Antibiotics in asthma

Antimicrobial Prescription Behavior in Equine Asthma Cases: An International Survey

Equine asthma is considered a non-infectious respiratory disease characterized by inflammation and hypersensitivity. Given the importance of antimicrobial stewardship, an international survey was designed to investigate the use of antimicrobials in asthmatic horses and the factors influencing prescription behavior. An online survey was distributed in six languages by international mailing lists and social media from December 2020 to January 2022. Of the 434 responses recorded, 249 veterinarians working in 25 countries finished the survey. These included 79 ECEIM/ACVIM diplomats. A total of 204 respondents confirmed national regulations concerning antimicrobial use in their country. Knowledge of the asthma definitions as presented in the revised ACVIM consensus statement was greater in veterinarians treating over 95% of equine patients compared to veterinarians treating more species, based on 10 questions (answers consistent with the consensus statement in 7 (IQR 5-9) and 4 (IQR 3-6) questions, respectively, (p < 0.001)). A total of 131 respondents stated to use antimicrobials (at least 'sometimes') in at least one of the three presented cases consistent with equine asthma. Trimethoprim-Sulfa combinations, penicillin(s), and tetracyclines were prescribed most (by 105, 53 and 38 veterinarians, respectively). Aminoglycosides, cephalosporins and fluoroquinolones were also selected (22, 15, 9 veterinarians respectively). Tetracyclines and cephalosporins are prescribed more often by veterinarians working without national regulations (p 0.019 and p 0.035, respectively). The most selected factors influencing prescription behavior were: 'tracheal wash culture' (62% of 131 veterinarians using antimicrobials in these cases), 'whether other horses in the barn have similar complaints' (60%), and 'response to other forms of therapy' (53%). In conclusion, insight into prescription behavior is the first step towards minimizing and optimizing antimicrobial use.

Effects of low-dose clarithromycin added to fluticasone on inflammatory markers and pulmonary function among children with asthma: A randomized clinical trial

BACKGROUND

Macrolides exert anti-inflammatory and immunomodulatory effects beyond their purely antibacterial action, as demonstrated by several bronchial inflammatory disorders, including asthma.

METHODS

Fifty-eight children with newly diagnosed mild persistent asthma were selected by using the Global Initiative for Asthma guidelines and were randomly divided into the study (group I) (n = 36) and control (group II) (n = 22) groups. Mycoplasma pneumonia-specific immunoglobulin G and -specific immunoglobulin M antibody levels of each participant were measured by enzyme-linked immunosorbent assay. Clarithromycin 5 mg/kg daily and placebo were given to groups I and II, respectively, for 4 weeks. All of the children had maintenance inhaled corticosteroid (fluticasone propionate, one puff twice [50 μg/puff] daily). Forced expiratory volume in 1 second, forced expiratory flow at 25-75% of the pulmonary volume, exhaled nitric oxide value, total IgE level, absolute eosinophil count, and eosinophilic cation protein value were measured at baseline and at the end of the treatment.

RESULTS

There are significantly increased forced expiratory volume in 1 second and forced expiratory flow at 25-75% of the pulmonary volume levels and decreased exhaled nitric oxide values after the 4-week clarithromycin treatment. The study group also had a decreased peripheral blood absolute eosinophil count and eosinophilic cation protein level, but not for the total IgE level, after the treatment.

CONCLUSION

Four weeks of sub-antimicrobial doses of clarithromycin may improve pulmonary function and decrease eosinophilic inflammation in children with asthma.

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.

Macrolide therapy and outcomes in a multicenter cohort of children hospitalized with Mycoplasma pneumoniae pneumonia

BACKGROUND

Mycoplasma pneumoniae is a common cause of community-acquired pneumonia in childhood. Few studies have addressed the association of antimicrobial treatment and outcomes.

OBJECTIVE

To determine whether macrolide therapy is associated with improved outcomes among children hospitalized with M. pneumoniae pneumonia.

DESIGN

Multicenter retrospective cohort study.

SETTING

Thirty-six children's hospitals which contribute data to the Pediatric Health Information System.

PATIENTS

Children 6-18 years of age discharged with a diagnosis of M. pneumoniae pneumonia.

MAIN EXPOSURE

Initial macrolide therapy.

MAIN OUTCOME MEASURES

Length of stay (LOS), all-cause readmissions, and asthma-related hospitalizations.

RESULTS

Empiric macrolide therapy was administered to 405 (58.7%) of 690 patients. The median LOS was 3 days (interquartile range, 2-6 days). Eight (1.2 %) patients were readmitted within 28 days, and 160 (23.2%) were readmitted within 15 months of index discharge. Ninety-five (13.7%) patients were hospitalized for asthma within 15 months of index discharge. Empiric macrolide therapy was associated with a 32% shorter overall LOS (adjusted beta-coefficient, -0.38; 95% confidence interval [CI]: -0.59 to -0.17). Macrolide therapy was not associated with all-cause readmission at 28 days (adjusted odds ratio, 1.12; 95% CI: 0.22-5.78) or 15 months (adjusted odds ratio, 1.00; 95% CI: 0.59-1.70) or with asthma-related hospitalizations at 15 months (adjusted odds ratio, 0.85; 95% CI: 0.36-1.97).

CONCLUSION

In this large multicenter study of children hospitalized with M. pneumoniae pneumonia, empiric macrolide therapy was associated with a shorter hospital LOS. Macrolide therapy was not associated with 28-day or 15-month hospital readmission.

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.

Macrolide immunomodulation of chronic respiratory diseases

Important immunomodulatory properties of 14- and 15-membered macrolides may benefit patients with respiratory diseases associated with chronic inflammation. These properties include decreased neutrophil chemotaxis and infiltration into the respiratory epithelium, inhibition of transcription factors leading to decreased proinflammatory cytokine production, downregulation of adhesion molecule expression, inhibition of microbial virulence factors including biofilm formation, reduced generation of oxygen-free radicals, enhanced neutrophil apoptosis, and decreased mucus hypersecretion with improved mucociliary clearance. Chronic, low-dose macrolides have dramatically improved survival in patients with diffuse panbronchiolitis (DPB). Given the overlap in pathogenesis between DPB and other chronic respiratory diseases, macrolides are being investigated for cystic fibrosis, asthma, chronic bronchitis, chronic sinusitis, and chronic obstructive pulmonary disease. Preliminary data (largely from open-label trials) are promising, but conclusive results are needed.

Induction of IL-8 by Mycoplasma pneumoniae membrane in BEAS-2B cells

Mycoplasma pneumoniae is an extracellular pathogen, residing on mucosal surfaces of the respiratory and genital tracts. The lack of cell walls in mycoplasmas facilitates the direct contact of the bacterial membrane with the host cell. The cell membrane of mycoplasma is the major inducer of the host pathogenic response. Airway diseases caused by M. pneumoniae include bronchiolitis, bronchitis, and rarely bronchiectasis. In such disorders, neutrophil infiltration of the airways predominates. More recently, M. pneumoniae has been implicated in the pathogenesis of asthma. Epithelial cells play an important role in recruiting inflammatory cells into the airways. Since M. pneumoniae infection of human epithelial cells induces expression of IL-8-a potent activator of neutrophils-we investigated the signaling and transcriptional mechanisms by which mycoplasma membrane induces expression of this chemokine. In BEAS-2B human bronchial epithelial cells, mycoplasma membrane fraction (MMF) increased IL-8 mRNA and protein production. Activation of the transcriptional elements activating protein-1, nuclear factor-interleukin-6, and particularly NF-kappaB are essential for optimal IL-8 production by MMF. The mitogen-activated protein kinases individually played a modest role in MMF-induced IL-8 production. Toll-like receptor-2 did not play a significant role in MMF-induction of IL-8. Antibiotics with microbicidal activity against M. pneumoniae are also known to have anti-inflammatory effects. Whereas clarithromycin, azithromycin, and moxifloxacin individually were able to inhibit TNF-alpha-induction of IL-8, each failed to inhibit MMF-induction of IL-8.

Macrolide antibiotics as immunomodulatory medications: proposed mechanisms of action

Macrolide antibiotics administered in sub-antimicrobial doses improve pulmonary function and decrease exacerbation frequency for persons with diffuse panbronchiolitis or cystic fibrosis. Data also suggest a beneficial effect of macrolide antibiotics in the treatment of steroid dependent asthma. Many potential immunomodulatory effects of macrolide antibiotics have been reported including the ability to down-regulate prolonged inflammation, decreasing airway mucus secretion, inhibiting bacterial biofilm, decreasing the production of reactive oxygen species, inhibiting neutrophil activation and mobilization, accelerating neutrophil apoptosis, and blocking the activation of nuclear transcription factors. Macrolides initially decrease, then increase, and have finally a sustained suppression of cytokine secretions from normal human bronchial epithelial cells through inhibition and activation of extracellular signal-regulated kinases (ERK) and then reversibly retard cell proliferation probably through ERK. Consistent with this, macrolide antibiotics possibly reduce mucin production as well as neutrophil migration by interfering with ERK signal transduction.

Chlamydophila pneumoniae and Mycoplasma pneumoniae: a role in asthma pathogenesis?

The potential role of atypical bacterial infection in the pathogenesis of asthma is a subject of continuing debate. There is an increasing body of literature concerning the association between the atypical bacteria Chlamydophila pneumoniae and Mycoplasma pneumoniae and asthma pathogenesis; however, many studies investigating such a link have been uncontrolled and have provided conflicting evidence, in part due to the difficulty in accurately diagnosing infection with these atypical pathogens. This article reviews the evidence for an association between atypical bacterial respiratory pathogens and the pathogenesis of asthma, and discusses the biological mechanisms that could account for such a link. The possible role of antibacterial therapy in the management of asthma and the need for well-designed studies to investigate this is also discussed.

Macrolides and airway inflammation in children

For more than 20 years macrolide antibiotics have been used to treat chronic inflammatory airway diseases based on their immunomodulatory activity. Macrolide antibiotics down-regulate damaging prolonged inflammation as well as increase mucus clearance, decrease bacterial virulence and prevent biofilm formation. Initially shown to decrease morbidity and mortality in diffuse panbronchiolitis and in steroid-dependent asthma, long-term macrolide therapy has now been shown to significantly reduce exacerbations and improve lung function and quality of life in children with cystic fibrosis. They have also proven beneficial in Japanese children and adults with chronic sinobronchitis especially when there is nasal polyposis. Long-term macrolides have also proven clinically beneficial in some patients with plastic bronchitis. Adverse reactions are few and generally self-limited when used at the recommended dosage for immunomodulation.

Modulation of neutrophil and inflammation markers in chronic obstructive pulmonary disease by short-term azithromycin treatment

The anti-inflammatory potential of azithromycin in chronic obstructive pulmonary disease (COPD) patients was explored following a standard oral dosing regimen. Patients with moderate and severe COPD were treated with azithromycin (500 mg, n=16) or placebo (n=8) once daily for 3 days in a randomized, double blind design, to compare effects on inflammation markers with those seen in a previous study in healthy volunteers. A battery of tests was made on serum, blood neutrophils and sputum on days 1 (baseline), 3, 4, 11, 18 and 32. In comparison to placebo, azithromycin resulted in an early transient increase in serum nitrites plus nitrates (day 3), associated with a tendency towards an increase in the blood neutrophil oxidative burst to phorbol myristic acetate. Subsequently, prolonged decreases in blood leukocyte and platelet counts, serum acute phase protein (including C reactive protein) and soluble E-selectin and blood neutrophil lactoferrin concentrations and a transient decrease in serum interleukin-8 were observed. Blood neutrophil glutathione peroxidase activity showed a prolonged increase after azithromycin treatment. The biphasic facilitatory-then-inhibitory response to azithromycin seen in healthy volunteers is not so clearly detectable in COPD patients, only potential anti-inflammatory effects. Treatment for longer periods may give therapeutic anti-inflammatory benefit in these patients.

Immunomodulatory effects of antimicrobials in the therapy of respiratory tract infections

PURPOSE OF REVIEW

Several classes of antibiotics, particularly macrolides and to some extent quinolones, exert modulatory effects on inflammatory cells. With a growing number of experimental and clinical studies being performed, the relevance of the immunomodulatory actions of antibiotics to the therapy of respiratory infections is discussed in the light of recent reports.

RECENT FINDINGS

Antibiotics, particularly macrolides, exert both stimulatory and inhibitory effects on leukocytes. These effects seem to be related to the activation state of the leukocytes, facilitating bacterial killing as well as the resolution of local inflammation. In community-acquired pneumonia, this may account for the therapeutic benefit of macrolides, even when bacterial eradication is not complete. A variety of effects of macrolides on Pseudomonas aeruginosa, including the inhibition of biofilm matrix, contribute with immunomodulation to the improvement of respiratory function seen with macrolides in cystic fibrosis.

SUMMARY

Macrolides can facilitate the killing of microorganisms in acute respiratory infections through the stimulation of neutrophil activation. On long-term administration, anti-inflammatory, T helper type 1 lymphocyte-enhancing and biofilm-thinning actions, among others, make macrolides valid therapeutic options in chronic infectious/inflammatory disorders, even for infections with microorganisms that are not completely eradicated.

Respiratory infections and asthma: current treatment strategies

Infections such as lower respiratory illness potentially contribute to the initiation of asthma and are major factors in recurring acute exacerbations of the condition. Although typical bacterial respiratory pathogens such as Streptococcus pyogenes, Streptococcus pneumoniae and Hemophilus influenzae do not initiate asthmatic exacerbations, data from a subgroup of adults suggest a potential role for Mycoplasma pneumoniae and Chlamydia pneumoniae in the onset of asthma. Common cold viruses, predominantly respiratory syncytial virus (RSV) in young children and rhinoviruses in older children and adults, are the major causes of acute exacerbations of asthma. These exacerbations are not prevented with maintenance therapies that are used for chronic asthma, but do respond to short courses of systemic corticosteroids. There are continued attempts to produce a successful vaccine and antiviral agents for the treatment of RSV that are more effective and more practical to use than ribavirin, which is currently the only available antiviral for RSV. The prevention and treatment of rhinovirus infections have focused on the major receptor for the virus, intercellular adhesion molecule-1 (ICAM-1), which is located on respiratory epithelial cells. A multivalent, recombinant, antibody fusion protein identified as CFY196 has high avidity for ICAM-1 and has the potential to protect against rhinovirus infection. Another approach for preventing and treating rhinovirus infection uses a recombinant, soluble, truncated form of ICAM-1 in which the transmembrane and intracellular domains of the protein have been deleted. An initial clinical study on this agent demonstrated clinical efficacy in ameliorating the symptoms of experimental rhinovirus infection in volunteers, but did not significantly prevent infection.