Risk factors for nontuberculous mycobacterial isolation in patients with cystic fibrosis: A meta-analysis

Eradication of Nontuberculous Mycobacteria in People with Cystic Fibrosis Treated with Elexacaftor/Tezacaftor/Ivacaftor: A Multicenter Cohort Study

BACKGROUND

The prevalence of nontuberculous mycobacteria (NTM) infections is rising in people with cystic fibrosis (pwCF). NTM infection, especially infection with Mycobacterium abscessus complex (MABC), is commonly associated with severe lung deterioration. The current treatment modalities, including multiple intravenous antibiotics, frequently fail to achieve airway eradication. Although treatment with elexacaftor/tezacaftor/ivacaftor (ETI) has been shown to modulate the lung microbiome, data regarding its role in eradicating NTM in pwCF is lacking. Our aim was to evaluate the impact of ETI on the rate of NTM eradication in pwCF.

METHODS

This retrospective multicenter cohort study included pwCF from five CF centers in Israel. PwCF aged older than 6 who had at least one positive NTM airway culture in the past two years and were treated with ETI for at least one year were included. The annual NTM and bacterial isolations, pulmonary function tests, and body mass index were analyzed before and after ETI treatment.

RESULTS

Fifteen pwCF were included (median age 20.9 years, 73.3% females, 80% pancreatic insufficient). In nine patients (66%) NTM isolations were eradicated following treatment with ETI. Seven of them had MABC. The median time between the first NTM isolation and treatment with ETI was 2.71 years (0.27-10.35 years). Eradication of NTM was associated with improved pulmonary function tests (p<0.05).

CONCLUSIONS

For the first time, we report successful eradication of NTM, including MABC, following treatment with ETI in pwCF. Additional studies are needed to assess whether treatment with ETI can result in the long-term eradication of NTM.

Treatable traits and challenges in the clinical management of non-tuberculous mycobacteria lung disease in people with cystic fibrosis

INTRODUCTION

Over the last ten years an increasing prevalence and incidence of non-tuberculous mycobacteria (NTM) has been reported among patients with cystic fibrosis (CF) Viviani (J Cyst Fibros, 15(5):619-623, 2016). NTM pulmonary disease has been associated with negative clinical outcomes and often requires pharmacological treatment. Although specific guidelines help clinicians in the process of diagnosis and clinical management, the focus on the multidimensional assessment of concomitant problems is still scarce.

MAIN BODY

This review aims to identify the treatable traits of NTM pulmonary disease in people with CF and discuss the importance of a multidisciplinary approach in order to detect and manage all the clinical and behavioral aspects of the disease. The multidisciplinary complexity of NTM pulmonary disease in CF requires careful management of respiratory and extra-respiratory, including control of comorbidities, drug interactions and behavioral factors as adherence to therapies.

CONCLUSIONS

The treatable trait strategy can help to optimize clinical management through systematic assessment of all the aspects of the disease, providing a holistic treatment for such a multi-systemic and complex condition.

Cystic Fibrosis-Related Nontuberculous Mycobacterial Pulmonary Disease

Non-tuberculous mycobacteria (NTM) infection is a major cause of morbidity in people with cystic fibrosis (pwCF) with rates of infection increasing worldwide. Accurate diagnosis and decisions surrounding best management remain challenging. Treatment guidelines have been developed to assist physicians in managing NTM in pwCF, but involve prolonged and complex mycobacterial regimens, often associated with significant toxicity. Fortunately, current management and outcomes of NTM in CF are likely to evolve due to improved understanding of disease acquisition, better diagnostics, emerging antimycobacterial therapies, and the widespread uptake of cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapies.

Nontuberculous Mycobacterial Infections in Cystic Fibrosis

Nontuberculous mycobacteria (NTM) are important pathogens, with a longitudinal prevalence of up to 20% within the cystic fibrosis (CF) population. Diagnosis of NTM pulmonary disease in people with CF (pwCF) is challenging, as a majority have NTM infection that is transient or indolent, without evidence of clinical consequence. In addition, the radiographic and clinical manifestations of chronic coinfections with typical CF pathogens can overlap those of NTM, making diagnosis difficult. Comprehensive care of pwCF must be optimized to assess the true clinical impact of NTM and to improve response to treatment. Treatment requires prolonged, multidrug therapy that varies depending on NTM species, resistance pattern, and extent of disease. With a widespread use of highly effective modulator therapy (HEMT), clinical signs and symptoms of NTM disease may be less apparent, and sensitivity of sputum cultures further reduced. The development of a disease-specific approach to the diagnosis and treatment of NTM infection in pwCF is a research priority, as a lifelong strategy is needed for this high-risk population.

Epidemiology and management of nontuberculous mycobacterial disease in people with cystic fibrosis, the Netherlands

BACKGROUND

Nontuberculous mycobacteria (NTM) are opportunistic, difficult to treat pathogens. With increasing prevalence of NTM infections in people with cystic fibrosis (pwCF) and the improved life expectancy, the burden is expected to grow.

METHODS

We assessed the epidemiology and management of NTM isolation and disease in pwCF in the Netherlands using a survey and retrospective, case-controlled data from the Dutch CF Registry. We determined the isolation prevalence, treatment and outcomes from 2013-2019.

RESULTS

NTM isolation prevalence increased from 1.0% to 3.6% (2013-2019). This was a single NTM isolation in 53.7% of the adults and 60.0% of the children. M. abscessus and M. avium complex (MAC) were most frequent (47.1 and 30.9%). Of the treated pwCF, 48.5% attained culture conversion of M. abscessus; 54.5% for MAC. Children with an NTM isolation showed more infections with S. maltophilia and/or A. fumigatus (p < 0.001) compared to controls. In the year prior to NTM isolation, children in the NTM group had a lower mean FEV1% predicted (81.5 ± 16.7 vs. 88.6 ± 15.3, p = 0.024), while adults in the NTM group had more IV antibiotic days compared to controls (60 vs. 17, p = 0.047). In the following years, FEV1% predicted declined faster in pwCF with NTM than the control group (children: -3.8% vs. -1.6%, p = 0.023; adults: -0.7% and 0.4%, ns).

CONCLUSIONS

The isolation prevalence of 3.6%, poor treatment outcomes and associated lung function decline emphasize that NTM pulmonary disease (NTM-PD) is a significant health issue among pwCF in the Netherlands. Its prevention and treatment require increased attention.

Nontuberculous Mycobacterial Lung Disease in the Patients with Cystic Fibrosis—A Challenging Diagnostic Problem

Background: Cystic fibrosis (CF) is an autosomal, recessive genetic disorder, caused by a mutation in the cystic fibrosis transmembrane conductance receptor regulator (CFTR) gene. Dysregulated mucous production, and decreased bronchial mucociliary clearance, results in increased susceptibility to bacterial and fungal infections. Recently, nontuberculous mycobacteria (NTM) infections were identified as an emerging clinical problem in CF patients. Aim: The aim of the present study was to assess the frequency of NTM isolations in CF patients hospitalized in the pulmonary department, serving as a hospital CF center, and to describe challenges concerning the recognition of NTMLD (nontuberculous mycobacterial lung disease) in those patients. Methods: Consecutive CF patients, who were hospitalized due to pulmonary exacerbations (PEX), in a single CF center, between 2010 and 2020, were retrospectively assessed for the presence of NTM in respiratory specimens. Clinical and radiological data were retrospectively reviewed. Results: Positive respiratory specimen cultures for NTM were obtained in 11 out of 151 patients (7%), mean age—35.7 years, mean BMI—20.2 kg/m², mean FEV1—58.6% pred. Cultures and phenotyping revealed the presence of Mycobacterium avium (M. avium)—in six patients, Mycobacterium chimaera (M. chimaera) in two, Mycobacterium kansasii (M. kansasii)—in one, Mycobacterium abscessus (M. abscessus)—in one, Mycobacterium lentifavum (M. lentiflavum)—in one. Simultaneously, respiratory cultures were positive for fungi in 91% of patients: Candida albicans (C. albicans)—in 82%, Aspergillus fumigatus (A. fumigatus)—in 45%. Clinical signs of NTMLD were non—specific, chest CT indicated NTMLD in five patients only. Conclusion: Due to non-specific clinical presentation, frequent sputum cultures for NTM and analysis of serial chest CT examinations are crucial for NTMLD recognition in CF patients. Further studies concerning the predictive role of fungal pathogens for NTMLD development in CF patients are needed.

Cystic fibrosis year in review 2020: Section 2 pulmonary disease, infections, and inflammation

The outlook for those with cystic fibrosis (CF) has never been brighter with ever increasing life expectancy and the approval of the highly effective CFTR modulators, such as elexacaftor/tezacaftor/ivacaftor. With that being said, the progressive pulmonary decline and importance of lung health, infection, and inflammation in CF remains. This review is the second part in a three-part CF Year in Review 2020. Part one focused on the literature related to CFTR modulators while part three will feature the multisystem effects related to CF. This review focuses on articles from Pediatric Pulmonology, including articles from other journals that are of particular interest to clinicians. Herein, we highlight studies published during 2020 related to CF pulmonary disease, infection, treatment, and diagnostics.

Exploring Potential COPD Immunosuppression Pathways Causing Increased Susceptibility for MAC Infections among COPD Patients

Although there has been a drastic decline in the cases of Tuberculosis in the United States, the prevalence of infections caused by Mycobacterium avium Complex (MAC) has steadily increased in the past decades. Mycobacterium avium (M. avium) is one of the most abundant microorganisms in the MAC species. The mycobacterium genus is divided into two major groups: tuberculosis causing mycobacteria and non-tuberculous mycobacteria. MAC is most prominent among the non-tuberculous mycobacteria. MAC is an opportunistic pathogen that is present in soil, water, and droplets in the air. MAC infections can result in respiratory disease and can disseminate in affected patients. MAC infections are especially prevalent in patients with preexisting respiratory conditions such as Chronic Obstructive Pulmonary Disease (COPD). COPD is one of the most common lung conditions in the world with the primary cause being smoking in developed countries. COPD involves chronic inflammation of lung tissue resulting in increased susceptibility to infection. There is a lack of research regarding the pathophysiology that leads COPD patients to be susceptible to MAC infection. Our review paper therefore aims to investigate how the pathogenicity of MAC bacteria and immune decline seen in COPD patients leads to a greater susceptibility to MAC infection among COPD patients.

Serological biomarkers for the diagnosis of Mycobacterium abscessus infections in cystic fibrosis patients

BACKGROUND

Culture conditions sometimes make it difficult to detect non-tuberculous mycobacteria (NTM), particularly Mycobacterium abscessus, an emerging cystic fibrosis (CF) pathogen. The diagnosis of NTM positive cases not detected by classical culture methods might benefit from the development of a serological assay.

METHODS

As part of a diagnostic accuracy study, a total of 173 sera CF-patients, including 33 patients with M. abscessus positive cultures, and 31 non-CF healthy controls (HC) were evaluated. Four M. abscessus antigens were used separately, comprising two surface extracts (Interphase (INP) and a TLR2 positive extract (TLR2eF)) and two recombinant proteins (rMAB_2545c and rMAB_0555 also known as the phospholipase C (rPLC)).

RESULTS

TLR2eF and rPLC were the most efficient antigens to discriminate NTM-culture positive CF-patients from NTM-culture negative CF-patients. The best clinical values were obtained for the detection of M. abscessus-culture positive CF-patients; with sensitivities for the TLR2eF and rPLC of 81.2% (95% CI:65.7-92.3%) and 87.9% (95% CI:71.9-95.6%) respectively, and specificities of 88.9% (95% CI:85.3-94.8%) and 84.8% (95% CI:80.6-91.5%) respectively. When considering as positive all sera, giving a positive response in at least one of the two tests, and, as negative, all sera negative for both tests, we obtained a sensitivity of 93.9% and a specificity of 80.7% for the detection of M. abscessus-culture positive CF-patients.

CONCLUSION

High antibody titers against TLR2eF and rPLC were obtained in M. abscessus-culture positive CF-patients, allowing us to consider these serological markers as potential tools in the detection of CF-patients infected with M. abscessus.

[Evidence-based treatment of cystic fibrosis]

Mucoviscidosis (cystic fibrosis [CF]) is the most common autosomal recessive inherited multisystem disease with fatal outcome. It is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which lead to a dysfunctional chloride channel and a defective CFTR protein. As a consequence, retention of insufficiently hydrated mucus affects multiple essential organs, mainly the lungs and airways, pancreas, liver, biliary tract and intestines. This leads to inflammation and infection, fibrosis and progressive tissue destruction. Respiratory failure is the major cause of mortality; however, in the no more than 30 years since the molecular characterization of the basic CFTR defect causing CF, tremendous success has been made with respect to the long-term prognosis of people with CF. This improvement in the prognosis was achieved by the cooperative spirit and networking of the very active and international CF research community and by establishing a multidisciplinary clinical CF team that implements the existing evidence in various aspects of standardized care together with the CF patient. This narrative review article presents the evidence in selected aspects of CF treatment, with special consideration of the most recent development of highly effective CFTR modulator treatment. This treatment will soon become available for more than 90% of the global CF patients and transform the pathophysiology as well as the course of disease towards a treatable chronic condition in internal medicine.