Repeated bronchoscopy in health and obstructive lung disease: is the airway microbiome stable?

OBJECTIVE

Little is known concerning the stability of the lower airway microbiome. We have compared the microbiota identified by repeated bronchoscopy in healthy subjects and patients with ostructive lung diseaseases (OLD).

METHODS

21 healthy controls and 41 patients with OLD completed two bronchoscopies. In addition to negative controls (NCS) and oral wash (OW) samples, we gathered protected bronchoalveolar lavage in two fractions (PBAL1 and PBAL2) and protected specimen brushes (PSB). After DNA extraction, we amplified the V3V4 region of the 16S rRNA gene, and performed paired-end sequencing (Illumina MiSeq). Initial bioinformatic processing was carried out in the QIIME-2 pipeline, identifying amplicon sequence variants (ASVs) with the DADA2 algorithm. Potentially contaminating ASVs were identified and removed using the decontam package in R and the sequenced NCS.

RESULTS

A final table of 551 ASVs consisted of 19 × 106 sequences. Alpha diversity was lower in the second exam for OW samples, and borderline lower for PBAL1, with larger differences in subjects not having received intercurrent antibiotics. Permutational tests of beta diversity indicated that within-individual changes were significantly lower than between-individual changes. A non-parametric trend test showed that differences in composition between the two exams (beta diversity) were largest in the PSBs, and that these differences followed a pattern of PSB > PBAL2 > PBAL1 > OW. Time between procedures was not associated with increased diversity.

CONCLUSION

The airways microbiota varied between examinations. However, there is compositional microbiota stability within a person, beyond that of chance, supporting the notion of a transient airways microbiota with a possibly more stable individual core microbiome.

Significance of the microbiome in obstructive lung disease

The composition of the lung microbiome contributes to both health and disease, including obstructive lung disease. Because it has been estimated that over 70% of the bacterial species on body surfaces cannot be cultured by currently available techniques, traditional culture techniques are no longer the gold standard for microbial investigation. Advanced techniques that identify bacterial sequences, including the 16S ribosomal RNA gene, have provided new insights into the depth and breadth of microbiota present both in the diseased and normal lung. In asthma, the composition of the microbiome of the lung and gut during early childhood development may play a key role in the development of asthma, while specific airway microbiota are associated with chronic asthma in adults. Early bacterial stimulation appears to reduce asthma susceptibility by helping the immune system develop lifelong tolerance to innocuous antigens. By contrast, perturbations in the microbiome from antibiotic use may increase the risk for asthma development. In chronic obstructive pulmonary disease, bacterial colonisation has been associated with a chronic bronchitic phenotype, increased risk of exacerbations, and accelerated loss of lung function. In cystic fibrosis, studies utilising culture-independent methods have identified associations between decreased bacterial community diversity and reduced lung function; colonisation with Pseudomonas aeruginosa has been associated with the presence of certain CFTR mutations. Genomic analysis of the lung microbiome is a young field, but has the potential to define the relationship between lung microbiome composition and disease course. Whether we can manipulate bacterial communities to improve clinical outcomes remains to be seen.

Activity of ciprofloxacin and azithromycin on biofilms produced in vitro by Haemophilus influenzae

BACKGROUND

It is recognized that Haemophilus influenzae isolated from patients with otitis media forms biofilms both in vitro and in vivo, suggesting that biofilm formation in vivo might play an important role in the pathogenesis and chronicity of otitis media, but the effect of antibiotics on biofilm has not been well studied. We investigated the impact of ciprofloxacin and azithromycin on bacterial biofilms formed by Haemophilus influenzae in vitro in this study.

METHODS

Eleven strains of Haemophilus influenzae were isolated from sputum specimens collected from patients with acute exacerbation of chronic obstructive pulmonary diseases. Formation of bacterial biofilm was examined by crystal violet assay and a scanning electron microscope. Alterations of biofilms were measured under varying concentrations of azithromycin and ciprofloxacin.

RESULTS

Striking differences were observed among strains with regard to the ability to form biofilm. Typical membrane-like structure formed by bacterial cells and extracellular matrix was detected. Initial biofilm synthesis was inhibited by azithromycin and ciprofloxacin at concentrations higher than two-fold minimal inhibitory concentration. Disruption of mature biofilms could be achieved at relatively higher concentration, and ciprofloxacin displayed more powerful activity.

CONCLUSIONS

Haemophilus influenzae is capable of forming biofilm in vitro. Sufficient dosage might control early formation of biofilms. Ciprofloxacin exerts better effects on breakdown of biofilm than azithromycin at conventional concentration in clinics.

Predictors of persistent airway stenosis in patients with endobronchial tuberculosis

SETTING

The university and municipal hospitals in Seoul, Korea.

OBJECTIVE

To evaluate the predictors of persistent airway stenosis following anti-tuberculosis chemotherapy in patients with endobronchial tuberculosis (TB).

DESIGN

Diagnosis of TB was confirmed by microbiology or histopathology. Bronchoscopic examinations revealed that patients had endobronchial lesions compatible with endobronchial TB. Study subjects had at least one follow-up bronchoscopy to evaluate their treatment response. Treatment response was determined by changes in the degree or extent of airway stenosis between the first and last bronchoscopic examinations.

RESULTS

Sixty-seven subjects were recruited retrospectively from Seoul National University Hospital and Seoul National University Boramae Hospital. Persistent bronchostenosis occurred in 41.8% of the patients. In multivariate regression analysis, age >45 years (OR 3.65), pure or combined fibrostenotic subtype (OR 5.54) and duration from onset of chief complaint to the initiation of anti-tuberculosis chemotherapy >90 days (OR 5.98) were identified as independent predictors of persistent airway stenosis. Oral corticosteroids (prednisolone equivalent >or=30 mg/d) did not reduce the frequency of persistent airway stenosis.

CONCLUSION

Early diagnosis and early administration of anti-tuberculosis chemotherapy before involvement of the deeper airways is important to prevent the development of unwanted sequelae of bronchostenosis.

Mucin overproduction in chronic inflammatory lung disease

Mucus overproduction and hypersecretion are commonly observed in chronic inflammatory lung disease. Mucins are gel-forming glycoproteins that can be stimulated by a variety of mediators. The present review addresses the mechanisms involved in the upregulation of secreted mucins. Mucin induction by neutrophil elastase, bacteria, cytokines, growth factors, smoke and cystic fibrosis transmembrane conductance regulator malfunction are also discussed.

Mycoplasma pneumoniae induces host-dependent pulmonary inflammation and airway obstruction in mice

Respiratory tract infections result in wheezing in a subset of patients. Mycoplasma pneumoniae is a common etiologic agent of acute respiratory infection in children and adults that has been associated with wheezing in 20-40% of individuals. The current study was undertaken to elucidate the host-dependent pulmonary and immunologic response to M. pneumoniae respiratory infection by studying mice with different immunogenetic backgrounds (BALB/c mice versus C57BL/6 mice). After M. pneumoniae infection, only BALB/c mice developed significant airway obstruction (AO) compared with controls. M. pneumoniae-infected BALB/c mice manifested significantly elevated airway hyperresponsiveness (AHR) compared with C57BL/6 mice 4 and 7 d after inoculation as well as BALB/c control mice. Compared with C57BL/6 mice, BALB/c mice developed worse pulmonary inflammation, including greater peribronchial infiltrates. Infected BALB/c mice had significantly higher concentrations of tumor necrosis factor-alpha, interferon-gamma, interleukin (IL)-1beta, IL-6, IL-12, KC (functional IL-8), and macrophage inflammatory protein 1alpha in the bronchoalveolar lavage fluid compared with infected C57BL/6 mice. No differences in IL-2, IL-4, IL-5, IL-10, and granulocyte/macrophage colony-stimulating factor concentrations were found. The mice in this study exhibited host-dependent infection-related AO and AHR associated with chemokine and T-helper type (Th)1 pulmonary host response and not Th2 response after M. pneumoniae infection.

Telithromycin is as effective as amoxicillin/clavulanate in acute exacerbations of chronic bronchitis

This randomized, double-blind study evaluated the efficacy and safety of a short, 5-day course of telithromycin, a new ketolide antibacterial, compared with a standard 10-day course of amoxicillin/clavulanate, in the treatment of acute exacerbations of chronic bronchitis (AECB). The study enrolled 325 adult patients with AECB and a history of chronic obstructive pulmonary disease (COPD). Patients received either telithromycin 800 mg once daily (qd) for 5 days (followed by placebo for 5 days) or amoxicillin/clavulanate 500/125 mg three times daily (tid) for 10 days. Clinical cure rates for telithromycin post-therapy (Days 17-21, test-of-cure) and late post-therapy (Days 31-36) were 86.1 and 78.1%, respectively; 82.1 and 75.0% for amoxicillin/clavulanate. Excellent clinical cure rates were also observed for high-risk patients. Bacteriologic outcome was satisfactory for 69.2% of telithromycin recipients vs 70.0% for amoxicillin/clavulanate recipients. Both treatments were generally well tolerated, although the frequency of drug-related adverse events was almost two-fold higher for amoxicillin/clavulanate (25.0 vs. 13.1%). Thus, a 5-day course of telithromycin 800 mg qd is an effective and well-tolerated alternative to a standard 10-day course of amoxicillin/clavulanate 500/125 mg tid for first-line empiric treatment of AECB in adults with COPD.

[Role of PCR analysis in complex bacteriological studies in phthisiology]

The study was undertaken to assess the role of polymerase chain reaction (PCR) analysis in complex bacteriological studies in diagnosing pulmonary tuberculosis in 197 patients by bacterioscopy, inoculation, and PCR. It was shown that in addition to conventional bacteriological methods, PCR might be used as an additional laboratory study in making a diagnosis in patients with restrictive pulmonary tuberculosis. A combination of cultural inoculation and PCR analysis enhances the sensitivity of bacteriological diagnosis and reduces its duration in oligo- and abacillary patients with tuberculosis. PCR analysis enhances the efficiency of laboratory control over antituberculous chemotherapy.

[Lung function in preadolescents after pertussis infection. Results of the epidemiologic study in Krakow]

The main goal of the study was to check the hypothesis that pertussis infection may cause a lung function deterioration in children. Cross sectional study was carried out in 1997 among 992 schoolchildren attending the fourth form of elementary schools in Krakow. In the course of the study the epidemiologic interviews on respiratory health of children and spirometric testing were performed. Spirometric indices (FVC, FEV1 and FEF25-75%) were inversely correlated with allergic diseases, wheezing symptoms and tobacco smoking of mother in pregnancy, however, the effect of the latter variable was of border significance. Socio-economic status of the family and number of infections in lower respiratory tract in children reported over the last year were not related to the lung function level. Children who reported pertussis infection in the past showed significantly lower values of FEV1 and FEF25-75%. The results obtained suggest that pertussis infection may have a detrimental effect on the lung function of preadolescent children. Since these children may be more susceptible to environmental hazards and development of obstructive lung disease, therefore, it is justified to postulate a monitoring of lung function in children after pertussis infection throughout a longer period to detect early lung obstruction and setting up proper prophylactic measures.

Chlamydia pneumoniae infection and acute exacerbation of chronic obstructive pulmonary disease (COPD)

The objective of the study was to investigate the possible association of Chlamydia pneumoniae (Cpn) in acute exacerbations of chronic obstructive pulmonary disease (COPD) patients. Thirty-eight acutely exacerbated COPD patients and 17 healthy smokers were enrolled in the study, as the study and control groups respectively. Nasopharyngeal swabs and paired serum samples for antibody testing of Cpn (microimmunofluorescence--MIF) were obtained from all subjects. Sputum cultures of COPD patients were also performed. No pathogenic bacteria were isolated from nasopharyngeal swabs in any subject. Serologic evidence of recent Cpn infection was observed in 13 (34%) COPD patients and in one (5%) control subject. The prevalence of Cpn IgG and IgM antibodies representing acute infection were significantly higher in COPD patients than in control subjects (P < 0.05 and P < 0.01 respectively). Prevalence of IgA antibodies and IgG pre-existing antibodies did not show any difference (P > 0.05). Microbiologic culture of the sputa yielded potentially pathogenic micro-organisms in 23 of 38 (60%) COPD patients. Alpha-haemolytic streptococcus (35%), Niesseria spp. (31%) and Candida spp. (9.5%) were most prominent micro-organisms in positive cultures. Although a high prevalence of IgG antibodies against Cpn was detected, it was the sole causative agent in only four (10%) patients. We conclude that a remarkable number of COPD patients (34%) are acutely infected with Cpn and it may either be the sole causative agent or frequently a co-agent in acute exacerbations.

COPD: management of acute exacerbations and chronic stable disease

Acute exacerbations of chronic obstructive pulmonary disease (COPD) are treated with oxygen (in hypoxemic patients), inhaled beta2 agonists, inhaled anticholinergics, antibiotics and systemic corticosteroids. Methylxanthine therapy may be considered in patients who do not respond to other bronchodilators. Antibiotic therapy is directed at the most common pathogens, including Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. Mild to moderate exacerbations of COPD are usually treated with older broad-spectrum antibiotics such as doxycycline, trimethoprim-sulfamethoxazole and amoxicillin-clavulanate potassium. Treatment with augmented penicillins, fluoroquinolones, third-generation cephalosporins or aminoglycosides may be considered in patients with more severe exacerbations. The management of chronic stable COPD always includes smoking cessation and oxygen therapy. Inhaled beta2 agonists, inhaled anticholinergics and systemic corticosteroids provide short-term benefits in patients with chronic stable disease. Inhaled corticosteroids decrease airway reactivity and reduce the use of health care services for management of respiratory symptoms. Preventing acute exacerbations helps to reduce long-term complications. Long-term oxygen therapy, regular monitoring of pulmonary function and referral for pulmonary rehabilitation are often indicated. Influenza and pneumococcal vaccines should be given. Patients who do not respond to standard therapies may benefit from surgery.

Microbial pattern of acute infective exacerbation of chronic obstructive airway disease in a hospital based study

Chronic bronchitis is associated with acute exacerbation, most often infective in origin. In order to study the bacteriological profile in such cases a total of 58 patients were enrolled in this study from the chest clinic of our hospital. The male to female ratio was 2 to 1. Mean age of study group was 47 years. All patients had increased cough and sputum production. Barlett count, gram stain and sputum cultures were done for all patients. IgM and IgG antibodies for M. pneumoniae by ELISA were estimated in all cases. The etiological diagnosis could be established in 72% cases. S. pneumoniae (25.8%), P. aeruginosa (12%), Klebsiella sp (10.3%), B. catarrhalis (3.4%), S. aureus (1.7%) were isolated. Although M. pneumoniae was not cultured it was demonstrated serologically in 20% of cases. H. influenzae was not isolated in any case. The frequency of isolating an etiological agent increased with severity of dysponea.

Infectious etiologies in acute exacerbation of COPD

Acute exacerbation (AE) is a frequent episode during the prolonged chronic course of chronic obstructive pulmonary disease (COPD), which entails significant morbidity and mortality. The purpose of this study was to determine the frequency distribution of infectious etiologies in these episodes. Two hundred forty hospitalizations for AECOPD were included in a prospective, purely serologically based study. Paired sera were obtained for each of the hospitalizations and were tested using immunofluorescence or EIA methods to identify 13 different pathogens. Only significant changes in antibody titers were considered diagnostic. The mean age ( +/- SD) of the patients was 66.8 +/- 9.0 years and 179 (84%) were males. In 175 (72.9%) hospitalizations at least one infectious etiology was identified. In 117 (48.8%) hospitalizations at least one of 7 viral etiologies was identified. In 72 (30.0%) hospitalizations at least one of the following atypical bacteria was identified: Legionella spp. in 40 (16.7%), Mycoplasma pneumoniae in 34 (14.2%), and Coxiella burnetii in a single hospitalization. In 58 (24.2%) hospitalizations at least one classic bacterial etiology was found: Streptococcus pneumoniae in 48 (20.0%), Hemophilus influenzae in 10 (4.2%) and Moraxella catarrhalis in 9 (3.8%). More than one etiology was found in 72 (30.0%) hospitalizations. There were no significant differences in the etiologic distribution when the patients were classified by severity of airway obstruction or the clinical type of the exacerbation. We conclude that in most cases of hospitalization due to AECOPD the infectious etiology is viral or atypical bacteria and is classic bacteria in only a minority of cases. More than one etiologic cause can be identified in a third of the cases. The frequency distribution of the etiologies is not associated with the severity of airway obstruction or the clinical type of the exacerbation. The results of our study suggest that atypical bacteria should be covered in antibiotic regimens recommended for AECOPD. This issue should be addressed in future studies.

[The study of the frequency and features of bacteria isolated in patients with non-tuberculosis respiratory disorders admitted in "M. Nasta" Institute in the first trimester 2001]

The aim of this study was to determine the spectrum of bacteria isolated in patients with non-TB respiratory disorders, in order to find the frequency of germs isolated globally and in each of the 6 clinical syndromes: suppurations, chronic obstructive diseases exacerbations (COPD, bronchial asthma), pneumopathies, post-TB syndromes, tumors and interstitial lung diseases. We found the greatest global frequency in anaerobes (35%). This is in concordance with the high frequency of broncho-pulmonary suppurations (51% of the cases studied). In second place comes Ps. aeruginosa (18%), followed by Str. Pneumoniae (16%), H. influenzae (11%) and Klebsiella pn. (10%). Considering the germs identified in the various clinical syndromes, we found a high frequency of anaerobes associated to suppurations (51%), interstitial lung diseases (43%) and tumors (37%), while Ps. aeruginosa is first in post-TB syndromes (50%) and COPD exacerbations (21%), equal to H. influenzae. In pneumonias, Str. Pneumoniae was most frequently isolated (38%) followed by H. influenzae (25%). The susceptibility testing of strains of Klebsiella and Ps. aeruginosa revealed the increasing tendency to resistance to broad spectrum antibiotics, especially for Ps. aeruginosa, with consecutive difficulties in finding the appropriate treatment.

Antimicrobial management of acute exacerbation of chronic airflow limitation

Antibiotics are frequently administered for exacerbations of chronic obstructive pulmonary disease and asthma, yet their role remains unclear. We prospectively audited the antimicrobial management of 167 patients aged >50 years hospitalized for exacerbations of chronic airflow limitation. Antibiotics were commenced on admission for 151 (90%) patients (oral 52%, intravenous 38%), including 17/23 (74%) with no evidence of fever, purulent sputum, leucocytosis or inflammatory chest X-ray changes. The mean number of different antibiotics prescribed was 1.8 (range 0-6); a wide range of antibiotics and antibiotic combinations were used. Sputum samples were sent for microbiological examination in 101 (61%) patients. Sputum culture was positive in 34, but only 11 (7% of the total) had amoxycillin-resistant organisms in their sputum. Seventeen patients (10%) developed diarrhoea while in hospital. Under logistic regression analysis, total number of antibiotics prescribed (p<0.0001) and age (p=0.0062) were the two factors associated with hospital-acquired diarrhoea. Only 34% of patients had received an influenza vaccination in the winter of the study, and 10% a pneumococcal vaccination within the last 5 years. In routine clinical practice, aggressive antibiotic therapy was frequently administered to patients admitted with chronic airflow limitation, despite limited clinical, radiological and microbial indications. Excessive use of antibiotics has important implications, including morbidity (antibiotic-associated diarrhoea), cost and the potential for increased microbial antibiotic resistance. A minority of patients with chronic airflow limitation are being vaccinated against influenza and Pneumococcus.

Conservation of outer membrane protein E among strains of Moraxella catarrhalis

Outer membrane protein E (OMP E) is a 50-kDa protein of Moraxella catarrhalis which has several features that suggest that the protein may be an effective vaccine antigen. To assess the conservation of OMP E among strains of M. catarrhalis, 22 isolates were studied with eight monoclonal antibodies which recognize epitopes on different regions of the protein. Eighteen of 22 strains were reactive with all eight antibodies. The sequences of ompE from 16 strains of M. catarrhalis were determined, including the 4 strains which were nonreactive with selected monoclonal antibodies. Analysis of sequences indicate a high degree of conservation among strains, with sequence differences clustered in limited regions of the gene. To assess the stability of ompE during colonization of the human respiratory tract, the sequences of ompE of isolates collected from patients colonized with the same strain for 3 to 9 months were determined. The sequences remained unchanged. These results indicate that OMP E is highly conserved among strains of M. catarrhalis, and preliminary studies indicate that the gene which encodes OMP E remains stable during colonization of the human respiratory tract.

Lipopolysaccharide of Haemophilus influenzae induces interleukin-5 mRNA expression in human peripheral blood mononuclear cells

Haemophilus influenzae is the bacterial species most often isolated from sputum of patients with chronic obstructive pulmonary disease (COPD). In this study, we examined the induction of interleukin-5 (IL-5) mRNA expression in human peripheral blood mononuclear cells (PBMC) stimulated with lipopolysaccharide (LPS) from H. influenzae to try to predict the effect of H. influenzae infection on the eosinophilic inflammation in COPD. Detection of IL-5 mRNA by RT-PCR showed that LPS from H. influenzae induced IL-5 mRNA expression in PBMC at a concentration of 1 microg/ml. Furthermore, the level of expression of IL-5 mRNA induced by LPS correlated with the amount of IL-5 protein in the culture supernatant. Inhibition of LPS-induced IL-5 mRNA expression by anti-CD14 antibody and diminution of this in a CD3(+) -cell-depleted fraction of PBMC, respectively, suggested that CD14 molecules were required for the increase in IL-5 mRNA and that T lymphocytes were the principal source of IL-5 mRNA expression in PBMC. Briefly, the IL-5 mRNA expression induced by LPS would be based on LPS-activated monocytes interacting with T lymphocytes to produce IL-5. These results may explain the role that colonization with H. influenzae plays in eosinophilic inflammation in patients with COPD.

Bacterial infection in chronic obstructive pulmonary disease in 2000: a state-of-the-art review

Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death in the United States. The precise role of bacterial infection in the course and pathogenesis of COPD has been a source of controversy for decades. Chronic bacterial colonization of the lower airways contributes to airway inflammation; more research is needed to test the hypothesis that this bacterial colonization accelerates the progressive decline in lung function seen in COPD (the vicious circle hypothesis). The course of COPD is characterized by intermittent exacerbations of the disease. Studies of samples obtained by bronchoscopy with the protected specimen brush, analysis of the human immune response with appropriate immunoassays, and antibiotic trials reveal that approximately half of exacerbations are caused by bacteria. Nontypeable Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae are the most common causes of exacerbations, while Chlamydia pneumoniae causes a small proportion. The role of Haemophilus parainfluenzae and gram-negative bacilli remains to be established. Recent progress in studies of the molecular mechanisms of pathogenesis of infection in the human respiratory tract and in vaccine development guided by such studies promises to lead to novel ways to treat and prevent bacterial infections in COPD.

Risk factors for acquisition of levofloxacin-resistant Streptococcus pneumoniae: a case-control study

A case-control study was conducted to identify the risk factors associated with levofloxacin-resistant Streptococcus pneumoniae (LRSP) colonization or infection. Twenty-seven case patients (patients with LRSP) were compared with 54 controls (patients with levofloxacin-susceptible S. pneumoniae). Risk factors that were significantly associated with LRSP colonization or infection, according to univariate analysis, included an older age (median age, 75 years for case patients versus 72.5 years for controls), residence in a nursing home (odds ratio [OR], 7.2), history of recent (OR, 4.6) and multiple (OR, 4.4) hospitalizations, prior exposure to fluoroquinolones (OR, 10.6) and beta-lactams (OR, 8.6), presence of chronic obstructive pulmonary disease (COPD; OR, 5.9), and nosocomial origin of the bacteria (OR, 5.7). Multivariate analysis showed that presence of COPD (OR, 10.3), nosocomial origin of the bacteria (OR, 16.2), residence in a nursing home (OR, 7.4), and exposure to fluoroquinolones (OR, 10.7) were independently associated with LRSP colonization or infection. Thus, a distinct group of patients with COPD is the reservoir of LRSP.

[Chronic Chlamydia pneumonia infection in patients with chronic obstructive pulmonary disease]

The aim of our study was to evaluate the frequency of Chlamydia pneumoniae infection (especially chronic infection) in COPD patients. Microimmunofluorescence method has been applied Chlamydia pneumoniae Micro-IF test (Labsystems) has been used. The levels of specific IgG, IgA and IgM have been estimated in patients' serum. According to serologic criteria, 64.1% of COPD patients and 20.5% of healthy controls appeared to be chronically infected with Chlamydia pneumoniae (p < 0.001). Taking in account COPD severity, persistent Chlamydia pneumoniae infection has been present in 68.2%, 57.1%, and 50% of patients with severe, moderate and mild COPD, respectively. Our study has revealed that chronic Chlamydia pneumoniae infection occurs more frequently in COPD patients than in healthy controls and in patients with severe COPD than in ones with mild and moderate disease. It is possible that persistent Chlamydia pneumoniae infection can initiate or amplify inflammatory reactions in the respiratory tract. The results suggest a need to diagnose chronic Chlamydia pneumoniae infection in COPD patients and, if confirmed, to take an attempt of antimicrobial therapy.

Chronic obstructive pulmonary disease patients with invasive pulmonary aspergillosis: benefits of intensive care?

OBJECTIVES

Invasive pulmonary aspergillosis (IPA) is increasingly recognized as a cause of acute respiratory failure in patients with chronic obstructive pulmonary disease (COPD) treated with corticosteroids. For these patients admission in intensive care unit (ICU) is often required for life-support and mechanical ventilation. Whether this approach improves outcome is unknown.

DESIGN AND SETTING

Retrospective study in a university hospital intensive care unit.

PATIENTS

Between November 1993 and December 1997, 23 COPD patients were admitted in our ICU and received antifungal agents for possible IPA.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

The clinical features and the outcome were reviewed. Diagnosis of IPA was classified as confirmed (positive lung tissue biopsy and/or autopsy) or probable (repeated isolation of Aspergillus from the airways with consistent clinical and radiological findings). Among the 23 patients treated for Aspergillus, 16 fulfilling these criteria for IPA were studied. Steroids had been administered at home to all patients but one and were increased during hospitalization in all. Twelve patients suffered a worsening of their bronchospasm precipitating acute respiratory failure. During ICU stay all patients required mechanical ventilation for acute respiratory failure. Although amphotericin B deoxycholate was started when IPA was suspected (0.5-1.5 mg/kg per day), all patients died in septic shock (n = 5) or in multiple-organ failure.

CONCLUSIONS

The poor prognosis of intubated COPD patients with IPA, in spite of antifungal treatment suggests that further studies are required to define the limits and indications for ICU management of these patients.

[Prospective, comparative study (1994-1998) of the influence of short-term prophylactic treatment with azithromycin on patients with advanced COPD]

Despite the advances in therapy, chronic obstructive pulmonary disease (COPD) requires frequent hospital admissions due to acute exacerbations. We carried out a prospective randomized study of two groups of patients with COPD, one (n = 54) treated with azithromycin (500 mg/day) for three days every 21 days during the winter months, and a control group (n = 40) without treatment. A statistically significant reduction in the number of acute infectious episodes (187) and hospital admissions (22) was observed in the treated group versus the control group (249 and 45, respectively). A short prophylactic treatment course with azithromycin is a good alternative in the management of patients with severe, advanced COPD, and could lead to an improvement in social and healthcare costs

Acute exacerbations in chronic obstructive pulmonary disease (COPD)--microbial patterns and risk factors

Around 25% of patients with stable chronic obstructive pulmonary disease (COPD) show some evidence of tracheobronchial colonization. It is, however, probable that the vast majority of patients become colonized at some time during the course of the disease. A variety of factors including current smoking and viral infections predispose to bacterial colonization and subsequently acute exacerbations. In fact, infectious aetiologies account for around 50-75% of acute COPD exacerbations. Bacterial pathogens are present in around 50% of patients, Haemophilus influenzae and Streptococcus pneumoniae being the most frequently encountered pathogens. Pseudomonas aeruginosa and probably also Gram-negative enteric bacilli are more frequently found in patients with more severe airflow limitation. Viral infections are present in around 10-20%, with Influenzavirus representing the most frequent viral pathogen. Only recently, evidence for infection by Chlamydia pneumoniae has been found in 5-20% of patients. Predictors of distinct aetiologies have only infrequently been studied so far. Thus, it currently remains difficult to make adequate predictions on clinical grounds in the individual patient. Nevertheless, we would advocate to tentatively stratify the initial antimicrobial treatment according to the severity of the acute exacerbation episode and the presence of individual risk factors. The validation of such an approach may result in significant progress in our understanding of the role of infection and infectious agents in different subgroups of patients with acute exacerbations.

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.

Association between airway bacterial load and markers of airway inflammation in patients with stable chronic bronchitis

PURPOSE

Viable bacteria are often isolated from airway secretions in clinically stable patients with chronic bronchitis. We hypothesized that the number of organisms and bacterial species might be important modulators of airway inflammation.

SUBJECTS AND METHODS

We performed quantitative sputum cultures in 160 stable patients [55 with chronic obstructive pulmonary disease (COPD) and normal serum alpha(1)-antitrypsin levels, 62 with COPD and severe alpha(1)-antitrypsin deficiency (PiZ), and 43 with idiopathic bronchiectasis]. The results were related to several indicators of the mechanisms and severity of airway inflammation.

RESULTS

Airway bacterial load correlated with sputum myeloperoxidase level, an indirect measure of neutrophil activation and number (r = 0.50, P<0. 001); sputum neutrophil chemoattractants [interleukin-8 level (r = 0. 68, P<0.001) and leukotriene B4 level (r = 0.53, P<0.001)]; sputum leukocyte elastase activity (r = 0.55, P<0.001); and albumin leakage from serum to sputum (r = 0.26, P<0.01). Markers of inflammation increased at bacterial loads of 10(6) to 10(7) colony-forming units per milliliter, and increased progressively with increasing bacterial load. For example, the median (interquartile range) sputum myeloperoxidase level was 0.3 U/mL (0.1 to 0.5 U/mL) for patients who were not colonized or who had mixed normal oropharyngeal flora alone; 0.5 U/mL (0.2 to 0.7 U/mL) for patients with 10(5) to 10(6) colony-forming units per milliliter (P = 0.07); 0.5 U/mL (0.3 to 1.2 U/mL) for patients with 10(6) to 10(7) colony-forming units per milliliter (P<0.01); 0.7 U/mL (0.3 to 1.2 U/mL) for patients with 10(7) to 10(8) colony-forming units per milliliter (P <0.005); and 2.4 U/mL (0.7 to 4.8 U/mL) for patients with 10(8) or greater colony-forming units per milliliter (P<0.0001). The bacterial species influenced airway inflammation; for example, sputum myeloperoxidase activity was greater (P<0.005) in patients colonized with Pseudomonas aeruginosa [median 32 U/mL (interquartile range, 20 to 65 U/mL)] than those colonized with nontypeable Hemophilus influenzae [4 U/mL (2 to 31 U/mL)], which in turn was greater (P = 0.01) than among those colonized with Moraxella catarrhalis [1.1 U/mL (0.6 to 1.8 U/mL)]. We did not find a relation between bacterial load and lung function.

CONCLUSIONS

The bacterial load and species contribute to airway inflammation in patients with stable chronic bronchitis. Further studies are required to determine the consequences of bacterial colonization on patient morbidity and decline in lung function.

Treating acute exacerbations of chronic bronchitis in the face of antibiotic resistance

Antibiotics can be effective against acute exacerbations of chronic bronchitis and chronic obstructive pulmonary disease, but with bacterial resistance to multiple antibiotics increasing worldwide, appropriate antibiotic selection is critical. Categorizing patients with acute exacerbations according to age, number of exacerbations per year, disease severity, degree of pulmonary impairment, and presence of comorbid conditions helps to direct therapy.

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.

Characterization of adherence of nontypeable Haemophilus influenzae to human epithelial cells

The adherence of 58 nontypeable Haemophilus influenzae isolates obtained from patients with otitis media or chronic obstructive pulmonary disease (COPD) and obtained from the throats of healthy individuals to Chang and NCI-H292 epithelial cells was compared. Otitis media isolates, but not COPD isolates, adhered significantly more to both cell lines than did throat isolates. Since high-molecular-weight (HMW) proteins are major adhesins of nontypeable H. influenzae, the isolates were screened for HMW protein expression by Western blotting with two polyclonal sera and PCR with hmw-specific primers. Twenty-three of the 32 adhering isolates (72%) and only 1 of the 26 nonadherent strains were HMW protein or hmw gene positive. Among the 32 isolates adhering to either cell line, 5 different adherence patterns were distinguished based on the inhibiting effect of dextran sulfate. Using H. influenzae strain 12 expressing two well-defined HMW proteins (HMW1 and HMW2) and its isogenic mutants as a reference, we observed HMW1-like adherence to both cell lines for 16 of the 32 adherent isolates. Four others showed HMW2-like adherence to NCI-H292. Of the three other patterns of adherence, one probably also involved HMW protein. Screening of the isolates with six HMW-specific monoclonal antibodies in a whole-cell enzyme-linked immunosorbent assay showed that the HMW proteins of COPD isolates and carrier isolates were more distinct from the HMW proteins from H. influenzae strain 12 than those from otitis media isolates. Characterization of the HMW protein of a COPD isolate by adherence and DNA sequence analysis showed that despite large sequence diversity in the hmwA gene, probably resulting in the antigenic differences, the HMW protein mediated the HMW2-like adherence of this strain.

The role of bacteria in exacerbations of COPD. A constructive view

The role of infection in exacerbations of COPD remains controversial and incompletely understood. Although some investigators believe that bacteria are not important for patients with exacerbation, we disagree and believe that patients with at least two of the three cardinal symptoms of exacerbation should receive antibiotic therapy. With an open-minded view of the area, we review the data, showing that bacteriologic studies, pathologic investigations, and clinical trials all support roles for bacteria and antibiotic therapy in this disease. Still, many questions remain, and future studies will be needed to better define the mechanisms of bacterial invasion in the bronchitic patient and to develop effective vaccines to prevent exacerbations. In the meantime, we must rely on antibiotic therapy, and we will need prospective studies to corroborate preliminary findings showing that different patients may require different therapies; thus, patient subsetting may be vital in the selection of antibiotic therapy for exacerbations of COPD.

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.

Stimulation of bacterial adherence by neutrophil defensins varies among bacterial species but not among host cell types

Adherence of Haemophilus influenzae to bronchial epithelial cells is enhanced by neutrophil defensins, which are released from activated neutrophils during inflammation [Gorter et al. (1998) J. Infect. Dis. 178, 1067-1078]. In this study, we showed that the adherence of H. influenzae to various epithelial, fibroblast-like and endothelial cell types was significantly enhanced by defensins (20 microg ml(-1)). Defensins stimulated also the adherence of Moraxella catarrhalis, Neisseria meningitidis and nonencapsulated Streptococcus pneumoniae to the NCI-H292 cell line. In contrast, defensins did not affect the adherence of Pseudomonas aeruginosa, encapsulated S. pneumoniae, Escherichia coli and Staphylococcus epidermidis. These results suggest that the defensin-enhanced adherence might support the adherence and possibly persistence of the selected bacterial species using the respiratory tract as port of entry.

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.

Bacterial infection and the pathogenesis of COPD

Bacterial infection of the lower respiratory tract can impact on the etiology, pathogenesis, and the clinical course of COPD in several ways. Several recent cohort studies suggest that lung growth is impaired by childhood lower respiratory tract infection, making these individuals more vulnerable to developing COPD on exposure to additional injurious agents. Impairment of mucociliary clearance and local immune defense in smokers allows bacterial pathogens to gain a foothold in the lower respiratory tract. These pathogens and their products can cause further impairment of mucociliary clearance due to enhanced mucus secretion, disruption of normal ciliary activity, and airway epithelial injury, and thus persist in the lower respiratory tract. This chronic colonization of the lower respiratory tract by bacterial pathogens could induce a chronic inflammatory response with lung damage. Nontypeable Haemophilus influenzae, usually regarded as an extracellular mucosal pathogen, has been demonstrated to cause intracellular infections of the upper and lower respiratory tract respiratory tissue. Increased incidence of chronic Chlamydia pneumoniae infection of the respiratory tract has been associated with COPD. These chronic infections of respiratory tissues could contribute to the pathogenesis of COPD by altering the host response to cigarette smoke or by inducing a chronic inflammatory response. Application of newer molecular and immunologic research techniques is helping us define precisely the role of bacterial infection in COPD.

Analysis of Moraxella catarrhalis by DNA typing: evidence for a distinct subpopulation associated with virulence traits

Two DNA typing methods, probe-generated restriction fragment length polymorphism analysis and single-adapter amplified fragment length polymorphism analysis, were used to study the genetic relationships among 90 Moraxella catarrhalis strains. Both methods were found to be highly concordant, generating a dendrogram with 2 main branches. The division of the M. catarrhalis population into 2 subspecies was supported by analysis of the 16S rRNA sequences. Both beta-lactamase-positive and beta-lactamase-negative strains were found in all main branches, suggesting horizontal transfer of the beta-lactamase gene. In contrast, 2 virulence traits, complement resistance and adherence to epithelial cells, were strongly associated with 1 of the 2 subspecies. The branch depth suggested that complement-resistant adherent strains diverged from a common ancestor more recently than did complement-sensitive nonadherent strains. These findings suggest the existence of subpopulations of M. catarrhalis that differ in virulence, and they may have implications for vaccine development.

Allergen-specific IgE levels against crude mould and storage mite extracts and recombinant mould allergens in sera from horses affected with chronic bronchitis

Immunoglobulin E antibody (IgE) levels against four recombinant (r) mould allergens (r-Aspergillus fumigatus [rAsp f] 7, 8 and 9; r-Alternaria alternata 1 [rAlta1]) and crude mould (Aspergillus fumigatus, Alternaria alternata, Penicillium notatum) and storage mite extracts were determined by ELISA in sera from 24 pulmonary sound control horses and 26 horses suffering from chronic bronchitis/bronchiolitis (CB), also called chronic obstructive pulmonary disease (COPD). Serum IgG and IgA titres were also determined against Aspergillus fumigatus extract and rAsp f 8.IgE against the crude extracts could be measured in all sera, but there was no significant difference between CB-affected and control horses. In contrast, only 8-30% of the horses, depending on the r-allergen tested, had detectable IgE levels in serum against the r-allergens. Horses with CB had significantly more often detectable IgE levels than controls against rAlt a 1 (10/26 and 3/24, respectively, p=0. 054), rAsp f 7 (13/26 and 2/24, respectively, p<0.01) and rAsp f 8 (11/26 and 1/24, respectively, p<0.01). Only four horses (three CB-affected and one healthy, p0.05) had detectable IgE levels against rAsp f 9. Furthermore, CB-affected horses were often sensitised against two or more r-allergens (13/26 of the CB-affected horses) while only one of the 24 healthy horses had positive IgE levels against more than one r-allergens. Similarly to IgE levels, no significant differences between CB-affected and healthy horses were found for IgG titres against the Aspergillus fumigatus extract. However, horses with CB had significantly higher serum IgG titres against rAsp f 8 than healthy controls (median=28 versus 10 relative ELISA units [REU], p<0.01). Additionally, horses with detectable IgE titres against rAsp f 8 had significantly higher IgG titres against this r-allergen than horses with undetectable IgE titres (median IgG titres=46 and 13 REU, respectively; p<0.01). For serum IgA titres, neither differences between healthy and CB-affected animals nor correlations between IgA and IgG or IgE titres could be found. These results show that horses suffering from CB are more often sensitised to some Aspergillus fumigatus and Alternaria alternata allergens than control horses and that they are partly sensitised to the same fungal proteins as mould-allergic human patients. Furthermore, this study shows that r-allergens allow a much more sensitive determination of specific serum antibody levels by ELISA than crude mould extracts.

[Influence of MP infection on immunologic function in patients with chronic obstructive pulmonary disease]

The aim of this study was to detect Mycoplasma pneumoniae(MP) in sputum with chronic obstructive pulmonary disease(COPD) by using polymerase chain reaction and measured the level of sIL-2R in chronic pulmonary heart disease(CPHD) patients by Enzyme Linked Immnosorbert Assay(ELISA). At the same time, we also measured the level of the serum total IgE in CPHD patients. We determine the relationship between the sIL-2R and lymphocytes. The results showed that rate of MP infection in COPD patients was 34.59%. The rate of MP infection in CPHD patients and asthmatic patients were significantly higher than that in patients with chronic bronchitis. The level of sIL-2R in patients with CPHD who had MP infection increased significantly higher than that in CPHD patients which didn't have MP infection. There was a linear negative correlation between the level of sIL-2R and lymphocytes. The level of serum total IgE in CPHD patients with MP infection was higher than that in patients with other infection. These data suggest that MP is a common agent in COPD patients, particularly in CPHD and asthma. MP infection can impair the cellular immunity and immunotherapy combined with antibiotics may be more effective.

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.

Bactericidal activity of a monocytic cell line (THP-1) against common respiratory tract bacterial pathogens is depressed after infection with respiratory syncytial virus

Non-typable Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis and respiratory syncytial virus (RSV) are commonly isolated from patients during the course of chronic obstructive pulmonary disease (COPD). Earlier studies found that virus infection enhanced binding of bacterial respiratory pathogens to epithelial cells in vitro. The objective of the present study was to assess the effect of RSV infection of a human monocytic cell line on bactericidal activity and cytokine production in response to these bacterial respiratory pathogens. The effect of RSV infection on binding, uptake and intracellular killing of bacteria by a human monocytic leukaemia cell line, THP-1, was assessed. Cell culture supernates were examined with a mouse fibroblast cell assay for tumour necrosis factor-alpha (TNF-alpha) bioactivity. Expression of CD14, CD11a, CD18, CD15 and CD29 on uninfected and RSV-infected THP-1 cells was assessed by flow cytometry in relation to differences in bacterial binding. RSV infection of THP-1 cells significantly decreased their ability to bind and kill bacteria. Compared with uninfected cells, fewer bacteria bound to RSV-infected THP-1 cells and the surface antigens that have been reported to bind bacteria were expressed at lower levels on RSV-infected cells. RSV-infected cells incubated with bacteria exhibited less TNF-alpha bioactivity than uninfected cell incubated with bacteria. The results elucidate some of the mechanisms involved in the increased susceptibility of virus-infected patients to secondary bacterial infection. Reduced bacterial killing by virus-infected monocytes might contribute to reduced clearance of bacteria from the respiratory tract and damage elicited by the bacteria or cytokine response in COPD patients.

Evaluation of antimicrobial treatment in mechanically ventilated patients with severe chronic obstructive pulmonary disease exacerbations

OBJECTIVE

To study microbial and susceptibility patterns and antimicrobial treatment responses in patients with severe, acute exacerbations of chronic obstructive pulmonary disease requiring mechanical ventilation.

DESIGN

Microbial investigation using tracheobronchial aspirates, bronchoscopy with a protected specimen brush, and bronchoalveolar lavage, as well as paired serologies. Evaluation of antimicrobial treatment by results of the initial investigation, susceptibility testing, and a repeated microbial investigation (tracheobronchial aspirates, bronchoscopy with a protected specimen brush, and bronchoalveolar lavage) after 72 hrs.

SETTING

A respiratory intensive care unit of a 1,000-bed teaching hospital.

PATIENTS

Fifty severely exacerbated and mechanically ventilated patients with chronic obstructive pulmonary disease.

INTERVENTIONS

Initial empirical antimicrobial treatment according to clinical judgment.

MEASUREMENTS AND MAIN RESULTS

Overall, 36 of 50 patients (72%) had evidence of a microbial origin. Community-acquired endogenous pathogens were present in 70% of patients, and Gram-negative enteric bacilli and Pseudomonas/Stenotrophomonas species were present in 30%. All five isolates of Streptococcus pneumoniae were resistant to penicillin (three intermediately and two highly), and three were resistant to multiple antibiotics. Pseudomonas species revealed multiresistance in four of nine isolates (44%), and Stenotrophomonas maltophilia revealed multiresistance in one of two isolates. Antimicrobial treatment was modified according to diagnostic results in 11 of 31 patients (36%) with potentially pathogenic microorganisms. In patients who underwent a repeat investigation after 72 hrs, 24% of the initially present and potentially pathogenic microorganisms persisted. Inappropriate initial antimicrobial therapy was associated significantly with bacterial persistence (p < .002).

CONCLUSIONS

Considering the diversity of microbial pathogens and the resistance rates especially to S. pneumoniae in this patient population, antimicrobial treatment should be based on the constant study of local microbial and susceptibility patterns along with routine microbial investigation of the individual patient.

Clinical and in vitro evaluation of membrane humidifier that does not require addition of water

It is well known that conventional bubbling humidifiers are capable of producing micro-aerosols contaminated with bacteria. We developed a unique humidifier, named a membrane humidifier, that does not require an external water supply. This new system obtains moisture from room air. We investigated the clinical and in vitro evaluation of the membrane humidifier. Ten patients with chronic pulmonary disease participated in the study. We evaluated the partial pressure of oxygen in arterial blood (PaO2) of 10 patients who used the new device. We conducted an in vitro study to determine whether the device could prevent the bacterial contamination of humidified-oxygen. We passed compressed air contaminated with Pseudomonas aeruginosa outside the hollow fibres of the membrane humidifier, and the humidified-oxygen passed inside the hollow fibres was sampled into nutrient broth periodically for 10 days. We also compared the relative humidity of oxygen humidified by a membrane humidifier with that of oxygen humidified by a bubbling humidifier. There was no significant difference between measured PaO2 while breathing oxygen humidified using a membrane humidifier and that while breathing oxygen humidified using a bubbling humidifier. Cultures of the humidified-oxygen passed through the hollow fibres were negative for bacteria. The membrane humidifier could produce good humidification. The new device appeared to prevent bacterial contamination, and may help to reduce the risk of infection in patients at hospital and home.

Airway inflammation and bronchial microbial patterns in patients with stable chronic obstructive pulmonary disease

The effect of bacterial colonization of the bronchi on the progress of airflow limitation is not well known. Therefore, the pattern of airway inflammation in smokers and patients with stable chronic obstructive pulmonary disease (COPD) and its relation to bronchial microbial colonization was assessed. Eight nonsmoking and 18 smoking controls as well as 52 patients with COPD (28 mild, 11 moderate and 13 severe) were studied. All subjects were investigated by means of flexible bronchoscopy including protected specimen brush and bronchoalveolar lavage (BAL) sampling. Differential cell counts, cytokine (interleukin (IL)-1beta, IL-6, IL-8, IL-10 and tumour necrosis factor-alpha(TNF-alpha) concentrations and microbial patterns were determined in BAL fluid. Forced expiratory volume in one second (FEV1) % of the predicted value was inversely correlated with pack-yrs of cigarette smoking (r=-0.47, p<0.0001), the percentage of neutrophil (p=-0.56, p<0.0001) and IL-6 (p=-0.37, p=0.01) and IL-8 concentration (p=-0.43, p=0.004) in BAL fluid. Accordingly, pk-yrs of cigarette smoking (p=0.39, p=0.01) and IL-8 (p=0.69, p<0.0001) and TNFalpha (p=0.4, p<0.005) were positively correlated with the percentage of neutrophils in BAL fluid. Smoking controls and COPD patients were mainly colonized in the bronchial tree (33%) by community endogenous potentially pathogenic micro-organisms (PPMs). Colonization rates and patterns of PPMs were not affected by severity of airflow obstruction. The presence of PPMs was significantly associated with higher percentages of neutrophils (33.2+/-10.4% versus 10.1+/-3.5%, p=0.02) and TNF-alpha concentration (29.9+/-10.8 versus 6.3+/-2.1 pg x mL(-1), p=0.01) in BAL fluid. In conclusion, bronchial neutrophilia is a key inflammatory pattern in chronic obstructive pulmonary disease patients. Bronchial colonization with potentially pathogenic micro-organisms may represent an independent stimulus for additional airway inflammation.

Simultaneous respiratory tract colonization by multiple strains of nontypeable haemophilus influenzae in chronic obstructive pulmonary disease: implications for antibiotic therapy

Nontypeable Haemophilus influenzae often causes exacerbations of chronic obstructive pulmonary disease (COPD), and these exacerbations are frequently treated with oral antibiotics. The goals of this study were to determine the frequency of the simultaneous presence of multiple strains of H. influenzae in sputum and to measure the MICs of antibiotics for the isolates. In a prospective study, adults with COPD were seen monthly. Sputum cultures were obtained, and individual colonies were subjected to genomic DNA typing and MIC determinations. Multiple strains of H. influenzae were present simultaneously in the sputum of 26.3% of adults with COPD. In 64.5% of these, MICs of >/=1 antibiotic varied by >/=4-fold among the strains. Therefore, multiple strains of H. influenzae are frequently present simultaneously in the sputum of adults with COPD, and the antimicrobial susceptibility of different strains in the same sputum sometimes differs.

Oropharyngeal gram-negative bacillary carriage in chronic obstructive pulmonary disease: relation to severity of disease

The prolonged presence of aerobic Gram-negative bacilli (AGNB) in the oropharynx is termed 'carriage'. AGNB carriage rates are low in populations of healthy individuals. Previously, severity of underlying disease has been positively correlated with oropharyngeal AGNB carriage rate. Overgrowth of AGNB at the oropharynx poses a significant risk of endogenous infection in end-stage chronic obstructive pulmonary disease (COPD) patients. The aims of this study were to undertake an epidemiological survey of the oropharyngeal flora of COPD patients and to correlate oropharyngeal carriage of AGNB with severity of disease. Two oral rinses were obtained, within a 2-day interval, from 40 COPD patients comprising three disease severity groups: 1. mild, 2. moderate and 3. severe. Eighty oral rinses were quantitatively (1:10 dilution series) cultured for AGNB and yeasts using broth enrichment. The mean AGNB carriage rate was 15%. AGNB carriage rates of 0, 7.7 and 29.4% were observed within the mild, moderate and severe disease groups, respectively. The mean yeast carriage rate was 33.3%. Yeast carriage rates of 33.3, 15.4 and 64.7% were observed within the mild, moderate and severe disease groups, respectively. Carriage of Staphylococcus aureus was 5%. Rates of oropharyngeal carriage of AGNB (1/23 vs. 5/17) and yeasts (5/23 vs. 11/17) were significantly higher within the severe disease group than in non-severe disease groups. Oropharyngeal carriage of AGNB in end-stage COPD patients (forced expiratory volume in 1 sec, FEV1 < 50% predicted) presents a potential source of Gram-negative endogenous pneumonia. This outcome may be promoted by intubation and some flora-suppressing antibiotic therapies.

Effect of carbon dioxide on testing of susceptibilities of respiratory tract pathogens to macrolide and azalide antimicrobial agents

The in vitro activities of erythromycin, azithromycin, and clarithromycin against 178 clinical isolates from the lower respiratory tract of patients with chronic obstructive pulmonary disease were determined by an agar dilution method. The plates were incubated in air alone or in 5% carbon dioxide. The MICs measured in air alone were lower for most isolates than those measured in 5% carbon dioxide, illustrating the "pH effect" of incubation in carbon dioxide. Testing of isolates in 5% carbon dioxide on pH-adjusted medium (pH 8.4) resulted in MICs of one or two doubling dilutions lower than those obtained on agar with a neutral pH. A bioassay of the three agents incubated in air and in 5% carbon dioxide resulted in a significant loss of activity of all three agents in the carbon dioxide-enriched atmosphere. However, this loss-of-activity effect was significantly reduced when the bioassay medium was adjusted to pH 8.4 prior to incubation in 5% carbon dioxide.

Hospital-related outbreak of infection with multidrug-resistant Streptococcus pneumoniae in the Netherlands

Multidrug-resistant strains of Streptococcus pneumoniae were isolated over a two-year period (July 1995 until August 1997) from the sputum of 36 patients who were hospitalized in a Dutch medical centre. Nosocomial transmission was confirmed by typing of the bacterial isolates: all 36 multidrug-resistant isolates shared the same genotype, serotype, and displayed overlapping drug resistance profiles. Thirty-two of the 36 (89%) patients had chronic obstructive pulmonary disease (COPD). The outbreak was initiated by a 76-year old patient, who had been colonized with the same strain since 1993. Because staff screening of the hospital and pulmonary function department was negative, patient-to-patient spread was the most likely cause of this outbreak. The epidemic ceased following the commencement of barrier nursing, a treatment course of ceftriaxone, and a five-day rifampicin eradication therapy for the positive patients. The outbreak resulted from failure to recognize quickly the rapid transmission of this multidrug-resistant pneumococcal clone. We conclude that patients with COPD are at high risk of acquiring multidrug resistant pneumococci, and suggest that COPD patients who are colonized or infected with multidrug-resistant pneumococci should be isolated to prevent future transmission.