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Respiratory infections are a major cause of global mortality and morbidity. In recent years, an increased incidence of multidrug-resistant (MDR) Gram-negative bacteria (GNB) has been described. Microorganisms such as Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae or Acinetobacter baumannii have been identified as causative pathogens of different respiratory tract infections. Several studies have detected MDR-GNB in patients with community-acquired and nosocomial pneumonia. Furthermore, MDR-GNB have also been isolated in patients with chronic obstructive pulmonary disease and bronchiectasis having acute or chronic bronchial infection. Prevalence varies depending on the geographical area but MDR-GNB has been reported in the Asia-Pacific region, Europe and the United States, reaching rates of 70% in hospital-acquired infection. The presence of MDR-GNB has been related to poor clinical outcomes, including increased mortality, although data regarding this relationship are limited. This is probably linked to inappropriate selection of empiric antibiotic treatment; this poses a threat of widespread resistance. GNB antibiotic resistance and the absence of new antibiotics are a major concern given limited treatment options; an aspect that deserves future research. We review current literature, highlight prevalence of MDR-GNB in different respiratory infections and explore their impact on clinical outcomes.

Background and objective Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) due to Pseudomonas aeruginosa (PA) are associated with worse outcomes. PA antibiotic resistance is important to determine treatment and may influence clinical outcomes. The aim was to study clinical characteristics and outcomes in patients with AECOPD associated with PA based on their antibiotic resistance. Methods This was a prospective observational study including all patients with AECOPD and positive PA sputum culture admitted in a respiratory ward in a tertiary hospital in Barcelona during 2013–2014. PA was defined as resistant (PA-R) when the antibiogram showed ≥1 resistance. Results Four hundred one patients with AECOPD were evaluated. Of them, 54 (13%) had a positive PA sputum culture. Eighty-two per cent were men, median age was 77 (SD 7) years old and FEV1 was less than 36% (SD 17) of predicted value. PA-R was isolated in 35 patients (66%), and PA-sensitive (PA-S) was isolated in 18 (34%) patients. No differences were found in demographics, lung function and comorbidities among groups. PA-R patients were more likely exposed to prior oral corticosteroids (77% vs 44%, P = 0.03) and antibiotics (77% vs 31%, P = 0.01), respectively. AECOPD patients associated with PA-S were more likely to die at 30 days (odds ratio 13.53, 95% confidence interval: 1.14–69.56, P = 0.03) and 90 days (odds ratio 7.09, 95% confidence interval: 1.33–37.89, P = 0.02), respectively. Conclusion Pseudomonas aeruginosa-resistant affects patients with severe AECOPD and previous use of corticosteroids and antibiotics. The presence of PA-S is associated with higher mortality. These results may suggest increased virulence in PA-S strains causing acute infections.

Background and objective Secreted mucins play a key role in antibacterial defence in the airway, but have not previously been characterized in non-cystic fibrosis (CF) bronchiectasis patients. We aim to investigate the relationship between secreted mucins levels and the presence of bacterial colonization due to potentially pathogenic microorganisms (PPM) in the airways of stable bronchiectasis patients. Methods Clinically stable bronchiectasis patients were studied prospectively at two centres. Patients with other pulmonary conditions were excluded. Spontaneous sputum was subject to bacterial culture, and secreted mucins (MUC2, MUC5AC and MUC5B) were measured in sputum supernatants by ELISA. Results A total of 50 patients were included. PPM were identified from sputum samples in 30 (60%), with Pseudomonas aeruginosa (n = 10) and Haemophilus influenzae (n = 10) as the most common PPM. There were no baseline differences among airway colonized and non-colonized patients. Patients with airways colonized by PPM presented higher levels of airway MUC2. No differences in MUC5AC levels were found among groups, whereas MUC5B levels were undetectable. Patients with P. aeruginosa colonization expressed the highest levels of MUC2. High levels of MUC2 and MUC5AC are also correlated with disease severity using the Bronchiectasis Severity Index. Conclusions Airway MUC2 levels were higher in bronchiectasis patients colonized with PPM compared with those without airway colonization, especially in patients with P. aeruginosa. These findings suggest that airway-secreted mucins levels may play a role in the pathogenesis of airway infection in non-CF bronchiectasis.

Respiratory infections are a major cause of global mortality and morbidity. In recent years, an increased incidence of multidrug-resistant (MDR) Gram-negative bacteria (GNB) has been described. Microorganisms such as Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae or Acinetobacter baumannii have been identified as causative pathogens of different respiratory tract infections. Several studies have detected MDR-GNB in patients with community-acquired and nosocomial pneumonia. Furthermore, MDR-GNB have also been isolated in patients with chronic obstructive pulmonary disease and bronchiectasis having acute or chronic bronchial infection. Prevalence varies depending on the geographical area but MDR-GNB has been reported in the Asia-Pacific region, Europe and the United States, reaching rates of 70% in hospital-acquired infection. The presence of MDR-GNB has been related to poor clinical outcomes, including increased mortality, although data regarding this relationship are limited. This is probably linked to inappropriate selection of empiric antibiotic treatment; this poses a threat of widespread resistance. GNB antibiotic resistance and the absence of new antibiotics are a major concern given limited treatment options; an aspect that deserves future research. We review current literature, highlight prevalence of MDR-GNB in different respiratory infections and explore their impact on clinical outcomes.

Background and objectiveAcute exacerbations of chronic obstructive pulmonary disease (AECOPD) due to Pseudomonas aeruginosa (PA) are associated with worse outcomes. PA antibiotic resistance is important to determine treatment and may influence clinical outcomes. The aim was to study clinical characteristics and outcomes in patients with AECOPD associated with PA based on their antibiotic resistance. MethodsThis was a prospective observational study including all patients with AECOPD and positive PA sputum culture admitted in a respiratory ward in a tertiary hospital in Barcelona during 2013-2014. PA was defined as resistant (PA-R) when the antibiogram showed 1 resistance. ResultsFour hundred one patients with AECOPD were evaluated. Of them, 54 (13%) had a positive PA sputum culture. Eighty-two per cent were men, median age was 77 (SD 7) years old and FEV1 was less than 36% (SD 17) of predicted value. PA-R was isolated in 35 patients (66%), and PA-sensitive (PA-S) was isolated in 18 (34%) patients. No differences were found in demographics, lung function and comorbidities among groups. PA-R patients were more likely exposed to prior oral corticosteroids (77% vs 44%, P=0.03) and antibiotics (77% vs 31%, P=0.01), respectively. AECOPD patients associated with PA-S were more likely to die at 30 days (odds ratio 13.53, 95% confidence interval: 1.14-69.56, P=0.03) and 90 days (odds ratio 7.09, 95% confidence interval: 1.33-37.89, P=0.02), respectively. ConclusionPseudomonas aeruginosa-resistant affects patients with severe AECOPD and previous use of corticosteroids and antibiotics. The presence of PA-S is associated with higher mortality. These results may suggest increased virulence in PA-S strains causing acute infections. Pseudomonas aeruginosa (PA) plays an important role in AECOPD. However, the impact of PA resistance patterns on clinical outcomes is not clear. Our study demonstrates that the presence of PA-sensitive is associated with higher mortality.

Background and objective: Secreted mucins play a key role in antibacterial defence in the airway, but have not previously been characterized in non-cystic fibrosis (CF) bronchiectasis patients. We aim to investigate the relationship between secreted mucins levels and the presence of bacterial colonization due to potentially pathogenic microorganisms (PPM) in the airways of stable bronchiectasis patients. Methods: Clinically stable bronchiectasis patients were studied prospectively at two centres. Patients with other pulmonary conditions were excluded. Spontaneous sputum was subject to bacterial culture, and secreted mucins (MUC2, MUC5AC and MUC5B) were measured in sputum supernatants by ELISA. Results: A total of 50 patients were included. PPM were identified from sputum samples in 30 (60%), with Pseudomonas aeruginosa (n = 10) and Haemophilus influenzae (n = 10) as the most common PPM. There were no baseline differences among airway colonized and non-colonized patients. Patients with airways colonized by PPM presented higher levels of airway MUC2. No differences in MUC5AC levels were found among groups, whereas MUC5B levels were undetectable. Patients with P. aeruginosa colonization expressed the highest levels of MUC2. High levels of MUC2 and MUC5AC are also correlated with disease severity using the Bronchiectasis Severity Index. Conclusions: Airway MUC2 levels were higher in bronchiectasis patients colonized with PPM compared with those without airway colonization, especially in patients with P. aeruginosa. These findings suggest that airway-secreted mucins levels may play a role in the pathogenesis of airway infection in non-CF bronchiectasis.