronic mucus hypersecretion. Our studies suggest that programmed cell death is crucial in the resolution of metaplastic mucous cells, and understanding these mechanisms may provide novel therapies to reduce the risk of COPD exacerbations.

Effects of N-acetylcysteine on outcomes in chronic obstructive pulmonary disease (Bronchitis Randomized on NAC Cost-Utility Study, BRONCUS): a randomised placebo-controlled trial

BACKGROUND

Increased oxidative stress is important in the pathogenesis of chronic obstructive pulmonary disease (COPD). We postulated that treatment with the antioxidant N-acetylcysteine would reduce the rate of lung-function decline, reduce yearly exacerbation rate, and improve outcomes.

METHODS

In a randomised placebo-controlled study in 50 centres, 523 patients with COPD were randomly assigned to 600 mg daily N-acetylcysteine or placebo. Patients were followed for 3 years. Primary outcomes were yearly reduction in forced expiratory volume in 1 s (FEV1) and the number of exacerbations per year. Analysis was by intention to treat.

FINDINGS

The yearly rate of decline in FEV1 did not differ between patients assigned N-acetylcysteine and those assigned placebo (54 mL [SE 6] vs 47 mL [6]; difference in slope between groups 8 mL [9]; 95% CI -25 to 10). The number of exacerbations per year did not differ between groups (1.25 [SD 1.35] vs 1.29 [SD 1.46]; hazard ratio 0.99 [95% CI 0.89-1.10, p=0.85]). Subgroup analysis suggested that the exacerbation rate might be reduced with N acetylcysteine in patients not treated with inhaled corticosteroids and secondary analysis was suggestive of an effect on hyperinflation.

INTERPRETATION

N-acetylcysteine is ineffective at prevention of deterioration in lung function and prevention of exacerbations in patients with COPD.

[Oxidative stress in bronchopulmonary disease: contribution of N-acetylcysteine (NAC)]

Oxidative stress is a frequent mechanism involved in the pathogenesis of bronchopulmonary disease. The cause can be exogenous, in particular related to to atmospheric pollution and tobacco smoke, or endogenous, related to mobilization of inflammatory cells (macrophages and polymorphonuclear neutrophils). In this general review, we present work demonstrating this oxidative stress and activation of inflammatory cells. We discuss the effect of oxidative stress on the bronchial tree and the need to maintain an adequate balance between oxidants and anti-oxidants. This reviews focuses on experimental studies proving the anti-oxidant effect of NAC on glutathione synthesis and on different pharmacological models. We then discuss human trials, initially experimental then in different bronchopulmonary pathologies related to oxidative stress. Acetaminophen intoxication and pulmonary fibrosis are models for use of NAC. Recent work on COPD appears to show a decrease in exacerbations, improvement in symptoms and quality-of-life, and perhaps a reduction in the alteration of ventilatory function.

Preventing exacerbations of chronic bronchitis and COPD: therapeutic potential of mucolytic agents

It is important to find interventions that will reduce the frequency and severity of exacerbations of COPD, because of their effect on morbidity and healthcare expenditure. A Cochrane systematic review included 23 studies that had evaluated the effects of treatment with mucolytic agents in patients with chronic bronchitis or COPD. Mucolytic treatment was associated with a significant reduction of 0.79 exacerbations per patient per year compared with placebo, a 29% decrease. Patients who received treatment with mucolytic agents were twice as likely to remain exacerbation-free in the study period than if they had received placebo, with six patients needing regular treatment with mucolytic agents for 3-6 months to achieve one less exacerbation over that time. Treatment with mucolytic agents resulted in nearly 7 days less illness per patient per year. How mucolytic agents work is unknown, although they may reduce exacerbations by altering mucus production, antioxidation, or antibacterial or immunostimulatory effects. They do not appear to affect the decline in lung function that occurs in COPD. The treatment appears to be without any adverse effects, apart from the need to take oral medication daily. Cost-effectiveness analysis suggests that the point at which the costs of treatment and non-treatment were equal was 1.2 less exacerbations per year. This is higher than the effect observed in the Cochrane review, suggesting that treating everyone with COPD with mucolytic agents would not be cost effective. Those with more frequent and severe exacerbations appear to have the most to gain.

Les mucorégulateurs dans les syndromes bronchiques aigus : point sur les pratiques en médecine générale et les données de la littérature

Antibiotics have long been used in the initial treatment of acute bronchitis (AB) and acute exacerbations of chronic bronchitis (AECB). However, their lack of value in AB has been clearly demonstrated and antibiotic therapy is justified in only a few cases of AECB. In parallel, although the value of mucoregulators in these diseases is still debated, their prescription remains important in general practice. In this context, our aim was to determine the prescribing behaviour of general practitioners (GPs) with regard to these drugs, as well as the beliefs of GPs concerning the place of mucoregulators in the treatment of AB in children and adult smokers, as well as in patients with non-obstructive AECB. A survey was carried out in 370 GPs, who were presented with three standardised and computerised medical cases: (i) rhinopharyngitis + AB in a child; (ii) AB in an adult smoker without a previous medical history; and (iii) a patient with non-obstructive AECB. The results showed that mucoregulators are frequently prescribed by GPs for children and adults with AB, or in AECB. This high prescribing rate is due to the belief of the GPs that these drugs are effective and well tolerated, which is confirmed by the literature. Their use avoids the frequent and unjustified prescription of antibiotics in situations where they are not recommended but where the patients request drug therapy.

Recent clinical evidence of the efficacy and safety of thiamphenicol glycinate acetylcysteinate and thiamphenicol glycinate

Thiamphenicol is a broad-spectrum antimicrobial agent active against penicillin-resistant Streptococcus pneumoniae, Staphylococcus aureus VISA strains, most methicillin-resistant isolates and atypical pathogens such as Mycoplasma pneumoniae and Chlamydia pneumoniae). Thiamphenicol is present as glycinate hydrochloride (TG) and glycinate acetylcysteinate (TGA) esters in the parenteral and aerosol dosage form. This multicenter, double-blind, randomized clinical trial aimed to evaluate the efficacy and tolerability of aerosol administration of TGA, compared to TG, in the treatment of acute and/or exacerbated infections of the respiratory tract. Results showed that both treatments ameliorated the symptoms (frequency and severity of cough, difficulty in expectoration) associated with the evaluated pathologies, i.e. tracheobronchitis, acute and exacerbated chronic bronchitis. The investigators rated both treatments Good or Very Good in 90% of patients at the end of treatment, with "Very Good" for patients treated with TGA (37%) compared to 28% of patients treated with TG. Both treatments were well tolerated with fewer than 5% of patients experiencing an adverse event.

IgG subclasses in smokers with chronic bronchitis and recurrent exacerbations

BACKGROUND

Tobacco smokers have lower serum levels of IgG than non-smokers. IgG subclass deficiency is common in patients with recurrent respiratory infections. Recurrent bronchial infections are common in smokers with chronic bronchitis (CB). We have investigated whether susceptibility to recurrent exacerbations in smokers with CB is associated with altered IgG subclass levels or IgG subclass deficiency.

METHODS

Serum levels of IgG, IgA, IgM, and IgG subclasses 1-4 were determined by radial immunodiffusion in 100 subjects: 33 smokers with stable CB and recurrent exacerbations, 24 asymptomatic smokers, and 43 healthy never smokers. Systemic tobacco exposure was verified and excluded using a serum cotinine ELISA. Immunoglobulin data were log transformed to enable use of parametric statistical methods.

RESULTS

Compared with never smokers, both patients with CB and asymptomatic smokers had significantly lower levels of IgG (median 9.7 g/l (range 5.6-15.2) and 9.9 (6.1-12.1) g/l v 12.0 (6.9-18.5) g/l) and IgG2 (2.8 (0.9-5.9) g/l and 2.5 (1.0-6.3) g/l v 4.0 (1.7-10.2) g/l). The estimated ratio of median values between the patients with CB and never smokers was 0.78 (95% confidence interval (CI) 0.69 to 0.89) for IgG and 0.65 (95% CI 0.50 to 0.83) for IgG2. The corresponding ratios between asymptomatic smokers and never smokers were 0.79 (95% CI 0.69 to 0.91) and 0.60 (95% CI 0.50 to 0.83), respectively. There were no significant differences between the smoking groups.

CONCLUSIONS

Susceptibility to recurrent exacerbations in smokers with CB is not associated with lower levels of IgG subclasses than can be accounted for by smoking per se.

IgG subclasses in smokers with chronic bronchitis and recurrent exacerbations

BACKGROUND

Tobacco smokers have lower serum levels of IgG than non-smokers. IgG subclass deficiency is common in patients with recurrent respiratory infections. Recurrent bronchial infections are common in smokers with chronic bronchitis (CB). We have investigated whether susceptibility to recurrent exacerbations in smokers with CB is associated with altered IgG subclass levels or IgG subclass deficiency.

METHODS

Serum levels of IgG, IgA, IgM, and IgG subclasses 1–4 were determined by radial immunodiffusion in 100 subjects: 33 smokers with stable CB and recurrent exacerbations, 24 asymptomatic smokers, and 43 healthy never smokers. Systemic tobacco exposure was verified and excluded using a serum cotinine ELISA. Immunoglobulin data were log transformed to enable use of parametric statistical methods.

RESULTS

Compared with never smokers, both patients with CB and asymptomatic smokers had significantly lower levels of IgG (median 9.7 g/l (range 5.6–15.2) and 9.9 (6.1–12.1) g/l v 12.0 (6.9–18.5) g/l) and IgG2 (2.8 (0.9–5.9) g/l and 2.5 (1.0–6.3) g/lv 4.0 (1.7–10.2) g/l). The estimated ratio of median values between the patients with CB and never smokers was 0.78 (95% confidence interval (CI) 0.69 to 0.89) for IgG and 0.65 (95% CI 0.50 to 0.83) for IgG2. The corresponding ratios between asymptomatic smokers and never smokers were 0.79 (95% CI 0.69 to 0.91) and 0.60 (95% CI 0.50 to 0.83), respectively. There were no significant differences between the smoking groups.

CONCLUSIONS

Susceptibility to recurrent exacerbations in smokers with CB is not associated with lower levels of IgG subclasses than can be accounted for by smoking per se.

Lower airway bacterial colonization in asymptomatic smokers and smokers with chronic bronchitis and recurrent exacerbations

Bacterial colonization of the lower airways in patients with chronic bronchitis (CB) has been described mainly in patients with co-existing chronic obstructive pulmonary disease (COPD). Although smoking has been identified as a risk factor for bacterial colonization it is not known whether asymptomatic smokers (AS) can be colonized. The aim of this study was to study lower airway bacterial colonization in smokers with stable CB and recurrent exacerbations and compare with AS and healthy never-smokers (NS). Thirty-nine smokers with CB and recurrent exacerbations (median FEV1 85% of predicted normal), 10 AS and 10 NS, underwent bronchoscopy and a two-step bronchoalveolar lavage (BAL) procedure where the first portion (20 ml, 'pre-BAL') was recovered separately from the rest (140 ml, 'BAL'). The degree of oropharyngeal contamination of pre-BAL and BAL samples was evaluated by cytology. Semiquantitative bacterial cultures were performed on all samples. Higher bacterial numbers than 10(3) colony-forming units (cfu) x ml(-1) in BAL were found only in the two smoking groups. Using 10(3) cfu x ml(-1) as cut-off, 6/10 (60%) in the AS-, and 7/35 (20%) in the CB-group were colonized in the lower airways. In all, 29% of all smokers had bacterial colonization. Only bacteria belonging to the normal oropharyngeal flora were found. The proportion of samples with oropharyngeal contamination was significantly lower in BAL than in pre-BAL (5% vs. 21%, P=0.039). The proportion of sterile samples was significantly higher in BAL than in pre-BAL (49% vs. 26%, P=0.002). Lower airway bacterial colonization was found both in asymptomatic smokers and in patients with CB. Colonization with potential respiratory pathogens is uncommon in patients with CB and recurrent exacerbations without severe airflow obstruction. The two-step BAL procedure seems to decrease oropharyngeal contamination.

Do bacteria cause exacerbations of COPD?

Exacerbations of COPD, which include combinations of dyspnea, cough, wheezing, increased sputum production (and a change in its color to green or yellow), are common. The role of bacterial infection in causing these episodes and the value of antibiotic therapy for them are debated. An assessment of the microbiological studies indicates that conventional bacterial respiratory pathogens, such as Streptococcus pneumoniae and Haemophilus influenzae, are absent in about 50% of attacks. The frequency of isolating these organisms, which often colonize the bronchi of patients in stable condition, does not seem to increase during exacerbations, and their density typically remains unchanged. Serologic studies generally fail to show rises in antibody titers to H influenzae; the only report available demonstrates none to Haemophilus parainfluenzae; and the sole investigation of S pneumoniae is inconclusive. Trials with vaccines against S pneumoniae and H influenzae show no clear benefit in reducing exacerbations. The histologic findings of bronchial biopsies and cytologic studies of sputum show predominantly increased eosinophils, rather than neutrophils, contrary to what is expected with bacterial infections. The randomized, placebo-controlled trials generally show no benefit for antibiotics, but most have studied few patients. A meta-analysis of these demonstrated no clinically significant advantage to antimicrobial therapy. The largest trials suggest that antibiotics confer no advantage for mild episodes; with more severe attacks, in which patients should receive systemic corticosteroids, the addition of antimicrobial therapy is probably not helpful.

Relationship of sputum color to nature and outpatient management of acute exacerbations of COPD

STUDY OBJECTIVES

To stratify COPD patients presenting with an acute exacerbation on the basis of sputum color and to relate this to the isolation and viable numbers of bacteria recovered on culture.

DESIGN

Open, longitudinal study of sputum characteristics and acute-phase proteins.

SETTING

Patients presenting to primary-care physicians in the United Kingdom. Patients were followed up as outpatients in specialist clinic.

PATIENTS

One hundred twenty-one patients with acute exacerbations of COPD were assessed together with a single sputum sample on the day of presentation (89 of whom produced a satisfactory sputum sample for analysis). One hundred nine patients were assessed 2 months later when they had returned to their stable clinical state.

INTERVENTIONS

The expectoration of green, purulent sputum was taken as the primary indication for antibiotic therapy, whereas white or clear sputum was not considered representative of a bacterial episode and the need for antibiotic therapy.

RESULTS

A positive bacterial culture was obtained from 84% of patients sputum if it was purulent on presentation compared with only 38% if it was mucoid (p < 0.0001). When restudied in the stable clinical state, the incidence of a positive bacterial culture was similar for both groups (38% and 41%, respectively). C-reactive protein concentrations were significantly raised (p < 0.0001) if the sputum was purulent (median, 4.5 mg/L; interquartile range [IQR], 6. 2 to 35.8). In the stable clinical state, sputum color improved significantly in the group who presented with purulent sputum from a median color number of 4.0 (IQR, 4.0 to 5.0) to 3.0 (IQR, 2.0 to 4. 0; p < 0.0001), and this was associated with a fall in median C-reactive protein level to 2.7 mg/L (IQR, 1.0 to 6.6; p < 0.0001).

CONCLUSIONS

The presence of green (purulent) sputum was 94.4% sensitive and 77.0% specific for the yield of a high bacterial load and indicates a clear subset of patient episodes identified at presentation that is likely to benefit most from antibiotic therapy. All patients who produced white (mucoid) sputum during the acute exacerbation improved without antibiotic therapy, and sputum characteristics remained the same even when the patients had returned to their stable clinical state.

Influence of clinical history on airways bacterial colonization in subjects with chronic tracheostomy

Patients with chronic tracheostomy are subject to significant bacterial colonization of the airways, a risk factor for respiratory infections. The aim of our study was to verify whether bacterial colonization and humoral immune response in the airways can be influenced by the disease which led to chronic respiratory failure and tracheostomy. Thirty-nine clinically stable outpatients with chronic tracheostomy were considered: 24 were affected by chronic obstructive pulmonary disease (COPD) (mean age 66 years, range 54-78, M/F 19/3; months since tracheostomy 23, range 3-62), 15 by restrictive lung disease (RLD) (12 thoracic wall deformities, three neuromuscular disease; age 57 years, range 41-72; M/F 3/12, months since tracheostomy 22, range 2-68). Recent antibiotic or corticosteroid treatments (< 1 month) were among exclusion criteria. Bacterial counts were assessed in tracheobronchial secretions with the method of serial dilutions. Identification of bacterial strains was performed by routine methods. Albumin, IgG, A, and M were measured in airways secretions with an immunoturbidimetric method. No significant differences were found between the two groups as regards either the quantitative bacterial cultures (RLD 81.4, 2.6-4200 x 10(4); COPD 75.9, 1.0-1530 x 10(4) colony forming units (cfu)/ml, geometric mean, range) or the prevalence of the main bacterial strains, (Pseudomonas species: 38 and 37%, Serratia marcescens: 31 and 23%, Staphylococcus aureus: 14 and 6%, Proteus species: 3 and 8%, for RLD and COPD respectively) as a percentage of total strains isolated (RLD = 26, COPD = 48). Immunoglobulin levels did not show significant differences, apart from being higher in underweight subjects. We conclude that in our series of stable outpatients with chronic tracheostomy, bacteria-host interaction in the airways was not influenced by the clinical history.

Antibiotics are associated with lower relapse rates in outpatients with acute exacerbations of COPD

BACKGROUND

COPD is a complex disease with exacerbations characterized by worsening of symptoms resulting in deteriorating lung function.

STUDY OBJECTIVE

To assess predictive factors of relapse for patients with acute exacerbations of COPD (AECB).

DESIGN

Retrospective cohort analysis of visits for AECB.

SETTING

Veterans Affairs Medical Center.

PATIENTS

Three hundred sixty-two visits (173 patients) with documented COPD treated as outpatients for AECB.

MEASUREMENTS

Severity of underlying COPD, severity of AECB, comorbid conditions, therapy, and relapse rates (return visit within 14 days with persistent or worsening symptoms).

RESULTS

Each visit was analyzed individually (referred to as a patient-visit). One group received antibiotics (270 patient-visits), and the second group (92 patient-visits) did not. Both groups had similar demographics and severity of underlying COPD. The overall relapse rate was 22%. The majority of patient-visits (95%) with severe symptoms at presentation were prescribed antibiotics vs only 40% of those with mild symptoms. Twenty-nine of 92 patient-visits (32%) were followed by relapse in the group that was not given antibiotics, whereas only 50 of 270 (19%) treated with antibiotics relapsed (p < 0.001). Those treated with amoxicillin had an even higher relapse rate (20 of 37 patient-visits, or 54%) than those who did not receive antibiotics (p = 0.006).

CONCLUSIONS

Relapse from AECB was not related to the severity of underlying disease or to the severity of the acute exacerbation. Patients treated with antibiotics had significantly lower relapse rates than those who did not receive antibiotics. However, the specific choice of antibiotic is important because those treated with amoxicillin had the highest relapse rates of all groups.

Serum and lung levels of thiamphenicol after administration of its glycinate N-acetylcysteinate ester in experimentally infected guinea pigs

Thiamphenicol is an analogue of chloramphenicol and is characterised by a broad spectrum of action. In this study, serum and lung levels of thiamphenicol (TAP) were studied in infected guinea pigs after the administration of thiamphenicol glycinate N-acetylcysteinate (TGA). Animals received a single dose of TGA (15 mg/kg, subcutaneously) immediately after intra-tracheal infection with Haemophilus influenzae (about 10(7) CFU/animal). Serum and lung concentrations of TAP were determined at 0, 1, 3, 6, 12 and 24 h after drug administration by means of HPLC. TAP serum levels were elevated at 1 h and remained detectable for 24 h after drug administration. Tissue lung levels were comparable to peak serum concentrations but remained higher and decreased more slowly than serum concentrations.

Efficacy of oral long-term N-acetylcysteine in chronic bronchopulmonary disease: a meta-analysis of published double-blind, placebo-controlled clinical trials

OBJECTIVE

This meta-analysis was performed to assess the possible prophylactic benefit of prolonged treatment with oral N-acetylcysteine (NAC) in chronic bronchitis (CB) based on qualifying clinical trials. Treatment of acute exacerbations with NAC was not investigated.

BACKGROUND

Prolonged treatment with oral NAC has been investigated in a number of studies of patients with CB. NAC prevented acute exacerbations and symptoms of CB in some but not all trials.

METHODS

The trials included in this analysis were selected from a MEDLINE search of the period from January 1, 1980, through June 30, 1995; references in the articles retrieved in the initial search; and consultation with 2 experts. Selection was based on the following criteria: published, double-blind, placebo-controlled, chronic bronchopulmonary disease, duration of therapy > or =2 months, and data sufficient to calculate an outcome variable permitting direct comparison of studies (effect size) for both NAC and placebo groups. The primary end point was the incidence of acute exacerbations in 7 of 8 trials and clinical assessment in the other. In 7 studies, inclusion criteria were based on Medical Research Council criteria for CB, with an additional criterion in some trials. For the meta-analysis, the end points of individual trials were transformed into an effect size as a common outcome.

RESULTS

Of 21 trials initially identified, 8 qualified for inclusion. References from the 8 papers and consultation with the experts produced 8 additional publications, 1 of which qualified for inclusion. NAC was administered orally at a daily dose of 400 mg (1 study), 600 mg (5 studies), or 1200 mg (1 study). One other trial used a dose of 600 mg 3 times per week. The duration of treatment was 3 months (1 study), > or =5 months (2 studies), or 6 months (7 studies). The results of this meta-analysis showed a statistically significant effect size for NAC compared with placebo. The overall value of effect size was -1.37 (95% CI, -1.5 to -1.25). Sensitivity analyses did not significantly alter these results. In a subset analysis of trials with the number of acute exacerbations as a clinical end point, a mean difference of -0.32 clinical event (95% CI, -0.50 to -0.18) was found (ie, a 23% decrease in the number of acute exacerbations compared with placebo).

CONCLUSION

These findings suggest that a prolonged course of oral NAC prevents acute exacerbations of CB, thus possibly decreasing morbidity and health care costs.

The facilitating effect of cigarette smoke on the colonization of instilled bacteria into the tracheal lumen in rats and the improving influence of supplementary vitamin E on this process

OBJECTIVE

The aim of the present study was to investigate the direct influence of cigarette smoke on the bacterial colonization of the lower respiratory tract and the effect of supplementary vitamin E on the colonization of instilled bacteria into the trachea of rats that do not have the chronic airway pathology associated with smoking.

METHODOLOGY

Thirty male Wistar albino rats, weighing approximately 250 g, were used as experimental animals. A 0.1 mL bacterial suspension containing six bacterial species (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumonia, Proteus mirabilis, Haemophilus influenza, Peptostreptococci spp.), isolated previously from pharynx of rats, were instilled into the trachea of three groups of rat (10 control, 10 cigarette smoke-treated and 10 cigarette smoke- and vitamin E-supplemented rats). The smoke-treated rats were exposed to cigarette smoke for 3 days prior to and after intratracheal instillation. The third group of rats were given vitamin E supplements (100 mg/kg per day). Tracheobronchial lavage samples of all rats were quantitatively cultured after 3 days from the instillation.

RESULTS

The colony numbers of isolated bacteria were significantly higher in cigarette smoke-treated rats than in the control group and in the smoke- and vitamin E-supplemented rats (P < 0.05). Only S. aureus and S. epidermidis were isolated from vitamin E-supplemented rats, while instilled all six bacterial species were isolated from the other two groups.

CONCLUSIONS

It is concluded that smoking impairs the elimination of bacteria or facilitates colonization of bacteria in the lower respiratory tract of rats. Supplementary treatment with vitamin E reduces the effect of cigarette smoke; however, some bacteria may be resistant to this action of vitamin E.

Bacterial colonization of central airways after stenting

Airway stenting (AS) is increasingly used in the management of obstructive lesions of the central airways. Although retention of secretions and infection have been reported as complications of AS, the microbiological consequences of AS have not yet been evaluated. In this study, we prospectively performed protected specimen brush (PSB) sampling of the airways, before and 3 to 4 wk after AS, in 14 consecutive patients (65 +/- 17 yr), suffering from bronchial (5), extensive esophageal (2), thyroid (1), and adenocystic (1) carcinoma, stenotic tracheal burn lesions (2), postintubation stenosis (2), and Wegener's granulomatosis (1). A cutoff value of >/= 10(2) colony-forming units (cfu). ml(-)(1) was considered diagnostic for airway colonization (AC). PSB results were related to the presence and degree of secretion retention (SR) at the level of the stent. In five of the 14 patients, AC was present prior to AS; in three of these, potentially pathogenic microorganisms (PPM) were identified. After AS, AC was found in 11 (including seven patients without prior AC) of the 14 patients. In six of these patients, one or more PPM were present (Pseudomonas aeruginosa [4], Staphylococcus aureus [3], Streptococcus pneumoniae [1], Klebsiella spp. [1]). Although AC tended to be associated with the presence of SR (PSB >/= 10(2) cfu. ml(-)(1) in 10 of 12 SR-positive and in zero SR-negative cases; PSB < 10(2) cfu. ml(-)(1) in two SR-positive and in two SR-negative cases), statistical significance was not reached (Fisher exact test, p = 0.06). We conclude that AS is frequently followed by AC, the majority of which occurs in patients without AC prior to AS, and is caused by PPM. In no case, however, AC was associated with clinical signs of infection. AC tended to be associated with SR in the stent.

Induction of phagocyte-stimulating cytokines by in vitro stimulation of human peripheral blood mononuclear cells with Haemophilus influenzae

The aim of this study was to analyse the in vitro response of human peripheral blood mononuclear cells to stimulation with killed Haemophilus influenzae strains of different capsular types, isolation sites and from cases with different forms of infections. The mean stimulatory index using 10(6) bacteria/well was 10, and 80 when 10(8) bacteria/well were used for stimulation. The mean+/-SD level was 13+/-4 ng/ml for interleukin (IL)-1beta, 128+/-73 ng/ml for IL-6, 203+/-122 ng/ml for IL-8, 3160+/-1220 pg/ml for IL-10, 29+/-40 pg/ml for IL-12, 2800+/-1790 pg/ml for tumour necrosis factor (TNF)-alpha and 4+/-7 ng/ml for interferon (IFN)-gamma, when stimulating cells with the lower dose of 10(6) bacteria/well. Using the higher bacterial dose, the levels of IL-1beta, TNF-alpha and IL-12 remained similar, whereas the IL-6, IL-8 and IL-10 levels were significantly lower, and IFN-gamma levels were significantly higher. Strains isolated from the bronchial tree induced significantly higher levels of IFN-gamma and significantly lower levels of IL-6, IL-8 and IL-10 than strains from other isolation sites. In conclusion, H. influenzae generated phagocyte-activating cytokines and an IL-10/IL-12 ratio that was 1090 times that described previously for Streptococcus pneumoniae.

The effect of cigarette smoke on adherence of respiratory pathogens to buccal epithelial cells

Smoking is associated with an increased risk of respiratory tract infection in adults. In children, exposure to cigarette smoke is a risk factor for respiratory tract infection and bacterial meningitis: Active smoking and passive exposure to cigarette smoke is also associated with carriage of some potentially pathogenic species of bacteria in both adults and children. The aims of the study were to determine the effect of active smoking on: (1) bacterial binding to epithelial cells; (2) expression of host cell antigens that act as receptors for some species; and (3) the effects of passive exposure to water-soluble components of cigarette smoke on bacterial binding. Flow cytometry was used to assess binding to buccal epithelial cells of the following species labelled with fluorescein isothiocyanate: Neisseria meningitidis, Neisseria lactamica, Streptococcus pneumoniae, Bordetella pertussis, Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus. Flow cytometry was also used to assess expression of host cell antigens which have been identified as bacterial receptors. For each species, binding to cells of smokers was significantly higher than to cells of non-smokers; however, expression of host cell antigens was similar on epithelial cells of both groups. Non-dilute cigarette smoke extract reduced binding of bacteria to epithelial cells, but dilutions between 1 in 10 and 1 in 320 enhanced binding. We conclude that smokers might be more densely colonised by a variety of potentially pathogenic bacteria. The enhanced bacterial binding to epithelial cells of smokers is not related to enhanced expression of host cell antigens that can act as receptors for some species, but possibly to components in the smoke that alter charge or other properties of the epithelial cell surface. Passive coating of mucosal surfaces with components of cigarette smoke might enhance binding of potentially pathogenic bacteria.

Are anti-oxidant and anti-inflammatory treatments effective in different subgroups of COPD? A hypothesis

The treatment of chronic obstructive pulmonary disease (COPD) with inhaled corticosteroids or anti-oxidants is still under debate and the identification of sub-groups of COPD patients who may benefit from either anti-inflammatory or anti-oxidant treatment is needed. We re-analysed data from an earlier study of inhaled beclomethasone therapy in COPD (n = 28) and asthma (n = 28) patients in order to determine patient characteristics that predict a favourable inhaled steroid treatment effect. A higher bronchodilatory response, a faster decline of FEV1 prior to the treatment period and a lower Tiffeneau index were significantly related to more beneficial treatment effects. Increased smoking tended to be related to less steroid treatment benefits, though it was not statistically significant. In this paper these findings are presented in light of the available literature on anti-inflammatory and anti-oxidant COPD treatment. On this basis the hypothesis is presented that anti-oxidant treatment might be relatively more effective among those COPD patients who respond less well to inhaled steroids (low reversibility and heavy smoking).

Infective exacerbations of chronic bronchitis: relation between bacteriologic etiology and lung function

STUDY OBJECTIVE

In patients with severe COPD, acute infective exacerbations are frequent. Streptococcus pneumoniae and Haemophilus influenzae are the most commonly isolated bacteria in sputum cultures from these patients. We hypothesized that in patients with advanced disease, Gram-negative bacteria other than H influenzae play at least an equally important role.

METHODS

We evaluated clinical data and sputum culture results from 211 unselected COPD patients admitted to our hospital with an acute infective exacerbation of COPD. One hundred twelve patients fulfilled our protocol criteria of reliable microbiologic results and reproducible lung function tests; the patients were categorized according to the recently published three stages of severity.

RESULTS

Lung function tests revealed an FEV1 of > or =50% of the predicted value in 30 patients (stage I), an FEV1 of 35% to <50% of the predicted value in 30 patients (stage II), and an FEV1 of < or =35% of the predicted value in 34 patients (stage III). Bacteria were classified into three groups: group 1 contained S pneumoniae and other Gram-positive cocci; group 2, H influenzae and Moraxella catarrhalis; and group 3, Enterobacteriaceae and Pseudomonas spp. For all patients together, the most frequently isolated bacteria were group 3 organisms (Enterobacteriaceae and Pseudomonas spp, 48.2%), followed by group 1 organisms (S pneumoniae and other Gram-positive cocci, 30.4%), and group 2 organisms (H influenzae and M catarrhalis, 21.4%). In stage I patients, 14 of 30 had bacteria from group 1, seven of 30 had group 2, and nine of 30 had group 3. In stage II patients, eight of 30 had group 1 bacteria, 10 of 30 had group 2, and 12 of 30 had group 3. In stage III patients, 12 of 52 had group 1 bacteria, seven of 52 had group 2, and 22 of 52 had group 3. The three groups of bacteria causing infective exacerbations were unevenly distributed among the three severity stages of lung function (p=0.016).

CONCLUSION

There is a correlation between deterioration of lung function and the bacteria isolated from patients with infective exacerbations of COPD. In acute infective exacerbations, Enterobacteriaceae and Pseudomonas spp are the predominant bacteria in patients with an FEV1 < or =35% of the predicted value.

The value of antibiotics and the outcomes of antibiotic therapy in exacerbations of COPD

COPD is the fifth leading cause of death in the United States, and acute respiratory infections account for a significant proportion of all primary care visits. Approximately one half of all exacerbations of COPD can be attributed to bacterial infection, and antibiotic therapy has been demonstrated to improve clinical outcomes and hasten clinical and physiologic recovery. The major pathogen continues to be Haemophilus influenzae, and resistance to beta-lactam antibiotics such as ampicillin can be expected in 20 to 40% of isolated strains. Certain high-risk patients, in whom the cost of clinical treatment failure is high, can be identified by simple clinical criteria. Patients with significant cardiopulmonary comorbidity, frequent purulent exacerbations of COPD, advanced age, generalized debility, malnutrition, chronic corticosteroid administration, long duration of COPD, and severe underlying lung function tend to fail therapy with older drugs, such as ampicillin, and early relapse can be expected. Treatment directed toward resistant pathogens with potent bactericidal drugs may be expected to lead to improved clinical outcomes and overall lower costs, particularly if hospital admissions and respiratory failure can be prevented. Future studies examining the role of antibiotics should enroll these high-risk patients to determine if new therapies have significant clinical, quality-of-life, and economic advantages over older agents.

Immunomodulatory and protective effects of N-acetylcysteine in mitogen-activated murine splenocytes in vitro

N-Acetylcysteine (NAC) is a pro-glutathione drug used to treat chronic lung disorders and because of its anti-AIDS virus activity in vitro, has been proposed for AIDS therapy. The effect of NAC on mitogen-activated-lymphocyte blastogenesis in C57B1/6 mouse splenocytes and ability of NAC to protect lymphocytes against mitogen-induced cytotoxicity was examined in vitro. NAC increased splenocyte proliferation in the presence of optimal and suboptimal concentrations of concanavalin A (Con A) and lipopolysaccharide (LPS). Stimulatory and costimulatory effects of NAC on mitogen-induced responses were also evident. The dose-response relationship describing the effects of NAC on lymphocyte proliferation with Con A-induced responses were enhanced in a dose-dependent manner, whereas the corresponding LPS-induced responses increased to a maximum level followed by decline in responses at higher concentrations of NAC. When splenocytes were incubated with inhibitory supraoptimal concentrations of Con A (10 microg/ml) or LPS (150 microg/ml), NAC partially enhanced the Con A-induced response but completely prevented the inhibitory effect of supraoptimal concentrations of LPS on splenocyte blastogenesis. Optimal and supraoptimal concentrations of Con A caused activation-induced cell death in the splenocytes whereas comparable concentrations of LPS did not produce a similar effect. Splenocyte cell death produced by the optimal mitogenic concentrations of Con A was completely blocked by the addition of NAC to cultures. Immunomodulation and protective effects of NAC were observed in mitogen-activated lymphocytes in vitro.

N-acetylcysteine inhibits germination of conidia and growth of Aspergillus spp. and Fusarium spp

N-Acetylcysteine inhibited hyphal growth and germination of conidia of Aspergillus spp. and Fusarium spp. N-Acetylcysteine inhibited conidial germination as well as or better than L-cysteine. Cysteine-related compounds may provide a potential therapeutic strategy against agriculturally and medically important fungal pathogens.

N-acetylcysteine: pharmacological considerations and experimental and clinical applications

The diversity of application of the thiol drug NAC in both the experimental setting, as a tool for the study of the mechanisms and consequences of oxidative stress, and the clinical setting, as a therapeutic agent, clearly reflects the central role played by the redox chemistries of the group XVI elements, oxygen and sulfur, in biology. As our understanding of such redox processes increases, particularly their roles in specific pathophysiological processes, new avenues will open for the use of NAC in the clinical setting. As a drug, NAC represents perhaps the ideal xenobiotic, capable of directly entering endogenous biochemical processes as a result of its own metabolism. Thus, it is hoped that the experience gained with this unique agent will help in future efforts to design antioxidants and chemoprotective principles which are able to more accurately utilize endogenous biochemical processes for cell- or tissue-specific therapy.