Membrane-stabilizing, anti-inflammatory interactions of macrolides with human neutrophils

Macrolide antibiotics (including azithromycin) for cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) is a life-limiting genetic condition, affecting over 90,000 people worldwide. CF affects several organs in the body, but airway damage has the most profound impact on quality of life (QoL) and survival. Causes of lower airway infection in people with CF are, most notably, Staphylococcus aureus in the early course of the disease and Pseudomonas aeruginosa at a later stage. Macrolide antibiotics, e.g. azithromycin and clarithromycin, are usually taken orally, have a broad spectrum of action against gram-positive (e.g. S aureus) and some gram-negative bacteria (e.g. Haemophilus influenzae), and may have a modifying role in diseases involving airway infection and inflammation such as CF. They are well-tolerated and relatively inexpensive, but widespread use has resulted in the emergence of resistant bacteria. This is an updated review.

OBJECTIVES

To assess the potential effects of macrolide antibiotics on clinical status in terms of benefit and harm in people with CF. If benefit was demonstrated, we aimed to assess the optimal type, dose and duration of macrolide therapy.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches, handsearching relevant journals, and abstract books of conference proceedings. We last searched the Group's Cystic Fibrosis Trials Register on 2 November 2022. We last searched the trial registries WHO ICTRP and clinicaltrials.gov on 9 November 2022. We contacted investigators known to work in the field, previous authors and pharmaceutical companies manufacturing macrolide antibiotics for unpublished or follow-up data, where possible.

SELECTION CRITERIA

We included randomised controlled trials of macrolide antibiotics in adults and children with CF. We compared them to: placebo; another class of antibiotic; another macrolide antibiotic; or the same macrolide antibiotic at a different dose or type of administration.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed risk of bias. We assessed the certainty of evidence using GRADE.

MAIN RESULTS

We included 14 studies (1467 participants) lasting 28 days to 36 months. All the studies assessed azithromycin: 11 compared oral azithromycin to placebo (1167 participants); one compared a high dose to a low dose (47 participants); one compared nebulised to oral azithromycin (45 participants); and one looked at weekly versus daily dose (208 participants). Oral azithromycin versus placebo There is a slight improvement in forced expiratory volume (FEV1 % predicted) in one second in the azithromycin group at up to six months compared to placebo (mean difference (MD) 3.97, 95% confidence interval (CI) 1.74 to 6.19; high-certainty evidence), although there is probably no difference at three months, (MD 2.70%, 95% CI -0.12 to 5.52), or 12 months (MD -0.13, 95% CI -4.96 to 4.70). Participants in the azithromycin group are probably at a decreased risk of pulmonary exacerbation with a longer time to exacerbation (hazard ratio (HR) 0.61, 95% CI 0.50 to 0.75; moderate-certainty evidence). Mild side effects were common, but there was no difference between groups (moderate-certainty evidence). There is no difference in hospital admissions at six months (odds ratio (OR) 0.61, 95% CI 0.36 to 1.04; high-certainty evidence), or in new acquisition of P aeruginosa at 12 months (HR 1.00, 95% CI 0.64 to 1.55; moderate-certainty evidence). High-dose versus low-dose azithromycin We are uncertain whether there is any difference in FEV1 % predicted at six months between the two groups (no data available) or in the rate of exacerbations per child per month (MD -0.05 (95% CI -0.20 to 0.10)); very low-certainty evidence for both outcomes. Only children were included in the study and the study did not report on any of our other clinically important outcomes. Nebulised azithromycin versus oral azithromycin We were unable to include any of the data into our analyses and have reported findings directly from the paper; we graded all evidence as being of very low certainty. The authors reported that there was a greater mean change in FEV1 % predicted at one month in the nebulised azithromycin group (P < 0.001). We are uncertain whether there was a change in P aeruginosa count. Weekly azithromycin versus daily azithromycin There is probably a lower mean change in FEV1 % predicted at six months in the weekly group compared to the daily group (MD -0.70, 95% CI -0.95 to -0.45) and probably also a longer period of time until first exacerbation in the weekly group (MD 17.30 days, 95% CI 4.32 days to 30.28 days). Gastrointestinal side effects are probably more common in the weekly group and there is likely no difference in admissions to hospital or QoL. We graded all evidence as moderate certainty.

AUTHORS' CONCLUSIONS

Azithromycin therapy is associated with a small but consistent improvement in respiratory function, a decreased risk of exacerbation and longer time to exacerbation at six months; but evidence for treatment efficacy beyond six months remains limited. Azithromycin appears to have a good safety profile (although a weekly dose was associated with more gastrointestinal side effects, which makes it less acceptable for long-term therapy), with a relatively minimal treatment burden for people with CF, and it is inexpensive. A wider concern may be the emergence of macrolide resistance reported in the most recent study which, combined with the lack of long-term data, means we do not feel that the current evidence is strong enough to support azithromycin therapy for all people with CF. Future research should report over longer time frames using validated tools and consistent reporting, to allow for easier synthesis of data. In particular, future trials should report important adverse events such as hearing impairment or liver disease. More data on the effects of azithromycin given in different ways and reporting on our primary outcomes would benefit decision-making on whether and how to give macrolide antibiotics. Finally, it is important to assess azithromycin therapy for people with CF who are established on the relatively new cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapies which correct the underlying molecular defect associated with CF (none of the trials included in the review are relevant to this population).

The Mechanism of Action and Clinical Efficacy of Low-Dose Long-Term Macrolide Therapy in Chronic Rhinosinusitis

Various chronic inflammatory airway diseases can be treated with low-dose, long-term (LDLT) macrolide therapy. LDLT macrolides can be one of the therapeutic options for chronic rhinosinusitis (CRS) due to their immunomodulatory and anti-inflammatory actions. Currently, various immunomodulatory mechanisms of the LDLT macrolide treatment have been reported, as well as their antimicrobial properties. Several mechanisms have already been identified in CRS, including reduced cytokines such as interleukin (IL)-8, IL-6, IL-1β, tumor necrosis factor-α, transforming growth factor-β, inhibition of neutrophil recruitment, decreased mucus secretion, and increased mucociliary transport. Although some evidence of effectiveness for CRS has been published, the efficacy of this therapy has been inconsistent across clinical studies. LDLT macrolides are generally believed to act on the non-type 2 inflammatory endotype of CRS. However, the effectiveness of LDLT macrolide treatment in CRS is still controversial. Here, we reviewed the immunological mechanisms related to CRS in LDLT macrolide therapy and the treatment effects according to the clinical situation of CRS.

The antimicrobial and immunomodulatory effects of Ionophores for the treatment of human infection

Ionophores are a diverse class of synthetic and naturally occurring ion transporter compounds which demonstrate both direct and in-direct antimicrobial properties against a broad panel of bacterial, fungal, viral and parasitic pathogens. In addition, ionophores can regulate the host-immune response during communicable and non-communicable disease states. Although the clinical use of ionophores such as Amphotericin B, Bedaquiline and Ivermectin highlight the utility of ionophores in modern medicine, for many other ionophore compounds issues surrounding toxicity, bioavailability or lack of in vivo efficacy studies have hindered clinical development. The antimicrobial and immunomodulating properties of a range of compounds with characteristics of ionophores remain largely unexplored. As such, ionophores remain a latent therapeutic avenue to address both the global burden of antimicrobial resistance, and the unmet clinical need for new antimicrobial therapies. This review will provide an overview of the broad-spectrum antimicrobial and immunomodulatory properties of ionophores, and their potential uses in clinical medicine for combatting infection.

Environmental impacts of COVID-19 treatment: Toxicological evaluation of azithromycin and hydroxychloroquine in adult zebrafish

One of the most impact issues in recent years refers to the COVID-19 pandemic, the consequences of which thousands of deaths recorded worldwide, are still inferior understood. Its impacts on the environment and aquatic biota constitute a fertile field of investigation. Thus, to predict the impact of the indiscriminate use of azithromycin (AZT) and hydroxychloroquine (HCQ) in this pandemic context, we aim to assess their toxicological risks when isolated or in combination, using zebrafish (Danio rerio) as a model system. In summary, we observed that 72 h of exposure to AZT and HCQ (alone or in binary combination, both at 2.5 μg/L) induced the reduction of total protein levels, accompanied by increased levels of thiobarbituric acid reactive substances, hydrogen peroxide, reactive oxygen species and nitrite, suggesting a REDOX imbalance and possible oxidative stress. Molecular docking analysis further supported this data by demonstrating a strong affinity of AZT and HCQ with their potential antioxidant targets (catalase and superoxide dismutase). In the protein-protein interaction network analysis, AZT showed a putative interaction with different cytochrome P450 molecules, while HCQ demonstrated interaction with caspase-3. The functional enrichment analysis also demonstrated diverse biological processes and molecular mechanisms related to the maintenance of REDOX homeostasis. Moreover, we also demonstrated an increase in the AChE activity followed by a reduction in the neuromasts of the head when zebrafish were exposed to the mixture AZT + HCQ. These data suggest a neurotoxic effect of the drugs. Altogether, our study demonstrated that short exposure to AZT, HCQ or their mixture induced physiological alterations in adult zebrafish. These effects can compromise the health of these animals, suggesting that the increase of AZT and HCQ due to COVID-19 pandemic can negatively impact freshwater ecosystems.

Antibiotics for secondary prevention of coronary heart disease

BACKGROUND

Coronary heart disease is the leading cause of mortality worldwide with approximately 7.4 million deaths each year. People with established coronary heart disease have a high risk of subsequent cardiovascular events including myocardial infarction, stroke, and cardiovascular death. Antibiotics might prevent such outcomes due to their antibacterial, antiinflammatory, and antioxidative effects. However, a randomised clinical trial and several observational studies have suggested that antibiotics may increase the risk of cardiovascular events and mortality. Furthermore, several non-Cochrane Reviews, that are now outdated, have assessed the effects of antibiotics for coronary heart disease and have shown conflicting results. No previous systematic review using Cochrane methodology has assessed the effects of antibiotics for coronary heart disease.

OBJECTIVES

We assessed the benefits and harms of antibiotics compared with placebo or no intervention for the secondary prevention of coronary heart disease.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, LILACS, SCI-EXPANDED, and BIOSIS in December 2019 in order to identify relevant trials. Additionally, we searched TRIP, Google Scholar, and nine trial registries in December 2019. We also contacted 11 pharmaceutical companies and searched the reference lists of included trials, previous systematic reviews, and other types of reviews.

SELECTION CRITERIA

Randomised clinical trials assessing the effects of antibiotics versus placebo or no intervention for secondary prevention of coronary heart disease in adult participants (≥18 years). Trials were included irrespective of setting, blinding, publication status, publication year, language, and reporting of our outcomes.

DATA COLLECTION AND ANALYSIS

Three review authors independently extracted data. Our primary outcomes were all-cause mortality, serious adverse event according to the International Conference on Harmonization - Good Clinical Practice (ICH-GCP), and quality of life. Our secondary outcomes were cardiovascular mortality, myocardial infarction, stroke, and sudden cardiac death. Our primary time point of interest was at maximum follow-up. Additionally, we extracted outcome data at 24±6 months follow-up. We assessed the risks of systematic errors using Cochrane 'Rosk of bias' tool. We calculated risk ratios (RRs) with 95% confidence intervals (CIs) for dichotomous outcomes. We calculated absolute risk reduction (ARR) or increase (ARI) and number needed to treat for an additional beneficial outcome (NNTB) or for an additional harmful outcome (NNTH) if the outcome result showed a beneficial or harmful effect, respectively. The certainty of the body of evidence was assessed by GRADE.

MAIN RESULTS

We included 38 trials randomising a total of 26,638 participants (mean age 61.6 years), with 23/38 trials reporting data on 26,078 participants that could be meta-analysed. Three trials were at low risk of bias and the 35 remaining trials were at high risk of bias. Trials assessing the effects of macrolides (28 trials; 22,059 participants) and quinolones (two trials; 4162 participants) contributed with the vast majority of the data. Meta-analyses at maximum follow-up showed that antibiotics versus placebo or no intervention seemed to increase the risk of all-cause mortality (RR 1.06; 95% CI 0.99 to 1.13; P = 0.07; I² = 0%; ARI 0.48%; NNTH 208; 25,774 participants; 20 trials; high certainty of evidence), stroke (RR 1.14; 95% CI 1.00 to 1.29; P = 0.04; I² = 0%; ARI 0.73%; NNTH 138; 14,774 participants; 9 trials; high certainty of evidence), and probably also cardiovascular mortality (RR 1.11; 95% CI 0.98 to 1.25; P = 0.11; I²= 0%; 4674 participants; 2 trials; moderate certainty of evidence). Little to no difference was observed when assessing the risk of myocardial infarction (RR 0.95; 95% CI 0.88 to 1.03; P = 0.23; I² = 0%; 25,523 participants; 17 trials; high certainty of evidence). No evidence of a difference was observed when assessing sudden cardiac death (RR 1.08; 95% CI 0.90 to 1.31; P = 0.41; I² = 0%; 4520 participants; 2 trials; moderate certainty of evidence). Meta-analyses at 24±6 months follow-up showed that antibiotics versus placebo or no intervention increased the risk of all-cause mortality (RR 1.25; 95% CI 1.06 to 1.48; P = 0.007; I² = 0%; ARI 1.26%; NNTH 79 (95% CI 335 to 42); 9517 participants; 6 trials; high certainty of evidence), cardiovascular mortality (RR 1.50; 95% CI 1.17 to 1.91; P = 0.001; I² = 0%; ARI 1.12%; NNTH 89 (95% CI 261 to 49); 9044 participants; 5 trials; high certainty of evidence), and probably also sudden cardiac death (RR 1.77; 95% CI 1.28 to 2.44; P = 0.0005; I² = 0%; ARI 1.9%; NNTH 53 (95% CI 145 to 28); 4520 participants; 2 trials; moderate certainty of evidence). No evidence of a difference was observed when assessing the risk of myocardial infarction (RR 0.95; 95% CI 0.82 to 1.11; P = 0.53; I² = 43%; 9457 participants; 5 trials; moderate certainty of evidence) and stroke (RR 1.17; 95% CI 0.90 to 1.52; P = 0.24; I² = 0%; 9457 participants; 5 trials; high certainty of evidence). Meta-analyses of trials at low risk of bias differed from the overall analyses when assessing cardiovascular mortality at maximum follow-up. For all other outcomes, meta-analyses of trials at low risk of bias did not differ from the overall analyses. None of the trials specifically assessed serious adverse event according to ICH-GCP. No data were found on quality of life.

AUTHORS' CONCLUSIONS

Our present review indicates that antibiotics (macrolides or quinolones) for secondary prevention of coronary heart disease seem harmful when assessing the risk of all-cause mortality, cardiovascular mortality, and stroke at maximum follow-up and all-cause mortality, cardiovascular mortality, and sudden cardiac death at 24±6 months follow-up. Current evidence does, therefore, not support the clinical use of macrolides and quinolones for the secondary prevention of coronary heart disease. Future trials on the safety of macrolides or quinolones for the secondary prevention in patients with coronary heart disease do not seem ethical. In general, randomised clinical trials assessing the effects of antibiotics, especially macrolides and quinolones, need longer follow-up so that late-occurring adverse events can also be assessed.

The Nonantibiotic Macrolide EM900 Attenuates House Dust Mite-Induced Airway Inflammation in a Mouse Model of Obesity-Associated Asthma

INTRODUCTION

Obesity-associated asthma is characterized by type 2-low airway inflammation. We previously showed that EM900, which is a 12-membered nonantibiotic macrolide, suppressed airway inflammation in a mouse model of asthma exacerbation. The aim of this study was to clarify the effects of EM900 in obesity-associated asthma.

METHODS

BALB/c mice were fed a low-fat diet (LFD) or high-fat diet (HFD). Mice were intranasally sensitized and challenged with house dust mites (HDMs) and were orally administered EM900. Airway inflammation was assessed using inflammatory cells in bronchoalveolar lavage (BALF). Cytokines were examined by ELISA in lung tissues. Lung interstitial macrophages (CD45+, CD11clow, CD11b+, and Ly6c-) were counted by flow cytometry in single cells from lung tissues.

RESULTS

Body weight increased significantly in the HFD compared with the LFD group. The total cell count and numbers of neutrophils and eosinophils in BALF were significantly suppressed by EM900 administration in the HFD-HDM group. The levels of interleukin (IL)-17A were increased in the HFD-HDM group compared with the LFD-HDM group, although the difference did not reach statistical significance. The levels of IL-17A, macrophage inflammatory protein 2, IL-1β, IL-5, and regulated on activation, normal T cell expressed and secreted in lung tissue were significantly suppressed by EM900 administration in the HFD-HDM group. The percentage of interstitial macrophages in lungs was significantly decreased by EM900 administration in the HFD-HDM group.

CONCLUSION

Both type 2 and type 2-low airway inflammation were attenuated by EM900 in this obesity-associated asthma model. These results show that EM900 might be a candidate agent for the treatment of obesity-associated asthma.

The Possible Role of Helicobacter pylori in Gastric Cancer and Its Management

Helicobacter pylori (HP) is a facultative anaerobic bacterium. HP is a normal flora having immuno-modulating properties. This bacterium is an example of a microorganism inducing gastric cancer. Its carcinogenicity depends on bacteria-host related factors. The proper understanding of the biology of HP inducing gastric cancer offers the potential strategy in the managing of HP rather than eradicating it. In this article, we try to summarize the biology of HP-induced gastric cancer and discuss the current pharmacological approach to treat and prevent its carcinogenicity.

Moving Past the Routine Use of Macrolides-Reviewing the Role of Combination Therapy in Community-Acquired Pneumonia

PURPOSE OF REVIEW

Despite advances in diagnostic microbiology and sepsis management, community-acquired pneumonia (CAP) remains a significant cause of morbidity and mortality. Current recommendations regarding the use of beta-lactams in combination with macrolides published in clinical practice guidelines are variable and based on low-quality evidence that is frequently retrospective, observational, and heterogeneous in nature. While population-based studies have historically suggested improved clinical outcomes with the routine use of macrolide combination therapy in hospitalized patients with CAP, emerging evidence from recent randomized controlled trials has challenged this practice. In this article, we discuss the historical rationale and current evidence for combination macrolide therapy in the management of CAP.

RECENT FINDINGS

Recent randomized controlled trials have assessed the non-inferiority of beta-lactam monotherapy compared to beta-lactam/macrolide combination therapy in adult patients hospitalized with CAP. Beta-lactam monotherapy was associated with equivalent clinical outcomes in patients with mild to moderate CAP. Patients with severe CAP managed with beta-lactam monotherapy have demonstrated worse clinical outcomes when compared to patients treated with combination therapy. In addition, previous beta-lactam exposure prior to hospitalization has not been shown to negatively impact outcomes in patients managed with beta-lactam monotherapy in the hospital. Current evidence supports the use of beta-lactam monotherapy in adult patients hospitalized with mild to moderate CAP. While existing evidence supports the use of combination therapy in patients with severe pneumonia, further large-scale randomized controlled trials are urgently needed to clarify the role of combination therapy in this population.

The Nonantibiotic Macrolide EM703 Improves Survival in a Model of Quinolone-Treated Pseudomonas aeruginosa Airway Infection

Macrolide antibiotics are used as anti-inflammatory agents, e.g., for prevention of exacerbations in chronic obstructive pulmonary disease and cystic fibrosis. Several studies have shown improved outcomes after the addition of macrolides to β-lactam antibiotics for treatment of severe community-acquired pneumonia. However, a beneficial effect of macrolides in treating Gram-negative bacterial airway infections, e.g., those caused by Pseudomonas aeruginosa, remains to be shown. Macrolide antibiotics have significant side effects, in particular, motility-stimulating activity in the gastrointestinal tract and promotion of bacterial resistance. In this study, EM703, a modified macrolide lacking antibiotic and motility-stimulating activities but with retained anti-inflammatory properties, was used as an adjunct treatment for experimental P. aeruginosa lung infection, in combination with a conventional antibiotic. Airway infections in BALB/cJRj mice were induced by nasal instillation of P. aeruginosa; this was followed by treatment with the quinolone levofloxacin in the absence or presence of EM703. Survival, inflammatory responses, and cellular influx to the airways were monitored. Both pretreatment and simultaneous administration of EM703 dramatically improved survival in levofloxacin-treated mice with P. aeruginosa airway infections. In addition, EM703 reduced the levels of proinflammatory cytokines, increased the numbers of leukocytes in bronchoalveolar lavage fluid, and reduced the numbers of neutrophils present in lung tissue. In summary, the findings of this study show that the immunomodulatory properties of the modified macrolide EM703 can be important when treating Gram-negative pneumonia, as exemplified by P. aeruginosa infection in this study.

Mechanisms of the Macrolide-Induced Inhibition of Superoxide Generation by Neutrophils

The effect of macrolides on the superoxide (O2 (-)) production by neutrophils was studied. Resting neutrophils become primed by lipopolysaccharide (LPS) or N-formyl-methionyl-leucyl-phenylalanine (fMLP), and primed neutrophils generate O2 (-) in response to fMLP or adhesion, respectively. Both LPS-primed fMLP-stimulated O2 (-) generation by macrolide-treated neutrophils and adhesion-stimulated O2 (-) generation by macrolide-treated fMLP-primed neutrophils were inhibited. Macrolide inhibition of O2 (-) generation was dependent on serum or pH. Serum could be substituted by NaHCO3. The intensity of inhibition was azithromycin = roxithromycin > clarithromycin > erythromycin, in that order. Non-antimicrobial derivatives of erythromycin, that is, EM703 and EM900, inhibited O2 (-) generation at pH 7.4. NH4Cl abolished the activity of azithromycin (AZ) only when added to neutrophils with AZ but not after incubation with AZ, suggesting that NH4Cl prevented the influx of AZ. AZ did not affect the expression of alkaline phosphatase, CD11b, and cytochrome b558 in both resting and LPS-primed neutrophils. These results suggested that macrolides did not affect granule mobilization but inhibited O2 (-) generation selectively.

Biological and Epidemiological Features of Antibiotic-Resistant Streptococcus pneumoniae in Pre- and Post-Conjugate Vaccine Eras: a United States Perspective

Streptococcus pneumoniae inflicts a huge disease burden as the leading cause of community-acquired pneumonia and meningitis. Soon after mainstream antibiotic usage, multiresistant pneumococcal clones emerged and disseminated worldwide. Resistant clones are generated through adaptation to antibiotic pressures imposed while naturally residing within the human upper respiratory tract. Here, a huge array of related commensal streptococcal strains transfers core genomic and accessory resistance determinants to the highly transformable pneumococcus. β-Lactam resistance is the hallmark of pneumococcal adaptability, requiring multiple independent recombination events that are traceable to nonpneumococcal origins and stably perpetuated in multiresistant clonal complexes. Pneumococcal strains with elevated MICs of β-lactams are most often resistant to additional antibiotics. Basic underlying mechanisms of most pneumococcal resistances have been identified, although new insights that increase our understanding are continually provided. Although all pneumococcal infections can be successfully treated with antibiotics, the available choices are limited for some strains. Invasive pneumococcal disease data compiled during 1998 to 2013 through the population-based Active Bacterial Core surveillance program (U.S. population base of 30,600,000) demonstrate that targeting prevalent capsular serotypes with conjugate vaccines (7-valent and 13-valent vaccines implemented in 2000 and 2010, respectively) is extremely effective in reducing resistant infections. Nonetheless, resistant non-vaccine-serotype clones continue to emerge and expand.

Clarithromycin Dose-Dependently Stabilizes Rat Peritoneal Mast Cells

BACKGROUND

Macrolides, such as clarithromycin, have antiallergic properties. Since exocytosis in mast cells is detected electrophysiologically via changes in membrane capacitance (Cm), the absence of such changes due to the drug indicates its mast cell-stabilizing effect.

METHODS

Employing the whole-cell patch clamp technique in rat peritoneal mast cells, we examined the effects of clarithromycin on Cm during exocytosis. Using a water-soluble fluorescent dye, we also examined its effect on deformation of the plasma membrane.

RESULTS

Clarithromycin (10 and 100 μM) significantly inhibited degranulation from mast cells and almost totally suppressed the GTP-x03B3;-S-induced increase in Cm. It washed out the trapping of the dye on the surface of mast cells.

CONCLUSIONS

This study provides for the first time electrophysiological evidence that clarithromycin dose-dependently inhibits the process of exocytosis. The mast cell-stabilizing action of clarithromycin may be attributable to its counteractive effect on plasma membrane deformation induced by exocytosis.

The Value of Macrolide-Based Regimens for Community-Acquired Pneumonia

Macrolide antimicrobials are commonly prescribed, specifically for the treatment of respiratory tract infections. Although still effective, the development of widespread macrolide resistance has limited their use. Aside from their antimicrobial effects, macrolides are also known to possess immune-modulatory properties which may confer a survival benefit in both acute and chronic inflammatory states. This review discusses the efficacy, potential mechanisms, and adverse effects of macrolide therapy specifically in community-acquired pneumonia in outpatients, hospitalized ward patients, and those requiring intensive care unit admission. Challenges for ongoing research in this field are discussed and treatment recommendations offered.

The role of macrolides in asthma: current evidence and future directions

Macrolides, such as clarithromycin and azithromycin, possess antimicrobial, immunomodulatory, and potential antiviral properties. They represent a potential therapeutic option for asthma, a chronic inflammatory disorder characterised by airway hyper-responsiveness that leads to recurrent episodes of wheezing, breathlessness, chest tightness, and coughing. Results from clinical trials, however, have been contentious. The findings could be confounded by many factors, including the heterogeneity of asthma, treatment duration, dose, and differing outcome measures. Recent evidence suggests improved effectiveness of macrolides in patients with sub-optimally controlled severe neutrophilic asthma and in asthma exacerbations. We examine the evidence from clinical trials and discuss macrolide properties and their relevance to the pathophysiology of asthma. At present, the use of macrolides in chronic asthma or acute exacerbations is not justified. Further work, including proteomic, genomic, and microbiome studies, will advance our knowledge of asthma phenotypes, and help to identify a macrolide-responsive subgroup. Future clinical trials should target this subgroup and place emphasis on clinically relevant outcomes such as asthma exacerbations.

Macrolide antibiotics for cystic fibrosis

BACKGROUND

Macrolide antibiotics may have a modifying role in diseases which involve airway infection and inflammation, like cystic fibrosis.

OBJECTIVES

To test the hypotheses that, in people with cystic fibrosis, macrolide antibiotics: 1. improve clinical status compared to placebo or another antibiotic; 2. do not have unacceptable adverse effects. If benefit was demonstrated, we aimed to assess the optimal type, dose and duration of macrolide therapy.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches, handsearching relevant journals and abstract books of conference proceedings.We contacted investigators known to work in the field, previous authors and pharmaceutical companies manufacturing macrolide antibiotics for unpublished or follow-up data (May 2010).Latest search of the Group's Cystic Fibrosis Trials Register: 29 February 2012.

SELECTION CRITERIA

Randomised controlled trials of macrolide antibiotics compared to: placebo; another class of antibiotic; another macrolide antibiotic; or the same macrolide antibiotic at a different dose.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed risk of bias. Seven groups were contacted and provided additional data which were incorporated into the review.

MAIN RESULTS

Ten of 31 studies identified were included (959 patients). Five studies with a low risk of bias examined azithromycin versus placebo and demonstrated consistent improvement in forced expiratory volume in one second over six months (mean difference at six months 3.97% (95% confidence interval 1.74% to 6.19%; n = 549, from four studies)). Patients treated with azithromycin were approximately twice as likely to be free of pulmonary exacerbation at six months, odds ratio 1.96 (95% confidence interval 1.15 to 3.33). With respect to secondary outcomes, there was a significant reduction in need for oral antibiotics and greater weight gain in those taking azithromycin. Adverse events were uncommon and not obviously associated with azithromycin, although a once-weekly high dose regimen was associated with more frequent gastrointestinal adverse events. Treatment with azithromycin was associated with reduced identification of Staphylococcus aureus on respiratory culture, but also a significant increase in macrolide resistance.

AUTHORS' CONCLUSIONS

This review provides evidence of improved respiratory function after six months of azithromycin. Data beyond six months were less clear, although reduction in pulmonary exacerbation was sustained. Treatment appeared safe over a six-month period; however, emergence of macrolide resistance was a concern. A multi-centre trial examining long-term effects of this antibiotic treatment is needed, especially for infants recognised through newborn screening.

Differential modulation of intracellular survival of cytosolic and vacuolar pathogens by curcumin

Curcumin, a principal component of turmeric, acts as an immunomodulator regulating the host defenses in response to a diseased condition. The role of curcumin in controlling certain infectious diseases is highly controversial. It is known to alleviate symptoms of Helicobacter pylori infection and exacerbate that of Leishmania infection. We have evaluated the role of curcumin in modulating the fate of various intracellular bacterial pathogens. We show that pretreatment of macrophages with curcumin attenuates the infections caused by Shigella flexneri (clinical isolates) and Listeria monocytogenes and aggravates those caused by Salmonella enterica serovar Typhi CT18 (a clinical isolate), Salmonella enterica serovar Typhimurium, Staphylococcus aureus, and Yersinia enterocolitica. Thus, the antimicrobial nature of curcumin is not a general phenomenon. It modulated the intracellular survival of cytosolic (S. flexneri and L. monocytogenes) and vacuolar (Salmonella spp., Y. enterocolitica, and S. aureus) bacteria in distinct ways. Through colocalization experiments, we demonstrated that curcumin prevented the active phagosomal escape of cytosolic pathogens and enhanced the active inhibition of lysosomal fusion by vacuolar pathogens. A chloroquine resistance assay confirmed that curcumin retarded the escape of the cytosolic pathogens, thus reducing their inter- and intracellular spread. We have demonstrated that the membrane-stabilizing activity of curcumin is crucial for its differential effect on the virulence of the bacteria.

Pathogen- and host-directed anti-inflammatory activities of macrolide antibiotics

Macrolide antibiotics possess several, beneficial, secondary properties which complement their primary antimicrobial activity. In addition to high levels of tissue penetration, which may counteract seemingly macrolide-resistant bacterial pathogens, these agents also possess anti-inflammatory properties, unrelated to their primary antimicrobial activity. Macrolides target cells of both the innate and adaptive immune systems, as well as structural cells, and are beneficial in controlling harmful inflammatory responses during acute and chronic bacterial infection. These secondary anti-inflammatory activities of macrolides appear to be particularly effective in attenuating neutrophil-mediated inflammation. This, in turn, may contribute to the usefulness of these agents in the treatment of acute and chronic inflammatory disorders of both microbial and nonmicrobial origin, predominantly of the airways. This paper is focused on the various mechanisms of macrolide-mediated anti-inflammatory activity which target both microbial pathogens and the cells of the innate and adaptive immune systems, with emphasis on their clinical relevance.

Antibiotics as immunomodulant agents in COPD

It is widely accepted that some antibiotics have activities beyond their direct antibacterial effects. Macrolide is the antibiotic class with more convincing studies and evidence on its immunomodulatory and anti-inflammatory activities. Different clinical studies have shown that macrolide prophylaxis in patients with moderate-severe chronic obstructive pulmonary disease (COPD) can have a significant impact on the exacerbation rate reducing morbidity and, potentially, mortality of the disease. Other antibiotics, such as fluoroquinolones, demonstrate a variety of immunomodulatory effects but only few clinical data are available in COPD. New macrolide derivatives devoid of antibacterial activity have been synthetized. This review analyses the relevance of immunomodulatory and anti-inflammatory effects of antibiotics in the management of COPD.

Macrolide antibiotics for cystic fibrosis

BACKGROUND

Macrolide antibiotics may have a modifying role in diseases which involve airway infection and inflammation, like cystic fibrosis.

OBJECTIVES

To test the hypotheses that, in people with cystic fibrosis, macrolide antibiotics: 1. improve clinical status compared to placebo or another antibiotic; 2. do not have unacceptable adverse effects. If benefit was demonstrated, we aimed to assess the optimal type, dose and duration of macrolide therapy.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches, handsearching relevant journals and abstract books of conference proceedings.We contacted investigators known to work in the field, previous authors and pharmaceutical companies manufacturing macrolide antibiotics for unpublished or follow-up data (May 2010).Latest search of the Group's Cystic Fibrosis Trials Register: 09 February 2011.

SELECTION CRITERIA

Randomised controlled trials of macrolide antibiotics compared to: placebo; another class of antibiotic; another macrolide antibiotic; or the same macrolide antibiotic at a different dose.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed risk of bias. Seven groups were contacted and provided additional data which were incorporated into the review.

MAIN RESULTS

Ten of 31 studies identified were included (959 patients). Five studies with a low risk of bias examined azithromycin versus placebo and demonstrated consistent improvement in forced expiratory volume in one second over six months (mean difference at six months 3.97% (95% confidence interval 1.74% to 6.19%; n = 549, from four studies)). Patients treated with azithromycin were approximately twice as likely to be free of pulmonary exacerbation at six months, odds ratio 1.96 (95% confidence interval 1.15 to 3.33). With respect to secondary outcomes, there was a significant reduction in need for oral antibiotics and greater weight gain in those taking azithromycin. Adverse events were uncommon and not obviously associated with azithromycin, although a once-weekly high dose regimen was associated with more frequent gastrointestinal adverse events. Treatment with azithromycin was associated with reduced identification of Staphylococcus aureus on respiratory culture, but also a significant increase in macrolide resistance.

AUTHORS' CONCLUSIONS

This review provides evidence of improved respiratory function after six months of azithromycin. Data beyond six months were less clear, although reduction in pulmonary exacerbation was sustained. Treatment appeared safe over a six-month period; however, emergence of macrolide resistance was a concern. A multi-centre trial examining long-term effects of this antibiotic treatment is needed, especially for infants recognised through newborn screening.

Mechanisms of action and clinical application of macrolides as immunomodulatory medications

Macrolides have diverse biological activities and an ability to modulate inflammation and immunity in eukaryotes without affecting homeostatic immunity. These properties have led to their long-term use in treating neutrophil-dominated inflammation in diffuse panbronchiolitis, bronchiectasis, rhinosinusitis, and cystic fibrosis. These immunomodulatory activities appear to be polymodal, but evidence suggests that many of these effects are due to inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation and nuclear factor kappa B (NF-kappaB) activation. Macrolides accumulate within cells, suggesting that they may associate with receptors or carriers responsible for the regulation of cell cycle and immunity. A concern is that long-term use of macrolides increases the emergence of antimicrobial resistance. Nonantimicrobial macrolides are now in development as potential immunomodulatory therapies.

Effect of erythromycin on bronchial hyperreactivity and inflammation in ovalbumin-sensitized brown Norway rats

To evaluate the effect of erythromycin on bronchial hyperreactivity, inflammation, and T-cell related cytokine mRNA expression in rats sensitized to ovalbumin, three experimental groups of 10 brown Norway rats each were sensitized by breathing aerosolized ovalbumin. From day 1 to day 15, one group was given oral erythromycin 80 mg/kg/day, another group oral erythromycin 20mg/kg/day, and the third group oral saline only. A fourth control group of 10 rats breathed aerosolized saline. After sensitization, the three experimental groups were provoked by breathing ovalbumin, with the controls again breathing saline. The rats were then anesthetized and paralyzed, and pulmonary function tests were performed at baseline and after varying doses of acetylcholine. Bronchoalveolar lavage (BAL) fluid and lung tissues were examined for expression of mRNA for T-cell cytokines. Our results showed that erythromycin had no beneficial effects on pulmonary function and lung inflammation in the two erythromycin-treated experimental groups compared with the saline experimental group. Th2-related cytokines and their mRNA expression in the three experimental groups were higher than in controls but did not differ among the experimental groups. In conclusion, erythromycin does not prevent bronchial hyperreactivity or an inflammatory response in ovalbumin-sensitized rats.

Azithromycin may reduce cholestasis in primary sclerosing cholangitis: a case report and serendipitous observation

The newer macrolides have been shown to exert additional anti-inflammatory effects. We report the possible effect of azithromycin on primary sclerosing cholangitis in a patient treated with the drug for severe asthma. A 45-year-old woman with Crohn?s disease and primary sclerosing cholangitis, also suffering from severe asthma, was treated with azithromycin 500 mg OD for 3 consecutive days a week because of the clinical suspicion of bronchiectasis and the severity of her asthma. When the therapy was discontinued, her urine again became darker, pruritus reappeared with the usual severity and laboratory parameters, evaluated after 6 weeks without azithromycin, also worsened. For these reasons macrolide treatment was re-established. Cholestasis-related symptoms and the dark colour of the urine were again reduced 6 weeks later and laboratory parameters were again reversed. We are therefore tempted to speculate that azithromycin may have an effect on primary sclerosing cholangitis on the basis of its anti-inflammatory properties.

Macrolide immunomodulatory effects and symptom resolution in acute exacerbation of chronic bronchitis and acute maxillary sinusitis: a focus on clarithromycin

Bacterial respiratory tract infections are common in the primary care setting and patients often seek the assistance of a healthcare professional in order to achieve resolution of their symptoms. Antibiotic agents that offer rapid symptom relief, in addition to excellent bacteriological and clinical cure, are highly desired. Macrolides have proven to be highly effective in treating acute bacterial exacerbations of chronic bronchitis and acute maxillary sinusitis. In addition, immunomodulatory effects that may contribute to symptom resolution have been reported. This article reviews current literature on symptom resolution in acute bacterial exacerbations of chronic bronchitis and acute maxillary sinusitis, with a focus on clarithromycin, and explores the potential mechanisms that may contribute to this action.

Infections and asthma

A new paradigm is developing in regard to the interaction between infection and asthma. This paradigm comprises the acute exacerbations seen in asthma and also asthma chronicity. Viral infections have been commonly evaluated in acute exacerbations, but findings suggest viral-allergen and viral-bacterial interactions are important for chronicity. Most recently, studies are also invoking atypical bacterial infections, Mycoplasma pneumoniae and Chlamydia pneumoniae, as factors in both acute exacerbation and chronic asthma.

Anti-inflammatory activity of azithromycin attenuates the effects of lipopolysaccharide administration in mice

Macrolide antibacterials inhibit the production of various cytokines and the migration of inflammatory cells. These anti-inflammatory actions of macrolides may be beneficial in attenuating inflammatory processes involved in bacterial sepsis. Therefore, we investigated the ability of azithromycin to attenuate the deleterious effects of lipopolysaccharide (LPS), in three different LPS-induced inflammatory models. Our results show that azithromycin (10 and 100 mg/kg) significantly attenuated the intraperitoneal LPS-induced increase in plasma TNF-alpha concentration. It also increased survival rate in a septic shock model in mice challenged with intravenous LPS. Oral treatment with azithromycin (up to 300 mg/kg) was less effective in suppressing neutrophil infiltration into the lungs 24 h after intranasal LPS challenge, possibly because of a slower onset of action or inadequate dosing. In the same model, azithromycin given intraperitoneally significantly improved inflammatory markers (total cell number, neutrophil percentage and MIP-2 concentration) in bronchoalveolar lavage fluid. In conclusion, azithromycin exhibits significant anti-inflammatory properties but the potency of such effects varies depending on the experimental model and route of administration.

Value of short-course antimicrobial therapy in acute bacterial rhinosinusitis

Traditional approaches to antimicrobial management of acute bacterial rhinosinusitis (ABRS) focus on courses of therapy of at least 10 days duration. The rationale for this length of therapy originated from studies in tonsillopharyngitis. Short-course antibiotic therapy for ABRS with 3-5 days of azithromycin has proved equally effective. Potential added benefits of short-course therapy include improved compliance, fewer adverse events as well as reduced risk of treatment failure, bacterial resistance and cost. Single-dose therapy is now possible with a novel microsphere formulation of azithromycin, which permits administration of a higher 2.0 g oral dose. This has proved as effective and well tolerated as 10 days levofioxacin 500 mg/day in patients with uncomplicated ABRS. High single-dose therapy has the potential to maximize adherence to prescribed therapy and thus to help in the battle to control rising antibiotic resistance among respiratory pathogens.

Stabilization of red blood cell membranes by thalidomide in vitro

The anti-inflammatory effect of thalidomide has been well established. The mechanism of this anti-inflammatory action is still not completely understood. Certain drugs exert their anti-inflammatory action by stabilizing the membranes of polymorphonuclear neutrophils (PMN) thereby reducing the production of reactive oxygen intermediates. We evaluated the effect of thalidomide on cell membranes by using red blood cells (RBC), PMN and the monocyte-like cell line THP-1. Osmotic fragility of RBC showed that in vitro, thalidomide stabilized the membrane of RBC from plasma free blood; whereas, it did not affect RBCs from whole blood. Red blood cells taken from subjects before and after ingestion of thalidomide were not affected after exposure to different concentrations of hypotonic NaCl solution. Thalidomide did not affect the membrane stability of PMNs as well as THP-1 in a significant manner. These data suggest that the anti-inflammatory mechanism of thalidomide is not related to events associated with the oxidative burst of PMNs or monocytes.

Effect of macrolides on in vivo ion transport across cystic fibrosis nasal epithelium

Fourteen- and 15-member macrolide antibiotics are under investigation as potential therapeutic agents for cystic fibrosis (CF). The nonantibiotic mechanisms of action of these compounds in CF are not understood. We used nasal potential difference (NPD) measurements to test the effect of macrolides on airway epithelial ion (chloride, sodium) transport of CF mice and humans. We tested clarithromycin and azithromycin in mice, and clarithromycin in patients with CF. Baseline and post-treatment NPD was measured in two strains (C57Bl6 and BalbC) of CF transmembrane regulator "knockout" and littermate control mice, and in DeltaF508/DeltaF508 mice. In addition, NPD was measured in 18 human subjects with CF (17 DeltaF-508/DeltaF-508 and 1 DeltaF-508/other) who were undergoing a 12-month, randomized, double-blind crossover study of the effects of clarithromycin on pulmonary outcome in CF. Neither clarithromycin nor azithromycin affected ion transport characteristics of normal or CF nasal epithelium in either mouse or humans. We conclude that the apparent beneficial effects of macrolides on pulmonary outcome in CF are not mediated by their modulation of ion transport.

Antibiotics in asthma

Asthma pathogenesis appears to be a result of a complex mixture of genetic and environmental influences. There is evidence that Mycoplasma pneumoniae and Chlamydia pneumoniae play a role in promoting airway inflammation that could contribute to the onset and clinical course of asthma. If antimicrobial therapy can eradicate these organisms, it might be possible to alter the course of the disease. Although antibiotics have no role in the routine management of acute exacerbations of asthma, certain macrolide antibiotics have been shown to have anti-inflammatory activity. Part of this effect is due to their known inhibition of steroid and theophylline metabolism, but through a myriad of mechanisms that are incompletely understood, macrolide antibiotics have additional broad anti-inflammatory properties that might prove useful in the management of asthma and other inflammatory diseases.

Clinical implications of the immunomodulatory effects of macrolides on sinusitis

This article reviews the treatment of chronic sinusitis with macrolides. Chronic sinusitis is often the result of bacterial infections that lead to chronic inflammation with thickening of the sinus mucosa and hypersecretion of mucus. In addition to their anti-infective properties, some macrolides possess immunomodulatory effects. These macrolides have been used successfully to treat diffuse panbronchiolitis, a progressive inflammatory lung disease, and may be useful for treatment of asthma, chronic bronchitis, chronic sinusitis, cystic fibrosis, and bronchiectasis. The clinical benefits of macrolides in patients with chronic sinusitis include decreased nasal secretions and postnasal drip, with improvement in nasal obstruction. In vivo and in vitro studies show that some macrolides affect neutrophil chemotaxis and infiltration, inflammatory cytokine production, mucus production, and the transportability of airway secretions. These findings indicate that macrolides are promising agents for treating chronic inflammation of the airways.

The Effect of Clarithromycin on Inflammatory Markers in Chronic Obstructive Pulmonary Disease: Preliminary Data

BACKGROUND:

Clarithromycin is an antimicrobial agent that can be used for treatment of chronic obstructive pulmonary disease (COPD) exacerbations with bronchodilator therapy. However, it has also been shown that clarithromycin has antiinflammatory effects by the inhibition of cytokine production.

OBJECTIVE:

To evaluate the antiinflammatory effect of clarithromycin on serum and sputum interleukin-8 (IL-8), tumor necrosis factor-α (TNF-α), and leukotriene B4 levels in patients with COPD.

METHODS:

Thirty men with mild to moderate COPD were enrolled in this prospective, single-center, double-blind, placebo-controlled study. None of the patients was receiving systemic or inhaled corticosteroids during the study. Subjects received either clarithromycin or placebo for 14 days. Before and after this treatment period, spirometric tests and arterial blood gas analysis were performed, blood was drawn for measurement of serum inflammatory markers, and sputum was induced.

RESULTS:

There were no statistically significant differences in baseline clinical or laboratory parameters between the groups. After the treatment, the induced sputum total cell counts, and IL-8 and TNF-α levels decreased significantly in the clarithromycin group compared with pretreatment levels (mean ± SD IL-8 1606 ± 367.3 vs 882 ± 143.6 pg/mL, p = 0.001; TNF-α 638.2 ± 287.5 vs 390 ± 235 pg/mL, p = 0.001). Similarly, decreases in serum inflammatory markers were found in the clarithromycin group while there was no significant change in the placebo group.

CONCLUSIONS:

This study demonstrated that the decrease in IL-8 and TNF-α levels might be related to the antiinflammatory effect of clarithromycin. Thus, we suggest that the use of clarithromycin in COPD exacerbations may either treat the infection or help control the inflammation. Future studies are needed to determine the clinical significance of these findings.

Clarithromycin in 2003: sustained efficacy and safety in an era of rising antibiotic resistance

Data from surveillance studies show increasing prevalence of respiratory pathogens resistant to commonly used antibiotics. Thus, a Medline search was conducted to identify studies of clarithromycin, especially those addressing macrolide resistance. Changing trends of in vitro susceptibility have not affected clinical efficacy with clarithromycin. Over the last 12 years, clarithromycin study results have shown consistent rates of clinical cure and bacteriological eradication, which are similar to those observed with comparator agents. The incidence of clarithromycin treatment failure in patients infected with Streptococcus pneumoniae is substantially less than that predicted by macrolide resistance rates from surveillance programmes. In summary, despite widespread use since its introduction, clarithromycin remains active both in vitro and in vivo against clinically relevant respiratory tract pathogens.

Effect of multiple doses of clarithromycin and amoxicillin on IL-6, IFNgamma and IL-10 plasma levels in patients with community acquired pneumonia

Inflammation is crucial for the pathogenesis of both infectious and chronic obstructive pulmonary diseases. It is therefore important to modulate pulmonary inflammation in patients with these lung disorders. Macrolide antibiotics modulate inflammation in vitro and in in vivo by inhibiting the production of proinflammatory cytokines and prostaglandin E2, neutrophil chemotactic activity and elastase activity. This study evaluates the effect of clarithromycin (500 mg b.i.d. x 7 days) in comparison to amoxicillin (1 g t.i.d. x 7 days) in patients with community acquired pneumonia by testing plasma levels of IL-6, IFNgamma and IL-10 before starting therapy and at the 3rd and 7th days of therapy. Clarithromycin significantly decreased plasma levels of IL-6 and significantly increased those of IFNgamma and IL-10 at the 3rd and 7th day in comparison to basal levels. In patients treated with amoxicillin a significant decrease in IL-6 plasma levels was observed at the 7th day of therapy, probably in relation to the resolution of inflammatory symptoms. In the same patients IFNgamma plasma levels decreased during treatment while IL-10 plasma levels were unaffected.

Evaluation of the Medical and Surgical Treatment Of Chronic Rhinosinusitis: A Prospective, Randomised, Controlled Trial

OBJECTIVES

To conduct the first prospective, randomized, controlled trial evaluating and comparing the medical and surgical treatment of polypoid and nonpolypoid chronic rhinosinusitis (CRS).

MATERIALS AND METHODS

Ninety patients with CRS were equally randomized either to medical or surgical therapy. All patients underwent pre- and posttreatment assessments of visual analogue score (VAS), the Sinonasal Outcome Test-20 (SNOT-20), the Short Form 36 Health Survey (SF-36), nitric oxide (NO), acoustic rhinometry, saccharine clearance time (SCT), and nasal endoscopy. Each patient had three assessments: before starting the treatment, after 6 months, and, finally, after 1 year.

RESULTS

Both the medical and surgical treatment of CRS significantly improved almost all the subjective and objective parameters of CRS (P <.01), with no significant difference being found between the medical and surgical groups (P >.05), except for the total nasal volume in CRS (P <.01) and CRS without polyposis (P <.01) groups, in which the surgical treatment demonstrated greater changes.

CONCLUSION

CRS should be initially targeted with maximal medical therapy (e.g., a 3 month course of a macrolide antibiotic, douche, and topical steroid), with surgical treatment being reserved for cases refractory to medical therapy. The presence of nasal polyps is not a poor prognostic factor for the efficacy of CRS therapy, either surgical or medical.

The office management of recalcitrant rhinosinusitis

The patient referred to the otolaryngologist for the treatment of CRS has received many therapies for the condition. Newer therapies available focus on the anti-inflammatory therapies and local application of antimicrobial and antifungal agents to the sinus cavities. Much clinical work remains to be done to prove the efficacy of currently available treatments. The recent advances in the understanding of allergic and immune mechanisms may allow eventual intervention at the level of cytokines and other immunomodulators of inflammation. The complex cascade of interleukins and proinflammatory agents in CRS patients may some day allow "silver bullet" therapies in the properly selected patient. Until then, a systematic approach to the evaluation of these patients and management with the currently available treatment modalities may help relieve the symptoms in patients with CRS.

Macrolides for the treatment of chronic sinusitis, asthma, and COPD

In addition to their well-known antimicrobial activity, macrolides possess immunomodulatory properties that may confer beneficial effects to patients with respiratory diseases associated with chronic inflammation. These properties include attenuation of inflammatory responses in the lung, mucoregulatory properties, and effects on bronchial responsiveness. Macrolides increase mucociliary clearance, improve sinusitis symptoms, and decrease nasal secretions and polyp size in patients with sinusitis. They also have been shown to modify the inflammatory response associated with chronic sinusitis. In patients with asthma, macrolides have been reported to reduce airway hyperresponsiveness and improve pulmonary function, and have historically been selected for their "steroid-sparing" effect. Preliminary data from studies of patients with COPD have shown improvements in symptom scores and FEV(1) after macrolide treatment. As biological response modifiers, macrolides have the potential to improve the outcomes of patients with inflammatory airway diseases. Large scale, placebo-controlled clinical trials designed to assess long-term efficacy and safety in these diseases are warranted.

The Effect of Oral Clarithromycin on Bronchial Airway Inflammation in Moderate-to-Severe Stable COPD

INTRODUCTION

COPD is characterized by bronchial neutrophilic inflammation. Clarithromycin is a macrolide antibiotic that has antibacterial and anti-inflammatory properties. Macrolide antibiotics have been shown to improve airway inflammation in diffuse pan-bronchiolitis but their role in COPD is undetermined. The aim of the study was to determine if 3 months of therapy with modified-release oral clarithromycin (Klaricid XL) 500 mg/day reduced bronchial airway inflammation in patients with moderate-to-severe stable COPD compared with placebo.

METHODS

A prospective, double-blind controlled trial randomized patients with moderate-to-severe stable COPD to 3 months' therapy with oral modified-release clarithromycin 500 mg/day or placebo. Patients underwent saline sputum induction before and after treatment with clarithromycin. The effects of clarithromycin on sputum total cell and neutrophil counts, supernatant interleukin-8 (IL-8), leukotriene B(4) (LTB(4)), tumor necrosis factor (TNF)-alpha, neutrophil elastase (NE), and neutrophil chemotaxis were assessed in comparison with placebo.

RESULTS

Of a total of 67 patients included in the trial, 31 were treated with clarithromycin and 36 with placebo. The groups were similar in age, body mass index, history of smoking, and spirometry. Of 60 evaluable patients, 26 and 34 completed 3 months' therapy with clarithromycin and placebo, respectively. Clarithromycin had no significant effect on sputum total cell count, neutrophil count, IL-8, LTB(4), TNFalpha levels or neutrophil elastase. However, clarithromycin did cause a small reduction in the neutrophil differential (p = 0.04 relative to placebo) and neutrophil chemotaxis (p = 0.058 relative to placebo).

CONCLUSIONS

Oral clarithromycin 500 mg/day administered for 3 months had no significant effect on sputum neutrophil numbers or cytokine levels in patients with moderate-to-severe stable COPD. However, clarithromycin did cause a small reduction in the neutrophil differential and neutrophil chemotaxis. Further studies may be warranted to determine the clinical significance of these findings.

Macrolide antibiotics for cystic fibrosis

BACKGROUND

Chronic severe infection with Pseudomonas aeruginosa, affects many people with cystic fibrosis (CF). There is evidence from the laboratory and from other disease processes that macrolide antibiotics, whilst not directly active against Pseudomonas aeruginosa, may have indirect actions against this organism.

OBJECTIVES

We aimed to test the hypotheses that, in people with CF, macrolide antibiotics:(1) improve clinical status compared to placebo or another antibiotic;(2) do not have unacceptable adverse effects. If benefit was demonstrated, we aimed to assess the optimal type, dose and duration of macrolide therapy.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group trials register comprising references identified from comprehensive electronic database searches, handsearching relevant journals and abstract books of conference proceedings. We contacted principal investigators known to work in the field, previous authors and pharmaceutical companies who manufacture macrolide antibiotics for unpublished or follow-up data (December 2003). Most recent search of the Group's register: January 2004

SELECTION CRITERIA

Published or unpublished randomised controlled trials of macrolide antibiotics compared to placebo, another class of antibiotic or another macrolide antibiotic. Studies comparing regimens of the same macrolide antibiotic at different doses will also be included.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and assessed study quality. Three groups were contacted for missing data and we hope to include these in future reviews.

MAIN RESULTS

Searches identified 14 studies, four were included in this review (296 participants). Two studies enrolled adults, one children (a significant number of whom were not colonised with Pseudomonas aeruginosa) and one both adults and children. All the clinical studies reported small but significant improvements in respiratory function with azithromycin versus placebo. Meta-analysis at the one-month and six-month time points demonstrates a significant benefit with respect to relative change in FEV1 (at six months, for n = 104, azithromycin and n = 114, placebo; WMD 5.82% (95% CI 2.45 to 9.20)). The largest study reported a significant increase in mild adverse events (nausea, diarrhoea and wheezing).

REVIEWERS' CONCLUSIONS

There is clear evidence from these studies of a small but significant improvement in respiratory function following treatment with azithromycin. The largest study employed a three times a week dose and, in this study, treatment with azithromycin was associated with a significant increase in mild adverse events. Further studies are needed to clarify the precise role of azithromycin in the treatment of CF lung disease.

Severe erythema nodosum due to Behçet's disease responsive to erythromycin

A patient with severe erythema nodosum due to Behçet's disease is reported on here. Erythema nodosum lesions did not respond to classical treatments; however, they cleared after erythromycin treatment, which was prescribed for the treatment of coincidental erythrasma. Erythromycin treatment appears to be an effective treatment option in erythema nodosum. The hypothetical anti-inflammatory effects of erythromycin, besides its antibiotic properties, are reviewed and discussed to explain such a clinical improvement.

Chlamydia pneumoniae and coronary artery disease: the antibiotic trials

Parallel with the mounting evidence that atherosclerosis has a major inflammatory component, provoking agents that may initiate and drive this process have been sought. Infectious agents such as Chlamydia pneumoniae have been alleged to be activators of inflammation that may contribute to atherosclerosis and thus coronary artery disease (CAD) and its associated complications. A logical pneumoniae extension of this theory whether treating C pneumoniae infection with antibiotics and/or modulating inflammatory processes can affect CAD and its sequelae. This article discusses the potential role of C pneumoniae in atherosclerosis, its detection, and the rationale for antibiotics. Additionally, it summarizes the current randomized clinical trials of antichlamydial antibiotics in patients with CAD and draws conclusions based on the results.

Macrolide antibiotics for cystic fibrosis

BACKGROUND

The antibiotic treatment of chest infections which characterise cystic fibrosis (CF) has significantly improved prospects for people with CF. The nature of organisms causing these infections has restricted antibiotic choice. Pseudomonas aeruginosa, especially, is resistant to most oral antibiotics. There is evidence from the laboratory and from other disease processes that macrolide antibiotics, whilst not directly active against Pseudomonas aeruginosa, may have indirect actions against this organism.

OBJECTIVES

We aimed to test the hypotheses that macrolide antibiotics:(1) improve clinical status compared to placebo or another antibiotic;(2) have no unacceptable adverse effects. If benefit was demonstrated, we aimed to assess the optimal type, dose and duration of macrolide therapy.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group trials register comprising references identified from comprehensive electronic database searches, handsearching relevant journals and abstract books of conference proceedings.We contacted principal investigators known to work in the field, previous authors and pharmaceutical companies who manufacture macrolide antibiotics for unpublished or follow-up data (December 2002). Date of the most recent search of the Group's register: March 2003.

SELECTION CRITERIA

Published or unpublished randomised controlled trials of macrolide antibiotics compared to placebo, another class of antibiotic or another macrolide antibiotic. Studies comparing regimens of the same macrolide antibiotic at different doses will also be included.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and assessed study quality. Two groups were contacted for missing data, but these were unavailable for the review.

MAIN RESULTS

Searches identified eleven studies, two were included in this review (101 participants). One study enrolled adults and the other children (a significant number of whom were not colonised with Pseudomonas aeruginosa). Both studies report small but significant changes in respiratory function (% change in FEV1) in favour of azithromycin. Meta-analysis at the two-month time point demonstrated a significant benefit with respect to percentage change in FVC (weighted mean difference 5.42 (1.77 to 9.07)) from azithromycin, but no difference with respect to percentage change of FEV1. There were no significant adverse effects reported.

REVIEWER'S CONCLUSIONS

The role of macrolides in the management of CF lung disease remains unclear and there are many unanswered questions. Two small randomised controlled trials have suggested short-term improvement in respiratory function with azithromycin. Until the results of further studies are available the widespread use of azithromycin in CF cannot be advocated and should be restricted to well-designed randomised controlled trials.

Tissue reparative effects of macrolide antibiotics in chronic inflammatory sinopulmonary diseases

It is well established that macrolide antibiotics are efficacious in treating sinopulmonary infections in humans. However, a growing body of experimental and clinical evidence indicates that they also express distinct salutary effects that promote and sustain the reparative process in the chronically inflamed upper and lower respiratory tract. Unlike the anti-infective properties, these distinct effects are manifested at lower doses, usually after a relatively prolonged period (weeks) of treatment, and in the absence of an identifiable, viable pathogen. Long-term, low-dose administration of macrolide antibiotics has been used most commonly for sinusitis, diffuse panbronchiolitis, asthma, bronchiectasis, and cystic fibrosis. It is associated with down-regulation of nonspecific host inflammatory response to injury and promotion of tissue repair. Although large-scale trials are lacking, the prolonged use of these drugs has not been associated with emergence of clinically significant bacterial resistance or immunosuppression. Long-term, low-dose administration of 14- and 15-membered ring macrolide antibiotics may represent an important adjunct in the treatment of chronic inflammatory sinopulmonary diseases in humans.

Disposition and intracellular activity of azithromycin in human THP-1 acute monocytes

Uptake of [14C]-azithromycin into THP-1 human monocytes was determined at pH 7.4, 6.8 or 5.5 over 4-log antibiotic concentrations for 24 h under a number of conditions. Stimulation of cells was with bacteria, latex beads, lipopolysaccharide (LPS), or zymogen A. Subcellular organelle disposition was determined after isolation by ultracentrifugation or sucrose gradients. Hydrolytic enzyme activities and mediators of intracellular inflammation (IL-1, IL-6, IL-8, and TNFalpha) were assessed. Azithromycin uptake into human THP-1 monocytes was initially linear achieving approximately 2% of the extracellular concentration. At pH 7.4, uptake was both passive- and carrier-mediated, but as the pH became more acidic, the uptake was exclusively passive. The intracellular concentration was not pH-dependent over 24 h. Uptake was dependent upon temperature but not the presence of foetal calf serum. Intracellular disposition in zymogen A-stimulated and unstimulated cells was throughout all compartments of the cell, but was higher in the nucleus and cell sap. Phagosomes of stimulated cells contained higher level of the antibiotic. Efflux from THP-1 monocytes was complete between 3 and 4 h. After 1 h treatment with zymogen A, THP-1 monocytes demonstrated an increase in intracellular acidity, protein kinase C, SOD and NAG activities, and NO, H(2)O(2), TNFalpha and IL-1 release over the 1st h. After 2-4 h the pH became alkaline, activities of NADPH reductase, NAG and cathepsin were reduced, and the release of NO, H(2)O(2), TNFalpha and IL-6 were suppressed. Protein synthesis and killing of the bacteria was evident in bacteria kept in monocyte-free medium and those phagocytized by the THP-1 monocytes moderately at 2 h, but more significantly at 24 h. The early killing of the bacteria appears to be a cidal mechanism whereas later, a standard bacteriostatic mechanism was evident. Nevertheless, suppression of these chemical mediators and hydrolytic enzyme activities would reduce the infection and the spread to adjacent areas.

Effect of antibiotics on polymorphonuclear neutrophil apoptosis

STUDY OBJECTIVE

To evaluate the effects of various antibiotics-direct and indirect as a result of bacterial killing-on polymorphonuclear neutrophil (PMN) apoptosis.

DESIGN

In vitro analysis.

SETTING

Research laboratory.

INTERVENTION

Whole blood collected from healthy human subjects was incubated with and without Klebsiella pneumoniae (1.0 x 10(5) colony-forming units [cfu]/ml) plus ceftazidime 50 microg/ml, gentamicin, ciprofloxacin, trovafloxacin, tetracycline, doxycycline, erythromycin, azithromycin (each 5 microg/ml), or lipopolysaccharide 10 microg/ml. After staining with fluorescein-conjugated annexin V, red blood cells were lysed, and the remaining white blood cells were assessed by flow cytometry with gating on PMNs.

MEASUREMENTS AND MAIN RESULTS

In the absence of K. pneumoniae infection, antibiotic exposure directly decreased PMN apoptosis by 17.8% (range -25.0% to -13.9%, p=0.008) compared with untreated cells. In the presence of K. pneumoniae, all antibiotic treatments, even those with poor in vitro activity for the bacterial isolate, decreased PMN apoptosis by 26.2% (range -38.0% to -17.8%, p<0.001) compared with untreated control cells and by 36.6% compared with untreated (no antibiotic) K. pneumoniae-stimulated cells (range -46.2% to -28.0%, p<0.001).

CONCLUSIONS

All tested antibiotics in clinically relevant concentrations resulted in modest yet consistent decreases in PMN apoptosis. The magnitude of this change increased slightly in the presence of K. pneumoniae infection. In vivo studies are needed to determine whether antibiotic-associated prolongation of PMN survival improves host response to infection.

One-year low-dose erythromycin treatment of persistent chronic sinusitis after sinus surgery: clinical outcome and effects on mucociliary parameters and nasal nitric oxide

OBJECTIVE

In 17 patients with chronic sinusitis persistent after sinus surgery, long-term, low-dose erythromycin therapy was tested. The aim of the investigation was to study the clinical outcome and effects on nasal nitric oxide (NO), ciliary beat frequency (CBF), and mucociliary transport (saccharine transit time).

STUDY DESIGN AND SETTING

We conducted a prospective open study at a tertiary teaching hospital. Symptoms were assessed using visual analog scales. NO was measured using a chemiluminescence analyzer, and mucociliary transport was measured with the saccharine crystal technique. CBF was measured in nasal brush samples using a phase contrast microscope. All patients were treated with erythromycin succinate 250 mg 2x daily or clarithromycin 250 mg 1x daily and were assessed after 3 months. In cases where there was no response, treatment was abandoned. The remaining patients (responders) were reassessed after 12 months of treatment.

RESULTS

Of 17 patients, 12 responded to treatment. The 12-month follow-up showed an improvement in saccharine transit time (P < 0.05) but no significant change in CBF. There was a trend toward an increase in NO (P = 0.12). Endoscopic nasal examination scoring improved significantly (P < 0.01). In the visual analog scale scoring, the most pronounced improvements were seen in nasal congestion, sticky secretion, and runny nose at 3 and 12 months (P < 0.01). Improvements were also seen in headache (P < 0.05).

CONCLUSION

The present study suggests that long-term, low-dose treatment with erythromycin is effective in persistent chronic sinusitis that does not respond to sinus surgery or systemic steroid/antibiotic treatment.

SIGNIFICANCE

Long-term, low-dose erythromycin therapy seems to be a promising alternative when more conventional therapy fails. However, placebo-controlled studies are needed to validate the potential of this treatment.

Effect of azithromycin on the severity of bronchial hyperresponsiveness in patients with mild asthma

The effect of azithromycin on bronchial hyperresponsiveness was measured in a group of 11 patients with mild asthma. Azithromycin 250 mg orally was administered intermittently to all the patients twice a week for eight weeks. The only other treatment was inhaled beta2 agonist, when required. A histamine inhalation test was performed at the beginning and at the fourth and the eighth week of the study. The mean PC20 values increased significantly over the initial value at the eighth week after the administration of azithromycin (p < 0.05) but mean values for FEV1 and FEV1 percent predicted did not differ significantly. These results suggested that eight weeks of intermittent, low-dose administration of azithromycin in patients with mild asthma might reduce the severity of bronchial hyperresponsiveness.