The role of the key CF bacteria such as P. aeruginosa and S. aureus on the course CF lung progression have been studied extensively. A key aspect of the CF care is to early detect bacteria, mainly gram-negative bacteria, and to treat it aggressively to impede colonization, which is well known to have a negative prognostic impact (180). According to the ECFS best
practice guidelines, regular bacterial respiratory cultures are recommended to monitor bacterial outcomes (3). Similar recommendation does not exist regarding the fungal outcomes. Study I and II demonstrated an association between lung function decline and persistent colonization with C. albicans, C dubliniensis and A. fumigatus. The current studies along with former ones emphasize the potential impact of fungi on CF lung progression. We strongly recommend obtaining fungal cultures regularly to monitor the fungal presence.
To enable studies across CF centers it is absolutely necessary to standardize the fungal detection methods and to have an agreement on the definition of colonization. To enable implying an agreed definition on colonization, it is demanded to have a minimum number of fungal cultures per year.
Candida species have been considered as innocent colonizer. The result of study I may disputes this notion. Study I indicated a negative association between colonization with C.
albicans and C. dubliniensis and lung function. Regarding C. albicans, the current study is in line with former longitudinal studies showing an association with lung function decline (10, 11). The prevalence of C. albicans increased with age along with the increased prevalence of P. aeruginosa. Thus, the reduction in ppFEV1 could be explained by P.
aeruginosa colonization. However, we have adjusted for colonization with P. aeruginosa and the number of IV antibiotic courses. We have clinically experienced patients who pointed out a change in the sputum properties and a clinical deterioration after an intravenous antibiotic course. This could be related to overgrowth of Candida species. More studies are warranted to evaluate the benefits of treatment in patients colonized with Candida species.
The reduction in lung function was most pronounced in patients repeatedly colonized with C. dubliniensis. C. dubliniensis is most known for its relatively high prevalence in HIV infected patients (145). Before 2005, C. dubliniensis was often diagnosed incorrectly as C.
albicans because of the similarity in microscopic features. Research and clinical experience on this fungus in CF is extremely scarce. Our study is the first to highlight the possible relevance for CF lung progression. Nevertheless, our study is insufficient to determine any causality. C. dubliniensis could be a mediator or a marker for progressive lung disease. The result is needed to be confirmed with further studies. We encourage clinicians to observe patients who frequently recover C. dubliniensis and gather experiences in this group of patients.
A. fumigatus is frequently recovered from CF airways. In study II, persistent colonization with A. fumigatus for more than one year was associated with a significant deterioration in lung function which may necessitate treatment. On the other hand, eradication of A. fumigatus
and remained negative during the second and third year (data was presented in the original article). Furthermore, treatment with antifungal agents is not without risks of potential adverse event and resistance development. In our cohort, the eradication required treatment more often in patients who were colonized with A. fumigatus for more than one year.
Therefore, we recommend considering treatment if A. fumigatus is recovered from sputum culture frequently because it may indicate that the lungs are not able to clear this pathogen, leading to its persistence. We do not recommend utilizing lung function (measured as FEV1) as a guide for treatment indication. Lung function is an insensitive method to assess small changes and is not sensitive enough in patients at early stage of the CF lung disease. Instead, clinical deterioration in form of increased sputum, increased the exacerbation rate or exacerbation that not resolved with antibiotic treatment could be a guide for treatment indication. A. fumigatus specific antibodies may guide clinicians for the treatment decision.
Yet, there is no consensus how to interpret A. fumigatus serology and further knowledge about this is warranted.
In study III, we used age, inhaled corticosteroids, antibiotics and hypertonic saline as well as intravenous antibiotics to identify risk factors for chronic colonization with A. fumigatus in a large cohort including four Scandinavian CF centers. Only inhaled antibiotics was strongly associated with chronic colonization with A. fumigatus. The results demonstrated the disadvantage of treatment with inhaled antibiotic and the importance of closer monitoring of the fungal outcomes in this group of patients.
CFTR modulators are an established treatment in CF. Restoring the CFTR function may theoretically improve the CF airways’ capacity to clear inhaled pathogens. Notably, patients treated with lumacaftor/ivacaftor did not display reduction in the prevalence of A. fumigatus one year after treatment initiation compared to the two years prior to treatment. Nevertheless, the numbers of antifungal treatment courses were significantly lower after lumacaftor/ivacaftor initiation. The prevalence of A. fumigatus tended to decrease before lumacaftor/ivacaftor and continued to decrease after lumacaftor/ivacaftor despite the reduction in the use of antifungal agents. Does this implicate that lumacaftor/ivacaftor maybe have an antifungal activity? The absence of alteration in the growth of A. fumigatus could also be explained by the short follow up period. On the other hand, other fungi such as C.
albicans, Penicillium species and S. apiospermum became more prevalent after start with lumacaftor/ivacaftor. Monitoring the fungal outcomes is needed in patients treated with CFTR modulator therapy.
We have identified two obstacles regarding fungi in the era of CFTR modulator. The first one is the reduced mucus experienced in patients treated with CFTR modulator. This will
reduce the possibility to obtain suitable sputum cultures, the most used method to monitor bacterial and fungal outcomes. New microbiological detection methods are needed to monitor this group of patients. The second obstacle was the drug-to-drug interactions between CFTR modulators and azoles. Concomitant treatment with lumacaftor/ivacaftor and drugs of the azole class is not recommended. Lumacaftor/ivacaftor reduces posaconazole concentrations levels and posaconazole is a strong CYP3A inhibitor increasing the concentrations levels of ivacaftor. Concomitant treatment with ivacaftor or tezacaftor/elexacaftor/ivacaftor and posaconazole or voriconazole is permissible, however, a substantial reduction of dosage of CFTR modulators is required. isavoconazole is a moderate CYP3A inhibitor, and less dose reduction is required in the concomitant treatment with ivacaftor or tezacaftor/elexacaftor/ivacaftor. Therapeutic drug monitoring for both azoles and CFTR modulators will be necessary to follow the concentration in this group of patients.
CONCLUSIONS
Fungi are prevalent in CF airways, but the clinical relevance is not fully elucidated. Our studies have identified a potential negative roll of C. albicans C. dubliniesis and A. fumigatus on lung function. Furthermore, eradication of A. fumigatus was associated with a better lung function. Inhaled antibiotics was associated with chronic colonization with A. fumigatus.
Finaly, treatment with lumacaftor/ivacaftor improved a number of clinical parameters.
FUTURE PERSPECTIVE
In Sweden there are less than 800 patients with CF. Therefore, cooperation between centers is essential for future studies. Fundamental cornerstones to facilitate national and international studies on fungi in CF is standardization of the microbiological detection methods and an agreement on the frequency of obtaining fungal cultures. Another cornerstone is an agreed definition on the fungal colonization and Aspergillus related entities.
In my opinion the criteria should include clinical, radiological, microbiological (either culture-based or non-culture-based method) and serological outcomes.
A complete understanding of the pathophysiology of fungi in CF airways is lacking.
Available studies conducted in vitro and animal models are mostly limited to Aspergillus species. In vivo studies in CF are warranted.
Fungi are frequently isolated from CF airways, however, distinguishing between colonization and infection is not possible based on fungal culture alone. Symptoms induced by fungi often overlap with other CF symptoms. The serological fungal detection methods and imaging may have a role in this field, but the existing methods need to be evaluated and validated. The role of imaging in the fungal diagnosis has yet not been studied. A standardized scoring system and ultra-low-dose CT will facilitate future studies on this topic (181, 182).
We demonstrated a negative association between persistent fungi and lung function, but the current studies cannot determine whether the fungal colonization per se induced lung function decline, or if it is a consequence of pulmonary deterioration. Further studies are needed to clarify this topic. CF is a complicated disease, and a number of parameters influence the trajectory of the disease which makes it difficult to assess causality. Another challenge is the selection of the outcome measure to assess the impact of colonization or the efficacy of treatment. As previously mentioned ppFEV1 is an insensitive method to detect small changes and LCI can only be used in patients with normal lung function. Future studies should include patients’ experiences and quality of live as important outcome measure. Other outcome measures could be the eradication status and the measuring of inflammatory markers in sputum, as well as low dose CT or chest magnetic resonance imaging (MRI).
Our study highlighted the potential virulence of Candida species in CF. C. albicans and more predominantly C. dubliniensis was associated with a significant decline in lung function. Certainly, causality is needed to be determined. Candida species have not been considered as respiratory pathogens and treatment is usually not recommended. In a case report, patients who were cultured positive for Candida species displayed clinical improvement when they received antifungal treatments. More studies are needed to clarify the role of Candida species in CF airways and how these patients should be treated.
Eradication of A. fumigatus was associated with a significantly higher lung function compared with patients who continued to be culture positive for A. fumigatus more than one consecutive year. Prospective studies on treatment efficacy are needed. Antifungal sensitivity tests and therapeutic drug monitoring should be performed.
CF patients treated with CFTR modulators experience less mucus, which is a challenge to monitor the fungal and bacterial outcomes. Another detection method will be warranted in this group of patients. Another challenge is the drug-to-drug interaction between CFTR modulator and azoles. Measuring the plasma concentrations for both CFTR modulators (already available at Karolinska University Hospital, department of clinical Pharmacology) and azoles will give clinicians the tools to perform dosage adjustments if needed and to follow up potential toxicity and other adverse events. Using nebulized antifungal treatment is also an option to avoid drug-to-drug interactions. There are no antifungal agents approved for nebulized use yet, but such attempts are under way (183).
Notably, there is very limited information available regarding the role of other less common fungi such as Exophiala dermatitidis and Scedosporium species in CF. Thus, cooperation between CF centers in Sweden and abroad is needed to facilitate such studies. Overall, fungi are very little studied in patients with bronchiectasis and in patients with obstructive lung disease. Hopefully the knowledge we gain from studies on fungi in CF can be relevant also for in these groups of patients.
ACKNOWLEDGEMENTS
Först av allt vill jag visa min tacksamhet till alla patienter och vårdnadshavare som har ställt upp och deltagit i mina studier. Stort tack för att ställde upp för bättre vård för CF patienter baserade på evidens och forskning.
Tack till patientföreningen riksförbundet cystisk fibros och hjärt- och lungfonden för deras generösa bidrag som gjorde att detta arbete blev möjlig.
Jag vill tacka min huvudhandledare, min vän och kollega Isabelle de Monestrol. Du har stött mig i min långa resa på alla möjliga vis och framför allt du fick mig att växa både som forskare, kliniker och person.
Stort tack till Lena Hjelte min bihandledare och min första chef på CF mottagningen. Jag har alltid varit imponerat av den otroliga kraften och starka viljan du har att driva CF-vården vidare på alla möjliga plan. Jag är så glad att jag fick jobba med dig och få en del av den energi du sprider runt omkring dig.
Stort tack till Lena Klingspor, min bihandledare och lärare inom mykologi. Du var den porten som fick mig att komma in en fantastik och spännande värd med svampar. Jag önskar att jag kan ta resan vidare och få fler att bli intresserade av det oerhört spännande och outforskade fältet.
Stort tack Peter Bergman för att du tackade ja till att vara min bihandledare. Jag är så glad att du gjorde det. Din skarpa syn har drivit min forskning framåt.
Till min idol Lena Mared. Jag ska bli som du. Du gör inget halvhjärtat. Ditt engagemang för patienter och strävan att göra det bästa för dem är helt underbart. Din positiva och samtidigt jordnära inställning är något jag har lärt mig av. Inom CF-vården var du min första lärare.
Jag ber om ursäkt för jag har torterat dig med mina oändliga frågor när jag var ny. Tack för du alltid är glad, positiv och alltid ställde upp. Tack för ditt fantastiska humör och härliga skratt.
Mina lärare inom lungmedicin och kollegor från Södersjukhuset Valiant Ukale, Karin Sandek and Anne Geborek. Jag är otroligt tacksam att jag fick äran att möta er både som personer och professioner. Ni var mina vägvisare inom lungmedicin. Tack för allt ni har lärt mig. Tack för att jag fick lära känna er. Ni finns alltid i mina tankar.
Anders Lindblad, tack för ditt tålamod och underbara hjälp med CF-registret. Tack för att du lät mig komma med i den fjärde studien.
Lisa Påhlman, du kom in nyligen i min forskningsresa men vilken tillgång. Tack för varje sekund du ägnat åt mina studier och till mig personligen. Tack för dina kloka råd. Jag hoppas innerligt att det här bara är början till långvarigt samarbete.
Stort tack till Anna Hollander, vår underbara fantastiska forskningssjuksköterska. Vi är lyckligt lottade att ha dig. Du har varit som en mentor för mig, Du har stöttat, peppat och framför allt trott på mig och visat det. Tack för allt stöd, för fina orden och för uppmuntran när saker inte bli som jag har tänkt mig.
Stort tack till Sten Samuelsson, vår underbara författare, låtskrivare, regissör, festfixare, lekfixare..…listan är lång. Din närvaro bringar ihop teamen och gör de till EN. Din lugna, din positiva och din underbara vardagliga vänlighet är det jag mest saknar när jag inte är på jobbet. Tack för att du är en del av teamet.
Tack till vår sekreterare Christl Fältström för att all hjälp med de praktiska. Jag vet att du alltid gör ditt bästa.
Mina underbara kollegor Ference Karpati, Adrienn Banki, Maria Rönnqvist, Aleksandra Kowalik och Louise Pedersen. Tack för alla de givande diskussionerna och den starka viljan att driva CF-vården framåt.
Tack till vår fantastiska CF-team, ni är bäst. Ni finns alltid där för patienterna. Ni har en otrolig förmåga och vilja att tänja på gränser och vända och vrida på varje sten för CF-patienternas bästa.
Till slut vill jag tacka de personer som utformade mig, min underbara familj. Jag älskar er alla mer än själva livet. Min pappa och mamma (Shaker och Sadyia) som gav oss så mycket värme och kärlek. Er strävan efter den viktigaste uppgiften i livet: att vara en god medmänniska, har alltid varit mitt motto. Mina syskon Hanan, Jinan, Manal, Fatima och Mohammad, ni är min skatt. Jag vet att ni alltid finns där för mig oavsett vad. Jag känner mig så trygg att jag har er. Ni är en del av mig.
Min andra halva, min kära make Adel. Det var tack vare din ständiga uppmuntran och din förmåga att se det positiva inom mig som ledd att jag har kommit hit. Du trodde på mig från allra första sekunden vi möttes och du har alltid stöttat mig att ta nästa steg. Du fick mig att växa som person. Du har gjort mig till en bättre version av mig. Och sist men inte minst, Mina fantastiska söner Hasan och Amir; ni är min glädje i livet och min stolthet, Så underbart att få se er växa och utvecklas. Älskar er.
REFERENCES
1. Davis PB. Cystic fibrosis since 1938. American Journal of Respiratory and Critical Care Medicine. 2006;173(5):475-82.
2. Bergeron C, Cantin AM. Cystic Fibrosis: Pathophysiology of Lung Disease.
Seminars in Respiratory and Critical Care Medicine. 2019;40(6):715-26.
3. Castellani C, Duff AJA, Bell SC, Heijerman HGM, Munck A, Ratjen F, et al.
ECFS best practice guidelines: the 2018 revision. Journal of Cystic Fibrosis. 2018;17(2):153-78.
4. Renner S, Nachbaur E, Jaksch P, Dehlink E. Update on Respiratory Fungal Infections in Cystic Fibrosis Lung Disease and after Lung Transplantation. Journal of Fungi.
2020;6(4):16.
5. Coron N, Pihet M, Frealle E, Lemeille Y, Pinel C, Pelloux H, et al. Toward the Standardization of Mycological Examination of Sputum Samples in Cystic Fibrosis: Results from a French Multicenter Prospective Study. Mycopathologia. 2018;183(1):101-17.
6. Harun SN, Wainwright CE, Grimwood K, Hennig S, Cheney J, George N, et al.
Aspergillus and progression of lung disease in children with cystic fibrosis. Thorax.
2019;74(2):125-31.
7. Amin R, Dupuis A, Aaron SD, Ratjen F. The Effect of Chronic Infection With Aspergillus fumigatus on Lung Function and Hospitalization in Patients With Cystic Fibrosis.
Chest. 2010;137(1):171-6.
8. Ramsey KA, Ranganathan S, Parkl J, Skoric B, Adams AM, Simpson SJ, et al.
Early Respiratory Infection Is Associated with Reduced Spirometry in Children with Cystic Fibrosis. American Journal of Respiratory and Critical Care Medicine. 2014;190(10):1111-6.
9. de Vrankrijker AMM, van der Ent CK, van Berkhout FT, Stellato RK, Willems RJL, Bonten MJM, et al. Aspergillus fumigatus colonization in cystic fibrosis: implications for lung function? Clinical Microbiology and Infection. 2011;17(9):1381-6.
10. Gileles-Hillel A, Shoseyov D, Polacheck I, Korem M, Kerem E, Cohen-Cymberknoh M. Association of chronic Candida albicans respiratory infection with a more severe lung disease in patients with cystic fibrosis. Pediatric Pulmonology. 2015;50(11):1082-9.
11. Chotirmall SH, O'Donoghue E, Bennett K, Gunaratnam C, O'Neill SJ, McElvaney NG. Sputum Candida albicans Presages FEV1 Decline and Hospital-Treated Exacerbations in Cystic Fibrosis. CHEST. 2010;138(5):1186-95.
12. Welsh MJ, Smith AE. CYSTIC-FIBROSIS. Scientific American.
1995;273(6):52-9.
13. Andersen DH, Hodges RG. CELIAC SYNDROME: V. Genetics of Cystic Fibrosis of the Pancreas With a Consideration of Etiology. Archives of Pediatrics & Adolescent Medicine. 1946;72(1):62-80.
14. Andersen DH. CYSTIC FIBROSIS OF THE PANCREAS AND ITS RELATION TO CELIAC DISEASE: A CLINICAL AND PATHOLOGIC STUDY. Archives of Pediatrics & Adolescent Medicine. 1938;56(2):344-99.
15. Gibson LE, Cooke RE. A test for concentration of electrolytes in sweat in cystic fibrosis of the pancreas utilizing pilocarpine by iontophoresis. Pediatrics. 1959;23(3):545-9.
16. Di Sant'Agnese PA, Darling RC, Perera GA, Shea E. Abnormal electrolyte composition of sweat in cystic fibrosis of the pancreas; clinical significance and relationship to the disease. Pediatrics. 1953;12(5):549-63.
17. Knowles MR, Stutts MJ, Spock A, Fischer N, Gatzy JT, Boucher RC. Abnormal Ion Permeation through Cystic Fibrosis Respiratory Epithelium. Science.
1983;221(4615):1067-70.
18. Quinton PM. Chloride impermeability in cystic fibrosis. Nature.
1983;301(5899):421-2.
19. Bat-sheva K, Johanna MR, Janet AB, Danuta M, Tara KC, Aravinda C, et al.
Identification of the Cystic Fibrosis Gene: Genetic Analysis. Science. 1989;245(4922):1073-80.
20. Riordan JR, Rommens JM, Kerem B, Alon N, Rozmahel R, Grzelczak Z, et al.
Identification of the cystic fibrosis gene: cloning and characterization of complementary DNA.
Science (New York, NY). 1989;245(4922):1066-73.
21. De Boeck K, Amaral MD. Progress in therapies for cystic fibrosis. Lancet Resp Med. 2016;4(8):662-74.
22. Farrell PM. The prevalence of cystic fibrosis in the European Union. Journal of Cystic Fibrosis. 2008;7(5):450-3.
23. Lannefors L, Lindgren A. Demographic transition of the Swedish cystic fibrosis community - results of modern care. Respiratory Medicine. 2002;96(9):681-5.
24. Mayell SJ, Munck A, Craig JV, Sermet I, Brownlee KG, Schwarz MJ, et al. A European consensus for the evaluation and management of infants with an equivocal diagnosis following newborn screening for cystic fibrosis. Journal of Cystic Fibrosis. 2009;8(1):71-8.
25. Sims EJ, Mugford M, Clark A, Aitken D, McCormick J, Mehta G, et al.
Economic implications of newborn screening for cystic fibrosis: a cost of illness retrospective cohort study. Lancet. 2007;369(9568):1187-95.
26. Canadian Cystic Fibrosis Registry. Annual Data Report 2018. Available online:
https://www.cysticfibrosis.ca
/uploads/RegistryReport2018/2018RegistryAnnualDataReport.pdf (accessed on 20 April 2020).
27. US Cystic Fibrosis Registry (Cystic Fibrosis Foundation). Annual Data Report 2018. Available online: https:
//www.cff.org/Research/Researcher-Resources/Patient-Registry/2018-Patient-Registry-Annual-Data-Report.pdf
(accessed on 20 April 2020).
28. UK Cystic Fibrosis Registry (Cystic Fibrosis Trust). Annual Data Report 2018.
Available online: https://www.cysticfi
brosis.org.uk/~{}/media/documents/the-work-we-do/uk-cf-registry/2018-registry-annual-data-report.ashx?la=en
(accessed on 20 April 2020).