Macrolide resistance of Staphylococcus aureus and Haemophilus species associated with long-term azithromycin use in cystic fibrosis

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known to work in the field, previous authors and pharmaceutical companies manufacturing macrolide antibiotics for unpublished or follow-up data, where possible.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).

Baseline azithromycin resistance in the gut microbiota of preterm born infants

BACKGROUND

Macrolides, including azithromycin, are increasingly used in preterm-born infants to treat Ureaplasma infections. The baseline carriage of macrolide resistance genes in the preterm stool microbiota is unknown.

OBJECTIVES

Identify carriage of azithromycin resistant bacteria and the incidence of macrolide resistant genes.

METHODS

Azithromycin resistant bacteria were isolated from serial stool samples obtained from preterm infants (≤32 weeks' gestation) by culturing aerobically/anaerobically, in the presence/absence of azithromycin. Using quantitative PCR, we targeted 6 common macrolide resistance genes (erm(A), erm(B), erm(C), erm(F), mef(A/E), msr(A)) in DNA extracted from selected bacteria resistant to azithromycin.

RESULTS

From 89 stool samples from 37 preterm-born infants, 93.3% showed bacterial growth in aerobic or anaerobic conditions. From the 280 azithromycin resistant isolates that were identified, Staphylococcus (75%) and Enterococcus (15%) species dominated. Macrolide resistance genes were identified in 91% of resistant isolates: commonest were erm(C) (46% of isolates) and msr(A) (40%). Multiple macrolide resistance genes were identified in 18% of isolates.

CONCLUSION

Macrolide resistance is common in the gut microbiota of preterm-born infants early in life, most likely acquired from exposure to the maternal microbiota. It will be important to assess modulation of macrolide resistance, if macrolide treatment becomes routine in the management of preterm infants.

IMPACT STATEMENT

Azithromycin resistance is present in the stool microbiota in the first month of life in preterm infants 91% of azithromycin resistant bacteria carried at least one of 6 common macrolide resistant genes Increasing use of macrolides in the preterm population makes this an important area of study.

Antibiotic dispensing during first year of COVID-19 pandemic in Brazilian public hospitals

Aim: To evaluate the impact of the first year of the COVID-19 pandemic on antibiotic dispensation in three Brazilian hospitals. Methods: Stock movement was accessed from pharmacy databases and microbiological reports from 2018 to 2021. Results: Reduced antibiotic dispensation occurred during 2020 in all hospitals. The most significant reduction was in April at Hospital Doutor Jayme dos Santos Neves (∼58%), and in May at Hospital Doutor Roberto Arnizaut Silvares (∼66%) and Hospital Doutor Dório Silva (∼29%). However, azithromycin dispensation increased in all hospitals in 2020. Macrolide-resistant bacterial isolates rose from 66.6% in 2019 to 77.1% in 2020 and 88.3% in 2021. Conclusion: Despite reduced antibiotic dispensation, the increase in azithromycin consumption in 2020 highlights the urgency to monitor macrolide resistance after the pandemic and improve stewardship activities.

The impact of long-term azithromycin on antibiotic resistance in HIV-associated chronic lung disease

Selection for resistance to azithromycin (AZM) and other antibiotics such as tetracyclines and lincosamides remains a concern with long-term AZM use for treatment of chronic lung diseases (CLD). We investigated the impact of 48 weeks of AZM on the carriage and antibiotic resistance of common respiratory bacteria among children with HIV-associated CLD. Nasopharyngeal (NP) swabs and sputa were collected at baseline, 48 and 72 weeks from participants with HIV-associated CLD randomised to receive weekly AZM or placebo for 48 weeks and followed post-intervention until 72 weeks. The primary outcomes were prevalence and antibiotic resistance of Streptococcus pneumoniae (SP), Staphylococcus aureus (SA), Haemophilus influenzae (HI) and Moraxella catarrhalis (MC) at these timepoints. Mixed-effects logistic regression and Fisher's exact test were used to compare carriage and resistance, respectively. Of 347 (174 AZM, 173 placebo) participants (median age 15 years (IQR 13-18), female 49%), NP carriage was significantly lower in the AZM (n=159) compared to placebo (n=153) arm for SP (18% versus 41%, p<0.001), HI (7% versus 16%, p=0.01) and MC (4% versus 11%, p=0.02); SP resistance to AZM (62% (18 out of 29) versus 13% (8 out of 63), p<0.0001) or tetracycline (60% (18 out of 29) versus 21% (13 out of 63), p<0.0001) was higher in the AZM arm. Carriage of SA resistant to AZM (91% (31 out of 34) versus 3% (1 out of 31), p<0.0001), tetracycline (35% (12 out of 34) versus 13% (4 out of 31), p=0.05) and clindamycin (79% (27 out of 34) versus 3% (1 out of 31), p<0.0001) was also significantly higher in the AZM arm and persisted at 72 weeks. Similar findings were observed for sputa. The persistence of antibiotic resistance and its clinical relevance for future infectious episodes requiring treatment needs further investigation.

Combination of kaempferol and azithromycin attenuates Staphylococcus aureus-induced osteomyelitis via anti-biofilm effects and by inhibiting the phosphorylation of ERK1/2 and SAPK

Osteomyelitis is bacterial infection of bone, commonly caused by Staphylococcus aureus. This work aims to study the potential of azithromycin and kaempferol against chronic osteomyelitis induced by azithromycin-resistant Staphylococcus aureus (ARSA). It was noticed that rats tolerated the treatments with no diarrhoea or weight loss; also, no deaths were observed in rats. The treatment by azithromycin alone failed to inhibit bacterial growth and also had no effect on the infection condition of bone, although the treatment decreased the levels of interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α), but did not improve the oxidative stress levels. Kaempferol monotherapy slightly inhibited bacterial growth and bone infection; the treatment also inhibited the levels of IL-6 and (TNF-α). The treatment also improved the antioxidant status. However, the combined treatment of azithromycin and kaempferol significantly suppressed bacterial growth and bone infection and modulated oxidative stress. In vitro, the combined treatment inhibited the levels of IL-6 and TNF-α, and also suppressed the phosphorylation of ERK1/2 and stress-activated protein kinase (SAPK). The combined treatment also showed anti-biofilm activity in ARSA. The combination attenuates ARSA-induced osteomyelitis in rats compared with their treatments alone by reducing oxidative stress, inhibiting the phosphorylation of ERK1/2 and SAPK and inhibiting biofilm formation.

Emergence of Thymidine-Dependent Staphylococcus aureus Small-Colony Variants in Cystic Fibrosis Patients in Southern Brazil

We characterized Staphylococcus aureus small-colony variant (SCV) strains isolated from cystic fibrosis (CF) patients in southern Brazil. Smaller colonies of S. aureus were isolated from respiratory samples collected consecutively from 225 CF patients from July 2013 to November 2016. Two phenotypic methods—the auxotrophic classification and a modified method of antimicrobial susceptibility testing—were employed. PCR was conducted to detect the mecA, ermA, ermB, ermC, msrA, and msrB resistance genes. Furthermore, DNA sequencing was performed to determine the mutations in the thyA gene, and multilocus sequence typing was used to identify the genetic relatedness. S. aureus strains were isolated from 186 patients (82%); suggestive colonies of SCVs were obtained in 16 patients (8.6%). The clones CC1 (ST1, ST188, and ST2383), CC5 (ST5 and ST221), and ST398 were identified. Among SCVs, antimicrobial susceptibility testing showed that 77.7% of the isolates were resistant to multiple drugs, and all of them were susceptible to vancomycin. mecA (2), ermA (1), ermB (1), ermC (3), and msrB (18) were distributed among the isolates. Phenotypically thymidine-dependent isolates had different mutations in the thyA gene, and frameshift mutations were frequently observed. Of note, revertants showed nonconservative or conservative missense mutations. SCVs are rarely identified in routine laboratory tests.

IMPORTANCE Similar findings have not yet been reported in Brazil, emphasizing the importance of monitoring small-colony variants (SCVs). Altogether, our results highlight the need to improve detection methods and review antimicrobial therapy protocols in cystic fibrosis (CF) patients.

Surface Composition and Aerosolization Stability of an Inhalable Combinational Powder Formulation Spray Dried Using a Three-Fluid Nozzle

PURPOSE

This study aims to understand the impact of spray drying nozzles on particle surface composition and aerosol stability.

METHODS

The combination formulations of colistin and azithromycin were formulated by 2-fluid nozzle (2 N) or 3-fluid (3 N) spray drying in a molar ratio of 1:1. A 3-factor, 2-level (2³) factorial design was selected to investigate effects of flow rate, inlet temperature and feed concentration on yield of spray drying and the performance of the spray dried formulations for the 3 N.

RESULTS

FPF values for the 2 N formulation (72.9 ± 1.9% for azithromycin & 73.4 ± 0.8% for colistin) were higher than those for the 3 N formulation (56.5 ± 3.8% for azithromycin & 55.1 ± 1.6% for colistin) when stored at 20% RH for 1 day, which could be attributed to smaller physical size for the 2 N. There was no change in FPF for both drugs in the 2 N formulation after storage at 75% RH for 90 days; however, there was a slight increase in FPF for colistin in the 3 N formulation at the same storage conditions. Surface enrichment of hydrophobic azithromycin was measured by X-ray photoelectron spectroscopy for both 2 N and 3 N formulations and interactions were studied using FTIR.

CONCLUSIONS

The 3-fluid nozzle provides flexibility in choosing different solvents and has the capability to spray dry at higher feed solid concentrations. This study highlights the impact of hydrophobic azithromycin enrichment on particle surface irrespective of the nozzle type, on the prevention of moisture-induced deterioration of FPF for hygroscopic colistin.

Thymidine-auxotrophic Staphylococcus aureus small-colony variant bacteremia in a patient with cystic fibrosis

BACKGROUND

Small-colony variants (SCVs) are a morphologic subtype of Staphylococcus aureus that may occur through several mechanisms including auxotrophism for thymidine, hemin, or menadione. Auxotrophic SCV for thymidine fail to synthesize DNA specifically because of mutations in the thymidylate synthase gene. We isolated S. aureus thymidine-dependent SCVs (TD-SCV) from blood and respiratory samples of a pediatric patient with cystic fibrosis and pulmonary exacerbation.

METHODS

Nutritional dependence of SCVs on hemin, menadione, and thymidine was evaluated. Antimicrobial susceptibility testing was performed through broth microdilution. Polymerase chain reaction was carried out for mecA, ermA, ermB, ermC, msrA, and msrB resistance genes. DNA sequencing was used to determine mutations in thyA and the multilocus sequence typing to identify genetic relatedness.

RESULTS

Methicillin-sensitive S. aureus with normal and TD-SCV phenotypes were isolated from respiratory samples and a TD-SCV phenotype was isolated from blood culture. Macrolides resistance was attributed to ermC and msrB genes. All isolates belonged to ST398. The thyA gene in S. aureus is 957 nucleotides in length and encodes a protein of 318 amino acids. The TD-SCV isolates carried a -2 nt frameshift mutation (delta 667GC668) in thyA, creating a stop codon at residue 222 close to the predicted binding site for deoxyuridine monophosphate.

CONCLUSIONS

The pathogenesis of SCVs is complex and not fully elucidated. Factors inherent to the patient such as physiological conditions, recurrent infections, or coinfection should be considered. Although SCVs are considered less virulent, they showed the ability to invade and cause bacteremia in the patient.

Life-long antimicrobial therapy: where is the evidence?

The decision to prescribe long-term or 'life-long' antibiotics in patients requires careful consideration by the treating clinician. While several guidelines exist to help assist in this decision, the long-term consequences are yet to be well studied. In this review, we aim to provide a summary of the available evidence for patient populations where long-term antibiotic therapy is currently recommended in clinical practice. We will also discuss the pitfalls of this approach, including medication adverse effects, economic cost and any possible contribution to the emerging epidemic of microbial resistance.

Impact of an Antibiotic Stewardship Program on Antibiotic Prescription for Acute Respiratory Tract Infections in Children: A Prospective Before-After Study

We assessed the effectiveness of an antibiotic stewardship program (ASP) on antibiotic prescriptions for acute respiratory tract infection (ARTI) in a medical school. Our ASP included delivering an antibiotic use guideline via e-mail and LINE (an instant messaging app) to faculty staff, fellows, and residents, and posting of the guideline in examination rooms. Medical records of pediatric patients diagnosed with ARTI were reviewed to assess the appropriateness of antibiotic prescription. ASP could increase the rate of appropriateness from 78% (1979 out of 2553 visits) to 83.4% (2449 out of 2935 visits; P < .001). The baseline of appropriateness was higher in residents (95%) compared with fellows (82%) and faculty staff (75%). The ASP significantly increased the appropriateness only in faculty staff, especially in semiprivate clinics (75% to 83%, P < .001). In conclusion, our ASP increased appropriateness of antibiotic prescriptions for ARTI, with the greatest impact among faculty staff in semiprivate clinics.

Viral-Bacterial Co-infections in the Cystic Fibrosis Respiratory Tract

A majority of the morbidity and mortality associated with the genetic disease Cystic Fibrosis (CF) is due to lung disease resulting from chronic respiratory infections. The CF airways become chronically colonized with bacteria in childhood, and over time commensal lung microbes are displaced by bacterial pathogens, leading to a decrease in microbial diversity that correlates with declining patient health. Infection with the pathogen Pseudomonas aeruginosa is a major predictor of morbidity and mortality in CF, with CF individuals often becoming chronically colonized with P. aeruginosa in early adulthood and thereafter having an increased risk of hospitalization. Progression of CF respiratory disease is also influenced by infection with respiratory viruses. Children and adults with CF experience frequent respiratory viral infections with respiratory syncytial virus (RSV), rhinovirus, influenza, parainfluenza, and adenovirus, with RSV and influenza infection linked to the greatest decreases in lung function. Along with directly causing severe respiratory symptoms in CF populations, the impact of respiratory virus infections may be more far-reaching, indirectly promoting bacterial persistence and pathogenesis in the CF respiratory tract. Acquisition of P. aeruginosa in CF patients correlates with seasonal respiratory virus infections, and CF patients colonized with P. aeruginosa experience increased severe exacerbations and declines in lung function during respiratory viral co-infection. In light of such observations, efforts to better understand the impact of viral-bacterial co-infections in the CF airways have been a focus of clinical and basic research in recent years. This review summarizes what has been learned about the interactions between viruses and bacteria in the CF upper and lower respiratory tract and how co-infections impact the health of individuals with CF.

Azithromycin promotes alternatively activated macrophage phenotype in systematic lupus erythematosus via PI3K/Akt signaling pathway

Alternatively activated macrophages have been reported to be helpful to alleviate systematic lupus erythematosus (SLE), and azithromycin could serve as an immunomodulator by promoting alternatively activated macrophage phenotype. However, the effect of azithromycin in SLE and the involved mechanism remain undetermined. The aim of this study is to characterize azithromycin and the underlying mechanism contributing to SLE therapy. First, we compared monocytes from SLE patients and matched healthy donors, and found monocytes from SLE patients exhibited more CD14⁺CD86⁺ cells, impaired phagocytic activity, and elevated interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α (the classical activated phenotype), which could be blocked by azithromycin. On the contrary, there were fewer CD14⁺CD163⁺ cells in SLE patients, accompanied by decreased arginase (Arg)-1 and found in inflammatory zone (Fizz)-1 (the alternatively activated phenotype). And IL-10, the crucial immune regulatory factor secreted by alternatively activated monocytes/macrophages, also showed a decreased trend in SLE patients. In addition, all these markers were up-regulated after azithromycin treatment. Next, we used activated lymphocyte-derived-DNA to imitate SLE macrophages in vitro to investigate the possible mechanism involved. Azithromycin showed the same effect in imitated SLE macrophages, with distinct Akt phosphorylation at 30 min and 12 h. After inhibiting Akt phosphorylation by LY294002, the down-regulation of CD80, IL-1β, IL-6, and TNF-α caused by azithromycin raised again, meanwhile, the up-regulation of CD206, Arg-1, Fizz-1, and IL-10 due to azithromycin was abolished. Additionally, insulin-like growth factor 1 (IGF-1), the specific agonist of Akt, played a similar role to azithromycin in imitated SLE macrophages. Taken together, our data indicated a novel role of azithromycin in alleviating SLE by promoting alternatively activated macrophage phenotype, and the PI3K/Akt signaling pathway was involved. Our findings provide a rationale for further investigation of novel therapeutic strategy for SLE patients.

Chronic Azithromycin Use in Cystic Fibrosis and Risk of Treatment-Emergent Respiratory Pathogens

RATIONALE

Azithromycin has been shown to improve lung function and reduce the number of pulmonary exacerbations in patients with cystic fibrosis. Concerns remain, however, regarding the potential emergence of treatment-related respiratory pathogens.

OBJECTIVES

To determine whether chronic azithromycin use (defined as three-times weekly administration) is associated with increased rates of detection of eight specific respiratory pathogens.

METHODS

We performed a new-user, propensity score-matched retrospective cohort study utilizing data from the Cystic Fibrosis Foundation Patient Registry. Incident azithromycin users were propensity score matched 1:1 with contemporaneous nonusers. Kaplan-Meier curves and Cox proportional hazards regression were used to evaluate the association between chronic azithromycin use and incident respiratory pathogen detection. Analyses were performed separately for each pathogen, limited to patients among whom that pathogen had not been isolated in the 2 years before cohort entry.

RESULTS

After propensity score matching, the mean age of the cohorts was approximately 12 years. Chronic azithromycin users had a significantly lower risk of detection of new methicillin-resistant Staphylococcus aureus, nontuberculous mycobacteria, and Burkholderia cepacia complex compared with nonusers. The risk of acquiring the remaining five pathogens was not significantly different between users and nonusers.

CONCLUSIONS

Using an innovative new-user, propensity score-matched study design to minimize indication and selection biases, we found in a predominantly pediatric cohort that chronic azithromycin users had a lower risk of acquiring several cystic fibrosis-related respiratory pathogens. These results may ease concerns that chronic azithromycin exposure increases the risk of acquiring new respiratory pathogens among pediatric patients with cystic fibrosis.

The treatment of the pulmonary and extrapulmonary manifestations of cystic fibrosis

Cystic fibrosis (CF) is a complex multisystem disease with considerable between patient variability in its manifestations and severity. In the past several decades, the range of treatments and the evidence to support their use for the pulmonary and extrapulmonary manifestations of CF have increased dramatically, contributing to the improved median survival of patients. As therapy for CF has evolved, new challenges including treatment adherence, medication intolerance and allergy, medical complications and coping with the burden of disease in the context of having a family and managing employment have arisen. While the majority of current therapy focuses primarily on improving symptoms, new therapies (CFTR modulators) target the underlying genetic defect.

Bronchiectasis in Children: Current Concepts in Immunology and Microbiology

Bronchiectasis is a complex chronic respiratory condition traditionally characterized by chronic infection, airway inflammation, and progressive decline in lung function. Early diagnosis and intensive treatment protocols can stabilize or even improve the clinical prognosis of children with bronchiectasis. However, understanding the host immunologic mechanisms that contribute to recurrent infection and prolonged inflammation has been identified as an important area of research that would contribute substantially to effective prevention strategies for children at risk of bronchiectasis. This review will focus on the current understanding of the role of the host immune response and important pathogens in the pathogenesis of bronchiectasis (not associated with cystic fibrosis) in children.

A Retrospective Longitudinal Within-Subject Risk Interval Analysis of Immunoglobulin Treatment for Recurrent Acute Exacerbation of Chronic Obstructive Pulmonary Disease

BACKGROUND

Recurrent acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are common, debilitating, costly and often difficult to prevent.

METHODS

We reviewed records of patients who had COPD and immunoglobulin (Ig) treatment as adjunctive preventative treatment for AECOPD, and documented all AECOPD episodes for one year before and after initiation of Ig treatment. We graded AECOPD episodes as moderate for prescription of antibiotics and/or corticosteroids or for visit to the Emergency Department, and as severe for hospital admission. We conducted a retrospective within-subject self-controlled risk interval analysis to compare the outcome of annual AECOPD rate before and after treatment.

RESULTS

We identified 22 cases of certain COPD, of which three had early discontinuation of Ig treatment due to rash and local swelling to subcutaneous Ig, and five had incomplete records leaving 14 cases for analyses. The median baseline IgG level was 5.9 g/L (interquartile range 4.1-7.4). Eight had CT radiographic bronchiectasis. Overall, the incidence of AECOPD was consistently and significantly reduced in frequency from mean 4.7 (± 3.1) per patient-year before, to 0.6 (± 1.0) after the Ig treatment (p = 0.0001). There were twelve episodes of severe AECOPD (in seven cases) in the year prior, and one in the year after Ig treatment initiation (p = 0.016).

CONCLUSIONS

Ig treatment appears to decrease the frequency of moderate and severe recurrent AECOPD. A prospective, controlled evaluation of adjunctive Ig treatment to standard therapy of recurrent AECOPD is warranted.

The road for survival improvement of cystic fibrosis patients in Arab countries

Cystic fibrosis (CF) is a lethal, monogenic disorder that affects multiple organ systems of the body. The incidence has been described before in the Middle East to be 1 in 2000 to 1 in 5800 live births, and the median survival was estimated to be from 10 to 20 years of age. The present article attempts to revisit various facets of this disease and specifically highlights the most important lacunae that exist in treating CF. In addition, it also tries to emphasize the steps in improving the median survival of patients with CF, in these countries.

Single center experience of five diffuse panbronchiolitis patients clinically presenting as severe asthma

Diffuse panbronchiolitis (DPB) is a bronchiolitis affecting the whole lung fields which can be treated by macrolide. Especially East Asian patients are more susceptible to diffuse panbronchiolitis. As asthma and DPB both can cause airway obstruction, differential diagnosis is important for the 2 diseases. Here we report 5 patients with DPB clinically presenting as severe asthma in Korea, who were well treated by macrolide. Among the 5 patients, 2 could stop their asthma inhalers and the other 3 could reduce asthma medications after diagnosis and treatment of DPB. In conclusion, considering DPB as differential diagnosis for asthmatics in Asian ethnic groups is important.

The design of novel classes of macrolides for neutrophil-dominated inflammatory diseases

Neutrophil-dominated inflammatory diseases, like chronic obstructive pulmonary disease, cystic fibrosis, bronchiectasis, bronchiolitis obliteras syndrome and non-eosinophilic asthma, present a significant medical problem lacking adequate therapy. Macrolide antibiotics have been reported to be effective in the treatment of the aforementioned diseases, for reasons unrelated to their antibacterial action. This has resulted in research activities aimed at gaining a better understanding of the immunomodulatory actions of macrolides and the synthesis of various novel anti-inflammatory macrolides without antimicrobial activity. Despite the difficult chemistry and lack of an extensive knowledge for their mechanism of action, several interesting molecules from this class, including potential clinical candidates, are on the horizon.

Azithromycin analogue CSY0073 attenuates lung inflammation induced by LPS challenge

BACKGROUND AND PURPOSE

Azithromycin is a macrolide antibiotic with anti-inflammatory and immunomodulating effects. Long-term azithromycin therapy in patients with chronic lung diseases such as cystic fibrosis has been associated with increased antimicrobial resistance, emergence of hypermutable strains, ototoxicity and cardiac toxicity. The aim of this study was to assess the anti-inflammatory effects of the non-antibiotic azithromycin derivative CSY0073.

EXPERIMENTAL APPROACH

We compared the effects of CSY0073 with those of azithromycin in experiments on bacterial cultures, Pseudomonas aeruginosa biofilm, lung cells and mice challenged intranasally with P. aeruginosa LPS.

KEY RESULTS

In contrast to azithromycin, CSY0073 did not inhibit the growth of P. aeruginosa, Staphylococcus aureus or Haemophilus influenzae and had no effect on an established P. aeruginosa biofilm. Bronchoalveolar lavage (BAL) fluids and lung homogenates collected after the LPS challenge in mice showed that CSY0073 and azithromycin (200 mg·kg(-1), i.p.) decreased neutrophil counts at 24 h and TNF-α, CXCL1 and CXCL2 levels in the BAL fluid after 3 h and IL-6, CXCL2 and IL-1β levels in the lung after 3 h compared with the vehicle. However, only azithromycin reduced IL-1β levels in the lung 24 h post LPS challenge. CSY0073 and azithromycin similarly diminished the production of pro-inflammatory cytokines by macrophages, but not lung epithelial cells, exposed to P. aeruginosa LPS.

CONCLUSIONS AND IMPLICATIONS

Unlike azithromycin, CSY0073 had no antibacterial effects but it did have a similar anti-inflammatory profile to that of azithromycin. Hence, CSY0073 may have potential as a long-term treatment for patients with chronic lung diseases.

Pharmacokinetics and pharmacodynamics of aerosolized antibacterial agents in chronically infected cystic fibrosis patients

Bacteria adapt to growth in lungs of patients with cystic fibrosis (CF) by selection of heterogeneously resistant variants that are not detected by conventional susceptibility testing but are selected for rapidly during antibacterial treatment. Therefore, total bacterial counts and antibiotic susceptibilities are misleading indicators of infection and are not helpful as guides for therapy decisions or efficacy endpoints. High drug concentrations delivered by aerosol may maximize efficacy, as decreased drug susceptibilities of the pathogens are compensated for by high target site concentrations. However, reductions of the bacterial load in sputum and improvements in lung function were within the same ranges following aerosolized and conventional therapies. Furthermore, the use of conventional pharmacokinetic/pharmacodynamic (PK/PD) surrogates correlating pharmacokinetics in serum with clinical cure and presumed or proven eradication of the pathogen as a basis for PK/PD investigations in CF patients is irrelevant, as minimization of systemic exposure is one of the main objectives of aerosolized therapy; in addition, bacterial pathogens cannot be eradicated, and chronic infection cannot be cured. Consequently, conventional PK/PD surrogates are not applicable to CF patients. It is nonetheless obvious that systemic exposure of patients, with all its sequelae, is minimized and that the burden of oral treatment for CF patients suffering from chronic infections is reduced.

Antimicrobial resistance in the respiratory microbiota of people with cystic fibrosis

Cystic fibrosis is characterised by chronic polymicrobial infection and inflammation in the airways of patients. Antibiotic treatment regimens, targeting recognised pathogens, have substantially contributed to increased life expectancy of patients with this disease. Although the emergence of antimicrobial resistance and selection of highly antibiotic-resistant bacterial strains is of major concern, the clinical relevance in cystic fibrosis is yet to be defined. Resistance has been identified in recognised cystic fibrosis pathogens and in other bacteria (eg, Prevotella and Streptococcus spp) detected in the airway microbiota, but their role in the pathophysiology of infection and inflammation in chronic lung disease is unclear. Increased antibiotic resistance in cystic fibrosis might be attributed to a range of complex factors including horizontal gene transfer, hypoxia, and biofilm formation. Strategies to manage antimicrobial resistance consist of new antibiotics or localised delivery of antimicrobial agents, iron sequestration, inhibition of quorum-sensing, and resistome analysis. Determination of the contributions of every bacterial species to lung health or disease in cystic fibrosis might also have an important role in the management of antibiotic resistance.

Anti-inflammatory effects of macrolides in childhood lung diseases

Macrolides are drugs that have antimicrobial effects, especially against intracellular pathogens. Various studies have shown that macrolides might also have anti-inflammatory effects. Macrolides inhibit the production of interleukins and can reduce pulmonary neutrophilic inflammation. Clinical trials have demonstrated beneficial effects of macrolides in various chronic lung diseases. The objective of this study was to review recent data in the medical literature on the anti-inflammatory effects of macrolides in childhood lung diseases by searching the Medline (PubMed) database. We used the following search terms: "macrolide and cystic fibrosis"; "macrolide and asthma"; "macrolide and bronchiolitis obliterans"; and "macrolide and acute bronchiolitis". We selected articles published in international scientific journals between 2001 and 2012. Clinical studies and in vitro evidence have confirmed the anti-inflammatory effect of macrolides in respiratory diseases. Some clinical trials have shown the benefits of the administration of macrolides in patients with cystic fibrosis, although the risk of bacterial resistance should be considered in the analysis of those benefits. Such benefits are controversial in other respiratory diseases, and the routine use of macrolides is not recommended. Further controlled clinical trials are required in order to assess the efficacy of macrolides as anti-inflammatory drugs, so that the benefits in the treatment of each specific clinical condition can be better established.

Longitudinal nasopharyngeal carriage and antibiotic resistance of respiratory bacteria in indigenous Australian and Alaska native children with bronchiectasis

Background

Indigenous children in Australia and Alaska have very high rates of chronic suppurative lung disease (CSLD)/bronchiectasis. Antibiotics, including frequent or long-term azithromycin in Australia and short-term beta-lactam therapy in both countries, are often prescribed to treat these patients. In the Bronchiectasis Observational Study we examined over several years the nasopharyngeal carriage and antibiotic resistance of respiratory bacteria in these two PCV7-vaccinated populations.

Methods

Indigenous children aged 0.5–8.9 years with CSLD/bronchiectasis from remote Australia (n = 79) and Alaska (n = 41) were enrolled in a prospective cohort study during 2004–8. At scheduled study visits until 2010 antibiotic use in the preceding 2-weeks was recorded and nasopharyngeal swabs collected for culture and antimicrobial susceptibility testing. Analysis of respiratory bacterial carriage and antibiotic resistance was by baseline and final swabs, and total swabs by year.

Results

Streptococcus pneumoniae carriage changed little over time. In contrast, carriage of Haemophilus influenzae declined and Staphylococcus aureus increased (from 0% in 2005–6 to 23% in 2010 in Alaskan children); these changes were associated with increasing age. Moraxella catarrhalis carriage declined significantly in Australian, but not Alaskan, children (from 64% in 2004–6 to 11% in 2010). While beta-lactam antibiotic use was similar in the two cohorts, Australian children received more azithromycin. Macrolide resistance was significantly higher in Australian compared to Alaskan children, while H. influenzae beta-lactam resistance was higher in Alaskan children. Azithromycin use coincided significantly with reduced carriage of S. pneumoniae, H. influenzae and M. catarrhalis, but increased carriage of S. aureus and macrolide-resistant strains of S. pneumoniae and S. aureus (proportion of carriers and all swabs), in a ‘cumulative dose-response’ relationship.

Conclusions

Over time, similar (possibly age-related) changes in nasopharyngeal bacterial carriage were observed in Australian and Alaskan children with CSLD/bronchiectasis. However, there were also significant frequency-dependent differences in carriage and antibiotic resistance that coincided with azithromycin use.

Long-term macrolide treatment of chronic inflammatory airway diseases: risks, benefits and future developments

Macrolide antibiotics were discovered over 50 years ago and following their use as antimicrobials it became apparent that this group of antibiotics also possessed anti-inflammatory properties. Subsequent clinical trials showed benefits of macrolides as long-term adjuncts in the treatment of a spectrum of chronic inflammatory respiratory diseases, particularly diffuse panbronchiolitis, cystic fibrosis, post-transplant bronchiolitis obliterans and more recently chronic obstructive pulmonary disease (COPD). The evidence for efficacy of macrolides in the long-term treatment of chronic asthma and bronchiectasis is less well established. The mechanism(s) of action of macrolides in the treatment of these diseases remains unexplained, but may be due to their antibacterial and/or anti-inflammatory actions, which include reductions in interleukin-8 production, neutrophil migration and/or function. Macrolides have additional potentially beneficial properties including anti-viral actions and an ability to restore corticosteroid sensitivity. The increased prescribing of macrolides for long-term treatment could result in the development of microbial resistance and adverse drug effects. New macrolides have been developed which do not possess any antimicrobial activity and hence lack the ability to produce microbial resistance, but which still retain immunomodulatory effects. Potentially novel macrolides may overcome a significant barrier to the use of this type of drug for the long-term treatment of chronic inflammatory airway diseases.

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.

Anti-inflammatory and immunomodulatory properties of azithromycin involved in treatment and prevention of chronic lung allograft rejection

Chronic lung allograft rejection is the single most important cause of death in lung transplant recipients after the first postoperative year, resulting in a 5-year survival rate of approximately 50%, which is far behind that of other solid organ transplantations. Spirometry is routinely used as a clinical marker for assessing pulmonary allograft function and diagnosing chronic lung allograft rejection after lung transplantation (LTx). As such, a progressive obstructive decline in pulmonary allograft function (forced expiratory volume in 1 sec [FEV1]) in absence of all other causes (currently defined as bronchiolitis obliterans syndrome [BOS]) is considered to reflect the evolution of chronic lung allograft rejection. BOS has a 5-year prevalence of approximately 45% and is thought to be the final common endpoint of various alloimmunologic and nonalloimmunologic injuries to the pulmonary allograft, triggering different innate and adaptive immune responses. Most preventive and therapeutic strategies for this complex process have thus far been largely unsuccessful. However, the introduction of the neomacrolide antibiotic azithromycin (AZI) in the field of LTx as of 2003 made it clear that some patients with established BOS might in fact benefit from such therapy due to its various antiinflammatory and immunomodulatory properties, as summarized in this review. Particularly in patients with an increased bronchoalveolar lavage neutrophilia (i.e., 15%-20% or more), AZI treatment could result in an increase in FEV1 of at least 10%. More recently, it has become clear that prophylactic therapy with AZI actually may prevent BOS and improve FEV1 after LTx, most likely through its interactions with the innate immune system. However, one should always be aware of possible adverse effects related to AZI when implementing this drug as prophylactic or long-term treatment. Even so, AZI therapy after LTx can generally be considered as safe.

State of progress in treating cystic fibrosis respiratory disease

Since the discovery of the gene associated with cystic fibrosis (CF), there has been tremendous progress in the care of patients with this disease. New therapies have entered the market and are part of the standard treatment of patients with CF, and have been associated with marked improvement in survival. Now there are even more promising therapies directed at different components of the pathophysiology of this disease. In this review, our current knowledge of the pathophysiology of lung disease in patients with CF is described, along with the current treatment of CF lung disease, and the therapies in development that offer great promise to our patients.

Azithromycin maintenance therapy in patients with cystic fibrosis: a dose advice based on a review of pharmacokinetics, efficacy, and side effects

Azithromycin maintenance therapy results in improvement of respiratory function in patients with cystic fibrosis (CF). In azithromycin maintenance therapy, several dosing schemes are applied. In this review, we combine current knowledge about azithromycin pharmacokinetics with the dosing schedules used in clinical trials in order to come to a dosing advise which could be generally applicable. We used data from a recently updated Cochrane meta analysis (2011), the reports of clinical trials and pharmacokinetic studies. Based on these data, it was concluded that a dose level of 22-30 mg/kg/week is the lowest dose level with proven efficacy. Due to the extended half-life in patients with CF, the weekly dose of azithromycin can be divided in one to seven dosing moments, depending on patient preference and gastro-intestinal tolerance. No important side effects or interactions with other CF-related drugs have been documented so far.

The role of macrolides in childhood non-cystic fibrosis-related bronchiectasis

Non-cystic fibrosis-related bronchiectasis is a chronic inflammatory lung disease, which is regarded as an “orphan” lung disease, with little research devoted to the study of this condition. Bronchiectasis results in impaired quality of life and mortality if left untreated. The tools available in the armamentarium for the management of bronchiectasis entail antibiotic therapy traditionally used to treat exacerbations, stratagems to improve mucociliary clearance, and avoidance of toxins. Macrolides have been known for the last two decades to have not only anti-bacterial effects but immunomodulatory properties as well. In cystic fibrosis, the use of macrolides is well documented in subjects colonized with Pseudomonas aeruginosa, to improve quality of life and lung function. There is currently emerging evidence to suggest the benefit of macrolides in subjects not colonized with Pseudomonas aeruginosa. This beneficial effect has been less explored in the context of bronchiectasis from other causes. The purpose of this paper is to review the current literature on the use of macrolides in non-cystic fibrosis related bronchiectasis in paediatrics.

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.

Macrolides: from in vitro anti-inflammatory and immunomodulatory properties to clinical practice in respiratory diseases

BACKGROUND

Macrolides have long been recognised to exert immunomodulary and anti-inflammatory actions. They are able to suppress the "cytokine storm" of inflammation and to confer an additional clinical benefit through their immunomodulatory properties.

METHODS

A search of electronic journal articles was performed using combinations of the following keywords: macrolides, COPD, asthma, bronchitis, bronchiolitis obliterans, cystic fibrosis, immunomodulation, anti-inflammatory effect, diabetes, side effects and systemic diseases.

RESULTS

Macrolide effects are time- and dose-dependent, and the mechanisms underlying these effects remain incompletely understood. Both in vitro and in vivo studies have provided ample evidence of their immunomodulary and anti-inflammatory actions. Importantly, this class of antibiotics is efficacious with respect to controlling exacerbations of underlying respiratory problems, such as cystic fibrosis, asthma, bronchiectasis, panbrochiolitis and cryptogenic organising pneumonia. Macrolides have also been reported to reduce airway hyper-responsiveness and improve pulmonary function.

CONCLUSION

This review provides an overview on the properties of macrolides (erythromycin, clarithromycin, roxithromycin, azithromycin), their efficacy in various respiratory diseases and their adverse effects.

Azithromycin for prevention of exacerbations of COPD

BACKGROUND

Acute exacerbations adversely affect patients with chronic obstructive pulmonary disease (COPD). Macrolide antibiotics benefit patients with a variety of inflammatory airway diseases.

METHODS

We performed a randomized trial to determine whether azithromycin decreased the frequency of exacerbations in participants with COPD who had an increased risk of exacerbations but no hearing impairment, resting tachycardia, or apparent risk of prolongation of the corrected QT interval.

RESULTS

A total of 1577 subjects were screened; 1142 (72%) were randomly assigned to receive azithromycin, at a dose of 250 mg daily (570 participants), or placebo (572 participants) for 1 year in addition to their usual care. The rate of 1-year follow-up was 89% in the azithromycin group and 90% in the placebo group. The median time to the first exacerbation was 266 days (95% confidence interval [CI], 227 to 313) among participants receiving azithromycin, as compared with 174 days (95% CI, 143 to 215) among participants receiving placebo (P<0.001). The frequency of exacerbations was 1.48 exacerbations per patient-year in the azithromycin group, as compared with 1.83 per patient-year in the placebo group (P=0.01), and the hazard ratio for having an acute exacerbation of COPD per patient-year in the azithromycin group was 0.73 (95% CI, 0.63 to 0.84; P<0.001). The scores on the St. George's Respiratory Questionnaire (on a scale of 0 to 100, with lower scores indicating better functioning) improved more in the azithromycin group than in the placebo group (a mean [±SD] decrease of 2.8±12.8 vs. 0.6±11.4, P=0.004); the percentage of participants with more than the minimal clinically important difference of -4 units was 43% in the azithromycin group, as compared with 36% in the placebo group (P=0.03). Hearing decrements were more common in the azithromycin group than in the placebo group (25% vs. 20%, P=0.04).

CONCLUSIONS

Among selected subjects with COPD, azithromycin taken daily for 1 year, when added to usual treatment, decreased the frequency of exacerbations and improved quality of life but caused hearing decrements in a small percentage of subjects. Although this intervention could change microbial resistance patterns, the effect of this change is not known. (Funded by the National Institutes of Health; ClinicalTrials.gov number, NCT00325897.).

The benefits of long-term systemic antimicrobial therapy in chronic obstructive pulmonary disease

Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are major contributors to the morbidity and mortality associated with this disease. Current approaches that likely reduce chronic obstructive pulmonary disease (COPD) exacerbations include smoking cessation, influenza and pneumococcal vaccinations, long-acting bronchodilator and inhaled corticosteroid therapy, pulmonary rehabilitation, and mucolytic drugs. However, with optimal treatment using all of these modalities, we are only able to reduce exacerbations by about 40%. A significant proportion of COPD exacerbations are bacterial, therefore long-term antimicrobial therapy could have a role in preventing exacerbations. Long-term antibiotic treatment in COPD regimens that are being evaluated include low-dose macrolide therapy, pulsed fluoroquinolone administration and the use of inhaled antibiotics. Although initial results have been promising with significant reductions in exacerbations with these regimens, additional studies are required to identify the appropriate patient and regimen and elucidate the risk-benefit as well as cost effectiveness of long-term antibiotics in COPD.

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.

Macrolide and clindamycin resistance in Streptococcus milleri group isolates from the airways of cystic fibrosis patients

Organisms belonging to the Streptococcus milleri group (SMG) are known for their role in pyogenic infections but have recently been implicated as etiological agents of pulmonary exacerbation in adult patients with cystic fibrosis (CF). The prolonged exposure of CF patients to antibiotics prompted us to investigate the susceptibility profiles of 118 SMG isolates from the airways of CF patients to 12 antibiotics compared to 43 SMG isolates from patients with invasive infections. We found that approximately 60% of all isolates failed to grow using the standard medium for disc diffusion, Mueller-Hinton blood agar (MHBA), so we explored the usefulness of brain heart infusion (BHI) agar for susceptibility testing. Zone-of-inhibition comparisons between BHI and MHBA showed strong correlations for six antibiotics, and interpretations were similar for both medium types. For ceftriaxone and cefepime, both groups of isolates were highly susceptible. Tetracycline resistance levels were comparable between the two groups (22% in CF isolates and 17.4% in invasive isolates). However, more than half of the CF isolates were not susceptible to azithromycin, erythromycin, and clindamycin, compared to 11%, 13%, and 6.5% of invasive isolates, respectively. There were 5-fold and 8-fold increased risks of azithromycin and clindamycin resistance, respectively, for the isolates from the airways of CF patients relative to the invasive isolates. Macrolide resistance was strongly linked to chronic azithromycin therapy in CF patients. This study shows that BHI agar is a suitable alternative for antimicrobial susceptibility testing for the SMG and that SMG isolates from the airways of CF patients are more resistant to macrolides and clindamycin than strains isolated from patients with invasive infections.

[Usefulness of macrolides as anti-inflammatories in respiratory diseases]

The macrolides are antibiotics that, besides their anti-bacterial action, have an anti-inflammatory effect, by decreasing the activity of the immune cells and bacteria cell changes. An increase the survival of patients suffering from diffuse panbronchiolitis was already seen in the 1980s, after being treated with erythromycin. Currently, the use of macrolides in various chronic inflammatory diseases has increased significantly. Clinical improvements associated to the administration of macrolides have been observed in diseases such as, cystic fibrosis, asthma, and bronchiectasis. However, despite the apparent clinical benefit they seem to provide, the published results up until now are controversial and conclusive results are unable to be obtained. This means that further clinical trials are necessary to confirm or refute the long-term use of these drugs, which are not free of adverse effects, mainly the appearance of resistant bacteria.

Molecular characterization of macrolide resistance determinants [erm(B) and mef(A)] in Streptococcus pneumoniae and viridans group streptococci (VGS) isolated from adult patients with cystic fibrosis (CF)

OBJECTIVES

Although long-term use of azithromycin has shown a significant clinical improvement for patients with cystic fibrosis (CF), its long-term effect on the susceptibility of commensal flora within CF airways has not yet been examined. We therefore suggest that long-term use of azithromycin increases macrolide resistance in commensal streptococci.

METHODS

Erythromycin susceptibility in naturally colonizing viridans group streptococci (VGS) was characterized, as well as macrolide resistance gene determinants through sequence analysis, in pneumococci (n = 15) and VGS [n = 84; i.e. Streptococcus salivarius (n = 30), Streptococcus mitis (n = 17), Streptococcus sanguinis (n = 11), Streptococcus oralis (n = 10), Streptococcus parasanguinis (n = 6), Streptococcus gordonii (n = 3), Streptococcus infantis (n = 3), Streptococcus cristatus (n = 2), Streptococcus anginosus (n = 1) and Streptococcus australis (n = 1)] isolated from sputum from 24 adult CF patients, who were on oral azithromycin therapy for at least the previous 7 months.

RESULTS

Almost three-quarters of isolates (74; 74.7%) were resistant to erythromycin, whilst a further 15 (15.2%) had reduced susceptibility, leaving only 10 (10.1%) isolates susceptible to erythromycin. The majority (89.8%) were not susceptible to erythromycin, as demonstrated by possession of the erm(B) gene in 25/99 (25.3%), the mef(A) gene in 1/99 (1.0%), the mef(E) gene in 75/99 (75.8%) and both erm(B) and mef(E) genes simultaneously in 11/99 (11.1%). These results indicate that genotypic resistance for macrolides is common in VGS in adult CF patients, with efflux being over three times more frequent.

CONCLUSIONS

Long-term treatment with azithromycin in CF patients may reduce antibiotic susceptibility in commensal VGS, where these organisms may potentially act as a reservoir of macrolide resistance determinants for newly acquired and antibiotic-susceptible pathogens.

Long-term, low-dose azithromycin treatment reduces the incidence but increases macrolide resistance in Staphylococcus aureus in Danish CF patients

BACKGROUND

Since 2001, long-term, low-dose azithromycin treatment has been used for CF patients chronically infected with Pseudomonas aeruginosa in the Copenhagen CF centre. Our study investigates changes in incidence of colonization with Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis and changes in macrolide sensitivity in these microorganisms during azithromycin treatment.

METHODS

CF patients treated continuously with azithromycin for at least 3 months were included. Results of microbiological examination, including phage typing results of S. aureus, obtained during treatment were compared to results obtained 2 years before treatment.

RESULTS

70 patients (median age 29.1 years) treated for a median of 4 years (range 0.7-5.1) were included. Before treatment, 44 patients had at least one culture positive for S. aureus compared to 25 patients during treatment (p<0.01). Mean percentage of sputum samples with growth of S. aureus decreased from 12.1% (range 0-82.6%) before treatment to 6.1% (range 0-93.2) during treatment (p<0.0006). Prevalence's of H. influenzae and S. pneumoniae also decreased significantly. Fifteen of 214 isolates (7%) of S. aureus were macrolide resistant before treatment, increasing to 95 of 181 isolates (52.5%) during treatment (p<0.001). Macrolide resistant strains were found in 3 of 44 S. aureus colonized patients before treatment and in 11 of 25 patients at some time during treatment (p<0.03), all belonging to different phage types. First resistant S. aureus isolate was isolated after a median treatment duration of 1.5 years (range 0.3-2.9). No MRSA were isolated. Only 1 macrolide resistant isolate of M. catarrhalis was found during treatment. No macrolide resistance was found in H. influenzae or S. pneumoniae.

CONCLUSION

Long-term, low-dose treatment with azithromycin in CF patients leads to reduced prevalence of S. aureus, S. pneumoniae, and H. influenzae, but increased macrolide resistance in S. aureus. Reduction in the prevalence of S. aureus will make increasing macrolide resistance clinically insignificant in these patients.

Once-weekly azithromycin in cystic fibrosis with chronic Pseudomonas aeruginosa infection

BACKGROUND

Data on the effects of long-term treatment with azithromycin (AZM) on inflammatory markers in cystic fibrosis patients chronically infected with Pseudomonas aeruginosa are scarce. So far there is no pharmacokinetic and clinical data on once-weekly dosage of AZM in CF patients.

METHODS

In a randomised double-blind, placebo-controlled trial, patients received AZM or placebo 1 per week for 8 weeks (AZM dosage--20-29 kg: 500 mg, 30-39 kg: 750 mg, 40-49 kg: 1000 mg and > or = 50 kg: 1250 mg) after a course of intravenous antipseudomonal antibiotics. Pulmonary function tests, the serum markers LPS-binding protein (LBP), interleukin-8 (IL-8), CRP, P. aeruginosa alginate in sputum samples and quality of life scores were evaluated.

RESULTS

Thirty-eight patients (21 AZM/17 placebo) (mean age: 23.7 years; mean FEV(1): 62% of predicted) were recruited. After treatment (mean dose of 21.2 mg/kg body weight once a week) pulmonary function declined in both groups compared to baseline (i.e. after cessation of i.v. antibiotics). The AZM group was significantly better for mean changes in serum CRP (AZM: +0.9 mg/l, placebo: +21.6 mg/l, p=0.019), lipopolysaccharide binding protein in serum, LBP (AZM: +0.9 microg/ml, placebo: +7.0 microg/ml, p=0.015), serum interleukin-8 (AZM: -3.1 pg/ml, placebo: +2.9 pg/ml, p=0.001) and alginate in sputum (AZM: +85 microg/ml, placebo: +353 microg/ml, p=0.048). Quality of life was significantly better after AZM and there was no increase in treatment-related adverse events.

CONCLUSION

Once-weekly azithromycin ameliorated inflammatory reactions and improved quality of life. A decline of pulmonary function after cessation of i.v. antibiotics could not be prevented.