Keywords
Cystic fibrosis, nebuliser therapy, pulmonary exacerbations, Pseudomonas aeruginosa
Cystic fibrosis, nebuliser therapy, pulmonary exacerbations, Pseudomonas aeruginosa
As recommended by Dr Lee, we have:
1. clarified that colomycin 2MU thrice daily was given intravenously alongside intravenous Tazocin
2. clarified the location (home / hospital) for all treatment courses
3. clarified that the subject was also using nebulised dornase alfa throughout all treatment courses
4. provided objective adherence (I-neb data) during the dual nebulised antibiotics courses
As recommended by Drs Frost and Nazareth, we have:
1. mentioned the 2014 randomised cross-over trial of inhaled tobramycin in the introduction
2. clarified that "typically one inhaled antibiotic is used as a time" referred to chronic setting
3. described organisms isolated from her sputum in the prior-year, follow-up year and subsequent year (this was also recommended by Dr Liou)
4. clarified the location (home / hospital) for all treatment courses
5. clarified the use of adjunctive therapies
As recommended by Dr Liou, we have:
1. clarified which treatment courses were specifically for acute exacerbation - the 1st dual nebulised antibiotics course was for acute exacerbation (subject was symptomatic although %FEV1 was relatively stable) and the 3rd intravenous antibiotics course was for acute exacerbation (4% absolute decline in FEV1 from previous although there was no clear symptoms)
2. iterated the sentence in 2nd paragraph of "case report" to clarify the more intensive treatment during the follow-up year
3. provided more detailed results for sputum cultures
4. provided in generic name with first use of trademarked names for nebulised antibiotics, and only using generic name for intravenous antibiotics
We have explained in our response to Dr Liou's comments that we felt adequate history has been provided (especially in terms of age and genotype), and that we have already provided a gold-standard adherence measure in the form of adherence data captured using I-neb (a data logging nebuliser).
See the authors' detailed response to the review by Theodore G. Liou
See the authors' detailed response to the review by Freddy Frost and Dilip Nazareth
See the authors' detailed response to the review by Tim Lee
Cystic fibrosis (CF) is a genetic condition whereby ~80% of mortalities are primarily due to lung disease1. People with CF are prone to recurrent respiratory infections (termed ‘pulmonary exacerbations’), which leads to progressive lung damage and respiratory failure2. This is especially so after Pseudomonas aeruginosa (Psae) is acquired3.
Although there is a lack of evidence for best practice in treating exacerbations among adults with CF and chronic Psae infection4, two weeks of dual intravenous antibiotics are generally used for synergistic effect4,5. The European CF Society recommend against using inhaled antibiotics to treat exacerbations, due to concerns that increased mucus plugs during exacerbations may prevent antibiotics from reaching smaller airways5.
There is scant research on using inhaled antibiotics to treat exacerbations. A Cochrane review in 2012 found only four relevant studies, with inadequate sample sizes to demonstrate efficacy6. Subsequently, a randomised cross-over trial among 20 adults with CF and pulmonary exacerbation in 2014 demonstrated longer time to next exacerbation with nebulised compared to intravenous tobramycin (all participants received intravenous colistin as the second antibiotic)7. A large observational study in North America found that ~24% of exacerbations are treated with inhaled antibiotics8. Inhaled antibiotics have several advantages. Systemic adverse effects e.g. allergic reactions, gastrointestinal manifestations, ototoxicity and renal failure are common with intravenous antibiotics9,10 but rare with inhaled antibiotics11. Higher antibiotic concentrations within the airways are achieved via inhaled route, which may be beneficial in overcoming resistance12. Inhaled route also overcomes difficulties associated with venous access.
For long-term suppressive therapy, typically one inhaled antibiotic is used at a time, and someone on multiple inhaled antibiotics would alternate between those antibiotics11. Of the five existing trials looking at inhaled antibiotics for acute exacerbation, only one study with 18 participants concomitantly administed two inhaled antibiotics (tobramycin and carbenicillin)6. Yet dual inhaled antibiotics (i.e. concomitant use of two different inhaled antibiotics) may have synergistic effect, thus achieve better results. We report on an adult with CF and chronic Psae infection who achieved good results when treating exacerbations using dual inhaled antibiotics.
A Caucasian female in her early thirties with F508del/Class I mutation, pancreatic insufficiency and CF related diabetes also fulfilled the Leeds criteria13 for chronic Psae infection. Only Psae (Liverpool epidemic strain sensitive only to colistin) was cultured from all 12 sputum samples in the previous year. Despite high objective adherence to nebulised dornase alfa 2.5mg once daily and alternating colistin (Promixin®) 1megaunit twice daily/tobramycin (TOBI®) 300mg twice daily (82.9% two years ago, 96.3% in the previous year; measured with an I-neb®), stable BMI around 23.1 and reasonable glycaemic control (HbA1c 47 in month 1 of the follow-up period), there was a trend of declining %FEV1. Her annual best FEV1 was 47%, 44% and 42% over the previous three years. There was no evidence of allergic bronchopulmonary aspergillosis (ABPA) or other CF complications compromising her %FEV1.
In month one, Promixin® was also switched to nebulised Aztreonam (AZLI®) 75mg thrice daily. She had two courses (28 days) of intravenous antibiotics throughout the previous year. She agreed to three-monthly intravenous antibiotics in the follow-up year to try halt the FEV1 decline. She had 14 days of home intravenous piperacillin/tazobactam 4.5g thrice daily and intravenous colistin 2megaunit thrice daily in month one (%FEV1 improved from 38% to 40%), and again in month 4 (%FEV1 declined from 40% to 38%).
She felt less well with increased sputum volume and dyspnoea at the start of month six. Her %FEV1 was 39%. She agreed to try 14 days of concomitant nebulised AZLI® 75mg thrice daily and TOBI® 300mg twice daily at home (nebulised dornase alfa was continued) as treatment for acute exacerbation. She used 69/70 (98.6%) of her nebuliser doses over the 14 days (note that TOBI® twice daily = 4 doses via I-neb® and AZLI® could not be administered via I-neb®). Her %FEV1 improved to 45% at day 7 and 44% at day 14. Her symptoms resolved by day 14.
She felt well but her %FEV1 declined to 39% during her next clinic review at the end of month seven. She went on another 14-day course of home intravenous piperacillin/tazobactam 4.5g thrice daily and intravenous colostin 2megaunit thrice daily as treatment for acute exacerbation. At day 14, her %FEV1 remained 39%. Another 14-day course of home concomitant nebulised AZLI® and TOBI® was started in month 8 (nebulised dornase alfa was continued). She used 66/70 (94.3%) of her nebuliser doses over the 14 days (note that TOBI® twice daily = 4 doses via I-neb® and AZLI® could not be administered via I-neb®). Her %FEV1 improved to 41% at day 7 and day 14, despite developing viral coryzal symptoms at day 12. With 14 days of hospital IV piperacillin/tazobactam 4.5g thrice daily and intravenous tobramycin 480mg once daily in month 11, her %FEV1 improved from 39% at day 1 to 41% at day 14. She received intensive physiotherapy during her in-patient stay in month 11 which may contribute to some of the %FEV1 improvement but received no other adjunctive therapies (e.g. corticosteroid) during all treatment courses. All her inhaled therapies were continued during dual intravenous antibiotic courses.
During the follow-up year, only Psae (Liverpool epidemic strain sensitive only to colistin) was cultured from all eight sputum samples. During the subsequent year, only Psae (Liverpool epidemic strain sensitive only to colistin) was cultured from all nine sputum samples.
In this case, %FEV1 improvement following acute treatment of exacerbations with dual inhaled antibiotics at home (mean 3.5% over two courses) was somewhat higher than with dual intravenous antibiotics (mean 0.5% over four courses), despite similar baseline %FEV1 and one of the intravenous antibiotics courses was delivered in hospital. The %FEV1 improvement also occurred despite severe background lung disease (high resolution CT in month eight showed extensive bronchiectasis and baseline %FEV1 was ~40%).
Although she reported symptomatic improvement during her first dual inhaled antibiotics course, we did not formally measure symptomatic responses to treatments with a validated tool. The sample size is too small for null hypothesis significance testing, and regression to the mean is potentially a threat to our results. Our results are nonetheless intriguing and suggest that dual inhaled antibiotics could potentially have a role in treating exacerbations among adults with CF and chronic Psae infection. With the increasing number of inhaled anti-pseudomonal antibiotics available, e.g. nebulised levofloxacin14, different combinations of concomitant inhaled antibiotics can be used in the future for synergistic effect.
Like all medications, there are adverse events associated with inhaled antibiotics. There is a case report of acute respiratory distress syndrome potentially due to inhaled colistin15. However, localised adverse events with inhaled antibiotics are usually mild, e.g. bronchoconstriction which tends to resolve spontaneously within hours or can be controlled by pre-dosing with nebulised bronchodilator11.
High adherence to inhaled therapies probably contributed to the good clinical response from dual inhaled antibiotics observed in this case. Real-world adherence with long-term inhaled antibiotics among adults with CF is only 35–50%16,17. Someone who is already struggling with a single inhaled antibiotic is unlikely to cope with dual inhaled antibiotics, thus may derive less benefit. However, adherence to short-term drug regimen tends to be higher18. Adults with CF might be able to summon adequate self-regulation during a 14-day dual antibiotics course to really focus on their nebuliser use19.
In conclusion, the %FEV1 improvements observed in this case report provide anecdotal evidence that dual inhaled antibiotics could potentially be a treatment option for exacerbations among adults with CF and chronic Psae infection. Given the lack of good quality evidence regarding optimum exacerbations treatments and the theoretical advantages of using inhaled antibiotics, this warrants further investigations.
Written informed consent for publication of her clinical details was obtained from the patient.
No data is associated with this article.
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Competing Interests: Please refer to first report COI statement.
Competing Interests: No competing interests were disclosed.
Competing Interests: No competing interests were disclosed.
Is the background of the case’s history and progression described in sufficient detail?
No
Are enough details provided of any physical examination and diagnostic tests, treatment given and outcomes?
No
Is sufficient discussion included of the importance of the findings and their relevance to future understanding of disease processes, diagnosis or treatment?
No
Is the case presented with sufficient detail to be useful for other practitioners?
Partly
Competing Interests: Dr Liou discloses that he is supported by grants from the National Institutes of Health/National Heart Blood and Lung Institute, the Ben B. and Iris M. Margolis Family Foundation of Utah, the Cystic Fibrosis Foundation, and funds from the Claudia Ruth Goodrich Stevens Endowment Fund. During the last three years, the Cystic Fibrosis Center at the University of Utah has received funds to conduct clinical trials from Cystic Fibrosis Foundation Therapeutics, Inc, the Foundation of the National Institute of Health, Gilead Sciences, Inc, Laurent Pharmaceuticals, Nivalis Therapeutics, Inc, Novartis, Proteostasis Therapeutics, Inc, Savara Pharmaceuticals and Vertex Pharmaceuticals. None of the clinical trials were related to the case reported here. Dr Liou is holder with colleagues at the U of Utah of a provisional patent for a novel polyketide antibiotic that is in pre-clinical research and development.
Is the background of the case’s history and progression described in sufficient detail?
Partly
Are enough details provided of any physical examination and diagnostic tests, treatment given and outcomes?
Yes
Is sufficient discussion included of the importance of the findings and their relevance to future understanding of disease processes, diagnosis or treatment?
Yes
Is the case presented with sufficient detail to be useful for other practitioners?
Partly
References
1. Al-Aloul M, Nazareth D, Walshaw M: Nebulized tobramycin in the treatment of adult CF pulmonary exacerbations.J Aerosol Med Pulm Drug Deliv. 2014; 27 (4): 299-305 PubMed Abstract | Publisher Full TextCompeting Interests: No competing interests were disclosed.
Is the background of the case’s history and progression described in sufficient detail?
Yes
Are enough details provided of any physical examination and diagnostic tests, treatment given and outcomes?
Partly
Is sufficient discussion included of the importance of the findings and their relevance to future understanding of disease processes, diagnosis or treatment?
Yes
Is the case presented with sufficient detail to be useful for other practitioners?
Yes
Competing Interests: No competing interests were disclosed.
Alongside their report, reviewers assign a status to the article:
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In vitro assessment of three-dimensional ... Continue reading The paper published by Herrmann G, et al. in 2010 gave a clear rationale for combined antibiotic inhalation in CF patients colonized with P. aeruginosa:
In vitro assessment of three-dimensional fluorescence imaging of the biofilm `allowed the localization of dead and surviving bacteria in the “mushroom” structures´
Colistin sulphate appears to be more effective in the biofilms´ basis while tobramycin caused more bacterial death in the top layers. The combination of both had the considerably best effects reducing living P. aeruginosa. Figure 3 of the cited publication gives a clear Image of these effects and chances of a combined therapy, which could be most intersting for eradication of the crucial pathogen from CF airways.
https://academic.oup.com/jid/article/202/10/1585/825102
Colistin-Tobramycin Combinations Are Superior to Monotherapy Concerning the Killing of Biofilm Pseudomonas aeruginosa
Herrmann G, Yang L, Wu H, Song Z, Wang H, Høiby N, Ulrich M, Molin S, Riethmüller J, Döring G.
J Infect Dis. 2010 Nov 15;202(10):1585-92. doi: 10.1086/656788. Epub 2010 Oct 13.
In vitro assessment of three-dimensional fluorescence imaging of the biofilm `allowed the localization of dead and surviving bacteria in the “mushroom” structures´
Colistin sulphate appears to be more effective in the biofilms´ basis while tobramycin caused more bacterial death in the top layers. The combination of both had the considerably best effects reducing living P. aeruginosa. Figure 3 of the cited publication gives a clear Image of these effects and chances of a combined therapy, which could be most intersting for eradication of the crucial pathogen from CF airways.
https://academic.oup.com/jid/article/202/10/1585/825102
Colistin-Tobramycin Combinations Are Superior to Monotherapy Concerning the Killing of Biofilm Pseudomonas aeruginosa
Herrmann G, Yang L, Wu H, Song Z, Wang H, Høiby N, Ulrich M, Molin S, Riethmüller J, Döring G.
J Infect Dis. 2010 Nov 15;202(10):1585-92. doi: 10.1086/656788. Epub 2010 Oct 13.