Genetic stability of Mycobacterium abscessus during antibiotic treatment.

OBJECTIVES: Genetic changes in Mycobacterium abscessus during antibiotic treatment are not fully understood. This study aimed to investigate the genetic changes in M. abscessus in patients receiving antibiotic treatment, and their clinical implications. METHODS: Pretreatment and 12-month post-treatment M. abscessus isolates were obtained from patients with M. abscessus pulmonary disease. Isolates from each time point were separated into six groups based on their distinctive morphological characteristics. Twenty-four isolates, comprising 12 from patient A exhibiting progressive disease and 12 from patient B demonstrating stable disease, underwent sequencing. Subsequently, minimal inhibitory concentrations (MICs) for the administered antibiotics were measured. RESULTS: Persistent infection with a single strain was observed in patients A and B. During 12 months of treatment, MICs for administered drugs did not generally change over time in either patient and single nucleotide variations (SNV) associated with antimicrobial resistance (rrl, rrs, erm(41), gyrA, gyrB, whiB7 and hflX) were not mutated. Although not significant, 47 and 52 non-synonymous SNVs occurred in M. abscessus from patients A and B, respectively, and the accumulation of these SNVs differed in patients A and B, except for five SNVs. The most variable positions were within a probable NADH-dependent glutamate synthase gene and a putative YrbE family protein gene in patients A and B, respectively. CONCLUSIONS: Persistent infections by a single strain of M. abscessus were observed in two patients with different clinical courses. Genetic changes in M. abscessus during antibiotic treatment were relatively stable in these patients. CLINICAL TRIALS IDENTIFIER: NCT01616745 (ClinicalTrials.gov ID).

Treatment outcome of continuation of intravenous amikacin for Mycobacterium abscessus pulmonary disease with a persistent culture positivity after the treatment initiation.

INTRODUCTION: Whether prolonged intravenous amikacin treatment would lead to better treatment results in patients with Mycobacterium abscessus subspecies abscessus (M. abscessus) pulmonary disease (PD) is unknown. We investigated the efficacy of continued amikacin treatment for the microbiological outcome of M. abscessus PD patients with persistent culture positivity after treatment initiation. METHODS: We retrospectively evaluated 62 patients with M. abscessus PD who were treated with intravenous amikacin and beta-lactams along with a macrolide-based regimen at 3 tertiary referral centers in South Korea. The intravenous antibiotic treatment duration was determined by the attending physician. RESULTS: The median treatment durations with amikacin and beta-lactam in the 62 patients were 25.1 and 8.2 weeks, respectively. The overall microbiological cure rate was 29.0%. Among the 62 patients, 44 showed persistent culture positivity at 8 weeks after treatment with an amikacin-containing multidrug regimen. The median parenteral amikacin treatment duration after 8 weeks in these patients was 18.0 weeks. The conditional probability of microbiological cure with continuation of the amikacin-containing regimen in these patients was 18.2% (95% confidence interval 8.2-32.7). Additionally, the conditional probability of microbiological cure in the 34 patients with persistent culture positivity at 12 weeks was 8.8% (95% confidence interval 1.9-23.7). After 16 weeks, the conditional probability of microbiological cure decreased further, reaching 0% at 28 weeks after treatment initiation. CONCLUSION: The continuation of intravenous amikacin therapy was usually not followed by culture conversion in M. abscessus PD patients with persistent sputum culture positivity after treatment initiation.

Minimal Inhibitory Concentration of Clofazimine Among Clinical Isolates of Nontuberculous Mycobacteria and Its Impact on Treatment Outcome.

BACKGROUND: Clofazimine has been regarded as a promising agent for the treatment of nontuberculous mycobacteria pulmonary disease (NTM-PD). However, its overall effectiveness in vitro and in the clinic remains unknown. RESEARCH QUESTION: What is the minimal inhibitory concentration (MIC) of clofazimine in clinical isolates and the association between MICs and treatment outcome? STUDY DESIGN AND METHODS: MICs for clofazimine were measured in clinical isolates from NTM-PD patients who participated in a prospective study at Seoul National University Hospital. The MIC was determined by using the broth microdilution concentration method. Correlation between MIC and conversion to negative of sputum culture with clofazimine was determined. RESULTS: Of a total 189 isolates, 133 strains were Mycobacterium avium complex (MAC) and 40 strains were M abscessus. Although the clofazimine MICs for MAC ranged from 0.031 mg/L to 8 mg/L, the values obtained for M abscessus ranged from 0.031 mg/L to 16 mg/L. Of 20 patients who were treated with a regimen including clofazimine, eight achieved negative conversion of sputum culture. All patients with isolates exhibiting clofazimine MIC values ≤ 0.25 mg/L achieved culture conversion. The likelihood of culture conversion in patients with MIC value ≤ 0.25 mg/L was much higher than that of patients with MIC value > 0.5 mg/L (OR, 39.3; P = .021). INTERPRETATION: The MICs of clofazimine varied widely in clinical isolates from patients with NTM-PD. Negative conversion of sputum culture with clofazimine use was associated with a lower MIC value. Clofazimine use could be considered in patients with NTM-PD when the MIC value is ≤ 0.25 mg/L. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT01616745; URL: www.clinicaltrials.gov.

Changes in treatment for multidrug-resistant tuberculosis according to national income.

The aim of this study was to analyse temporal changes in treatments for and outcomes of multidrug-resistant (MDR)/rifampin-resistant (RR)-tuberculosis (TB) in the context of national economic status.We analysed data collected by the Collaborative Group for the Meta-Analysis of Individual Patient Data in MDR-TB Treatment on MDR/RR-TB patients from 37 countries. The data were stratified by three national income levels (low-/lower-middle, upper-middle and high) and grouped by time of treatment initiation (2001-2003, 2004-2006, 2007-2009, 2010-2012 and 2013-2015). Temporal trends over the study period were analysed. The probability of treatment success in different income groups over time was calculated using generalised linear mixed models with random effects.In total, 9036 patients were included in the analysis. Over the study period, use of group A drugs (levofloxacin/moxifloxacin, bedaquiline and linezolid) recommended by the World Health Organization increased and treatment outcomes improved in all income groups. Between 2001-2003 and 2013-2015, treatment success rates increased from 60% to 78% in low-/lower-middle-income countries, from 40% to 67% in upper-middle-income countries, and from 73% to 81% in high-income countries. In earlier years, the probability of treatment success in upper-middle-income countries was lower than that in low-/lower-middle-income countries, but no difference was observed after 2010. However, high-income countries had persistently higher probability of treatment success compared to upper-middle income countries.Improved treatment outcomes and greater uptake of group A drugs were observed over time for patients with MDR/RR-TB at all income levels. However, treatment outcomes are still unsatisfactory, especially in upper-middle-income countries.

M ycobacterium abscessus pulmonary disease: individual patient data meta-analysis.

Treatment of Mycobacterium abscessus pulmonary disease (MAB-PD), caused by M. abscessus subsp. abscessus, M. abscessus subsp. massiliense or M. abscessus subsp. bolletii, is challenging.We conducted an individual patient data meta-analysis based on studies reporting treatment outcomes for MAB-PD to clarify treatment outcomes for MAB-PD and the impact of each drug on treatment outcomes. Treatment success was defined as culture conversion for ≥12 months while on treatment or sustained culture conversion without relapse until the end of treatment.Among 14 eligible studies, datasets from eight studies were provided and a total of 303 patients with MAB-PD were included in the analysis. The treatment success rate across all patients with MAB-PD was 45.6%. The specific treatment success rates were 33.0% for M. abscessus subsp. abscessus and 56.7% for M. abscessus subsp. massiliense For MAB-PD overall, the use of imipenem was associated with treatment success (adjusted odds ratio (aOR) 2.65, 95% CI 1.36-5.10). For patients with M. abscessus subsp. abscessus, the use of azithromycin (aOR 3.29, 95% CI 1.26-8.62), parenteral amikacin (aOR 1.44, 95% CI 1.05-1.99) or imipenem (aOR 7.96, 95% CI 1.52-41.6) was related to treatment success. For patients with M. abscessus subsp. massiliense, the choice among these drugs was not associated with treatment outcomes.Treatment outcomes for MAB-PD are unsatisfactory. The use of azithromycin, amikacin or imipenem was associated with better outcomes for patients with M. abscessus subsp. abscessus.