Antibiotic therapy and prophylaxis in COPD

Bacterial Adaptation during Chronic Respiratory Infections

Chronic lung infections are associated with increased morbidity and mortality for individuals with underlying respiratory conditions such as cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD). The process of chronic colonisation allows pathogens to adapt over time to cope with changing selection pressures, co-infecting species and antimicrobial therapies. These adaptations can occur due to environmental pressures in the lung such as inflammatory responses, hypoxia, nutrient deficiency, osmolarity, low pH and antibiotic therapies. Phenotypic adaptations in bacterial pathogens from acute to chronic infection include, but are not limited to, antibiotic resistance, exopolysaccharide production (mucoidy), loss in motility, formation of small colony variants, increased mutation rate, quorum sensing and altered production of virulence factors associated with chronic infection. The evolution of Pseudomonas aeruginosa during chronic lung infection has been widely studied. More recently, the adaptations that other chronically colonising respiratory pathogens, including Staphylococcus aureus, Burkholderia cepacia complex and Haemophilus influenzae undergo during chronic infection have also been investigated. This review aims to examine the adaptations utilised by different bacterial pathogens to aid in their evolution from acute to chronic pathogens of the immunocompromised lung including CF and COPD.

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

Chronic obstructive pulmonary disease (COPD) remains a major cause of morbidity and mortality worldwide. COPD is especially prevalent in the elderly, affecting 25% of those aged>or=75 years. The course of the disease in the elderly is often complicated by co-morbid conditions, and its management is complicated by drug-drug interactions. Exacerbations of COPD increase rates of hospitalization and mortality and decrease quality of life. Exacerbations are marked by an increase from baseline in dyspnoea, sputum volume and sputum purulence. Approximately 50% of acute exacerbations of symptoms in COPD are caused by non-typeable Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pneumoniae and Pseudomonas aeruginosa. Stratification of exacerbations based on severity of symptoms and signs, and severity of underlying COPD, is useful in selecting patients likely to benefit from antibacterial therapy. Patients who are hospitalized with exacerbations, those who have all three symptoms (increased dyspnoea, sputum volume and sputum purulence), and those with severe underlying COPD and exacerbations benefit most from antibacterials. Antibacterial susceptibility patterns among the bacterial pathogens are evolving, and knowledge of local susceptibility patterns is useful in antibacterial selection. Penicillin, amoxicillin, cotrimoxazole (trimethoprim/sulfamethoxazole) and doxycycline should not be used as an initial antibacterial because of resistance patterns. We recommend second-/third-generation cephalosporins, amoxicillin/clavulanic acid, azithromycin and respiratory fluoroquinolones as initial choices. In patients at risk of colonization by, and infection as a result of, P. aeruginosa, ciprofloxacin, levofloxacin or an advanced penicillin/penicillinase combination effective against this species should be used. Drug-drug interactions should be considered in antibacterial choice. The goals of antibacterial therapy for exacerbations of COPD are the prevention of complications such as respiratory failure and death, and the reduction of treatment failures. The role of pathogenic bacteria in progression of stable COPD and the use of prophylactic antibacterials in stable COPD are under investigation. Currently available evidence does not support routine clinical use of prophylactic antibacterials in stable COPD. In conclusion, pathogenic bacteria cause a significant proportion of acute exacerbations of COPD. Use of antibacterials, based on current susceptibility patterns, is beneficial in patients with severe COPD experiencing exacerbations and in patients with severe exacerbations.

Baicalin attenuates inflammation by inhibiting NF-kappaB activation in cigarette smoke induced inflammatory models

Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kappaB) is a key player in the inflammatory response. Baicalin is an extract from roots of the plant scutellaria baicalensis. Many studies show that baicalin has anti-inflammatory, anti-bacterial and antiviral activities. Here we investigated the influence of baicalin on COPD inflammation and the mechanism of anti-inflammatory effect in vivo and in vitro. In vivo, COPD rat model was established by cigarette smoke (CS) exposure. Thirty-six Sprague-Dawley (SD) rats were randomly assigned to six experimental groups: control, CS, dexamethasone (DXM), and baicalin (20 mg/kg, 40 mg/kg, 80 mg/kg). The lung pathology was observed and leukocytes in bronchoalveolar lavage fluid (BALF) were counted by Optical microscope. Pulmonary function was measured by using an animal plethysmograph. The production of cytokines was measured by ELISA and the expression levels of NF-kappaB p65 protein were detected by immunohistochemistry. The results in vivo show CS exposure significantly increased the expression of IL-8, IL-6 and TNF-alpha in plasma and BALF and enhanced NF-kappaB p65 expression in the lungs. Baicalin treatment markedly attenuated the inflammatory effects of CS. In vitro, cell model was established by using cigarette smoke extract (CSE) to stimulate type II pneumocytes. Type II pneumocytes were also divided into six groups: control, CSE, pyrrolidine dithiocarbamate (PDTC), and baicalin (5 mumol, 10 mumol, 20 mumol). Cytokines levels were measured by ELISA. Expression of IkappaB and p65 phosphorylation was detected by western blotting. NF-kappaB DNA-binding activity was detected by EMSA. The results show that CSE resulted in increasing IL-8, IL-6 and TNF-alpha expression and activation of NF-kappaB. The proinflammatory effects of CSE were inhibited by treatment of baicalin in a dose-dependent manner. It can be concluded that baicalin has significant anti-inflammatory effects on CS induced COPD rat models and CSE-induced cell models, and the effectiveness increases with increasing baicalin dosage. The anti-inflammatory effect is likely achieved by inhibiting the NF-kappaB pathway.