Infectious etiologies in acute exacerbation of COPD

Extracellular vesicles and COPD: foe or friend?

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory airway disease characterized by progressive airflow limitation. The complex biological processes of COPD include protein hydrolysis tissue remodeling, innate immune inflammation, disturbed host-pathogen response, abnormal cellular phenotype conversion, and cellular senescence. Extracellular vesicles (EVs) (including apoptotic vesicles, microvesicles and exosomes), are released by almost all cell types and can be found in a variety of body fluids including blood, sputum and urine. EVs are key mediators in cell-cell communication and can be used by using their bioactive substances (DNA, RNA, miRNA, proteins and other metabolites) to enable cells in adjacent and distant tissues to perform a wide variety of functions, which in turn affect the physiological and pathological functions of the body. Thus, EVs is expected to play an important role in the pathogenesis of COPD, which in turn affects its acute exacerbations and may serve as a diagnostic marker for it. Furthermore, recent therapeutic approaches and advances have introduced EVs into the treatment of COPD, such as the modification of EVs into novel drug delivery vehicles. Here, we discuss the role of EVs from cells of different origins in the pathogenesis of COPD and explore their possible use as biomarkers in diagnosis, and finally describe their role in therapy and future prospects for their application. Graphical Abstract.

How and when to manage respiratory infections out of hospital

Lower respiratory infections include acute bronchitis, influenza, community-acquired pneumonia, acute exacerbation of COPD and acute exacerbation of bronchiectasis. They are a major cause of death worldwide and often affect the most vulnerable: children, elderly and the impoverished. In this paper, we review the clinical presentation, diagnosis, severity assessment and treatment of adult outpatients with lower respiratory infections. The paper is divided into sections on specific lower respiratory infections, but we also dedicate a section to COVID-19 given the importance of the ongoing pandemic. Lower respiratory infections are heterogeneous entities, carry different risks for adverse events, and require different management strategies. For instance, while patients with acute bronchitis are rarely admitted to hospital and generally do not require antimicrobials, approximately 40% of patients seen for community-acquired pneumonia require admission. Clinicians caring for patients with lower respiratory infections face several challenges, including an increasing population of patients with immunosuppression, potential need for diagnostic tests that may not be readily available, antibiotic resistance and social aspects that place these patients at higher risk. Management principles for patients with lower respiratory infections include knowledge of local surveillance data, strategic use of diagnostic tests according to surveillance data, and judicious use of antimicrobials.

Seroreactivity to Coxiella burnetii in an Agricultural Population and Prevalence of Coxiella burnetii Infection in Ticks of a Non-Endemic Region for Q Fever in South Korea

Coxiella burnetii infects humans and wild and domesticated animals. Although reported cases on Jeju Island, off the coast of South Korea, are rare, the region is considered to have a high potential for Q fever. We investigated the seroprevalence of antibodies to C. burnetii in 230 farmers living in ten rural areas on Jeju Island between January 2015 and December 2019. Blood samples were collected and examined for C. burnetii Phase I/II IgM and IgG antibodies. Trained researchers collected ticks from rural areas. Clone XCP-1 16S ribosomal RNA gene sequencing was performed to identify Coxiella species from the collected ticks. The overall seroprevalence of antibodies to C. burnetii in farmers was 35.7%. The seroprevalence was significantly higher in fruit farmers. Of the collected ticks, 5.4% (19/351) of the Haemaphysalis longicornis ticks harbored C. burnetti. A high seroprevalence of antibodies to C. burnetii was observed in this region of Jeju Island, confirming that C. burnetti is endemic. Physicians should thus consider Q fever in the differential diagnosis of patients that present with acute fever after participating in outdoor activities.

Diagnosis of pulmonary embolism in patients with acute exacerbations of chronic obstructive pulmonary disease: A cross-sectional study

INTRODUCTION

Pulmonary embolism (PE) remains a frequent complication in patients with chronic obstructive pulmonary disease (COPD). It is unclear that the extent to which the traditional risk stratifying scores for PE are accurate in this population.

METHODS

Cross-sectional study of adult patients with COPD and suspected PE included in an Institutional Registry of Thromboembolic Disease at a tertiary teaching hospital in the city of Buenos Aires, Argentina. We estimated the area under the receiver operating characteristic curves (AU-ROC), sensitivity and specificity of the Wells and Geneva scores using a positive computed tomography angiography as the gold standard for PE. We also estimated the sensitivity and specificity for the presence of isolated worsening of dyspnea at presentation, without other cardinal symptoms of acute exacerbation of COPD.

RESULTS

A total of 168 patients were included, of which 22% had confirmed PE. The AUC was 0.66 (95% CI 0.56-0.76) and 0.56 (95% CI 0.45-0.67) for the Wells and Geneva, respectively. Considering the most widely used cutoff points, the sensitivity and specificity were 24% and 90% for the Wells and 59% and 43% for the Geneva score, respectively. Isolated worsening of dyspnea on presentation had a sensitivity of 92% and specificity of 37%.

CONCLUSIONS

Both Wells and Geneva scores exhibit poor diagnostic accuracy for the diagnosis of PE in patients with COPD. The presence of isolated worsening of dyspnea on presentation could be an easy to identify criteria for the initial triage in this population. Further validation of our findings remains warranted.

Protein Network Analysis Identifies Changes in the Level of Proteins Involved in Platelet Degranulation, Proteolysis and Cholesterol Metabolism Pathways in AECOPD Patients

Chronic obstructive pulmonary disease (COPD) is characterised by a progressive pulmonary and systemic inflammation. Acute exacerbations of COPD (AECOPD) are associated with acute inflammation and infection, increase in the rates of morbidity and mortality. Previous proteomic studies have focussed on identifying proteins involved in COPD pathogenesis in samples collected from the lung (e.g. lung tissue biopsies, bronchoalveolar lavage and sputum) but not from blood of patients who experienced AECOPD. In this study, plasma was analysed by two independent quantitative proteomics techniques; isobaric tag for relative and absolute quantitation (iTRAQ) and multiple reaction monitoring (MRM) to identify differential expression of circulating proteins in patients with stable COPD (sCOPD) and AECOPD. Firstly, iTRAQ performed on pooled plasma samples from AECOPD, sCOPD, and healthy non-smoking controls (HC) revealed 15 differentially expressed proteins between the 3 groups. MRM subsequently performed on a separate cohort of AECOPD, sCOPD, and HC patients confirmed 9 proteins to be differentially expressed by AECOPD compared to HC (Afamin, alpha-1-antichymotrypsin, Apolipoprotein E, Beta-2-glycoprotein 1, Complement component C9, Fibronectin, Immunoglobulin lambda like polypeptide 5, Inter-alpha-trypsin inhibitor heavy chain H3, Leucine rich alpha-2-glycoprotein 1). Network analysis demonstrates that most of these proteins are involved in proteolysis regulation, platelet degranulation and cholesterol metabolism. In conclusion, several potential plasma biomarkers for AECOPD were identified in this study. Further validation studies of these proteins may elucidate their roles in the development of AECOPD.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Use of serology and polymerase chain reaction to detect atypical respiratory pathogens during acute exacerbation of chronic obstructive pulmonary disease

BACKGROUND/AIMS

To use serological and multiplex polymerase chain reaction (PCR) assays to examine sputum samples from patients experiencing acute exacerbation of chronic obstructive pulmonary disease (AECOPD) for the presence of atypical pathogens, including Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella pneumophila.

METHODS

From September 2012 to February 2014, 341 patients with AECOPD attending outpatient clinics were enrolled as part of a randomized, double-blind, multicenter study. A commercial enzyme-linked immunosorbent assay was used to measure serum immunoglobulin M (IgM) and IgG antibody titers on the first day of the study and at 36 days post-enrollment. Multiplex PCR was used to test sputum samples for the presence of atypical pathogens. A urinary antigen test for L. pneumophila was performed on the first day.

RESULTS

Nineteen patients (5.6%) showed serological evidence of acute infection with M. pneumoniae. Also, one and seven patients (2%) showed serological evidence of acute infection with C. pneumoniae and L. pneumophila, respectively. All DNA samples were negative for M. pneumoniae, C. pneumoniae, and L. pneumophila according to PCR. Only one urine sample was positive for L. pneumophila antigen, but serologic evidence was lacking.

CONCLUSION

Serological testing suggested that infection by atypical pathogens during AECOPD was relatively uncommon. In addition, PCR provided no direct evidence of infection by atypical pathogens. Thus, atypical pathogens may not be a major cause of AECOPD in South Korea.

Application of albumin/globulin ratio in elderly patients with acute exacerbation of chronic obstructive pulmonary disease

Background

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) has become an important disease of hospitalized elderly patients, which lack simple and inexpensive indicators for evaluating the condition and prognosis. This study was performed to investigate the clinical significance of the serum albumin/globulin ratio (AGR) in elderly patients with AECOPD.

Methods

The data of 252 hospitalized elderly patients with AECOPD, 89 stable COPD patients and 115 elderly healthy individuals were analyzed and compared. The differences in the AGR, logarithm of the serum C-reactive protein (LogCRP) level, prealbumin (PA) level, and immunoglobulin G (IgG) level were compared. AECOPD patients were grouped using the optimal cutoff values of each index to compare the difference in the combined infection rate. The correlation between hospital stays and AGR was analyzed.

Results

The AGR, LogCRP, PA level, and IgG level were different among the AECOPD group, stable COPD group and healthy control groups (P<0.05). The AGR, LogCRP, and PA level were different (P<0.05) among the Global Initiative for Chronic Obstructive Lung Disease (GOLD) I, II, II, and IV groups. Age, AGR, LogCRP, and PA level were different (P<0.05) between the infection and non-infection groups. After grouping according to the optimal cutoff values, the combined infection rate was different (P<0.05). The AGR was negatively correlated with the hospital stay (r=-0.583, P<0.001). The hospital stay was longer in patients with an AGR of <1.37 than ≥1.37 (P<0.001).

Conclusions

The AGR can be regarded as a reference index for evaluating the condition of elderly patients with AECOPD, determining the presence of combined infection, and predicting the prognosis.

Symptom-related sputum microbiota in stable chronic obstructive pulmonary disease

Background

The role of airway microbiota in COPD is highly debated. Symptomology assessment is vital for the management of clinically stable COPD patients; however, the link between symp toms and the airway microbiome is currently unknown.

Purpose

The present study aimed to evaluate the relationship among stable COPD patients.

Patients and methods

We conducted pyrosequencing of bacterial 16S rRNA using induced sputum samples in a Han Chinese cohort that included 40 clinically stable COPD patients and 19 healthy controls.

Results

Alterations in community composition and core bacte rial taxa (Neisseria subflava, etc.) were observed in patients with severe symptoms compared with controls. The co-occurrence network indicated that the key microbiota enriched in COPD patients showed higher expression in patients with severe symptoms. The association pattern of symptoms with the sputum microbiome was obviously different from that of lung function in COPD patients.

Conclusion

These findings broaden our insights into the relationship between the sputum microbiota and the symptom severity in COPD patients, emphasizing the role of symptoms in the airway microbiome, independent of lung function.

Association of ambient pollution with inhaler use among patients with COPD: a panel study

BACKGROUND

Studies have linked ambient air pollution to chronic obstructive pulmonary disease (COPD) healthcare encounters. However, the association between air quality and rescue medication use is unknown.

OBJECTIVES

We assessed the role of air pollution exposure for increased short-acting beta-2-agonist (SABA) use in patients with COPD through use of remote monitoring technology.

METHODS

Participants received a portable electronic inhaler sensor to record the date, time and location for SABA use over a 3-month period. Ambient air pollution data and meteorological data were collected from a centrally located federal monitoring station. Mixed-effects Poisson regression was used to examine the association of daily inhaler use with pollutant levels. Four criteria pollutants (PM_2.5, PM₁₀, O₃ and NO₂), two particulate matter species (elemental carbon (EC) and organic carbon), estimated coarse fraction of PM₁₀ (PM_10-2.5) and four multipollutant air quality measures were each examined separately, adjusting for covariates that passed a false discovery rate (FDR) screening.

RESULTS

We enrolled 35 patients with COPD (94.3% male and mean age: 66.5±8.5) with a mean forced expiratory volume in 1 s (FEV₁) % predicted of 44.9+17.2. Participants had a median of 92 observation days (range 52-109). Participants' average SABA inhaler use ranged from 0.4 to 13.1 puffs/day (median 2.8). Controlling for supplemental oxygen use, long-acting anticholinergic use, modified Medical Research Council Dyspnoea Scale and influenza season, an IQR increase in PM₁₀ concentration (8.0 µg/m³) was associated with a 6.6% increase in daily puffs (95% CI 3.5% to 9.9%; FDR <0.001). NO₂ and EC concentration were also significantly associated with inhaler use (3.9% and 2.9% per IQR increase, respectively).

CONCLUSIONS

Exposure to increased ambient air pollution were associated with a significant increase in SABA use for patients with COPD residing in a low-pollution area.

Hospital Procalcitonin Testing and Antibiotic Treatment of Patients Admitted for Chronic Obstructive Pulmonary Disease Exacerbation

RATIONALE

Randomized trials suggest that assessment of serum procalcitonin (PCT) levels can be used to safely limit antibiotic use among patients hospitalized for exacerbations of chronic obstructive pulmonary disease (COPD).

OBJECTIVES

To determine the impact of PCT testing on antibiotic treatment of patients hospitalized for exacerbations of COPD in routine practice.

METHODS

We conducted a series of cross-sectional and longitudinal multivariable analyses using data from 2009 to 2011 and 2013 to 2014 from a sample of 505 U.S. hospitals.

RESULTS

Of 203,177 patients hospitalized for COPD exacerbation in 2013 to 2014, nearly 9 out of 10 were treated with antibiotics. Hospital PCT testing rates ranged from 0 to 83%. In cross-sectional analysis, there was a weak negative association between the rate of PCT testing and risk-adjusted rates of antibiotic initiation (Spearman correlation, -0.12; P = 0.005); each 10-point increase in the percentage of patients undergoing PCT testing was associated with a 0.7% decline in risk-adjusted antibiotic use (P = 0.001). There was no association between hospital rates of PCT testing and duration of antibiotic treatment. In a longitudinal analysis, comparing treatment patterns in 2009 to 2011 and 2013 to 2014, we did not observe a significant difference in the change in antibiotic treatment rates or duration of therapy between hospitals that had adopted PCT testing compared with those that had not.

CONCLUSIONS

As currently implemented, PCT testing appears to have had little impact on decisions to initiate antibiotic therapy or on duration of treatment for COPD exacerbations. Implementation research is necessary to translate the promising outcomes from PCT testing observed in randomized trials into clinical practice.

Trends in use and impact on outcome of empiric antibiotic therapy and non-invasive ventilation in COPD patients with acute exacerbation

BACKGROUND

Empiric antibiotic therapy is routinely prescribed in patients with acute COPD exacerbations (AECOPD) requiring ventilatory support on the basis of studies including patients conventionally ventilated. Whether this practice remains valid to current management with first-line non-invasive ventilation (NIV) is unclear.

METHODS

In a cohort of ICU patients admitted between 2000 and 2012 for AECOPD, we analyzed the trends in empiric antibiotic therapy and in primary ventilatory support strategy, and their respective impact on patients' outcome.

RESULTS

440 patients admitted for 552 episodes were included; primary NIV use increased from 29 to 96.7 % (p < 0.001), whereas NIV failure rate decreased significantly (p = 0.004). In parallel, ventilator-associated pneumonia (VAP) rate, VAP density and empiric antibiotic therapy use decreased (p = 0.037, p = 0.002, and p < 0.001, respectively). These figures were associated with a trend toward lower ICU mortality rate (p = 0.058). Logistic regression showed that primary NIV use per se was protective against fatal outcome [odds ratios (OR) = 0.08, 95 %CI 0.03-0.22; p < 0.001], whereas NIV failure, VAP occurrence, and cardiovascular comorbidities were associated with increased ICU mortality [OR = 17.6 (95 %CI 5.29-58.93), 11.5 (95 %CI 5.17-25.45), and 3 (95 %CI 1.37-6.63), respectively]. Empiric antibiotic therapy was associated with decreased VAP rate (log rank; p < 0.001), but had no effect on mortality (log rank; p = 0.793).

CONCLUSIONS

The sustained increase in NIV use allowed a decrease in empiric antibiotic prescriptions in AECOPD requiring ventilatory support. Primary NIV use and its success, but not empiric antibiotic therapy, were associated with a favorable impact on patients' outcome.

Pathogens in COPD exacerbations identified by comprehensive real-time PCR plus older methods

Respiratory infection is a major cause of exacerbation in chronic obstructive pulmonary disease (COPD). Infectious contributions to exacerbations remain incompletely described. We therefore analyzed respiratory tract samples by comprehensive real-time polymerase chain reaction (PCR) in combination with conventional methods. We evaluated multiple risk factors for prolonged hospitalization to manage COPD exacerbations, including infectious agents. Over 19 months, we prospectively studied 46 patients with 50 COPD exacerbations, collecting nasopharyngeal swab and sputum samples from each. We carried out real-time PCR designed to detect six bacterial species and eleven viruses, together with conventional procedures, including sputum culture. Infectious etiologies of COPD exacerbations were identified in 44 of 50 exacerbations (88%). Infections were viral in 17 of 50 exacerbations (34%). COPD exacerbations caused by Gram-negative bacilli, including enteric and nonfermenting organisms, were significantly associated with prolonged hospitalization for COPD exacerbations. Our results support the use of a combination of real-time PCR and conventional methods for determining both infectious etiologies and risk of extended hospitalization.

Prevalence and resistance pattern of Moraxella catarrhalis in community-acquired lower respiratory tract infections

Introduction

Moraxella catarrhalis previously considered as commensal of upper respiratory tract has gained importance as a pathogen responsible for respiratory tract infections. Its beta-lactamase-producing ability draws even more attention toward its varying patterns of resistance.

Methods

This was an observational study conducted to evaluate the prevalence and resistance pattern of M. catarrhalis. Patients aged 20–80 years admitted in the Department of Chest Medicine of Liaquat National Hospital from March 2012 to December 2012 were included in the study. Respiratory samples of sputum, tracheal secretions, and bronchoalveolar lavage were included, and their cultures were followed.

Results

Out of 110 respiratory samples, 22 showed positive cultures for M. catarrhalis in which 14 were males and eight were females. Ten samples out of 22 showed resistance to clarithromycin, and 13 samples out of 22 displayed resistance to erythromycin, whereas 13 showed resistance to levofloxacin. Hence, 45% of the cultures showed resistance to macrolides so far and 59% showed resistance to quinolones.

Conclusion

Our study shows that in our environment, M. catarrhalis may be resistant to macrolides and quinolones; hence, these should not be recommended as an alternative treatment in community-acquired lower respiratory tract infections caused by M. catarrhalis. However, a study of larger sample size should be conducted to determine if the recommendations are required to be changed.

Comparison of diagnostic values of procalcitonin, C-reactive protein and blood neutrophil/lymphocyte ratio levels in predicting bacterial infection in hospitalized patients with acute exacerbations of COPD

BACKGROUND

Viral or bacterial upper respiratory infections are the most common cause of acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Based on available data, no reliable parameter has been presented to distinguish between bacterial and nonbacterial exacerbations. Therefore, we compared the diagnostic value of procalcitonin (PCT) level, which is a newer marker for predicting bacterial infections in patients with AECOPD, to routine parameters such as C-reactive protein (CRP) levels and the neutrophil/lymphocyte (N/L) ratio.

METHODS

This study included all consecutive patients who were admitted for a diagnosis of AECOPD between January 1 and March 31, 2014. PCT, CRP, and the N/L ratio were assessed in addition to cultures from tracheal aspirates or sputum on the first day of admission. Patients with a pneumonic infiltration on chest radiographs, or an extrapulmonary infection focus, or whose blood samples were not obtained for PCT and/or CRP at the same time as sputum culture were excluded from the study.

RESULTS

A total of 77 patients were included with a mean age of 71.7 ± 9.5 years. Bacteria were isolated in 37.4 % of the patients. Mean PCT levels were significantly higher in patients with positive sputum cultures than in patients with negative sputum cultures. The cut-off values for PCT, CRP, and the N/L ratio for predicting a bacterial infection were 0.40 ng/mL, 91.50 mg/L, and 11.5, respectively; sensitivity was 61, 54, and 61 % respectively; specificity was 67, 52, and 58 %, respectively; and the area under the curve (AUC) values were 0.64, 0.52, and 0.58, respectively. The AUC value of PCT was significantly better for predicting bacterial infection compared with the CRP level or the N/L ratio (p = 0.042).

CONCLUSION

PCT was better than CRP and the N/L ratio for predicting a bacterial infection in hospitalized patients with AECOPD. However, we find PCT not so reliable in predicting bacterial infection in AECOPD due to sensitivity and specificity of less than 80 % and a low AUC value.

AcuteChlamydia pneumoniaeandMycoplasma pneumoniaeInfections in Community-Acquired Pneumonia and Exacerbations of COPD or Asthma: Therapeutic Considerations

Rates of acute Chlamydia pneumoniae and Mycoplasma pneumoniae infections were determined in 115 adults hospitalized for community-acquired pneumonia (CAP), purulent exacerbations of COPD and acute exacerbations of bronchial asthma, by means of serology and molecular methods. Results were compared with those obtained in a matched control group. Common respiratory pathogens were isolated by cultures in 22.5% and 22.2% of CAP and exacerbated COPD patients, respectively. Cultures from exacerbated asthma patients were always negative. Serological and molecular evidence of current C. pneumoniae infection was obtained in 10.0%, 8.9% and 3.3% of CAP, COPD and asthma cases. The corresponding rates of acute M. pneumoniae infection were 17.5%, 6.7% and 3.3%, respectively. Finally, no difference was found between typical and atypical pathogen rates. These findings highlight the importance of taking into account C. pneumoniae and M. pneumoniae infections in guiding the choice of empirical antibacterial treatment for CAP and purulent exacerbations of COPD.

Chlamydophila pneumoniae re-infection triggers the production of IL-17A and IL-17E, important regulators of airway inflammation

OBJECTIVE

Investigation of the effects of interleukin (IL)-17 cytokines in Chlamydophila pneumoniae-infected mice.

METHODS

Mice were infected with C. pneumoniae once or three times and the expression of IL-17 cytokines was followed by RT qPCR from day 1 to day 28 after infection and re-infection. After the treatment of mice with anti-IL-17A, ELISA was used to detect the differences in cytokine and chemokine production. The number and phenotype of the IL-17A-producing cells were determined by ELISPOT.

RESULTS

Chlamydophila pneumoniae induced IL-17A and IL-17F from day 2 after infection, and their levels remained elevated on day 28. The expression of IL-17C, IL-17D and IL-17E mRNA did not change significantly in response to a single infection. The in vivo neutralization of IL-17A resulted in a higher C. pneumoniae burden in the mouse lungs, a decreased cell influx, and diminished chemokine levels. The phenotype of IL-17A-producing cells was CD4(+). The re-infection of mice led to an increased expression of IL-17E mRNA.

CONCLUSION

These results facilitate an understanding of the early inflammatory response after C. pneumoniae infection and suggest that C. pneumoniae re-infection induces the production of a high amount of IL-17E, which has an important role in the pathogenesis of allergic pulmonary diseases.

Chronic bronchial infection in COPD. Is there an infective phenotype?

Microorganisms, particularly bacteria, are frequently found in the lower airways of COPD patients, both in stable state and during exacerbations. The host–pathogen relationship in COPD is a complex, dynamic process characterised by frequent changes in pathogens, their strains and loads, and subsequent host immune responses.

Exacerbations are detrimental events in the course of COPD and evidence suggests that 70% may be caused by microorganisms. When considering bacterial exacerbations, recent findings based on molecular typing have demonstrated that the acquisition of new strains of bacteria or antigenic changes in pre-existing strains are the most important triggers for exacerbation onset.

Even in clinically stable COPD patients the presence of microorganisms in their lower airways may cause harmful effects and induce chronic low-grade airway inflammation leading to increased exacerbation frequency, an accelerated decline in lung function and impaired health-related quality of life. Besides intraluminal localisation in the distal airways, bacteria can be found in the bronchial walls and parenchymal lung tissue of COPD patients. Therefore, the isolation of pathogenic bacteria in stable COPD should be considered as a form of chronic infection rather than colonisation. This new approach may have important implications for the management of patients with COPD.

Pseudomonal Infections in Patients with COPD

COPD is a common disease with increasing prevalence. The chronic course of the disease is characterized by acute exacerbations that cause significant worsening of symptoms. Bacterial infections play a dominant role in approximately half of the episodes of acute exacerbations of COPD. The importance of pseudomonal infection in patients with acute exacerbations of COPD stems from its relatively high prevalence in specific subgroups of these patients, and particularly its unique therapeutic ramifications. The colonization rate of Pseudomonas aeruginosa in patients with COPD in a stable condition is low.A review of a large number of clinical series of unselected outpatients with acute exacerbations of COPD revealed that P. aeruginosa was isolated from the patients' sputum at an average rate of 4%. This rate increased significantly in COPD patients with advanced airflow obstruction, in whom the rate of sputum isolates of P. aeruginosa reached 8-13% of all episodes of acute exacerbations of COPD. However, the great majority of bacteria isolated in these patients were not P. aeruginosa, but the three classic bacteria Streptococcus pneumoniae, Hemophilus influenzae, and Moraxella catarrhalis. The subgroup of patients, with acute exacerbations of COPD, with the highest rate of P. aeruginosa infection, which approaches 18% of the episodes, is mechanically ventilated patients. However, even in this subgroup the great majority of bacteria isolated are the above-mentioned three classic pathogens. In light of these epidemiologic data and other important considerations, and in order to achieve optimal antibacterial coverage for the common infectious etiologies, empiric antibacterial therapy should be instituted as follows. Patients with acute exacerbations of COPD with advanced airflow obstruction (FEV(1) <50% of predicted under stable conditions) should receive once daily oral therapy with one of the newer fluoroquinolones, i.e. levofloxacin, moxifloxacin, gatifloxacin, or gemifloxacin for 5-10 days. Patients with severe acute exacerbations of COPD who are receiving mechanical ventilation should receive amikacin in addition to one of the intravenous preparations of the newer fluoroquinolones or monotherapy with cefepime, a carbapenem or piperacillin/tazobactam. In both subgroups it is recommended that sputum cultures be performed before initiation of therapy so that the results can guide further therapy.

Assessment of some inflammatory biomarkers as predictors of outcome of acute respiratory failure on top of chronic obstructive pulmonary disease and evaluation of the role of bacteria

Objective. To study the value of the inflammatory markers (interleukin-6 (IL-6), interleukin-8 (IL-8), and C-reactive protein (CRP)) in predicting the outcome of noninvasive ventilation (NIV) in the management of acute respiratory failure (ARF) on top of chronic obstructive pulmonary disease (COPD) and the role of bacteria in the systemic inflammation. Methods. Thirty three patients were subjected to standard treatment plus NIV, and accordingly, they were classified into responders and nonresponders. Serum samples were collected for IL-6, IL-8, and CRP analysis. Sputum samples were taken for microbiological evaluation. Results. A wide spectrum of bacteria was revealed; Gram-negative and atypical bacteria were the most common (31% and 28% resp.; single or copathogen). IL-8 and dyspnea grade was significantly higher in the non-responder group (P = 0.01 and 0.023 resp.). IL-6 correlated positivity with the presence of infection and type of pathogen (P = 0.038 and 0.034 resp.). Gram-negative bacteria were associated with higher significant IL-6 in comparison between others (196.4 ± 239.1 pg/dL; P = 0.011) but insignificantly affected NIV outcome (P > 0.05). Conclusions. High systemic inflammation could predict failure of NIV. G-ve bacteria correlated with high IL-6 but did not affect the response to NIV.

Q fever in Japan: an update review

As neglected zoonosis for many years, Q fever is now ubiquitous in Japan. Similarly to elsewhere in the world, domestic animals are considered to be important reservoirs of the causal agent, Coxiella burnetii, a resistant intracellular bacterium. Infected animals shed bacteria in milk, feces, urine, vaginal mucous and birth products. Inhalation of bacteria present in the environment is the main route of animal and human infection. Shedding of C. burnetii in milk by domestic ruminants has a very limited impact as raw milk is seldom ingested by the Japanese population. The clinical expression of Q fever in Japan is similar to its clinical expression elsewhere. However clinical cases in children are more frequently reported in this country. Moreover, C. burnetii is specified as one of the causative organisms of atypical pneumonia in the Japanese Respiratory Society Guideline for the management of community-acquired pneumonia. In Japan, C. burnetii isolates are associated with acute illness and are mainly of moderate to low virulence. Cats are considered a significant source of C. burnetii responsible for human outbreaks in association with the presence of infected parturient cats. Since its recognition as a reportable disease in 1999, 7-46 clinical cases of Q fever have been reported by year. The epidemiology of Q fever in Japan remains to be elucidated and the exact modes of transmission are still unproven. Important further research is necessary to improve knowledge of the disease itself, the endogenous hosts and reservoirs, and the epidemiological cycle of coxiellosis in Japan.

Th-17 cells in the lungs?

Naive CD4 cells are capable of integrating signals from antigen-activated cells of the innate immune system and differentiating into effector CD4 cells, also termed T helper (Th) cells. According to the traditional paradigm explaining adaptive CD4 cell responses, there are two subsets of Th cells: the Th-1 and Th-2 subset. Each of these subsets undergoes a distinct differentiation pathway (a pathway that is characterized by a unique profile of cytokine production and has specific immunoregulatory functions). However, recent studies in mouse models have forwarded evidence of a third subset of Th cells: the Th-17 subset. As indicated predominantly in studies on mice, the Th-17 subset is characterized by an ability to produce the neutrophil-mobilizing cytokine IL-17 in response to stimulation with the cytokine IL-23, an IL-12-related cytokine released from antigen-presenting cells. There is now a growing body of evidence from animal models that the Th-17 subset plays an important role in host defence in the lungs and other organs. Altered IL-17 levels have also been demonstrated in human patients with asthma, exacerbations of cystic fibrosis or following lung transplantation. There is now also evidence that the Th-17 subset is functionally distinct from the Th-2 subset but little is known of the functional inter-relationship between the Th-1 and Th-17 cell subsets; this is particularly true in human lungs. It has been proposed that the Th-17 subset plays a unique role by linking the arms of innate and adaptive immunity. Thus, an improved understanding of the human correlate to the Th-17 subset may reveal new targets for pharmacotherapy against lung disorders that are characterized by aberrant innate responses in host defense.

Comparative effectiveness of macrolides and quinolones for patients hospitalized with acute exacerbations of chronic obstructive pulmonary disease (AECOPD)

BACKGROUND

Meta-analyses of randomized trials have found that antibiotics are effective in acute exacerbations of chronic obstructive pulmonary disease (AECOPD), but there is insufficient evidence to guide antibiotic selection. Current guidelines offer conflicting recommendations.

OBJECTIVE

To compare the effectiveness of macrolides and quinolones for AECOPD DESIGN: Retrospective cohort study using logistic regression, propensity score-matching, and grouped treatment models.

SETTING

A total of 375 acute care hospitals throughout the United States.

PATIENTS

Age > or =40 years and hospitalized for AECOPD.

INTERVENTION

Macrolide or quinolone antibiotic begun in the first 2 hospital days.

MEASUREMENTS

Treatment failure (defined as the initiation of mechanical ventilation after hospital day 2, inpatient mortality, or readmission for AECOPD within 30 days), length of stay, and hospital costs.

RESULTS

Of the 19,608 patients who met the inclusion criteria, 6139 (31%) were treated initially with a macrolide and 13,469 (69%) with a quinolone. Compared to patients treated initially with a quinolone, those who received macrolides had a lower risk of treatment failure (6.8% vs. 8.1%; P < 0.01), a finding that was attenuated after multivariable adjustment (odds ratio [OR], 0.89; 95% confidence interval [CI], 0.78-1.01), and disappeared in a grouped-treatment analysis (OR, 1.01; 95% CI, 0.75-1.35). There were no differences in adjusted length of stay (ratio, 0.98; 95% CI, 0.97-1.00) or adjusted cost (ratio, 1.00; 95% CI, 0.99-1.02). After propensity score-matching, antibiotic-associated diarrhea was more common with quinolones (1.2% vs. 0.6%; P < 0.001).

CONCLUSIONS

Macrolide and quinolone antibiotics are associated with similar rates of treatment failure in AECOPD; however, macrolides are less frequently associated with diarrhea.

Role of Mycoplasma pneumoniae infection in acute exacerbations of chronic obstructive pulmonary disease

Eighty per cent of the cases of acute exacerbation of chronic obstructive pulmonary disease (AECOPD) have an infective aetiology, atypical bacteria including Mycoplasma pneumoniae accounting for 5–10 % of these. However, the importance of association of M. pneumoniae with episodes of AECOPD still remains doubtful. The present study was therefore undertaken to delineate the extent of involvement of M. pneumoniae in patients with AECOPD at a referral hospital in Delhi, India. Sputum samples and throat swabs from a total of 100 AECOPD patients attending the Clinical Research Center of Vallabhbhai Patel Chest Institute, Delhi, were collected during a 2-year period (January 2004–June 2006). The samples were investigated for the presence of aerobic bacterial pathogens and M. pneumoniae. Diagnosis of infection with M. pneumoniae was based on culture, serology, direct detection of M. pneumoniae specific antigen and PCR. Bacterial aetiology could be established in 16 of the 100 samples studied. Pseudomonas spp. were recovered from eight cases, Streptococcus pneumoniae from four and Klebsiella spp. from two cases. Acinetobacter sp. and Moraxella catarrhalis were isolated from one case each. Serological evidence of M. pneumoniae infection and/or detection of M. pneumoniae specific antigen were seen in 16 % of the cases. One case with definite evidence of M. pneumoniae infection also had coinfection with Pseudomonas spp. However, no direct evidence of M. pneumoniae infection was found in our study population as defined by culture isolation or PCR. In conclusion, although the serological prevalence of M. pneumoniae infection in our study population was significantly higher than in the control group, there was no direct evidence of it playing a role in AECOPD.

Association of Mycoplasma pneumoniae and asthma among Indian children

The role of Mycoplasma pneumoniae infection as a trigger for asthma exacerbations is well supported in previous studies. This study was designed to investigate the role of M. pneumoniae infection in acute exacerbation of asthma in children. A total of 150 patients (110 males, 40 females) were studied and immunoglobulin M (IgM) antibodies to M. pneumoniae were detected by enzyme-linked immunosorbent assay (ELISA), and PCR amplification was performed for the P1 gene to associate M. pneumoniae infection with asthma. As compared with 33 children with asthma, only two of the control subjects had positive IgM titers for M. pneumoniae, which was statistically significant (P=0.002). A total of 15 children with asthma were positive by PCR for the P1 gene while none of the controls had a positive PCR. Of these positive cases, 24 cases were positive only by ELISA, six were positive only by PCR and nine patients were found to be positive by both ELISA and PCR. All the clinical characteristics of the patients at baseline were comparable between the moderate and the severe group of patients statistically, except for the peak expiratory flow rate. Mycoplasma pneumoniae infection was found to have a significant association with acute exacerbation in the moderate group of asthma patients by PCR (P=0.01). These data suggest that M. pneumoniae infection may contribute to asthma exacerbation.

Role of bacteria in acute exacerbations of chronic obstructive pulmonary disease

BACKGROUND AND STUDY OBJECTIVE

Infections are major causes of acute exacerbations of chronic obstructive pulmonary disease (COPD) which result in significant mortality and morbidity. The primary aim of the study was to determine the microbiological spectrum including atypical agents in acute exacerbations. The secondary aim was to evaluate resistance patterns in the microorganisms.

METHODS

The sputum culture of 75 patients admitted to our clinic from January 1, 1999 to December 31, 2002 was evaluated prospectively, for aerobic Gram-positive and Gram-negative bacteria, and serologically for Chlamydophila pneumoniae and Mycoplasma pneumoniae. Sensitivity patterns in potentially pathogenic microorganisms (PPMs) were also investigated.

RESULTS

An infectious agent was identified in 46 patients, either serologically or with sputum culture. Pathogens most commonly demonstrated were: Haemophilus influenzae (30%), Chlamydophila pneumoniae (17%), and Mycoplasma pneumoniae (9%). Mixed infections were diagnosed in 9 patients. PPMs showed a high resistance rate to commonly used antibiotics.

CONCLUSION

We have shown that microorganisms causing acute exacerbations of COPD are not only typical bacteria (46%) but also atypical pathogens (26%), with unpredictable high rates. Typical agents showed a high resistance to commonly used antibiotics.

Cigarette smoke decreases MARCO expression in macrophages: implication in Mycoplasma pneumoniae infection

Bacterial infections including Mycoplasma pneumoniae (Mp) are a major cause of exacerbations in chronic obstructive pulmonary disease (COPD). Cigarette smoke (CS) is the leading cause of COPD, and affects the function of alveolar macrophages that act as the first line of defense against the invading respiratory pathogens. Macrophages express a transmembrane receptor called macrophage receptor with collagenous structure (MARCO) that is involved in the clearance of microorganisms. Whether CS down-regulates MARCO and eventually decreases the clearance of Mp has not been investigated. We utilized human monocytic cell line (THP-1)-derived macrophages to examine the effects of CS extract (CSE) on MARCO expression and Mp growth. Specifically, macrophages were pre-exposed to CSE for 6 h, and then infected with or without Mp for 2 h. MARCO was examined at both mRNA and protein levels by using real-time PCR and immunofluorescent staining, respectively. Mp in the supernatants was quantified by quantitative culture. In addition, a neutralizing MARCO antibody was added to macrophages to test if blockade of MARCO impaired Mp clearance. We found that CSE significantly decreased MARCO expression in a dose-dependant manner at 6 h post-CSE. Mp levels in CSE-treated cells were higher than those in non-CSE-treated cells, indicating a decreased pathogen clearance. Additionally, neutralizing MARCO in macrophages markedly increased Mp levels. Our results indicate that cigarette smoke exposure down-regulates MARCO expression in macrophages, which may be in part responsible for impaired bacterial (e.g., Mp) clearance.

Acute exacerbations and respiratory failure in chronic obstructive pulmonary disease

Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) describe the phenomenon of sudden worsening in airway function and respiratory symptoms in patients with COPD. These exacerbations can range from self-limited diseases to episodes of florid respiratory failure requiring mechanical ventilation. The average patient with COPD experiences two such episodes annually, and they account for significant consumption of health care resources. Although bacterial infections are the most common causes of AECOPD, viral infections and environmental stresses are also implicated. AECOPD episodes can be triggered or complicated by other comorbidities, such as heart disease, other lung diseases (e.g., pulmonary emboli, aspiration, pneumothorax), or systemic processes. Pharmacologic management includes bronchodilators, corticosteroids, and antibiotics in most patients. Oxygen, physical therapy, mucolytics, and airway clearance devices may be useful in selected patients. In hypercapneic respiratory failure, noninvasive positive pressure ventilation may allow time for other therapies to work and thus avoid endotracheal intubation. If the patient requires invasive mechanical ventilation, the focus should be on avoiding ventilator-induced lung injury and minimizing intrinsic positive end-expiratory pressure. These may require limiting ventilation and "permissive hypercapnia." Although mild episodes of AECOPD are generally reversible, more severe forms of respiratory failure are associated with a substantial mortality and a prolonged period of disability in survivors.

Mycoplasma pneumoniae infection and environmental tobacco smoke inhibit lung glutathione adaptive responses and increase oxidative stress

Chronic cigarette smoking evokes a lung glutathione (GSH) adaptive response that results in elevated GSH levels in the lung epithelial lining fluid (ELF). Currently, little is known about how the lung regulates or maintains steady-state levels of ELF GSH. Pathogens such as Mycoplasma pneumoniae can exacerbate airway inflammation and oxidative stress. The present study examined whether M. pneumoniae infections synergize with environmental tobacco smoke (ETS) to disrupt lung GSH adaptive responses. Mice were exposed separately and in combination to ETS and M. pneumoniae for 16 weeks. ETS exposure resulted in a doubling of ELF GSH levels, which was blocked in the M. pneumoniae-exposed mice. In addition, the ETS-plus-M. pneumoniae-exposed mice had elevated levels of oxidized glutathione (GSSG), resulting in a dramatic change in the ELF redox state that corresponded with an increase in lung tissue DNA oxidation. Similar findings were observed in human lung epithelial cells in vitro. Cells exposed separately or in combination to cigarette smoke extract and M. pneumoniae for 48 h had elevated apical levels of GSH compared to control cells, and these increases were blocked by M. pneumoniae and were also associated with increased cellular DNA oxidation. Further studies showed that M. pneumoniae exposure blocked ETS-induced increases in GSH reductase, an enzyme that recycles GSSG back to GSH, both in vitro and in vivo. These studies suggest that M. pneumoniae infection synergizes with ETS and suppresses the lung's ability to respond appropriately to environmental challenges leading to enhanced oxidative stress.

Pathogen-directed therapy in acute exacerbations of chronic obstructive pulmonary disease

Acute exacerbations of chronic obstructive pulmonary disease (COPD) are important events in the natural history of this chronic lung disorder. These events can be caused by a large number of infectious and noninfectious agents and are associated with an increased local and systemic inflammatory response. Their frequency and severity have been linked to progressive deterioration in lung function and health status. Infectious pathogens ranging from viral to atypical and typical bacteria have been implicated in the majority of episodes. Most therapeutic regimens to date have emphasized broad, nonspecific approaches to bronchoconstriction and pulmonary inflammation. Increasingly, therapy that targets specific etiologic pathogens has been advocated. These include clinical and laboratory-based methods to identify bacterial infections. Further additional investigation has suggested specific pathogens within this broad class. As specific antiviral therapies become available, better diagnostic approaches to identify specific pathogens will be required. Furthermore, prophylactic therapy for at-risk individuals during high-risk times may become a standard therapeutic approach. As such, the future will likely include aggressive diagnostic algorithms based on the combination of clinical syndromes and rapid laboratory modalities to identify specific causative bacteria or viruses.

Coxiella burnetii and acute exacerbations/infections in patients with chronic lung disease

The aim of the present study was to determine the incidence of Q fever in patients with an acute exacerbation of a chronic lower respiratory tract infection. Eighty patients treated for acute exacerbation of chronic lower respiratory tract infections during a 30-month period were studied. Q fever was diagnosed by ELISA. Two elderly woman with pre-existing bronchiectasis (2.5%) were diagnosed as having an acute infection by Coxiella burnetii. The acute illness was considered to be a result of mixed infection with Pseudomonas aeruginosa and Haemophilus influenzae with C. burnetii. Co-infection with C. burnetii can occur during a bacterial exacerbation of a chronic lower respiratory tract infection.

High-throughput amplification fragment length polymorphism (htAFLP) analysis identifies genetic lineage markers but not complement phenotype-specific markers in Moraxella catarrhalis

Comparative high-throughput amplified fragment length polymorphism (htAFLP) analysis was performed on a set of 25 complement-resistant and 23 complement-sensitive isolates of Moraxella catarrhalis in order to determine whether there were complement phenotype-specific markers within this species. The htAFLP analysis used 21 primer-pair combinations, generating 41 364 individual fragments and 2273 fragment length polymorphisms, with an average of 862 polymorphisms per isolate. Analysis of polymorphism data clearly indicated the presence of two phylogenetic lineages and 40 (2%) lineage-specific polymorphisms. However, despite the presence of 361 (16%) statistically significant complement phenotype-associated polymorphisms, no single marker was 100% complement phenotype-specific. Furthermore, no complement phenotype-specific marker was found within different phylogenetic lineages. These findings agree with previous results indicating that the complement resistance phenotype within M. catarrhalis is probably defined by multiple genes, although not all of these genes may be present within all M. catarrhalis isolates.

IL-23-dependent IL-17 production is essential in neutrophil recruitment and activity in mouse lung defense against respiratory Mycoplasma pneumoniae infection

IL-23 induces IL-17 production in activated CD4+ T cells and participates in host defense against many encapsulated bacteria. However, whether the IL-23/IL-17 axis contributes to a Mycoplasma pneumoniae (Mp)-induced lung inflammation (e.g., neutrophils) has not been addressed. Using an acute respiratory Mp infection murine model, we found significantly up-regulated lung IL-23p19 mRNA in the early phase of infection (4h), and alveolar macrophages were an important cell source of Mp-induced IL-23. We further showed that Mp significantly increased IL-17 protein levels in bronchoalveolar lavage (BAL). Lung gene expression of IL-17, IL-17C and IL-17F was also markedly up-regulated by Mp in vivo. IL-17 and IL-17F were found to be derived mainly from lung CD4+ T cells, and were increased upon IL-23 stimulation in vitro. In vivo blocking of IL-23p19 alone or in combination with IL-23/IL-12p40 resulted in a significant reduction of Mp-induced IL-17 protein and IL-17/IL-17F mRNA expression, which was accompanied by a trend toward reduced lung neutrophil recruitment, BAL neutrophil activity, and Mp clearance. However, IL-23 neutralization had no effect on Mp-induced lung IL-17C mRNA expression. These results demonstrate that IL-17/IL-17F production is IL-23-dependent in an acute Mp infection, and contributes to neutrophil recruitment and activity in the lung defense against the infection.

[Contribution of microbiological investigations to the diagnosis of lower respiratory tract infections]

The diagnosis of community-acquired pneumonia is usually based on clinical and radiological criteria. The identification of a causative organism is not required for the diagnosis. Although numerous microbiological techniques are available, their sensitivity and specificity are not high enough to guide first-line antimicrobial therapy. Consequently, this treatment remains most often empiric. If the causative organism is identified, the antimicrobial treatment is adapted. Sputum analysis may be proposed as a diagnostic tool for patients with an acute exacerbation of chronic obstructive pulmonary disease, in specific cases (prior antibiotherapy, hospitalization, failure of the empiric antimicrobial treatment).

Repeated respiratory Mycoplasma pneumoniae infections in mice: effect of host genetic background

Respiratory Mycoplasma pneumoniae (Mp) infection is involved in several acute and chronic lung diseases including community-acquired pneumonia, asthma and chronic obstructive pulmonary disease. In the chronic disease process, recurrent respiratory bacterial infections could occur, which may result in varying degrees of symptoms and lung inflammation among patients. However, the lung immunologic differences of host responses to repeated bacterial (i.e., Mp) infections remain to be determined. In the present study, we examined cellular and humoral responses to multiple (up to 3) Mp infections in two genetically different strains of mice (BALB/c and C57BL/6). Mice were intranasally inoculated with one Mp infection, two or three Mp infections (4 weeks apart), and sacrificed on days 3, 7 and 14 after the last Mp infection. Overall, compared to C57BL/6 mice, BALB/c mice demonstrated a significantly higher degree of lung tissue inflammatory cell infiltrate, BAL cellularity, and release of pro-inflammatory cytokines (TNF-alpha, keratinocyte-derived chemokine (KC, a mouse homolog of human chemokine Gro-alpha [CXCL1], and IFN-gamma). In addition, BALB/c mice presented higher levels of serum Mp-specific IgG and IgM, but not IgA. Consistently with lung and serum data, Mp load in BAL and lung specimens was significantly higher in BALB/c mice than C57BL/6 mice. Moreover, repeated Mp infections in BALB/c, but not C57BL/6 mice, produced a greater inflammatory response than did a single Mp infection. Our results suggest that hosts with different genetic background may have different susceptibility to repeated respiratory Mp infections along with inflammatory responses.

Managing acute lower respiratory tract infections in an era of antibacterial resistance

Respiratory tract infections account for more than 116 million office visits and an estimated 3 million visits to hospital EDs annually. Patients presenting at EDs with symptoms suggestive of lower respiratory tract infections of suspected bacterial etiology are often severely ill, thus requiring a rapid presumptive diagnosis and empiric antimicrobial treatment. Traditionally, clinicians have relied on beta-lactam or macrolide antibiotics to manage community-acquired lower respiratory tract infections. However, the emerging resistance of Streptococcus pneumoniae to beta-lactams and/or macrolides may affect the clinical efficacy of these agents. Inappropriate use of antibiotics and use of agents with an overly broad spectrum of antimicrobial activity have contributed to the emergence of antibiotic resistance. When treating respiratory infections, clinicians need to prescribe antimicrobial agents only for those individuals with infections of suspected bacterial etiology; to select agents with a targeted spectrum of activity that ensures coverage against typical S pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis strains, including antibiotic-resistant strains and atypical pathogens; and to consider agents with specific chemical properties that limit the development of antimicrobial resistance and that achieve concentrations at sites of infection that exceed those required for bactericidal activity. Newer classes of antimicrobial agents, such as the oxazolidinones and ketolides, will likely play a significant role in this era of antimicrobial resistance.

COPD exacerbations . 2: aetiology

Exacerbations of COPD are thought to be caused by complex interactions between the host, bacteria, viruses, and environmental pollution. These factors increase the inflammatory burden in the lower airways, overwhelming the protective anti-inflammatory defences leading to tissue damage. Frequent exacerbations are associated with increased morbidity and mortality, a faster decline in lung function, and poorer health status, so prevention or optimal treatment of exacerbations is a global priority. In order to evolve new treatment strategies there has been great interest in the aetiology and pathophysiology of exacerbations, but progress has been hindered by the heterogeneous nature of these episodes, vague definitions of an exacerbation, and poor stratification of known confounding factors when interpreting results. We review how an exacerbation should be defined, its inflammatory basis, and the importance of exacerbations on disease progression. Important aetiologies, with their potential underlying mechanisms, are discussed and the significance of each aetiology is considered.

Physical Activity and Hospitalization for Exacerbation of COPD

BACKGROUND

Acute exacerbations (AEs) have a negative impact on various aspects of the progression of COPD, but objective and detailed data on the impact of hospitalizations for an AE on physical activity are not available. Objective and measurements: We aimed to investigate physical activity using an activity monitor (DynaPort; McRoberts; the Hague, the Netherlands), pulmonary function, muscle force, 6-min walking distance, and arterial blood gas levels in 17 patients (mean age, 69 +/- 9 years [+/- SD]; body mass index, 24 +/- 5 kg/m(2)) at the beginning and end of a hospitalization period for an AE and 1 month after discharge.

RESULTS

Time spent on weight-bearing activities (walking and standing) was markedly low both at day 2 and day 7 of hospitalization (median, 7%; interquartile range [IQR], 3 to 18% of the time during the day; and median, 9%; IQR, 7 to 21%, respectively) and 1 month after discharge (median, 19% [IQR, 10 to 34%]; Friedman test, p = 0.13). Time spent on weight-bearing activities was positively correlated to quadriceps force at the end of the hospitalization period (r = 0.47; p = 0.048). Patients with hospitalization for an AE in the previous year had an even lower activity level when compared to those without a recent hospitalization. In addition, patients with a lower activity level at 1 month after discharge were more likely to be readmitted in the following year.

CONCLUSIONS

Patients with COPD are markedly inactive during and after hospitalization for an AE. Efforts to enhance physical activity should be among the aims of the disease management during and following the AE periods.

Chlamydophila pneumoniae and Mycoplasma pneumoniae in respiratory specimens of children with chronic lung diseases

BACKGROUND

Persistent infection with Mycoplasma pneumoniae and Chlamydophila pneumoniae has been implicated in the progression or induction of asthma and chronic obstructive pulmonary disease. Evidence for this hypothesis has been obtained in adults either by serological methods or by direct pathogen detection using invasive procedures.

METHODS

We investigated nasal brush specimens and induced sputum from 38 children with stable chronic lung disease (asthma, n = 26; chronic bronchitis n = 12) and from 42 healthy controls for the presence of M pneumoniae or C. pneumoniae DNA by polymerase chain reaction (PCR) using nested primers.

RESULTS

None of the controls but 23.6% and 10.5% of the children with lung disease had positive PCR for C pneumoniae (p = 0.001) and M pneumoniae (p = 0.044) respectively. Significantly more children with non-atopic asthma than with atopic asthma were positive for C pneumoniae or M pneumoniae (4/8 v 1/18; p = 0.018). There were no unwanted side effects from sputum induction. No correlation was found between detection of Chlamydophila and severity of lung disease. Colonisation with both organisms had occurred before adulthood in a significant proportion of children with stable chronic lung diseases.

CONCLUSION

Combining nasal brush specimens with induced sputum may be a useful non-invasive method for studying the role of C pneumoniae and M pneumoniae infection in children with different chronic lung diseases.

Seroprevalence of Mycoplasma pneumoniae and Chlamydia pneumoniae in stable asthma and chronic obstructive pulmonary disease

Mycoplasma pneumoniae and Chlamydia pneumoniae have been suggested to take part in the acute exacerbation of bronchial asthma and chronic obstructive pulmonary disease (COPD). Several studies have questioned whether they may play pathogenic roles in connection with bronchial asthma and COPD. This study was designed to evaluate the seroprevalences of M. pneumoniae and C. pneumoniae in stable asthma and COPD patients, and to compare with control patients. The medical records of one hundred forty patients who underwent M. pneumoniae and C. pneumoniae serology were retrospectively reviewed. Seroprevalences of M. pneumoniae and C. pneumoniae in the asthma group (11.1% and 8.3%, respectively) were higher than in the control group (4.4% and 2.2%, respectively) without statistical significance. The seroprevalence of M. pneumoniae in the COPD group (16.9%) was significantly higher than in the control group, and the seroprevalence of C. pneumoniae in the COPD group (3.4%) was higher than in the control group without statistical significance. This study raises important questions about the relation of M. pneumoniae and C. pneumoniae infection with stable asthma or COPD.

Telithromycin new product overview

Community-acquired respiratory tract infections (CARTIs), including community-acquired pneumonia, acute exacerbations of chronic bronchitis, and acute bacterial sinusitis, contribute substantially to health care costs in the United States. Although many prescriptions for antibiotics are written each year for the treatment of CARTIs, most are prescribed on an empiric basis. Concerns about the increasing prevalence of antimicrobial resistance and the changing pattern of pathogens isolated from subjects with CARTIs have raised questions about the empiric treatment paradigm. When choosing appropriate antimicrobial therapy for CARTIs, physicians must consider not only the spectrum of activity of antibiotics but also the potential risk of resistance. Telithromycin is the first member of the ketolide class, a new family of antimicrobials structurally related to the macrolides, to be approved by the US Food and Drug Administration for the treatment of CARTIs. The spectrum of activity of telithromycin includes common typical and atypical causative pathogens associated with community-acquired respiratory tract infections, including antibiotic-resistant strains of Streptococcus pneumoniae. Clinical trials have shown that telithromycin is as effective as traditionally used antimicrobial agents in the treatment of mild-to-moderate community-acquired pneumonia, acute exacerbations of chronic bronchitis, and acute bacterial sinusitis.

Antimicrobial selection for community-acquired lower respiratory tract infections in the 21st century: a review of gemifloxacin

Community-acquired lower respiratory tract infections (LRTIs) are more prevalent in the elderly than in children and younger adults and form a significant proportion of all consultations and hospital admissions in this older age group. Furthermore, in a world of increasing life expectancy the trend seems unlikely to be reversed. Antimicrobial treatment of community-acquired pneumonia (CAP) must cover Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis, and in many circumstances should also cover the intracellular (atypical) pathogens. In contrast, acute exacerbations of chronic bronchitis (AECB) are mainly associated with H. influenzae and S. pneumoniae and not with atypical bacteria: in severe cases, other Gram-negative bacteria may be involved. Frequently in LRTIs, the aetiology of the infection cannot be identified from the laboratory specimens and treatment has to be empirical. In such situations it is important to not only to use an antibiotic that covers all likely organisms, but also one that has good activity against these organisms given the local resistance patterns. Gemifloxacin is a new quinolone antibiotic that targets pneumococcal DNA gyrase and topoisomerase IV and is highly active against S. pneumoniae including penicillin-, macrolide- and many ciprofloxacin-resistant strains, as well as H. influenzae and the atypical pathogens. In clinical trials in CAP and AECB, gemifloxacin has been shown to be as effective a range of comparators and demonstrated an adverse event profile that was in line with the comparator agents. In one long-term study in AECB significantly more patients receiving gemifloxacin than clarithromycin remained free of recurrence after 26 weeks. The improved potency, broad spectrum of activity and proven clinical and bacteriological efficacy and safety profile should make it a useful agent in the 21st century battle against community-acquired LRTIs.

Management of respiratory infections in the elderly

Respiratory infections are common at all ages but are particularly sinister among the elderly because of the fragility and chronic comorbidity associated with this age group. The three types of respiratory infection in the elderly are community-acquired pneumonia, acute exacerbation of chronic obstructive pulmonary disease and nonpneumonic respiratory tract infection. The etiology of these three types of infection includes classic bacteria, atypical pathogens and respiratory viruses. The relative frequency of each of the etiological groups as the causative agent of the infection varies significantly among these types of infection, but in all three types a significant proportion of infections involves more than one pathogen. The causative agent of respiratory infection in the elderly cannot be determined on the basis of clinical manifestation or the results of routine imaging procedures or laboratory tests. Thus, initial antibiotic therapy in these patients should be empiric, based on accepted guidelines. In recent years, the antipneumococcal fluoroquinolones have gained in stature as one of the best options to treat these infections. Pneumococcal and influenza vaccinations can reduce morbidity and mortality from respiratory infections in the elderly, so it is important that all elderly individuals are vaccinated through a structured program in the framework of primary care. The economic impact of respiratory infections in the elderly is primarily associated with the requirement for hospitalization in many of the cases. Any action that can reduce hospitalization rates has important economic ramifications. In light of the difficulty in reaching an early etiologic diagnosis in respiratory infections, it is essential to invest in the development of a compact diagnostic kit for the early stages of the disease, which could change reality in this important area of medicine.

Emerging intracellular bacterial infections

Human infections by intracellular bacteria have been recognized for many years, but much of what we know about the pathogenesis of these diseases and their etiologic organisms has emerged within the past few years as a result of improved molecular-based means for their detection and classification. New insights concerning the epidemiology and pathogenesis of intracellular bacterial infections and methods for the detection of Chlamydophila pneumoniae, Ehrlichia chaffeensis, Anaplasma phagocytophilum, and Rickettsia species have made an impact on how we view them as agents of human disease. Emerging evidence suggesting a possible intracellular existence for another organism, Mycoplasma pneumoniae, may explain how this organism interacts with the host to induce chronic inflammatory conditions of the respiratory tract.

Mycoplasma pneumoniae and its role as a human pathogen

Mycoplasma pneumoniae is a unique bacterium that does not always receive the attention it merits considering the number of illnesses it causes and the degree of morbidity associated with it in both children and adults. Serious infections requiring hospitalization, while rare, occur in both adults and children and may involve multiple organ systems. The severity of disease appears to be related to the degree to which the host immune response reacts to the infection. Extrapulmonary complications involving all of the major organ systems can occur in association with M. pneumoniae infection as a result of direct invasion and/or autoimmune response. The extrapulmonary manifestations are sometimes of greater severity and clinical importance than the primary respiratory infection. Evidence for this organism's contributory role in chronic lung conditions such as asthma is accumulating. Effective management of M. pneumoniae infections can usually be achieved with macrolides, tetracyclines, or fluoroquinolones. As more is learned about the pathogenesis and immune response elicited by M. pneumoniae, improvement in methods for diagnosis and prevention of disease due to this organism may occur.

Pharmacologic therapy for acute exacerbations of chronic obstructive pulmonary disease: a review

This article reviews available data on the drug therapy armamentarium for the acute exacerbation of chronic obstructive pulmonary disease (COPD). Summaries of studies and therapeutic issues for bronchodilators, antibiotic therapy, corticosteroid use, and a few miscellaneous agents are presented. Many controversies exist in the criteria defining the acute exacerbation, in defining appropriate outcome parameters for assessment, and, consequently, in developing specific consistent recommendations for drug therapy. Five published guidelines assist the clinician in therapeutic drug management of the acute exacerbation of COPD, and each differs in its recommendations for drug therapy prescription. The article includes synopses for drug therapy recommendations from the guidelines.

Chronic obstructive pulmonary disease: role of bacteria and guide to antibacterial selection in the older patient

Chronic obstructive pulmonary disease (COPD) is a common problem in the elderly. The disease is characterised by intermittent worsening of symptoms and these episodes are called acute exacerbations. The best estimate, based on several lines of evidence, is that approximately half of all exacerbations are caused by bacteria. These lines of evidence include studies of lower respiratory tract bacteriology during exacerbations, correlation of airways' inflammation with results of sputum cultures during exacerbations, analysis of immune responses to bacterial pathogens, and the observation in randomised, prospective, placebo-controlled trials that antibacterial therapy is of benefit. The most important bacterial causes of exacerbations of COPD are nontypeable Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pneumoniae and Chlamydia pneumoniae. In approaching the elderly patient with an exacerbation, it is useful to consider the severity of the exacerbation based on three cardinal symptoms: increased sputum volume, increased sputum purulence and increased dyspnoea compared with baseline. Patients experiencing moderate (two symptoms) or severe (all three symptoms) exacerbations benefit from antibacterial therapy. Consideration of underlying host factors allows for a rational choice of antibacterial agent. Patients are considered to have 'simple COPD' or 'complicated COPD' based on: (i) the severity of underlying lung disease; (ii) the frequency of exacerbations; and (iii) the presence of comorbid conditions. It is proposed that patients with simple COPD are treated with doxycycline, a newer macrolide, or an extended-spectrum oral cephalosporin; and patients with complicated COPD are treated with amoxicillin/clavulanate or a fluoroquinolone. The major goals of antibacterial therapy for exacerbations of COPD are acceleration of symptom resolution and prevention of the complications of exacerbation.