Nontuberculous mycobacterial infection in young children with cystic fibrosis

Successful management of Mycobacterium abscessus pneumonia in a 53-day-old immunocompetent infant

Pulmonary infection due to Mycobacterium abscessus complex (MABC) usually occurs in children with underlying risk factors including cystic fibrosis (CF), chronic lung disease, and immunocompromised status, but rarely in immunocompetent children without underlying lung disease, especially in infants. We present a case of MABC pulmonary disease (MABC-PD) in an otherwise healthy 53-day-old male infant with one week of cough and respiratory distress. Computed tomography showed multiple masses across both lungs. Isolated mycobacteria from his bronchoalveolar lavage fluid were identified as MABC. We describe our complete evaluation, including immunodeficiency evaluation incorporating whole exome sequencing and our therapeutic process given complicated susceptibility pattern of the M. abscessus isolate, and review literature for MABC-PD in immunocompetent children. The infant was successfully treated through prolonged treatment with parenteral Amikacin, Cefoxitin, Linezolid, and Clarithromycin, combined with inhaled Amikacin.

A Novel Inhibitor against the Biofilms of Non-Tuberculous Mycobacteria

Non-tuberculous Mycobacteria (NTM), previously classified as environmental microbes, have emerged as opportunistic pathogens causing pulmonary infections in immunocompromised hosts. The formation of the biofilm empowers NTM pathogens to escape from the immune response and antibiotic action, leading to treatment failures. NF1001 is a novel thiopeptide antibiotic first-in-class compound with potent activity against planktonic/replicating and biofilm forms of various NTM species. It is potent against both drug-sensitive and -resistant NTM. It has demonstrated a concentration-dependent killing of replicating and intracellularly growing NTM, and has inhibited and reduced the viability of NTM in biofilms. Combination studies using standard-of-care (SoC) drugs for NTM exhibited synergetic/additive effects, but no antagonism against both planktonic and biofilm populations of Mycobacterium abscessus and Mycobacterium avium. In summary, the activity of NF1001 alone or in combination with SoC drugs projects NF1001 as a promising candidate for the treatment of difficult-to-treat NTM pulmonary diseases (NTM-PD) and cystic fibrosis (CF) in patients.

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.

Analysis of Phenotypic and Genotypic Susceptibility to Clarithromycin and Amikacin of Mycobacterium abscessus Complex Strains Isolated from Cystic Fibrosis Patients

Mycobacterium abscessus complex infections are ever on the rise. To curb their increasing evolution, we performed an in-depth study of 43 clinical isolates of cystic fibrosis patients obtained from 2009 to 2020. We identified their subspecies, uncovered their genotypic resistance profiles, characterised their antibiotic-resistant genes, and assessed their phenotypic antibiotic susceptibilities. The phenotypic and genotypic methods showed total agreement in terms of resistance to clarithromycin and amikacin. Of the 43 clinical strains, 28 belonged to M. abscessus subsp. abscessus (65.1%), 13 to M. abscessus subsp. massiliense (30.2%), and 2 to M. abscessus subsp. bolletii (4.6%). The resistant rates for clarithromycin and amikacin, the two main drugs against M. abscessus complex pulmonary infections, were 64.2% and 14.2%, respectively. We found three strains of M. abscessus subsp. abscessus that showed heteroresistance in the rrl and rrs genes, and these strains also presented double-resistance since they were macrolide- and aminoglycoside-resistant. M. abscessus subsp. abscessus showed a high minimum inhibitory concentration (MIC) and a resistant percentage larger than or equal to 88% to cefoxitin, ciprofloxacin, moxifloxacin, doxycycline, imipenem, and trimethoprim-sulfamethoxazole. These results show a panorama of the high resistance of Mycobacterium abscessus complex to current drugs for cystic fibrosis patients. Thus, other treatment methods are urgently needed.

Biofilm infection of a central venous port-catheter caused by Mycobacterium avium complex in an immunocompetent child with cystic fibrosis

BACKGROUND

Mycobacterium (M.) chimaera is a non-tuberculous mycobacterium (NTM) that belongs to M. avium complex (MAC). In patients with cystic fibrosis (CF), MAC can cause bronchopulmonary infections that can be prolonged and difficult to treat. MAC infections of sites other than the lungs or central catheters are rare and almost exclusively associated with immunodeficiency.

CASE PRESENTATION

We present a case of an 8-year-old CF patient (delF508 homozygous) with recurrent pulmonary exacerbations, gradual clinical deterioration, B-symptoms (fever, fatigue, weight loss, night sweat), elevated transaminases and intermittent detection of M. chimaera in the sputum without radiological signs of NTM-associated lung disease with a central venous port-catheter. Next-generation sequencing (NGS) revealed M. chimaera port infection that was also confirmed by mycobacterial culture. The patient recovered within 4 weeks after removal of the catheter and initiation of MAC targeted antimicrobial therapy. Electron microscopy of the catheter illustrated the presence of mycobacteria in a biofilm.

CONCLUSIONS

MAC central venous catheter infection needs to be considered in immunocompetent people. NGS is a valuable tool for rapid identification of rare infections. MAC capability of biofilm formation renders catheter removal the central therapeutic intervention for the clearance of the infection.

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.

Opportunistic Pathogens in Cystic Fibrosis: Epidemiology and Pathogenesis of Lung Infection

Cystic fibrosis (CF) is one of the most common life-shortening genetic diseases in Caucasians. Due to abnormal accumulation of mucus, respiratory failure caused by chronic infections is the leading cause of mortality in this patient population. The microbiology of these respiratory infections includes a distinct set of opportunistic pathogens, including Pseudomonas aeruginosa, Burkholderia spp., Achromobacter spp., Stenotrophomonas maltophilia, anaerobes, nontuberculous mycobacteria, and fungi. In recent years, culture-independent methods have shown the polymicrobial nature of lung infections, and the dynamics of microbial communities. The unique environment of the CF airway predisposes to infections caused by opportunistic pathogens. In this review, we will highlight how the epidemiology and role in disease of these pathogens in CF differ from that in individuals with other medical conditions. Infectious diseases (ID) physicians should be aware of these differences and the specific characteristics of infections associated with CF.

The frequency and related factors of non-tuberculosis mycobacteria infections among patients with cystic fibrosis

BACKGROUND

Non-tuberculous mycobacteria (NTM) can cause chronic lung infection particularly in patients who have structural lung disease such as cystic fibrosis (CF). We evaluated the incidence and management of NTM infections in patients with CF in our center.

METHODS

A retrospective cohort study was carried out on CF patients having at least one positive NTM isolate between 2012 and 2020.

RESULTS

Ten patients (2.1%) had at least one positive NTM culture from respiratory samples. All of them were vaccinated with Bacille Calmette-Guérin (BCG) vaccine, which is in the national vaccination program in our country. Eight patients had the Mycobacterium abscessus complex, one had Mycobacterium avium, and one had Mycobacterium szulgai growth in their respiratory samples. Three patients had transient NTM infection, two had persistent, and five had active NTM infection (NTM pulmonary disease). Patients with NTM pulmonary disease received antibiogram-directed antimycobacterial therapy. In patients with NTM pulmonary disease, the median ppFEV1 and BMI decreased by 17% and 1%, respectively, at the time of the first NTM isolation when compared with the values one year before the first NTM isolation. Culture conversion was not seen in any patient infected with Mycobacteriunm abscessus complex.

CONCLUSIONS

The NTM infection incidence is lower in our country than in those countries where the BCG vaccine is not routinely applied. The BCG vaccine may be a protective factor for NTM infection. Further studies are needed about the prevalence of NTM infections, facilitating and protective factors, and appropriate management of NTM infections in patients with CF.

Antibiotic treatment for nontuberculous mycobacteria lung infection in people with cystic fibrosis

BACKGROUND

Nontuberculous mycobacteria are mycobacteria, other than those in the Mycobacterium tuberculosis complex, and are commonly found in the environment. Nontuberculous mycobacteria species (most commonly Mycobacterium avium complex and Mycobacterium abscessus) are isolated from the respiratory tract of approximately 5% to 40% of individuals with cystic fibrosis; they can cause lung disease in people with cystic fibrosis leading to more a rapid decline in lung function and even death in certain circumstances. Although there are guidelines for the antimicrobial treatment of nontuberculous mycobacteria lung disease, these recommendations are not specific for people with cystic fibrosis and it is not clear which antibiotic regimen may be the most effective in the treatment of these individuals. This is an update of a previous review.

OBJECTIVES

The objective of our review was to compare antibiotic treatment to no antibiotic treatment, or to compare different combinations of antibiotic treatment, for nontuberculous mycobacteria lung infections in people with cystic fibrosis. The primary objective was to assess the effect of treatment on lung function and pulmonary exacerbations and to quantify adverse events. The secondary objectives were to assess treatment effects on the amount of bacteria in the sputum, quality of life, mortality, nutritional parameters, hospitalizations and use of oral antibiotics.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and hand searching of journals and conference abstract books. Date of last search: 24 February 2020. We also searched a register of ongoing trials and the reference lists of relevant articles and reviews. Date of last search: 21 March 2019.

SELECTION CRITERIA

Any randomized controlled trials comparing nontuberculous mycobacteria antibiotics to no antibiotic treatment, as well as one nontuberculous mycobacteria antibiotic regimen compared to another nontuberculous mycobacteria antibiotic regimen, in individuals with cystic fibrosis.   DATA COLLECTION AND ANALYSIS: Data were not collected because in the one trial identified by the search, data specific to individuals with cystic fibrosis could not be obtained from the pharmaceutical company.

MAIN RESULTS

One completed trial was identified by the searches, but data specific to individuals with cystic fibrosis could not be obtained from the pharmaceutical company.

AUTHORS' CONCLUSIONS

This review did not find any evidence for the effectiveness of different antimicrobial treatment for nontuberculous mycobacteria lung disease in people with cystic fibrosis. Until such evidence becomes available, it is reasonable for clinicians to follow published clinical practice guidelines for the diagnosis and treatment of nodular or bronchiectatic pulmonary disease due to Mycobacterium avium complex or Mycobacterium abscessus in patients with cystic fibrosis.

Upper versus lower airway microbiome and metagenome in children with cystic fibrosis and their correlation with lung inflammation

Objective

Airways of children with cystic fibrosis (CF) harbor complex polymicrobial communities which correlates with pulmonary disease progression and use of antibiotics. Throat swabs are widely used in young CF children as a surrogate to detect potentially pathogenic microorganisms in lower airways. However, the relationship between upper and lower airway microbial communities remains poorly understood. This study aims to determine (1) to what extent oropharyngeal microbiome resembles the lung microbiome in CF children and (2) if lung microbiome composition correlates with airway inflammation.

Method

Throat swabs and bronchoalveolar lavage (BAL) were obtained concurrently from 21 CF children and 26 disease controls. Oropharyngeal and lung microbiota were analyzed using 16S rRNA deep sequencing and correlated with neutrophil counts in BAL and antibiotic exposure.

Results

Oropharyngeal microbial communities clustered separately from lung communities and had higher microbial diversity (p < 0.001). CF microbiome differed significantly from non-CF controls, with a higher abundance of Proteobacteria in both upper and lower CF airways. Neutrophil count in the BAL correlated negatively with the diversity but not richness of the lung microbiome. In CF children, microbial genes involved in bacterial motility proteins, two-component system, flagella assembly, and secretion system were enriched in both oropharyngeal and lung microbiome, whereas genes associated with synthesis and metabolism of nucleic acids and protein dominated the non-CF controls.

Conclusions

This study identified a unique microbial profile with altered microbial diversity and metabolic functions in CF airways which is significantly affected by airway inflammation. These results highlight the limitations of using throat swabs as a surrogate to study lower airway microbiome and metagenome in CF children.

Improved Clinical Outcome After Treatment of Mycobacterium abscessus Complex Pulmonary Disease in Children With Cystic Fibrosis

BACKGROUND

Mycobacterium abscessus complex pulmonary disease (M. abscessus PD) in cystic fibrosis (CF) is challenging to treat. Current guideline therapeutic regimens involving an intensive phase of intravenous (IV) antibiotics followed by a consolidation phase of inhaled and oral antibiotics are not evidence-based. The objectives of this study were to characterize the clinical outcomes and clearance of Mycobacterium abscessus complex (M. abscessus) from respiratory cultures in children with CF M. abscessus PD.

METHODS

This retrospective longitudinal cohort analysis evaluated the first course of treatment for M. abscessus PD in 33 children in Queensland, Australia between 2001 and 2015. Spirometry and nutritional outcomes 2 years pretreatment and 1 year posttreatment were compared with clearance or relapse/persistence of Mycobacterium abscessus complex from respiratory cultures.

RESULTS

Nine of 18 children who completed therapy, cleared infection. Three of 7 children who completed only intensive therapy cleared sputum compared with 0/8 children who did not. The trajectory of the percent predicted forced expiratory volume in 1 s and age standardized body mass index significantly improved posttreatment in those that cleared sputum (P < 0.0001).

CONCLUSIONS

These results suggest that current treatment recommendations for M. abscessus PD are associated with some success in clearing infection in children with CF and improvement in lung function and body mass index. Clinical trials are required to determine the best treatment approaches.

Mycobacterium bolletii Lung Disease in Cystic Fibrosis

BACKGROUND

The cystic fibrosis (CF) pathogen, Mycobacterium abscessus complex, covers three subspecies: M. abscessus, M. massiliense, and M. bolletii. There are no clinical outcome data concerning M. bolletii. Our aim was to characterize M. bolletii lung infections in patients with CF.

METHODS

We included patients with M. bolletii lung infection recorded between 1994 and 2012 in France. Data were collected from the CF registry, medical records, and questionnaires submitted to the CF primary physician. Strains were typed by multilocus sequence typing analysis.

RESULTS

Fifteen cases were identified in nine CF centers. Nine patients (60%) presented with nontuberculous mycobacterial pulmonary disease. Follow-up of 13 patients showed a trend to more rapid decline in FEV₁ in the first year of colonization (-9.4%; SD 19.3) in comparison with noninfected control subjects (-2.3%; SD 12.1) (P = .16). Twelve patients were treated, and 11 received oral macrolides. Treatment-induced eradication occurred in five patients (41.7%). Four patients died (26.7%), including one patient with fatal nontuberculous mycobacterial pulmonary disease. Inducible macrolide resistance was demonstrated in all strains. Patients always harbored unique strains.

CONCLUSIONS

Our study reports the largest study cohort of CF patients infected with M. bolletii. M. bolletii infection affects both children and young adults, is most often symptomatic, and may be fatal. Macrolide-based therapies have poor effectiveness. There is no evidence of patient-to-patient transmission.

Nontuberculous Mycobacterial Infections in Cystic Fibrosis

Nontuberculous mycobacteria (NTM) are important emerging cystic fibrosis (CF) pathogens, with estimates of prevalence ranging from 6% to 13%. Diagnosis of NTM disease in patients with CF is challenging, as the infection may remain indolent in some, without evidence of clinical consequence, whereas other patients suffer significant morbidity and mortality. Treatment requires prolonged periods of multiple drugs and varies depending on NTM species, resistance pattern, and extent of disease. The development of a disease-specific approach to the diagnosis and treatment of NTM infection in CF patients is a research priority, as a lifelong strategy is needed for this high-risk population.

Clinical course and significance of nontuberculous mycobacteria and its subtypes in cystic fibrosis

BACKGROUND

Nontuberculous mycobacteria (NTM) infections in patients with cystic fibrosis (CF) is increasing globally. However, the related epidemiology, comorbidities, and clinical impact of NTM infection remains unclear in the progress of CF lung disease and patient survival.

METHODS

We performed a retrospective, case-control, cohort study (10 years), comparing NTM culture-positive CF patients (N = 28) to matched controls (N = 26). NTM positive patients were divided in to two groups of slow-growing (N = 17) and rapid- growing NTM (N = 8). Three patients were positive for both slow and rapid NTM. For independent group comparisons, a non-parametric Mann-Whitney test (Kruskal-Wallis test for more than two groups) was used to compare the continuous variables, and a Fisher's exact test was used for the categorical variables. Paired comparisons were performed using a Wilcoxon signed-rank test.

RESULTS

The prevalence of NTM isolation was 8%. The age at CF diagnosis was significantly lower in the slow-growing NTM group compared to the rapidly growing NTM group (P = 0.04). The median percent predicted forced expiratory flow of 25% - 75% (FEF25-75) was significantly higher before NTM acquisition in slow-growing (P = 0.013) and rapidly growing NTM group (P = 0.028). The slow-growing NTM group received significantly more penicillin/beta lactamase (P = 0.010) and rifampin (P = 0.042) following isolation. Macrolide use was significantly higher after isolation in both the slow-growing NTM (P = 0.018) and rapidly growing NTM groups (P = 0.042).

CONCLUSIONS

An earlier CF diagnosis was associated with a higher isolation of slow-growing NTM and greater antimicrobial use after infection. NTM acquisition is associated with a worsening of FEF25-75. Thus, both the early diagnosis and treatment of an NTM infection in patients with CF may positively impact lung function.

Non-Tuberculous Mycobacteria multispecies biofilms in cystic fibrosis: development of an in vitro Mycobacterium abscessus and Pseudomonas aeruginosa dual species biofilm model

Lung disease in cystic fibrosis (CF) is characterized by the progressive colonization of the respiratory tract by different bacteria, which develop polymicrobial biofilms. In the past decades, there has been an increase in the number of CF patients infected with Non-Tuberculous Mycobacteria (NTM). Although Mycobacterium abscessus is the main NTM isolated globally, little is known about M. abscessus multispecies biofilm formation. In the present study we developed an in vitro model to study the phenotypic characteristics of biofilms formed by M. abscessus and Pseudomonas aeruginosa, a major pathogen in CF. For that purpose, dual species biofilms were grown on polycarbonate membranes with a fixed concentration of P. aeruginosa and different inoculums of M. abscessus. The biofilms were sampled at 24, 48, and 72 h and bacteria were quantified in specific media. The results revealed that the increasing initial concentration of M. abscessus in dual species biofilms had an effect on its population only at 24 and 48 h, whereas P. aeruginosa was not affected by the different concentrations used of M. abscessus. Time elapsed increased biofilm formation of both species, specially between 24 and 48 h. According to the results, the conditions to produce a mature dual species biofilm in which the relative species distribution remained stable were 72 h growth of the mixed microbial culture at a 1:1 ratio. A significant decrease in mycobacterial population in dual compared to single species biofilms was found, suggesting that P. aeruginosa has a negative influence on M. abscessus. Finally, in a proof of concept experiment, young and mature dual species biofilms were exposed to clarithromycin.

Emergence and spread of a human-transmissible multidrug-resistant nontuberculous mycobacterium

Lung infections with Mycobacterium abscessus, a species of multidrug-resistant nontuberculous mycobacteria, are emerging as an important global threat to individuals with cystic fibrosis (CF), in whom M. abscessus accelerates inflammatory lung damage, leading to increased morbidity and mortality. Previously, M. abscessus was thought to be independently acquired by susceptible individuals from the environment. However, using whole-genome analysis of a global collection of clinical isolates, we show that the majority of M. abscessus infections are acquired through transmission, potentially via fomites and aerosols, of recently emerged dominant circulating clones that have spread globally. We demonstrate that these clones are associated with worse clinical outcomes, show increased virulence in cell-based and mouse infection models, and thus represent an urgent international infection challenge.

Outcomes associated with antibiotic regimens for treatment of Mycobacterium abscessus in cystic fibrosis patients

BACKGROUND

Mycobacterium abscessus infection is associated with declining lung function in cystic fibrosis (CF), but there is little evidence on clinical efficacy to guide treatment.

METHODS

Retrospective review of 37 CF patients treated for M. abscessus respiratory infection at a single center from 2006 to 2014. Outcomes included change in FEV₁ at 30, 60, 90, 180, and 365days after treatment and clearance of M. abscessus from sputum cultures.

RESULTS

Lung function was significantly improved after 30 and 60days of treatment, but not at later time points. Gains were inversely related to starting lung function. Antibiotic choices did not influence outcomes except for greater clearance with clarithromycin.

CONCLUSIONS

Treatment of M. abscessus resulted in short term improvement in lung function that is inversely related to pre-treatment FEV₁.

Household proximity to water and nontuberculous mycobacteria in children with cystic fibrosis

BACKGROUND

Nontuberculous mycobacteria (NTM) have a particular affinity for patients with cystic fibrosis (CF). Recent studies suggest a possible relationship between acquiring NTM and the level of environmental water in a given area. We sought to determine if there is an association between household proximity to water and NTM in children with CF.

MATERIALS AND METHODS

An IRB-approved retrospective chart review was completed on 150 children with CF in Florida. Inclusion criteria required regular follow-up, at least two acid-fast bacilli cultures, and a consistent home address over a 3-year period. The distance from each patient's home to the nearest body of water was measured using ArcMap®, a Geographic Information System, and the mean distance to water for NTM-positive and NTM-negative groups were compared. A stepwise backwards logistic regression was used to evaluate for predictors of NTM-positivity.

RESULTS

Of the 150 CF patients, 65 met inclusion criteria and 21 (32.3%) tested positive for NTM. Comparison of the mean distance to water for NTM-positive versus NTM-negative groups revealed a cutoff of 500 meters. On the logistic regression, CF patients who lived within 500 meters of water were 9.4 times more likely to acquire NTM (P = 0.013). Other significant predictors included a history of Aspergillus fumigatus (OR 7.9, P = 0.011) and recent history of Pseudomonas aeruginosa (OR 2.5, P = 0.007).

CONCLUSIONS

In the regions studied, children with CF who live closer to water are more likely to acquire nontuberculous mycobacteria. Future studies in other geographic areas are needed to determine if these results are generalizable. Pediatr Pulmonol. 2017;52:324-330. © 2016 Wiley Periodicals, Inc.

High incidence of non-tuberculous mycobacteria-positive cultures among adolescent with cystic fibrosis

BACKGROUND

We evaluated the prevalence of non-tuberculous mycobacteria (NTM)-positive cultures among our cystic fibrosis (CF) center patients, reviewed risk factors for NTM positivity, and determined its impact on lung function evolution.

METHODS

From 2009 to 2014, CF adults and children attending the CF center of Lyon (France) and having at least one positive NTM isolate were included. Each case was matched by age and gender with two CF patients with no NTM isolate (controls).

RESULTS

48 CF patients with NTM-positive isolates were matched to 96 controls. The age group for whom incident NTM was higher was young adolescents aged 13 to 17. A significant association for NTM positivity was found with Staphylococcusaureus in multivariate analysis and with allergic bronchopulmonary aspergillosis, corticosteroid and itraconazole in univariate analysis. Mean annual FEV1 decline was faster for NTM-positive patients compared to controls.

CONCLUSION

These data highlight the high incidence of NTM-positive cultures among young adolescents with CF.

Antibiotic treatment for nontuberculous mycobacteria lung infection in people with cystic fibrosis

BACKGROUND

Nontuberculous mycobacteria are mycobacteria, other than those in the Mycobacterium tuberculosis complex, and are commonly found in the environment. Nontuberculous mycobacteria species (most commonly Mycobacterium avium complex and Mycobacterium abscessus) are isolated from the respiratory tract of approximately 5% to 40% of individuals with cystic fibrosis; they can cause lung disease in people with cystic fibrosis leading to more a rapid decline in lung function and even death in certain circumstances. Although there are guidelines for the antimicrobial treatment of nontuberculous mycobacteria lung disease, these recommendations are not specific for people with cystic fibrosis and it is not clear which antibiotic regimen may be the most effective in the treatment of these individuals. This is an update of a previous review.

OBJECTIVES

The objective of our review was to compare antibiotic treatment to no antibiotic treatment, or to compare different combinations of antibiotic treatment, for nontuberculous mycobacteria lung infections in people with cystic fibrosis. The primary objective was to assess the effect of treatment on lung function and pulmonary exacerbations and to quantify adverse events. The secondary objectives were to assess treatment effects on the amount of bacteria in the sputum, quality of life, mortality, nutritional parameters, hospitalizations and use of oral antibiotics.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and hand searching of journals and conference abstract books. Date of last search: 02 September 2016.We also searched a register of ongoing trials and the reference lists of relevant articles and reviews. Date of last search: 03 November 2016.

SELECTION CRITERIA

Any randomized controlled trials comparing nontuberculous mycobacteria antibiotics to no antibiotic treatment, as well as one nontuberculous mycobacteria antibiotic regimen compared to another nontuberculous mycobacteria antibiotic regimen, in individuals with cystic fibrosis.   DATA COLLECTION AND ANALYSIS: Data were not collected because in the one trial identified by the search, data specific to individuals with cystic fibrosis could not be obtained from the pharmaceutical company.

MAIN RESULTS

One completed trial was identified by the searches, but data specific to individuals with cystic fibrosis could not be obtained from the pharmaceutical company.

AUTHORS' CONCLUSIONS

This review did not find any evidence for the effectiveness of different antimicrobial treatment for nontuberculous mycobacteria lung disease in people with cystic fibrosis. Until such evidence becomes available, it is reasonable for clinicians to follow published clinical practice guidelines for the diagnosis and treatment of nodular or bronchiectatic pulmonary disease due to Mycobacterium avium complex or Mycobacterium abscessus in patients with cystic fibrosis.

Nontuberculous Mycobacteria in Cystic Fibrosis

Nontuberculous mycobacteria (NTM) are found in approximately 10 % of cystic fibrosis (CF) patients, but only a portion will develop NTM disease. The management of CF lung disease should be optimized, including antibiotic therapy targeted to the individual's usual airway bacteria, prior to considering treatment for NTM lung disease. Those who meet criteria for NTM lung disease may not necessarily require treatment and could be monitored expectantly if symptoms and radiographic findings are minimal. However, the presence of Mycobacterium abscessus complex (MABSC), severe lung disease, and/or anticipated lung transplant should prompt NTM therapy initiation. For CF patients with Mycobacterium avium complex (MAC), recommended treatment includes triple antibiotic therapy with a macrolide, rifampin, and ethambutol. Azithromycin is generally our preferred macrolide in CF as it is better tolerated and has fewer drug-drug interactions. MABSC treatment is more complex and requires an induction phase (oral macrolide and two IV agents including amikacin) as well as a maintenance phase (nebulized amikacin and two to three oral antibiotics including a macrolide). The induction phase may range from one to three months (depending on infection severity, treatment response, and medication tolerability). For both MAC and MABSC, treatment duration is extended 1-year post-culture conversion. However, in patients who do not achieve culture negative status but tolerate therapy, we consider ongoing treatment for mycobacterial suppression and prevention of disease progression.

MgtC as a Host-Induced Factor and Vaccine Candidate against Mycobacterium abscessus Infection

Mycobacterium abscessus is an emerging pathogenic mycobacterium involved in pulmonary and mucocutaneous infections, presenting a serious threat for patients with cystic fibrosis (CF). The lack of an efficient treatment regimen and the emergence of multidrug resistance in clinical isolates require the development of new therapeutic strategies against this pathogen. Reverse genetics has revealed genes that are present in M. abscessus but absent from saprophytic mycobacteria and that are potentially involved in pathogenicity. Among them, MAB_3593 encodes MgtC, a known virulence factor involved in intramacrophage survival and adaptation to Mg(2+) deprivation in several major bacterial pathogens. Here, we demonstrated a strong induction of M. abscessus MgtC at both the transcriptional and translational levels when bacteria reside inside macrophages or upon Mg(2+) deprivation. Moreover, we showed that M. abscessus MgtC was recognized by sera from M. abscessus-infected CF patients. The intramacrophage growth (J774 or THP1 cells) of a M. abscessus knockout mgtC mutant was, however, not significantly impeded. Importantly, our results indicated that inhibition of MgtC in vivo through immunization with M. abscessus mgtC DNA, formulated with a tetrafunctional amphiphilic block copolymer, exerted a protective effect against an aerosolized M. abscessus challenge in CF (ΔF508 FVB) mice. The formulated DNA immunization was likely associated with the production of specific MgtC antibodies, which may stimulate a protective effect by counteracting MgtC activity during M. abscessus infection. These results emphasize the importance of M. abscessus MgtC in vivo and provide a basis for the development of novel therapeutic tools against pulmonary M. abscessus infections in CF patients.

Culture-Independent Identification of Nontuberculous Mycobacteria in Cystic Fibrosis Respiratory Samples

Respiratory tract infections with nontuberculous mycobacteria (NTM) are increasing in prevalence and are a significant cause of lung function decline in individuals with cystic fibrosis (CF). NTM have been detected in culture-independent analyses of CF airway microbiota at lower rates than would be expected based on published prevalence data, likely due to poor lysing of the NTM cell wall during DNA extraction. We compared a standard bacterial lysis protocol with a modified method by measuring NTM DNA extraction by qPCR and NTM detection with bacterial 16S rRNA gene sequencing. The modified method improved NTM DNA recovery from spiked CF sputum samples by a mean of 0.53 log10 copies/mL for M. abscessus complex and by a mean of 0.43 log10 copies/mL for M. avium complex as measured by qPCR targeting the atpE gene. The modified method also improved DNA sequence based NTM detection in NTM culture-positive CF sputum and bronchoalveolar lavage samples; however, both qPCR and 16S rRNA gene sequencing remained less sensitive than culture for NTM detection. We highlight the limitations of culture-independent identification of NTM from CF respiratory samples, and illustrate how alterations in the bacterial lysis and DNA extraction process can be employed to improve NTM detection with both qPCR and 16S rRNA gene sequencing.

Nontuberculous Mycobacterial Infections in Cystic Fibrosis

Nontuberculous mycobacteria (NTM) are important emerging cystic fibrosis (CF) pathogens, with estimates of prevalence ranging from 6% to 13%. Diagnosis of NTM disease in patients with CF is challenging, as the infection may remain indolent in some, without evidence of clinical consequence, whereas other patients suffer significant morbidity and mortality. Treatment requires prolonged periods of multiple drugs and varies depending on NTM species, resistance pattern, and extent of disease. The development of a disease-specific approach to the diagnosis and treatment of NTM infection in CF patients is a research priority, as a lifelong strategy is needed for this high-risk population.

Management of Pseudomonas aeruginosa infection in cystic fibrosis patients using inhaled antibiotics with a focus on nebulized liposomal amikacin

Pseudomonas aeruginosa (PsA) is a highly prevalent bacterial organism recovered from the lungs of cystic fibrosis (CF) patients and chronic PsA infection is linked to progressive pulmonary function decline. The eradication and treatment of this organism from CF airways is particularly challenging to CF care providers. Aerosolized antibiotics that target PsA help to slow down growth, maintain lung function and reduce the frequency of pulmonary exacerbations. In this review, we discuss the currently available inhaled antibiotics for management of PsA lung infections in CF patients, with a focus on liposomal amikacin for inhalation (LAI). LAI is a unique formulation of amikacin under development that enhances drug delivery and retention in CF airways via drug incorporation into neutral liposomes. Factors such as once-daily dosing, mucus and biofilm penetration and potentially prolonged off-drug periods make LAI a potentially attractive option to manage chronic PsA lung infections in CF patients.

Host susceptibility to non-tuberculous mycobacterial infections

Non-tuberculous mycobacteria cause a broad range of clinical disorders, from cutaneous infections, such as cervical or intrathoracic lymphadenitis in children, to disseminated infections at all ages. Recognition of the underlying immune defect is crucial for rational treatment, preventive care, family screening, and, in some cases, transplantation. So far, at least seven autosomal mutations (in IL12B, IL12RB1, ISG15, IFNGR1, IFNGR2, STAT1, and IRF8) and two X-linked mutations (in IKBKG and CYBB), mostly presenting in childhood, have been reported to confer susceptibility to disseminated non-tuberculous mycobacterial infection. GATA2 deficiency and anti-interferon γ autoantibodies also give rise to disseminated infection, typically in late childhood or adulthood. Furthermore, isolated pulmonary non-tuberculous mycobacterial infection has been increasing in prevalence in people without recognised immune dysfunction. In this Review, we discuss how to detect and differentiate host susceptibility factors underlying localised and systemic non-tuberculous mycobacterial infections.

Antibiotic treatment for nontuberculous mycobacteria lung infection in people with cystic fibrosis

BACKGROUND

Nontuberculous mycobacteria are mycobacteria, other than those in the Mycobacterium tuberculosis complex, and are commonly found in the environment. Nontuberculous mycobacteria species (most commonly Mycobacterium avium complex and Mycobacterium abscessus) are isolated from the respiratory tract of approximately 5% to 20% of individuals with cystic fibrosis; they can cause lung disease in people with cystic fibrosis leading to more a rapid decline in lung function and even death in certain circumstances. Although there are guidelines for the antimicrobial treatment of nontuberculous mycobacteria lung disease, these recommendations are not specific for people with cystic fibrosis and it is not clear which antibiotic regimen may be the most effective in the treatment of these patients.

OBJECTIVES

The objective of our review was to compare antibiotic treatment to no antibiotic treatment, or to compare different combinations of antibiotic treatment, for nontuberculous mycobacteria lung infections in people with cystic fibrosis. The primary objective was to assess the effect of treatment on lung function and pulmonary exacerbations and to quantify adverse events. The secondary objectives were to assess treatment effects on the amount of bacteria in the sputum, quality of life, mortality, nutritional parameters, hospitalizations and use of oral antibiotics.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and hand searching of journals and conference abstract books. Date of last search: 13 November 2014.We also searched a register of ongoing trials and the reference lists of relevant articles and reviews. Date of last search: 24 September 2014.

SELECTION CRITERIA

Any randomized controlled trials comparing nontuberculous mycobacteria antibiotics to no antibiotic treatment, as well as one nontuberculous mycobacteria antibiotic regimen compared to another nontuberculous mycobacteria antibiotic regimen, in individuals with cystic fibrosis.  

DATA COLLECTION AND ANALYSIS

Data were not collected because no completed trials were identified by the searches.

MAIN RESULTS

No completed trials were identified by the searches, but one ongoing trial was identified, which may be eligible for inclusion in this review when completed.

AUTHORS' CONCLUSIONS

This review did not find any evidence for the effectiveness of different antimicrobial treatment for nontuberculous mycobacteria lung disease in people with cystic fibrosis. Until such evidence becomes available, it is reasonable for clinicians to follow the American Thoracic Society guidelines for the diagnosis and treatment of nodular or bronchiectatic pulmonary disease due to Mycobacterium avium complex or Mycobacterium abscessus in patients with cystic fibrosis.

Clinical significance of a first positive nontuberculous mycobacteria culture in cystic fibrosis

RATIONALE

Little is known about outcomes of infection with nontuberculous mycobacteria (NTM) in cystic fibrosis (CF) or about the significance of a positive NTM culture. Determining which patients are at risk for active NTM disease is clinically valuable.

OBJECTIVES

To examine the clinical course of subjects with CF with an initial positive NTM culture and identify characteristics associated with active NTM disease.

METHODS

We performed a retrospective study of pediatric and adult subjects with CF with at least one positive NTM culture at the Colorado CF Center from 2000 to 2010.

MEASUREMENTS AND MAIN RESULTS

Mycobacterium avium complex was the first identified NTM in the majority of subjects (73%). The frequency of growing a second NTM species was 26% at 5 years. Clinical characteristics and distribution of NTM species between pediatric and adult subjects were similar except for differences in baseline FEV1 (89% vs. 71%; P < 0.001) and coinfection with Pseudomonas aeruginosa (33% vs. 55%; P = 0.04). Over 60% of subjects had transient or persistent infection but not active NTM disease. Subjects who developed active NTM disease were distinguished from those with transient or persistent infection, respectively, by FEV1 at the time of first positive NTM culture (72% vs. 84 or 86%; P = 0.02) and FEV1 decline in the prior year (-5.8%/yr vs. -0.7%/yr [P = 0.009] or -0.4%/yr [P = 0.001]).

CONCLUSIONS

The majority of patients with CF with a first positive NTM culture do not progress to active disease. Lower lung function and accelerated lung function decline appear to be indicators of the significance of an initial positive NTM culture.

Epidemiology of nontuberculous mycobacteria among patients with cystic fibrosis in Scandinavia

Background

Nontuberculous mycobacteria (NTM) are an emerging threat to cystic fibrosis (CF) patients but their epidemiology is not well described.

Methods

In this retrospective observational study we identified all Scandinavian CF patients with a positive NTM culture from airway secretions from 2000 to the end of 2012 and used national CF databases to describe microbiological and clinical characteristics.

Results

During the 13-year period 157 (11%) CF patients were culture positive for NTM at least once. Mycobacterium abscessus complex (MABSC) (45%) and Mycobacterium avium complex (MAC) (32%) were the predominant species with geographical differences in distribution. Younger patients were more prone to MABSC (p < 0.01). Despite treatment, less than one-third of MABSC patients with repeated positive cultures cleared their infection and a quarter had a lung transplant or died.

Conclusion

NTM are significant CF pathogens and are becoming more prevalent in Scandinavia. MABSC and MAC appear to target distinct patient groups. Having multiple positive cultures despite treatment conveys a poor outcome.

Multidrug-resistant nontuberculous mycobacteria isolated from cystic fibrosis patients

Worldwide, nontuberculous mycobacteria (NTM) have become emergent pathogens of pulmonary infections in cystic fibrosis (CF) patients, with an estimated prevalence ranging from 5 to 20%. This work investigated the presence of NTM in sputum samples of 129 CF patients (2 to 18 years old) submitted to longitudinal clinical supervision at a regional reference center in Rio de Janeiro, Brazil. From June 2009 to March 2012, 36 NTM isolates recovered from 10 (7.75%) out of 129 children were obtained. Molecular identification of NTM was performed by using PCR restriction analysis targeting the hsp65 gene (PRA-hsp65) and sequencing of the rpoB gene, and susceptibility tests were performed that followed Clinical and Laboratory Standards Institute recommendations. For evaluating the genotypic diversity, pulsed-field gel electrophoresis (PFGE) and/or enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR) was performed. The species identified were Mycobacterium abscessus subsp. bolletii (n = 24), M. abscessus subsp. abscessus (n = 6), Mycobacterium fortuitum (n = 3), Mycobacterium marseillense (n = 2), and Mycobacterium timonense (n = 1). Most of the isolates presented resistance to five or more of the antimicrobials tested. Typing profiles were mainly patient specific. The PFGE profiles indicated the presence of two clonal groups for M. abscessus subsp. abscessus and five clonal groups for M. abscesssus subsp. bolletii, with just one clone detected in two patients. Given the observed multidrug resistance patterns and the possibility of transmission between patients, we suggest the implementation of continuous and routine investigation of NTM infection or colonization in CF patients, including countries with a high burden of tuberculosis disease.

Nontuberculous mycobacteria: the changing epidemiology and treatment challenges in cystic fibrosis

PURPOSE OF REVIEW

Although patients with cystic fibrosis (CF) face numerous infectious pathogens over the course of their lifespan, increasing attention has recently been paid to nontuberculous mycobacteria (NTM). As reported prevalence rates rise across many countries such as the United States, the ability to recognize disease caused by NTM and subsequently treat such disease has become increasingly important. This review summarizes new observations on the epidemiology of NTM in CF as well as key elements to consider during the treatment phase.

RECENT FINDINGS

Although overall rates of NTM isolation appear to be increasing, particular concern has focused on the emerging predominance of Mycobacterium abscessus. New data suggest that chronic macrolide therapy now part of routine CF care has contributed to this rise; however, these have yet to be confirmed prospectively. Transmission of M. abscessus between CF patients has also now been described through the use of genome sequencing. Although the greater virulence of M. abscessus makes it a challenging species to treat, identification of the subspecies type can now determine the presence of inducible macrolide resistance, thereby helping to guide treatment.

SUMMARY

Given increasing prevalence rates, clinicians should maintain a high level of suspicion for NTM as disease-causing organisms in CF, particularly for M. abscessus. New knowledge regarding this species, however, can help to tailor appropriate therapy.

Shifting paradigms of nontuberculous mycobacteria in cystic fibrosis

Important paradigms of pulmonary disease with nontuberculous mycobacteria (NTM) are currently shifting based on an increasing attention within the field of cystic fibrosis (CF). These shifts are likely to benefit the management of all patients with pulmonary NTM, regardless of underlying pathology. Currently several key areas are being revised: The first outbreak of human NTM transmission has been proven and new evidence of biofilm growth in vivo has been demonstrated. A better understanding of the clinical impact of NTM infection has led to increased diagnostic vigilance and new recommendations for lung transplantation are under way. While recent changes have reinvigorated the interest in NTM disease, the challenge remains, whether such advances can be successfully translated into improved management and care.

Multilocus sequence typing scheme for the Mycobacterium abscessus complex

We developed a multilocus sequence typing (MLST) scheme for Mycobacterium abscessus sensu lato, based on the partial sequencing of seven housekeeping genes: argH, cya, glpK, gnd, murC, pta and purH. This scheme was used to characterize a collection of 227 isolates recovered between 1994 and 2010 in France, Germany, Switzerland and Brazil. We identified 100 different sequence types (STs), which were distributed into three groups on the tree obtained by concatenating the sequences of the seven housekeeping gene fragments (3576bp): the M. abscessus sensu stricto group (44 STs), the "M. massiliense" group (31 STs) and the "M. bolletii" group (25 STs). SplitTree analysis showed a degree of intergroup lateral transfers. There was also evidence of lateral transfer events involving rpoB. The most prevalent STs in our collection were ST1 (CC5; 20 isolates) and ST23 (CC3; 31 isolates). Both STs were found in Europe and Brazil, and the latter was implicated in a large post-surgical procedure outbreak in Brazil. Respiratory isolates from patients with cystic fibrosis belonged to a large variety of STs; however, ST2 was predominant in this group of patients. Our MLST scheme, publicly available at www.pasteur.fr/mlst, offers investigators a valuable typing tool for M. abscessus sensu lato in future epidemiological studies throughout the world.

Epidemiology of nontuberculous mycobacterial infections and associated chronic macrolide use among persons with cystic fibrosis

RATIONALE

Persons with cystic fibrosis (CF) are at high risk of nontuberculous mycobacterial (NTM) infection, with treatment requiring prolonged multidrug regimens that include macrolides. Although macrolides, specifically azithromycin, are used in the management of patients with CF with chronic Pseudomonas, macrolide-resistant NTM infections are of growing concern.

OBJECTIVES

To evaluate the relationship between chronic macrolide use and NTM infection among patients with CF included in the 2011 CF Patient Registry (CFPR).

METHODS

We performed a nested case-control study: incident NTM cases were persons aged more than 5 years with at least one positive culture for NTM in 2011. Controls were persons with negative cultures in 2010 and 2011.

MEASUREMENTS AND MAIN RESULTS

The 2011 CFPR included 27,112 patients; 5,403 (20%) were cultured for mycobacteria in 2010-2011 and met all inclusion criteria. Of these, 191 (4%) were NTM-positive in 2011 only (cases); 5,212 (96%) were NTM-negative in 2010 and 2011 (control subjects). Among the cases, 122 (64%) were culture-positive for Mycobacterium avium complex (MAC) and 69 (36%) for M. abscessus. Azithromycin use in 2010 was less frequently reported among MAC cases (57%; odds ratio = 0.7, P < 0.05) and M. abscessus cases (51%; odds ratio = 0.5, P < 0.01) than in control subjects (66%). Among adolescents and adults, patients with the greatest number of years on chronic macrolides were the least likely to develop incident NTM in 2011 (P < 0.01).

CONCLUSIONS

Patients with incident NTM infections from either MAC or M. abscessus were less likely to have had chronic azithromycin treatment in the past year. However, because macrolide monotherapy may lead to macrolide resistance, routine screening for NTM should be considered for persons with CF.

Antibiotic treatment for nontuberculous mycobacteria lung infection in people with cystic fibrosis

BACKGROUND

Nontuberculous mycobacteria are mycobacteria, other than those in the Mycobacterium tuberculosis complex, and are commonly found in the environment. Nontuberculous mycobacteria species (most commonly Mycobacterium avium complex and Mycobacterium abscessus) are isolated from the respiratory tract of approximately 5% to 20% of individuals with cystic fibrosis; they can cause lung disease in people with cystic fibrosis leading to more a rapid decline in lung function and even death in certain circumstances. Although there are guidelines for the antimicrobial treatment of nontuberculous mycobacteria lung disease, these recommendations are not specific for people with cystic fibrosis and it is not clear which antibiotic regimen may be the most effective in the treatment of these patients.

OBJECTIVES

The objective of our review was to compare antibiotic treatment to no antibiotic treatment, or to compare different combinations of antibiotic treatment, for nontuberculous mycobacteria lung infections in people with cystic fibrosis. The primary objective was to assess the effect of treatment on lung function and pulmonary exacerbations and to quantify adverse events. The secondary objectives were to assess treatment effects on the amount of bacteria in the sputum, quality of life, mortality, nutritional parameters, hospitalizations and use of oral antibiotics.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and hand searching of journals and conference abstract books. Date of last search: 19 July 2012.We also searched a register of ongoing trials and the reference lists of relevant articles and reviews. Date of last search: 10 August 2012.

SELECTION CRITERIA

Any randomized controlled trials comparing nontuberculous mycobacteria antibiotics to no antibiotic treatment, as well as one nontuberculous mycobacteria antibiotic regimen compared to another nontuberculous mycobacteria antibiotic regimen, in individuals with cystic fibrosis.  

DATA COLLECTION AND ANALYSIS

Data were not collected because no completed trials were identified by the searches.

MAIN RESULTS

No completed trials were identified by the searches, but one ongoing trial was identified, which may be eligible for inclusion in this review when completed.

AUTHORS' CONCLUSIONS

This review did not find any evidence for the effectiveness of different antimicrobial treatment for nontuberculous mycobacteria lung disease in people with cystic fibrosis. Until such evidence becomes available, it is reasonable for clinicians to follow the American Thoracic Society guidelines for the diagnosis and treatment of nodular or bronchiectatic pulmonary disease due to Mycobacterium avium complex or Mycobacterium abscessus in patients with cystic fibrosis.

Comparative drug resistance of Mycobacterium abscessus and M. chelonae isolates from patients with and without cystic fibrosis in the United Kingdom

The isolation of rapidly growing mycobacteria (RGM), particularly Mycobacterium abscessus, from individuals with cystic fibrosis (CF) is associated with poor clinical outcome due to broad drug resistance and the difficulty of eradicating the organisms. Susceptibility testing is recommended to guide therapy. A disc diffusion method is used in the United Kingdom, whereas in the United States, the CLSI (Clinical and Laboratory Standards Institute) recommends the broth dilution method. The purpose of this study was to investigate whether the two methods produced comparable drug resistance profiles and to test the hypotheses that the disc diffusion method overscores resistance and that isolates of M. abscessus/M. chelonae from CF patients are more likely than those from non-CF patients to show drug resistance, as a result of CF patients' greater exposure to antibiotic therapy. A total of 82 isolates (58 M. abscessus and 24 M. chelonae isolates) were tested blindly against 15 antimicrobials by broth dilution and the disc diffusion method. Isolates tested by the broth microdilution showed high levels of resistance; susceptibility to amikacin, clarithromycin, tobramycin (only in M. chelonae), and cefoxitin (only in M. abscessus) was shown. Tigecycline results varied widely depending on which breakpoint was used. Agreement between methods for a few drugs (e.g., cefoxitin and amikacin) was poor. Although there were drug resistance differences between CF and non-CF isolates, these did not reach statistical significance. The CLSI method provided more robust breakpoints, standardization, and reproducibility. An analysis of the implementation of the CLSI method demonstrated ease of use and similar drug resistance findings for the two species.