Treatment of Nontuberculous Mycobacterial Pulmonary Disease: An Official ATS/ERS/ESCMID/IDSA Clinical Practice Guideline

The epidemiology of pulmonary Mycobacterium abscessus species in Japanese population

BACKGROUND

Mycobacterium abscessus species (MABS) is now a most virulent rapidly growing mycobacteria (RGM), and the rapid increase of MABS was recently observed worldwide, including in Japan. Thus, we gathered evidences of the presence of pulmonary MABS in Japanese population from Japanese articles.

METHODS

we searched studies that addressed the isolation of pulmonary non-tuberculous Mycobacteria (NTM) or MABS from clinical respiratory specimens in Japan.

RESULTS

the ratio of MABS to NTM was 3.04% (95% confidence interval [CI]: 2.51-3.68), found using the meta-analysis of single proportions. The estimated mean age of patients infected with MABS was 67.72 years (95% CI: 65.41-70.02), found using the meta-analysis of single means. The estimated proportion of females, never smoker, and the co-infection with Mycobacterium avium complex (MAC) was 66.75% (95% CI: 59.23-73.50), 67.57% (95% CI: 62.43-72.32), and 36.74% (95% CI: 25.30-49.90), respectively. The characteristics of MABS in Japan were considerably different from that in Europe and United States from the perspective of age, gender, and complications, wherein the patients in these countries tended to be younger, had lower number of females, and had more occurrences of hereditary diseases, including cystic fibrosis (CF).

CONCLUSION

we hypothesized that the characteristics of MABS in the Japanese were involved in those of non-CF MABS, and the distribution of gender and age of MABS were similar to that of MAC in the Japanese.

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.

Improvement in Health-Related Quality of Life Following Antibiotic Treatment in Nontuberculous Mycobacterial Pulmonary Disease: Initial Analysis of the NTM-KOREA Cohort

BACKGROUND

Improving health-related quality of life (HRQOL) has emerged as a priority in the management of nontuberculous mycobacterial pulmonary disease (NTM-PD). We aimed to evaluate HRQOL and its changes after 6 months' treatment in patients with NTM-PD.

METHODS

The NTM-KOREA is a nationwide prospective cohort enrolling patients initiating treatment for NTM-PD in 8 institutions across South Korea. We conducted the Quality of Life-Bronchiectasis (QOL-B) at 6-month intervals and evaluated baseline scores (higher scores indicate better quality of life) and changes after 6 months' treatment. Multivariate logistic regression was performed to identify factors associated with improvement in the QOL-B physical functioning and respiratory symptoms domains.

RESULTS

Between February 2022 and August 2023, 411 patients were included in the analysis. Baseline scores (95% confidence interval [CI]) for physical functioning and respiratory symptoms were 66.7 (46.7-86.7) and 81.5 (70.4-92.6), respectively. Among 228 patients who completed the QOL-B after 6 months' treatment, improvements in physical functioning and respiratory symptoms were observed in 61 (26.8%) and 71 (31.1%) patients, respectively. A lower score (adjusted odds ratio; 95% CI) for physical functioning (0.93; 0.91-0.96) and respiratory symptoms (0.92; 0.89-0.95) at treatment initiation was associated with a greater likelihood of physical functioning and respiratory symptom improvement, respectively; achieving culture conversion was not associated with improvement in physical functioning (0.62; 0.28-1.39) or respiratory symptoms (1.30; 0.62-2.74).

CONCLUSIONS

After 6 months of antibiotic treatment for NTM-PD, HRQOL improved in almost one-third, especially in patients with severe initial symptoms, regardless of culture conversion.

CLINICAL TRIALS REGISTRATION

ClinicalTrials.gov identifier: NCT03934034.

Changes in Skin Discoloration according to Clofazimine Dosage in Nontuberculous Mycobacterial Pulmonary Disease

Although clofazimine is currently one of the standard regimens for Mycobacterium abscessus, it frequently causes skin discoloration, posing esthetic concerns for patients. We studied thirteen Asian patients with pulmonary nontuberculous mycobacterial disease treated with clofazimine at the NHO Kinki Chuo Chest Medical Center. In three patients (two women and one man) whose dosing regimens were altered owing to skin discoloration, we continuously measured luminance (L*), red-green (a*), and yellow-blue (b*) values (using a colorimeter) in both sun-exposed and sun-unexposed skin areas at each visit. Compared to baseline L* and a* values, the ΔL* values were negative (decreased brightness) and Δa* values were positive (increased redness) while patients received daily clofazimine. After switching to intermittent or reduced dosing, these changes gradually diminished. If such a dose reduction does not affect the therapeutic outcome, an even lower clofazimine dose may be attempted to minimize skin adverse effects.

In vitro effects of the new oral β-lactamase inhibitor xeruborbactam in combination with oral β-lactams against clinical Mycobacterium abscessus isolates

Non-tuberculosis mycobacteria (NTM), particularly Mycobacterium abscessus subsp. abscessus (M. abscessus), are increasingly being recognized as etiological agents of NTM pulmonary disease. However, treatment options for M. abscessus are limited owing to their natural resistance to most antibiotics, including β-lactams. M. abscessus produces a class A β-lactamase, whose activity is inhibited by cyclic boronic acid β-lactamase inhibitors. We aimed to evaluate the in vitro effects of xeruborbactam, a cyclic boronic acid β-lactamase inhibitor, against M. abscessus when combined with five β-lactams (amoxicillin, tebipenem, cefdinir, cefuroxime, and cefoxitin). The drug susceptibilities of 43 M. abscessus clinical isolates obtained from 43 patients between August 2005 and May 2014 were tested. The MIC results for each β-lactam with or without 4 µg/mL xeruborbactam were examined. Xeruborbactam lowered the MIC90 values of tebipenem, amoxicillin, cefuroxime, and cefdinir by 5, ≥4, 3, and 3 dilutions, respectively. The MIC90 values of cefoxitin without xeruborbactam were 32 µg/mL and did not change upon the addition of xeruborbactam. The lowest MIC90 value was obtained for tebipenem with xeruborbactam. Almost all isolates had an MIC of 4 µg/mL; one isolate had an MIC of 2 µg/mL. With respect to the susceptibility to the same family drug, the number of susceptible isolates increased from 1/43 (2%) to 43/43 (100%) for tebipenem with xeruborbactam. Combining tebipenem and xeruborbactam could be considered an effective all-oral regimen that benefits outpatient treatment of M. abscessus pulmonary disease.

IMPORTANCE

Mycobacterium abscessus subsp. abscessus (M. abscessus) disease is treated in two phases; injectable drugs for initial followed by others for continuation. There is a need to develop all-oral treatment methods for M. abscessus infection, especially in the continuation phase. However, treatment options for M. abscessus are limited owing to their natural resistance to most antibiotics. This is the first report to evaluate the in vitro effects of xeruborbactam, a cyclic boronic acid β-lactamase inhibitor capable of inhibiting the class A β-lactamase produced by M. abscessus, against 43 M. abscessus clinical isolates when combined with five β-lactam antibiotics. Xeruborbactam lowered the MIC90 values of tebipenem by five dilutions, and the number of susceptible isolates increased from 1/43 (2%) to 43/43 (100%). We showed that the tebipenem-xeruborbactam combination might be of interest to explore further as a potentially effective oral regimen for outpatient treatment of M. abscessus pulmonary disease.

Minimum inhibitory concentrations of azithromycin in clinical isolates of Mycobacterium avium complex in Japan

The latest guidelines include azithromycin as a preferred regimen for treating Mycobacterium avium complex (MAC) pulmonary disease. However, serially collected susceptibility data on clinical MAC isolates are limited, and no breakpoints have been determined. We investigated the minimum inhibitory concentrations (MICs) of azithromycin and clarithromycin for all MAC strains isolated in 2021 from a single center in Japan, excluding duplicates. The MICs were determined using a panel based on the microbroth dilution method, according to the latest Clinical and Laboratory Standards Institute recommendations. The MICs were determined for 318 MAC strains. Although there was a significant positive correlation between the MICs of azithromycin and clarithromycin, the MICs of azithromycin tended to be higher than those of clarithromycin. Among the cases in which the strains were isolated, 18 patients initiated treatment, including azithromycin treatment, after sample collection. Some patients infected with stains with relatively high azithromycin MICs achieved a microbiological cure with azithromycin-containing regimens. This study revealed a higher MIC distribution for azithromycin than clarithromycin, raising questions about the current practice of estimating azithromycin susceptibility based on the clarithromycin susceptibility test result. However, this was a single-center study that included only a limited number of cases treated with azithromycin. Therefore, further multicenter studies that include a greater number of cases treated with azithromycin are warranted to verify the distribution of azithromycin MICs and examine the correlation between azithromycin MICs and treatment effectiveness.IMPORTANCEThe macrolides serve as key drugs in the treatment of pulmonary Mycobacterium avium complex infection, and the administration of macrolide should be guided by susceptibility test results. Azithromycin is recommended as a preferred choice among macrolides, surpassing clarithromycin; however, drug susceptibility testing is often not conducted, and clarithromycin susceptibility is used as a surrogate. This study represents the first investigation into the minimum inhibitory concentration of azithromycin on a scale of several hundred clinical isolates, revealing an overall tendency for higher minimum inhibitory concentrations compared with clarithromycin. The results raise questions about the appropriateness of using clarithromycin susceptibility test outcomes for determining the administration of azithromycin. This study highlights the need for future discussions on the clinical breakpoints of azithromycin, based on large-scale clinical research correlating azithromycin susceptibility with treatment outcomes.

Epidemiology of Mycobacterium abscessus

BACKGROUND

Nontuberculous mycobacteria (NTM) are highly abundant in soil, dust, and water sources, making human-pathogen contact frequent and recurrent. NTM represents over 200 species/subspecies; some are considered strict or opportunistic pathogens. Mycobacterium abscessus, often regarded as one of the most antibiotic-resistant mycobacteria, is the second most frequent NTM pulmonary disease pathogen.

OBJECTIVES

To describe the epidemiology of M. abscessus through a literature review focusing on clinical aspects.

SOURCES

We conducted searches on PubMed and Web of Knowledge for articles published from 2010 to the present using the keywords 'Mycobacterium abscessus', 'Nontuberculous mycobacteria', and 'epidemiology'. Our search prioritized original reports on the occurrence of NTM and M. abscessus infection/disease.

CONTENT

Advanced molecular and genetic diagnostic techniques have refined the M. abscessus complex (MABC) microbiological classification over the last few decades. MABC can adhere to surfaces and form a biofilm. This characteristic and its resistance to common disinfectants allow these microorganisms to persist in the water distribution systems, becoming a constant reservoir. The frequency and manifestation of NTM species vary geographically because of environmental conditions and population susceptibility differences. MABC lung disease, the most frequent site of NTM infection in humans, is often seen in patients with underlying lung diseases such as bronchiectasis, whereas MABC disseminated disease is related to immunosuppression. Skin and soft tissue infections are associated with surgical or injection procedures. Epidemiological evidence suggests an overall increase in MABC infection and disease in the last decade.

IMPLICATIONS

Establishing the burden of this disease is challenging because of varying measures of incidence and prevalence, referral bias, and differences in medical practices and reporting. Furthermore, environmental and structural determinants, infection routes, and MABC pulmonary disease mechanisms require additional investigation. This review contributes to a better understanding of the epidemiology of MABC, which could inform clinical practice and future research.

Antimicrobial susceptibility of Mycobacterium abscessus and treatment of pulmonary and extra-pulmonary infections

BACKGROUND

Mycobacterium abscessus (MAB) is the mycobacterial species least susceptible to antimicrobials. Infections are difficult to treat, and cure rates are below 50% even after a combination of 4-5 drugs for many months.

OBJECTIVES

To examine antimicrobial susceptibilities and treatment recommendations in light of what is known about mechanisms of resistance and pharmacodynamics/pharmacokinetics (PK/PD) interactions.

SOURCES

Original papers on the topics of 'antimicrobials', 'susceptibility', 'treatment', and 'outcome' from 2019 onwards, in the context of the evidence brought by the guidelines published in 2020 for pulmonary infections.

CONTENT

MAB is susceptible in vitro to only a few antimicrobials. Breakpoints were set by the Clinical and Laboratory Standards Institute and are revised by the European Committee on Antimicrobial Susceptibility Testing for epidemiological cut-off values. Innate resistance is due to multiple resistance mechanisms involving efflux pumps, inactivating enzymes, and low drug-target affinity. In addition, MAB may display acquired resistance to macrolides and amikacin through mutations in drug binding sites. Treatment outcomes are better for macrolide-based combinations and MAB subspecies massiliense. New compounds in the family of cyclines, oxazolidinones, and penem-β-lactamase inhibitor combinations (described in another paper), as well as bedaquiline, a new antituberculous agent, are promising, but their efficacy remains to be proven. PK/PD studies, which are critical for establishing optimal dosing regimens, were mainly done for monotherapy and healthy individuals.

IMPLICATIONS

Medical evidence is poor, and randomized clinical trials or standardized cohorts are needed to compare outcomes of patients with similar underlying disease, clinical characteristics, and identified MAB subspecies/sequevar. Microbiological diagnosis and susceptibility testing need to be harmonized to enable the comparison of agents and the testing of new compounds. Testing antimicrobial combinations requires new methods, especially for PK/PD parameters. Molecular testing may help in assessing MAB resistance prior to treatment. New antimicrobials need to be systematically tested against MAB to find an effective antimicrobial regimen.

Drugs for treating infections caused by non-tubercular mycobacteria: a narrative review from the study group on mycobacteria of the Italian Society of Infectious Diseases and Tropical Medicine

BACKGROUND

Non-tuberculous mycobacteria (NTM) are generally free-living organism, widely distributed in the environment, with sporadic potential to infect. In recent years, there has been a significant increase in the global incidence of NTM-related disease, spanning across all continents and an increased mortality after the diagnosis has been reported. The decisions on whether to treat or not and which drugs to use are complex and require a multidisciplinary approach as well as patients' involvement in the decision process.

METHODS AND RESULTS

This review aims at describing the drugs used for treating NTM-associated diseases emphasizing the efficacy, tolerability, optimization strategies as well as possible drugs that might be used in case of intolerance or resistance. We also reviewed data on newer compounds highlighting the lack of randomised clinical trials for many drugs but also encouraging preliminary data for others. We also focused on non-pharmacological interventions that need to be adopted during care of individuals with NTM-associated diseases CONCLUSIONS: Despite insufficient efficacy and poor tolerability this review emphasizes the improvement in patients' care and the needs for future studies in the field of anti-NTM treatments.

Management of infectious disease syndromes in thoracic organ transplants and mechanical circulatory device recipients: a Delphi panel

PURPOSE

Antimicrobial misuse contributes to antimicrobial resistance in thoracic transplant (TTx) and mechanical circulatory support (MCS) recipients. This study uses a modified Delphi method to define the expected appropriate antimicrobial prescribing for the common clinical scenarios encountered in TTx and MCS recipients.

METHODS

An online questionnaire on managing 10 common infectious disease syndromes was submitted to a multidisciplinary Delphi panel of 25 experts from various disciplines. Consensus was predefined as 80% agreement for each question. Questions where consensus was not achieved were discussed during live virtual live sessions adapted by an independent process expert.

RESULTS

An online survey of 62 questions related to 10 infectious disease syndromes was submitted to the Delphi panel. In the first round of the online questionnaire, consensus on antimicrobial management was reached by 6.5% (4/62). In Round 2 online live discussion, the remaining 58 questions were discussed among the Delphi Panel members using a virtual meeting platform. Consensus was reached among 62% (36/58) of questions. Agreement was not reached regarding the antimicrobial management of the following six clinical syndromes: (1) Burkholderia cepacia pneumonia (duration of therapy); (2) Mycobacterium abscessus (intra-operative antimicrobials); (3) invasive aspergillosis (treatment of culture-negative but positive BAL galactomannan) (duration of therapy); (4) respiratory syncytial virus (duration of antiviral therapy); (5) left ventricular assist device deep infection (initial empirical antimicrobial coverage) and (6) CMV (duration of secondary prophylaxis).

CONCLUSION

This Delphi panel developed consensus-based recommendations for 10 infectious clinical syndromes seen in TTx and MCS recipients.

Phenotypic amikacin resistance may not indicate poor response to amikacin in Mycobacterium avium complex pulmonary disease

When using amikacin to treat Mycobacterium avium complex pulmonary disease (MAC-PD), a minimum inhibitory concentration resistance breakpoint of ≥64 mcg/mL is recommended. We explored whether amikacin resistance characterized by phenotypic drug susceptibility testing was associated with clinical outcomes or mutational resistance in a retrospective cohort of patients with MAC-PD. Despite little aminoglycoside exposure, amikacin resistance was common in our MAC-PD patients but was not associated with worse outcomes or rrs gene mutations.

Serum Cell-Free DNA-based Detection of Mycobacterium avium Complex Infection

Rationale: Mycobacterium avium complex (MAC) is the most common cause of nontuberculous mycobacterial (NTM) pulmonary disease (PD), which exhibits increasing global incidence. Current microbiologic methods routinely used in clinical practice lack sensitivity and have long latencies, leading to delays in diagnosis and treatment initiation and evaluation. A clustered regularly interspaced short palindromic repeats (CRISPR)-based assay that measures MAC cell-free DNA (cfDNA) concentrations in serum could provide a rapid means to detect MAC infection and monitor response to antimicrobial treatment. Objectives: To develop and optimize a CRISPR MAC assay for MAC infection detection and to evaluate its diagnostic and prognostic performance in two MAC disease cohorts. Methods: MAC cfDNA serum concentrations were measured in individuals with diagnoses of MAC disease or who had bronchiectasis or chronic obstructive pulmonary disease diagnoses without histories of NTM PD or NTM-positive sputum cultures. Diagnostic performance was analyzed using pretreatment serum from two cohorts. Serum MAC cfDNA changes during MAC PD treatment were evaluated in a subset of patients with MAC PD who received macrolide-based multidrug regimens. Measurements and Main Results: The CRISPR MAC assay detected MAC cfDNA in MAC PD with 97.6% (91.6-99.7%) sensitivity and 97.6% (91.5-99.7%) specificity overall. Serum MAC cfDNA concentrations markedly decreased after MAC-directed treatment initiation in patients with MAC PD who demonstrated MAC culture conversion. Conclusions: This study provides preliminary evidence for the utility of a serum-based CRISPR MAC assay to rapidly detect MAC infection and monitor the response to treatment.

Sputum bacterial microbiota signature as a surrogate for predicting disease progression of nontuberculous mycobacterial lung disease

OBJECTIVES

Predicting progression of nontuberculous mycobacterial lung disease (NTM-LD) remains challenging. This study evaluated whether sputum bacterial microbiome diversity can be the biomarker and provide novel insights into related phenotypes and treatment timing.

METHODS

We analyzed 126 sputum microbiomes of 126 patients with newly diagnosed NTM-LD due to Mycobacterium avium complex, M. abscessus complex, and M. kansasii between May 2020 and December 2021. Patients were followed for 2 years to determine their disease progression status. We identified consistently representative genera that differentiated the progressor and nonprogressor by using six methodologies. These genera were used to construct a prediction model using random forest with 5-fold cross validation.

RESULTS

Disease progression occurred in 49 (38.6%) patients. Compared with nonprogressors, α-diversity was lower in the progressors. Significant compositional differences existed in the β-diversity between groups (p=0.001). The prediction model for NTM-LD progression constructed using seven genera (Burkholderia, Pseudomonas, Sphingomonas, Candidatus Saccharibacteria, Phocaeicola, Pelomonas, and Phascolarctobacterium) with significantly differential abundance achieved an area under curve of 0.871.

CONCLUSIONS

Identification of the composition of sputum bacterial microbiome facilitates prediction of the course of NTM-LD, and maybe used to develop precision treatment involving modulating the respiratory microbiome composition to ameliorate NTM-LD.

CT findings as predictive factors for treatment failure in Mycobacterium abscessus complex lung disease: a retrospective cohort study

PURPOSE

Mycobacterium abscessus complex (MABC) commonly causes lung disease (LD) and has a high treatment failure rate of around 50%. In this study, our objective is to investigate specific CT patterns for predicting treatment prognosis and monitoring treatment response, thus providing valuable insights for clinical physicians in the management of MABC-LD treatment.

METHODS

We retrospectively assessed 34 patients with MABC-LD treated between January 2015 and December 2020. CT scores for bronchiectasis, cellular bronchiolitis, consolidation, cavities, and nodules were measured at initiation and after treatment. The ability of the CT scores to predict treatment outcomes was analyzed in logistic regression analyses.

RESULTS

The CT scoring system had excellent inter-reader agreement (all intraclass correlation coefficients, > 0.82). The treatment failure (TF) group (17/34; 50%) had higher cavitation diameter (p = 0.049) and extension (p = 0.041) at initial CT and higher cavitation diameter (p = 0.049) and extension (p =0 .045), consolidation (p = 0.022), and total (p = 0.013) scores at follow-up CT than the treatment success (TS) group. The changes of total score and consolidation score (p = 0.049 and 0.024, respectively) increased in the TF group more than the TS group between the initial and follow-up CT. Multivariable logistic regression analysis showed initial cavitation extension, follow-up consolidation extension, and change in consolidation extension (adjusted odds ratio: 2.512, 2.495, and 9.094, respectively, per 1-point increase; all p < 0.05) were significant predictors of treatment failure.

CONCLUSIONS

A high pre-treatment cavitation extension score and an increase in the consolidation extension score during treatment on CT could be alarm signs of treatment failure requiring tailor the treatment of MABC-LD carefully.

Navigating a Complex Case of Mycobacterium Xenopi in a Patient with Blue Rubber Bleb Nevus Syndrome

Introduction

Blue rubber bleb nevus syndrome is a rare disorder of venous malformations, with around 200 cases reported. We present a case of Mycobacterium xenopi infection in a patient with blue rubber bleb nevus syndrome.

Case Description

A 40-year-old female with blue rubber bleb nevus syndrome, asthma, and bronchiectasis came to the pulmonology clinic with shortness of breath and a cough. She was recently admitted for a bronchiectasis exacerbation but continued to have a worsening productive cough and fevers. The most recent CT scan of the chest showed interval stable right upper lobe fibrocavitary disease, demonstrating gradual progression over two years. She had occasional positive cultures for Mycobacterium Avium Complex and M. xenopi one year previously, assumed to be a colonizer and not treated. Most recent hospital cultures were negative for bacteria and an acid-fast bacilli smear. She was sent to the emergency department for bronchiectasis exacerbation and returned to the clinic six weeks later with two sputum cultures growing M. xenopi. It was decided to treat M. xenopi as this was likely the cause of her cavitary lung lesion and frequent infections. Azithromycin, rifampin, and sulfamethoxazole/trimethoprim were initiated. Intravenous amikacin was added later on. She finally had a right partial lung resection done after one year at an outside hospital. She was on and off antibiotics for M. xenopi for approximately three years with negative repeat cultures for non-tuberculous mycobacteria.

Conclusion

Due to the high mortality of M. xenopi infections (which can be as high as 69%), treatment of at least twelve months is recommended. To our knowledge, this is the first reported case of M. xenopi in a patient with blue rubber bleb nevus syndrome.

LEARNING POINTS

The decision to initiate treatment for non-tuberculous mycobacterium infections is often challenging with prolonged treatment.Lifetime monitoring is required in patients with blue rubber bleb nevus syndrome, which can have pulmonary complications.M. xenopi has the highest mortality among non-tuberculous mycobacterium infections and requires at least 12 months of treatment.

In vitro activity of cefoxitin, imipenem, meropenem, and ceftaroline in combination with vaborbactam against Mycobacterium abscessus

Mycobacterium abscessus (MAB) infections pose a growing public health threat. Here, we assessed the in vitro activity of the boronic acid-based β-lactamase inhibitor, vaborbactam, with different β-lactams against 100 clinical MAB isolates. Enhanced activity was observed with meropenem and ceftaroline with vaborbactam (1- and >4-fold MIC50/90 reduction). CRISPRi-mediated blaMAB gene knockdown showed a fourfold MIC reduction to ceftaroline but not the other β-lactams. Our findings demonstrate vaborbactam's potential in combination therapy against MAB infections.

Iatrogenically Acquired Mycobacterium abscessus Infection in an Indwelling Intercostal Drainage In Situ in a Patient With Alcoholic Liver Disease and Bilateral Hepatic Hydrothorax: A Report of a Rare Case

A 47-year-old male, a known case of alcoholic chronic liver disease with portal hypertension, presented with complaints of abdominal distension and shortness of breath. A provisional diagnosis of ethanol-related compensated chronic liver disease (CLD) with portal hypertension and splenomegaly, gross ascites with bilateral hepatic hydrothorax was made. The left-sided pleural effusion subsided after three pleural taps, but the right-sided effusion kept refilling even after four to five days of repeated therapeutic taps, so a pigtail catheter was left in situ. The pleural fluid was sent for culture which did not grow any pathogenic organisms. Cartridge-based nucleic acid amplification tests where Mycobacterium tuberculosis complex (MTBC) was not detected, Ziehl-Neelsen staining was done in which acid-fast bacilli were not seen, and cytology was done where no malignant cells were seen. The patient was discharged with the pigtail in situ on the right side and, after 20 days, the patient again presented with shortness of breath, and imaging revealed moderate right-side pleural effusion. Draining of pleural fluid was done and sent for investigation which again revealed no infective etiology. The patient was admitted to the hospital for one month as the right-sided effusion did not resolve. Suddenly, the patient developed shortness of breath, and a chest X-ray was done, which showed pigtail blockage; pigtail flushing was done, and the bag was drained. The patient was empirically started on IV meropenem 500 mg TID, IV teicoplanin 400 mg BD, and inj polymyxin B 500,000 IU IV BD. The pleural fluid was sent continuously for investigation for the first two months which again did not reveal any infective etiology. After two months of pigtail in situ, the pleural fluid was sent for CBNAAT where MTBC was not detected, and ZN stain showed smooth acid-fast bacilli. The sample was cultured, and it grew acid-fast bacilli in 72 hours on blood agar, MacConkey agar, and Lowenstein-Jensen media. A line probe assay done from the isolate revealed it to be Mycobacterium abscessus subsp. abscessus which was resistant to macrolides and sensitive to aminoglycosides. Mycobacterium abscessus subsp. abscessus was isolated from repeated cultures of pleural fluid, and the patient was advised on a combination treatment of amikacin, tigecycline, and imipenem. The patient was discharged with the indwelling pigtail with the advised treatment; unfortunately, we lost patient follow-up as the patient never returned to us.

Cancer immunotherapy with immune checkpoint inhibitors and infections: A particular focus on mycobacterial infections

Cancer treatment is undergoing a major transformation with the advent of immunotherapy with immune checkpoint inhibitors. These drugs, which have a different mechanism of action from conventional cytotoxic chemotherapy, are transforming treatment paradigms for many patients suffering from advanced cancer. On the other hand, they are often complicated by specific adverse events, known as immune-related adverse events (irAEs). Infections occurring during immunotherapy with immune checkpoint inhibitors have recently received increasing attention and sometimes are seen as part of irAEs. Amongst these, mycobacterial infections have attracted particular attention. Recent reports have shown that infections occurring during immunotherapy can not only be caused by immunosuppression, but in addition new type of infections are observed that are not caused by immunosuppression. Specifically, tuberculosis (TB) has recently been shown to develop as a result of an imbalance in immunoregulation and an excessive immune response. This review highlights reports of infections during immunotherapy with immune checkpoint inhibitors, followed by a focus on the association with TB and nontuberculous mycobacteria. It concludes with a discussion of the possible mechanisms of pathogenesis and the implications for clinical practice.

Why do we use 100 mg of clofazimine in TB and NTM treatment?

Current tuberculosis and non-tuberculous mycobacterial disease guidelines recommend the use of clofazimine in a 100 mg once-daily dose. The rationale behind this exact dose is not provided. I performed a literature review to determine the reasoning behind the current dosing regimen. The current 100 mg once-daily dose of clofazimine stems from a deliberate attempt to find the minimum effective daily dose in leprosy treatment, driven by efficacy, economical and toxicity considerations. While this dose is safe, economical and practical, a higher dose with a loading phase may add relevant efficacy and treatment-shortening potential to both tuberculosis and non-tuberculous mycobacterial disease treatment. We need to revisit dose-response and maximum tolerated dose studies to get the best out of this drug, while continuing efforts to generate more active r-iminophenazine molecules that accumulate less in skin and intestinal tissues and have pharmacokinetic properties that do not require loading doses.

OPTIMA: An Open-Label, Noncomparative Pilot Trial of Inhaled Molgramostim in Pulmonary Nontuberculous Mycobacterial Infection

Rationale: Inhaled granulocyte-macrophage colony-stimulating factor (GM-CSF) has been proposed as a potential immunomodulatory treatment for nontuberculous mycobacterial (NTM) infection.Objectives: This open-label, noncomparative pilot trial investigated the efficacy and safety of inhaled GM-CSF (molgramostim nebulizer solution) in patients with predominantly treatment-refractory pulmonary NTM infection (Mycobacterium avium complex [MAC] and M. abscessus [MABS]), either in combination with ongoing guideline-based therapy (GBT) or as monotherapy in patients who had stopped GBT because of lack of efficacy or intolerability.Methods: Thirty-two adult patients with refractory NTM infection (MAC, n = 24; MABS, n = 8) were recruited into two cohorts: those with (n = 16) and without (n = 16) ongoing GBT. Nebulized molgramostim 300 μg/d was administered over 48 weeks. Sputum cultures and smears and clinical assessments (6-min-walk distance, symptom scores, Quality of Life-Bronchiectasis Questionnaire score, and body weight) were collected every 4 weeks during treatment and 12 weeks after the end of treatment. The primary endpoint was sputum culture conversion, defined as three consecutive monthly negative cultures during the treatment period.Results: Eight patients (25%) achieved culture conversion on treatment (seven [29.2%] patients with MAC infection, one [12.5%] patient with MABS infection); in four patients, this was durable after the end of treatment. Of the 24 patients with MAC infection, an additional 4 patients had a partial response, converting from smear positive at baseline to smear negative at the end of treatment, and time to positivity in liquid culture media increased. Two of these patients sustained negative cultures from the end of treatment. Other clinical endpoints were unchanged. Serious adverse events were mainly pulmonary exacerbations or worsening NTM infection. Three deaths, not treatment related, were reported.Conclusions: In this population of patients with severe NTM disease, molgramostim was safe and well tolerated. Sputum culture conversion rates for patients with MAC infection (29.2%) were greater than reported for similar refractory MAC cohorts managed with GBT alone. Less benefit was seen for MABS infection. No serious safety concerns were identified. Further evaluation in a larger cohort is warranted.Clinical trial registered with www.clinicaltrials.gov (NCT03421743).

Antimicrobial activity of carvacrol and its derivatives on Mycobacterium spp.: systematic review of preclinical studies

Background: The scope of the study was to analyze original preclinical studies on the antimicrobial effects of carvacrol and derivatives on the Mycobacterium genus. Materials & methods: According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, four databases (PubMed, Web of Science, SCOPUS and EMBASE) were searched. Results: The search retrieved 392 records, of which 11 papers were selected. Heterogeneity in the techniques and mycobacterial targets was observed. Carvacrol demonstrated synergistic antimycobacterial activity with rifampicin against multidrug-resistant Mycobacterium tuberculosis on membranes and biofilms. In silico approaches showed specific targets in mycobacteria, by inhibition and molecular docking assays, on the enzyme chorismate mutase and the heat shock protein 16.3. Conclusion: Carvacrol has been shown to be a scaffold candidate for future molecules with activity against mycobacteria.

Adjuvant surgical resection for nontuberculous mycobacterial pulmonary disease: Effectiveness and complications

BACKGROUND

Standard antibiotic treatment for nontuberculous mycobacteria pulmonary disease (NTMPD) has unsatisfactory success rates. Pulmonary resection is considered adjunctive therapy for patients with refractory disease or severe complications, but surgical indications and extent of resection remain unclear. We present surgical treatment outcomes for NTMPD and analyzes risk factors for unfavorable outcomes.

METHODS

We conducted a retrospective investigation of medical records for patients diagnosed with NTMPD who underwent surgical treatment at Asan Medical Center between 2007 and 2021. We analyzed clinical data including microbiological and surgical outcomes.

RESULTS

A total of 71 NTMPD patients underwent thoracic surgery. Negative conversion of acid-fast bacillus (AFB) culture following pulmonary resection was observed in 51 (73.9%) patients. In terms of long-term outcomes, negative conversion was sustained in 38 cases (55.1%). Mortality occurred in 7 patients who underwent pulmonary resections for NTMPD. Statistically significant associations with factors for recurrence or non-negative conversion of AFB culture were found in older age (odds ratio [OR] =1.093, 95% confidence interval [CI]: 1.029-1.161, P = 0.004), male sex (OR = 0.251, 95% CI: 0.071-0.892, P = 0.033), and extensive NTMPD lesions involving three lobes or more (OR = 5.362, 95% CI: 1.315-21.857, P = 0.019). Interstitial lung disease (OR = 13.111, 95% CI: 1.554-110.585, P = 0.018) and pneumonectomy (OR = 19.667, 95% CI: 2.017-191.797, P = 0.018) were statistically significant risk factors for postoperative mortality.

CONCLUSION

Pulmonary resection can be an effective adjuvant treatment option for NTMPD patients, with post-operative antibiotic treatment as the primary treatment. Careful patient selection is crucial, considering the associated risk factors and resectability due to complications and recurrence.

Close monitoring and early intervention: management principles for cystic fibrosis in Denmark

Cystic fibrosis (CF) care in Denmark has been characterized by close monitoring and pre-emptive treatment of lung disease and other CF-related complications. Continuous evaluation through data collection and commitment to clinical research has incrementally improved outcomes. This approach has been in line with best practices set forth by European Standards of Care but has also gone beyond Society standards particularly pertaining to early treatment with high-dose combination antimicrobial therapy. Despite a high prevalence of severe CF variants, lung function has been among the best in Europe. In this review, the Danish approach to management of CF prior to the introduction of new CF modulator treatment is explained and benchmarked. Downsides to the Danish approach are discussed and include increased burden of treatment, risk of antimicrobial resistance, side-effects and costs.

Biofilm Development by Mycobacterium avium Complex Clinical Isolates: Effect of Clarithromycin in Ultrastructure

BACKGROUND

The Mycobacterium avium complex includes the commonest non-tuberculous mycobacteria associated with human infections. These infections have been associated with the production of biofilms in many cases, but there are only a few studies about biofilms produced by the species included in this group.

METHODS

Three collection strains (M. avium ATCC25291, M. intracellulare ATCC13950, and M. chimaera DSM756), three clinically significant strains (647, 657, and 655), and three clinically non-significant ones (717, 505, and 575) of each species were included. The clinical significance of the clinical isolates was established according to the internationally accepted criteria. The biofilm ultrastructure was studied by Confocal-Laser Scanning Microscopy by using BacLight Live-Dead and Nile Red stains. The viability, covered surface, height, and relative autofluorescence were measured in several images/strain. The effect of clarithromycin was studied by using the technique described by Muñoz-Egea et al. with modifications regarding incubation time. The study included clarithromycin in the culture medium at a concentration achievable in the lungs (11.3 mg/L), using one row of wells as the control without antibiotics. The bacterial viability inside the biofilm is expressed as a percentage of viable cells. The differences between the different parameters of the biofilm ultrastructure were analyzed by using the Kruskal-Wallis test. The correlation between bacterial viability in the biofilm and treatment time was evaluated by using Spearman's rank correlation coefficient (ρ).

RESULTS

The strains showed differences between them with all the studied parameters, but neither a species-specific pattern nor a clinical-significance-specific pattern were detected. For the effect of clarithromycin, the viability of the bacteria contained in the biofilm was inversely proportional to the exposure time of the biofilm (ρ > -0.3; p-value < 0.05), excluding two M. chimaera strains (M. chimaera DSM756 and 575), which showed a weak positive correlation with treatment time (0.2 < ρ < 0.39; p-value < 0.05). Curiously, despite a clarithromycin treatment of 216 h, the percentage of the biofilm viability of the strains evaluated here was not less than 40% at best (M. avium 717).

CONCLUSIONS

All the M. avium complex strains studied can form biofilm in vitro, but the ultrastructural characteristics between them suggest that these are strain-specific characteristics unrelated to the species or the clinical significance. The clarithromycin effect on MAC species is biofilm-age/time-of-treatment-dependent and appears to be strain-specific while being independent of the clinical significance of the strain.

Rates and Risk Factors of Progression in Patients With Nontuberculous Mycobacterial Pulmonary Disease: Secondary Analysis of a Prospective Cohort Study

BACKGROUND

The clinical course of nontuberculous mycobacterial pulmonary disease (NTM-PD) is varied, and a watchful waiting management strategy is appropriate for a subset of patients. Understanding disease progression and risk factors for progression is essential for deciding on an appropriate follow-up strategy.

RESEARCH QUESTION

What is the rate of NTM-PD progression, and what are the predictors of progression?

STUDY DESIGN AND METHODS

Patients with NTM-PD who were enrolled in a prospective observational cohort study between July 1, 2011, and December 31, 2022, were included in this analysis. Clinical, bacterial, laboratory, and radiographic data were collected at enrollment and then regularly during follow-up. NTM-PD progression was defined as either the initiation of treatment or the clinician's intention to treat. The rate of progression was calculated and the predictors for progression were analyzed.

RESULTS

Of the 477 patients enrolled, NTM-PD progressed in 192 patients over a median follow-up of 5.4 years. The incidence of NTM-PD progression was 11.0 cases per 100 person-years (95% CI, 9.5-12.7 cases per 100 person-years). The proportion of patients experiencing disease progression was 21.4% at 1 year, 33.8% at 3 years, and 43.3% at 5 years. The final multivariable analysis model identified female sex (adjusted hazard ratio [aHR], 1.69; 95% CI, 1.19-2.39), elevated erythrocyte sedimentation rate (aHR, 1.79; 95% CI, 1.31-2.43), FEV1 % predicted (aHR, 0.89; 95% CI, 0.82-0.96), and the presence of a cavity (aHR, 2.78; 95% CI, 2.03-3.80) as predictors of progression.

INTERPRETATION

About half of patients with NTM-PD experienced progression during an observation period of > 5 years. Patients with risk factors for progression should be observed closely.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT01616745; URL: www.

CLINICALTRIALS

gov.

Clinical course of nontuberculous mycobacterial pulmonary disease in patients with rheumatoid arthritis

OBJECTIVES

The impact of rheumatoid arthritis (RA) on nontuberculous mycobacterial pulmonary disease (NTM-PD) has not been well established. In this study, we investigated the clinical course of NTM-PD in patients with RA and the impact of RA on the prognosis of NTM-PD.

METHODS

We analyzed patients who developed NTM-PD after being diagnosed with RA from January 2004 to August 2023 at a tertiary referral hospital in South Korea. The patient's baseline characteristics, clinical course, and prognosis were evaluated. An optimal matching analysis was performed to measure the impact of RA on the risk of mortality.

RESULTS

During the study period, 18 patients with RA [median age, 68 years; interquartile range (IQR) 59-73; female, 88.9%] developed NTM-PD. The median interval between RA diagnosis and subsequent NTM-PD development was 14.8 years (IQR, 8.6-19.5). At a median of 30 months (IQR, 27-105) after NTM-PD diagnosis, 10 of 18 (55.6%) patients received anti-mycobacterial treatment for NTM-PD and 5 (50.0%) patients achieved microbiological cure. When matched to patients with NTM-PD but without RA, patients with both RA and NTM-PD had a higher risk of mortality (adjusted hazard ratio, 8.14; 95% confidence interval, 2.43-27.2).

CONCLUSION

NTM-PD occurring after RA is associated with a higher risk of mortality than NTM-PD in the absence of RA.

Disseminated Mycobacterium abscessus with endocarditis

We present an uncommon case of endocarditis caused by Mycobacterium abscessus in an immunocompetent patient following a caesarean section. We discuss her turbulent admission course leading to her diagnosis following persistent M. abscessus bacteraemia, medical and surgical management, including a splenectomy and valve resection and repair, and subsequent prolonged course of combination antimicrobials for 24 months post valve surgery. The patient is alive 9 months after completing her treatment and 36 months after her valve surgery. We emphasise the importance of a multidisciplinary team approach in the management of such a complex case.

Evaluation of the FluoroType Mycobacteria assay for identification of mycobacteria

Accurate species identification is a prerequisite for successful management of tuberculosis and non-tuberculous mycobacterial (NTM) diseases. The novel FluoroType Mycobacteria assay combines three established GenoType DNA strip assays (CM, AS, and NTM-DR), allowing detection of Mycobacterium tuberculosis and 32 NTM species/subspecies in a single assay with automatic detection and result analysis. We evaluated the clinical performance of the FluoroType assay and its feasibility in replacing the GenoType Mycobacterium CM assay as the initial method for mycobacterial identification. A total of 191 clinical mycobacterial cultures were analyzed in this study: 180 identified for one mycobacterial species, 6 for multiple, and 5 for no mycobacterial species. Positive percent agreement (PPA) for the FluoroType assay was 87.8% (n = 158), with full agreement for 23/29 species. Weakest PPA was observed for Mycobacterium gordonae (50%, n = 9/18), Mycobacterium interjectum (40%, n = 2/5), and Mycobacterium intracellulare (42%, n = 5/12). Clinical and mixed cultures containing multiple mycobacterial species gave equally single species and genus level identifications (n = 30). No cross-reactivity with non-mycobacterial species was observed (n = 22). In a separate in silico analysis of 2016-2022 HUS area (Finland) register data (n = 2,573), the FluoroType assay was estimated to produce 18.8% (n = 471) inadequate identifications (genus/false species) if used as the primary identification method compared to 14.2% (n = 366) with the GenoType CM assay. The FluoroType assay was significantly more convenient in terms of assay workflow and result interpretation compared to the entirely manual and subjective GenoType CM assay. However, the feasibility of the assay should be critically assessed with respect to the local NTM species distribution.

IMPORTANCE

This study is the first clinical evaluation report of the novel FluoroType Mycobacteria assay. The assay has the potential to replace the established GenoType NTM product family in identification of culture-enriched mycobacteria. However, our research results suggest that the assay performs suboptimally and may not be feasible for use in all clinical settings.

Nontuberculous mycobacteria testing and culture positivity in the United States

BACKGROUND

Nontuberculous mycobacteria (NTM) are environmental bacteria which may cause chronic lung disease. The prevalence of NTM pulmonary infection and disease has been increasing in the United States and globally. The predominant clinically relevant species of NTM in the United States are Mycobacterium avium complex (MAC) species and Mycobacterium abscessus. With the development of rapid species identification methods for NTM (e.g. PCR probes), more testing for NTM is being conducted through commercial labs, such as Laboratory Corporation of America (Labcorp), which provides deidentified real-time testing data to the Centers for Disease Control (CDC) pursuant to a data sharing agreement. Because NTM lung infections are not reportable in most states, other data sources are key to understanding NTM testing patterns, positivity rates, and species distributions to track infection trends and identify clinical care needs.

METHODS

We obtained national Labcorp data for the period January 2019 through mid-April 2022. We subset the data to only respiratory samples sent for Acid Fast Bacilli (AFB) cultures. NTM positive results were defined as those which identified an NTM species and are not Mycobacterium tuberculosis, Mycobacterium bovis, or Mycobacterium gordonae.

RESULTS

Overall, 112,528 respiratory samples were sent for AFB testing during the study period; 26.3% were from the Southeast U.S., identified as HSS Region IV in the Labcorp dataset, and 23.0% were from the Pacific and South Pacific region (Region IX). The culture positive prevalence ranged from 20.2% in the Southeast to 9.2% in the East North Central region (Region V). In the Southeast US, M. abscessus prevalence was 4.0%. For MAC, the highest prevalence was observed in the Mountain region (Region VII) (13.5%) and the lowest proportion was in the East South Central region (7.3%, Region III). Among positive tests, the proportion which was MAC varied from 61.8% to 88.9% and was highest in the Northeast U.S. The proportion of positive samples which were M. abscessus ranged from 3.8% to 19.7% and was highest in the Southeast.

CONCLUSIONS

The Southeastern region of the U.S. has the highest rate of culture positivity in Labcorp tests for total NTM and, of all positive tests, the highest proportion of M. abscessus. These estimates may underrepresent the true number of M. abscessus infections because M. absesscus-specific probes are not commercially available and not all NTM testing in the United States is done by Labcorp. Analysis of real-time testing data from commercial laboratories may provide insights into risk factors for NTM culture positivity in 'hotspot' areas.

External Validation of the BACES Score in Canadian Patients With Nontuberculous Mycobacterial Pulmonary Disease

BACKGROUND

The clinical course of nontuberculous mycobacterial pulmonary disease (NTM-PD) can be variable and difficult to predict. Recently, the BACES score was developed as a tool to predict all-cause mortality in patients with NTM-PD. This score is calculated based on five patient characteristics (BMI, age, cavity, erythrocyte sedimentation rate, and sex), and higher scores portend worse prognosis. Although the BACES score has been validated in a cohort of South Korean patients, it has not yet been validated in other settings or ethnic groups.

RESEARCH QUESTION

How well does the BACES mortality score perform in a cohort of Canadian patients with NTM-PD?

STUDY DESIGN AND METHODS

We performed a single-center retrospective chart review. Patients who were seen between July 2003 and June 2021 were eligible for inclusion if they met guideline-based diagnostic criteria for NTM-PD and were excluded if any component of the BACES score was missing. To assess the model's discriminatory performance, we compared Kaplan-Meier curves between risk groups and calculated Harrell's C index. To assess calibration, we used a graphical calibration curve.

RESULTS

The cohort included 435 patients with a median follow-up of 5.8 years. The median age was 64 years and 74% were female. Based on the BACES scores, patients were classified into three risk groups: low, moderate, or high. Survival curves showed clear separation of the risk groups. Harrell's C index was 0.733 in the study cohort, indicating moderate to good discriminatory performance, although this was lower than the value reported in the derivation cohort (0.812). The graphical calibration curve showed a tendency of the BACES model to underpredict mortality.

INTERPRETATION

The BACES model was evaluated in a multicultural cohort of Canadian patients and demonstrated good discriminatory performance but suboptimal calibration, which may be due to population differences, the use of dichotomized variables in model construction, or both.

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).

Amikacin Liposome Inhalation Suspension in the Real-World Management of Refractory Mycobacterium avium Complex Pulmonary Disease

The increasing prevalence of Mycobacterium avium complex (MAC) pulmonary disease poses a significant therapeutic challenge, particularly due to the limited efficacy and systemic toxicity associated with conventional guideline-based therapy. Amikacin liposome inhalation suspension (ALIS) has been developed, yet its real-world application remains underreported. This retrospective analysis, conducted from March 2021 to February 2024, examined ALIS's clinical use in patients aged 20 years or older with refractory MAC pulmonary disease at our institution. The primary objective of this study is to describe the patient characteristics and clinical trajectories associated with the initiation of ALIS therapy in real-world settings for individuals diagnosed with MAC pulmonary disease. Of 11 patients initiated on ALIS, one was excluded due to financial constraints impacting continuation. The analysis proceeded with the remaining 10 subjects. The mean age of participants was 70.2 years, with a predominance of female patients (n = 7, 70%) and a higher incidence of M. avium infections (n = 6, 60%). Forty percent of the cohort (n = 4) had a history of ethambutol-induced optic neuritis leading to the cessation of the drug. The average interval from the initiation of guideline-based therapy to the start of ALIS was 8.5 ± 6.9 years (mean ± standard deviation). The majority (80%) presented with positive Gaffky scores at ALIS initiation, and a significant proportion exhibited resistance to clarithromycin and ethambutol. Comorbid conditions, including diabetes and previous cancer, were noted. The study also observed elevated anti-MAC antibody levels. Treatment duration varied, with fatigue leading to discontinuation in two cases. Treatment-emergent adverse events were documented in individual patients, each presenting with grade 1 severity: hemoptysis (n = 1, 10%), elevated creatinine levels (n = 1, 10%), and dysphonia (n = 2, 20%) were observed, respectively. Correlation analysis revealed a significant inverse relationship between body mass index (BMI) and ALIS discontinuation due to fatigue, and a positive correlation between Gaffky scores and C-reactive protein (CRP) levels. These results underscore the potential benefits and limitations of ALIS, suggesting that timely intervention and comprehensive healthcare support are crucial for optimal outcomes in the treatment of advanced MAC pulmonary disease.

Opportunistic Infections Post-Lung Transplantation: Viral, Fungal, and Mycobacterial

Opportunistic infections are a leading cause of lung transplant recipient morbidity and mortality. Risk factors for infection include continuous exposure of the lung allograft to the external environment, high levels of immunosuppression, impaired mucociliary clearance and decreased cough reflex, and impact of the native lung microbiome in single lung transplant recipients. Infection risk is mitigated through careful pretransplant screening of recipients and donors, implementation of antimicrobial prophylaxis strategies, and routine surveillance posttransplant. This review describes common viral, fungal, and mycobacterial infectious after lung transplant and provides recommendations on prevention and treatment.

Identification and Antimicrobial Susceptibilities for Patients with Non-tuberculous Mycobacteria Infection in Jeju Island: Single-Center Retrospective Study

BACKGROUND

The distribution of species and characteristics of non-tuberculous mycobacteria (NTM) differ, and surveillance data for changes in antimicrobial susceptibilities of NTM is insufficient. This study analyzed the changes in antimicrobial susceptibility trends across NTM species and assessed the appropriateness of empirical antimicrobial drugs for NTM.

MATERIALS AND METHODS

We retrospectively analyzed the clinical characteristics, including demographics, distribution of NTM species, antimicrobial drug susceptibilities, and outcomes, at a teaching hospital in Jeju Island from 2009 - 2022.

RESULTS

Overall, 342 patients were included in the analysis; 93.0% were classified into the pulmonary group (PG) and 7.0% into the extrapulmonary group (EPG). The isolation rate of Mycobacterium avium was significantly higher in PG (36.8% vs. 0%, P = 0.001), while that of Mycobacterium fortuitum was significantly higher in EPG (4.5% vs. 31.3%, P = 0.001). The antimicrobial susceptibility rate is higher against clarithromycin (89.9%) and amikacin (83.3%) and lower against rifampin (54.7%) and ethambutol (28.1%). The susceptibility rate to clarithromycin was over 80%, but those to rifampin and ethambutol showed decreasing annual trends. Of the 162 patients who received empirical antimicrobial therapy, actual antimicrobial susceptibility rates were high (90.1%) using empirical macrolide, and relatively low using ethambutol and rifampin (28.0% and 58.8%, respectively).

CONCLUSION

This is the first study of analysis of the distribution, baseline characteristics, and antimicrobial susceptibility of isolated NTM species in pulmonary and extrapulmonary patients in Jeju Island over 10 years. Policies that continuously monitor changes in susceptibility rate are required to ensure effective treatment strategies.

Effect of multidrug therapy on the prognosis of Mycobacterium avium complex pulmonary disease

Multidrug therapy for Mycobacterium avium complex pulmonary disease (MAC-PD) results in negative sputum cultures. However, the prognostic value of this treatment approach remains unclear. This study aimed to clarify whether multidrug therapy reduces the incidence of events related to MAC-PD and improves the mortality rate. Patients who met the diagnostic criteria for MAC-PD at our hospital between 2003 and 2019 were retrospectively evaluated using medical records. Events related to MAC-PD were defined as hospitalisation for haemoptysis or respiratory infection and the development of chronic respiratory failure. There were 90 and 108 patients in the multidrug and observation groups, respectively. The median observation period was 86 months. Intergroup differences in body mass index, proportion of patients with cavities, and erythrocyte sedimentation rate were not significant. However, the observation group was older with a higher mean age (multidrug group: 62 years, observation group: 69 years; P < 0.001) and had a higher proportion of male patients (multidrug group: 13/90 [14.4%], observation group: 35/108 [32.4%]; P < 0.01). Furthermore, intergroup differences in the incidence of events related to MAC-PD (multidrug group: 26.69/1000 person-years, observation group: 25.49/1000 person-years), MAC-PD-associated mortality rate (multidrug group: 12.13/1000 person-years, observation group: 12.74/1000 person-years), and total mortality (multidrug group: 24.26/1000 person-years, observation group: 29.50/1000 person-years) were not significant. Many patients relapse even after multidrug therapy, and our findings suggest that multidrug therapy has no effect in preventing the onset of respiratory events or prolonging life expectancy.

An anti-mycobacterial conjugated oligoelectrolyte effective against Mycobacterium abscessus

Infections caused by nontuberculous mycobacteria have increased more than 50% in the past two decades and more than doubled in the elderly population. Mycobacterium abscessus (Mab), one of the most prevalent of these rapidly growing species, is intrinsically resistant to numerous antibiotics. Current standard-of-care treatments are not satisfactory, with high failure rate and notable adverse effects. We report here a potent anti-Mab compound from the flexible molecular framework afforded by conjugated oligoelectrolytes (COEs). A screen of structurally diverse, noncytotoxic COEs identified a lead compound, COE-PNH2, which was bactericidal against replicating, nonreplicating persisters and intracellular Mab.COE-PNH2 had low propensity for resistance development, with a frequency of resistance below 1.25 × 10-9 and showed no detectable resistance upon serial passaging. Mechanism of action studies were in line with COE-PNH2 affecting the physical and functional integrity of the bacterial envelope and disrupting the mycomembrane and associated essential bioenergetic pathways. Moreover, COE-PNH2 was well-tolerated and efficacious in a mouse model of Mab lung infection. This study highlights desirable in vitro and in vivo potency and safety index of this COE structure, which represents a promising anti-mycobacterial to tackle an unmet medical need.

FDA's proposed rule for the regulation of laboratory-developed tests

In October 2023, the Food and Drug Administration (FDA) released a proposed rule that ends enforcement discretion for laboratory-developed tests (LDTs). The FDA's proposal outlines a five-stage implementation to begin regulating LDTs as they do for commercial in vitro diagnostics (IVDs), including modified FDA-approved/cleared tests. We outline here concerns from the clinical and public health microbiology laboratory perspective. It is our opinion that LDTs performed by individual Clinical Laboratory Improvement Amendments-certified diagnostic laboratories should not be regulated in the same way as commercial IVDs. This rule, if finalized, will negatively impact the diagnostic services currently offered by clinical and public health laboratories and, therefore, patients and the providers who care for them. Ending enforcement discretion will likely stifle diagnostic innovation and decrease access to diagnostic testing and health equity. Furthermore, the lack of infrastructure, including personnel and funding, at the FDA and diagnostic laboratories to support the required submissions for review is an obstacle. Like the FDA, diagnostic laboratories prioritize patient safety, accurate clinical diagnostics, and health equity. Since the scope of the LDT landscape is currently unknown, we are supportive of a registration process, along with non-burdensome adverse event reporting, to first understand the scope of clinical use of LDTs and any associated safety concerns. Any regulatory rule should be based on data that have been gathered systematically, not anecdotes or case reports. A rule must also balance the potential negative impact to patient care with realistic safety risks for infectious disease diagnostics.

Five-year species distribution and antimicrobial susceptibility of non-tuberculous mycobacteria in Malaysia, 2018-2022

Introduction. Non-tuberculous Mycobacteria (NTM) is a group of mycobacteria distinct from the Mycobacterium tuberculosis complex. They can cause opportunistic infections, especially in immunocompromised individuals.Gap Statement. Over the last few years, there has been a growing concern regarding the distribution and antimicrobial resistance of NTM in Malaysia. however, a comprehensive study to fully grasp the NTM situation has yet to be conducted.Aim. This study aimed to investigate the species distribution and antimicrobial susceptibility patterns of NTM isolated from clinical samples in Malaysia from 2018 to 2022.Methodology. A retrospective analysis was conducted on NTM isolates obtained from various clinical specimens over a span of five years. The isolates were identified using phenotypic and molecular techniques, and antimicrobial susceptibility profiles for clinically significant isolates were determined using minimum inhibitory concentration.Results. The study revealed a diverse distribution of NTM species in Malaysia, with Mycobacteroides abscessus complex and Mycobacterium avium complex emerging as the most predominant. Furthermore, the antimicrobial susceptibility patterns showed varying degrees of resistance to commonly used antibiotics, highlighting the significance of treatment tailored to susceptibility testing results.Conclusion. This study provides valuable perspective into the epidemiology of NTM in Malaysia. The information gained from this study should prove useful for empirically treating serious NTM infections prior to species identification and the availability of antimicrobial susceptibility testing results.

Bedaquiline for treatment of non-tuberculous mycobacteria (NTM): a systematic review and meta-analysis

BACKGROUND

Non-tuberculous mycobacteria (NTM) infections are increasing in incidence and associated mortality. NTM are naturally resistant to a variety of antibiotics, complicating treatment. We conducted a literature assessment on the efficacy of bedaquiline in treating NTM species in vitro and in vivo (animal models and humans); meta-analyses were performed where possible.

METHOD

Four databases were searched using specific terms. Publications were included according to predefined criteria. Bedaquiline's impact on NTM in vitro, MICs and epidemiological cut-off (ECOFF) values were evaluated. A meta-analysis of bedaquiline efficacy against NTM infections in animal models was performed. Culture conversion, cure and/or relapse-free cure were used to evaluate the efficacy of bedaquiline in treating NTM infection in humans.

RESULTS

Fifty studies met the inclusion criteria: 33 assessed bedaquiline's impact on NTM in vitro, 9 in animal models and 8 in humans. Three studies assessed bedaquiline's efficacy both in vitro and in vivo. Due to data paucity, an ECOFF value of 0.5 mg/mL was estimated for Mycobacterium abscessus only. Meta-analysis of animal studies showed a 1.86× reduction in bacterial load in bedaquiline-treated versus no treatment within 30 days. In humans, bedaquiline-including regimens were effective in treating NTM extrapulmonary infection but not pulmonary infection.

CONCLUSIONS

Bedaquiline demonstrated strong antibacterial activity against various NTM species and is a promising drug to treat NTM infections. However, data on the genomic mutations associated with bedaquiline resistance were scarce, preventing statistical analyses for most mutations and NTM species. Further studies are urgently needed to better inform treatment strategies.

Treatment Outcomes of Clofazimine-Containing Regimens in Severe Mycobacterium avium Complex Pulmonary Disease

Background

Clofazimine is suggested as a promising drug for the treatment of nontuberculous mycobacterial pulmonary disease. However, the role of clofazimine in severe Mycobacterium avium complex pulmonary disease (MAC-PD) remains unclear. In this study, we investigated the treatment outcomes of patients with severe MAC-PD treated with regimens containing clofazimine.

Methods

This study included patients diagnosed with severe MAC-PD at Seoul National University Hospital who underwent anti-mycobacterial treatment between 1 January 2011 and 31 December 2022. We assessed the rate of culture conversion within 6 months and microbiological cure in patients receiving clofazimine-containing regimens, considering the dose and duration of clofazimine administration.

Results

A total of 170 patients with severe MAC-PD, treated with regimens containing clofazimine, were included in the analysis. The median age of patients was 68 years (interquartile range, 59-75 years), with a female predominance (n = 114 [67.1%]). Cavities were identified in 121 patients (71.2%). Within 6 months, 77 patients (45.3%) achieved culture conversion, and 84 of 154 (54.6%) patients attained microbiological cure. The dose of clofazimine (100 mg vs 50 mg) was not associated with culture conversion (adjusted odds ratio [aOR], 0.64 [95% confidence interval {CI}, .29-1.42]) or microbiological cure (aOR, 1.21 [95% CI, .52-2.81]). The microbiological cure rate reached 71.0% when clofazimine was administered for 6-12 months, compared to 23.1% when administered for <6 months.

Conclusions

Clofazimine demonstrated a relatively favorable efficacy in severe MAC-PD, regardless of the maintenance dose. This effect was more pronounced when administered for a duration exceeding 6 months.

The role of treatment regimen and duration in treating patients with Mycobacterium avium complex lung disease: A real-world experience and case-control study

PURPOSE

The treatment advantage of guideline-based therapy (GBT) in Mycobacterium avium complex lung disease (MAC-LD) is well-known. However, GBT is not always feasible. The aim of the study was to analyze the relationship of treatment regimens and duration with outcomes.

MATERIALS AND METHODS

This study screened patients with MAC-LD from Jan 2011 to Dec 2020 and enrolled those who received treatment. The treatment regimens were categorized to triple therapy (three active drugs) and non-triple therapy. The favorable outcomes included microbiological cure or clinical cure if no microbiologic persistence.

RESULTS

A total of 106 patients with MAC-LD were enrolled. Among them, 88 subjects (83 %) received triple therapy, 58 (54.7 %) had MAC treatment >12 months, and 66 (62.3 %) had favorable outcomes. Patients receiving triple therapy (90.9 % vs. 67.5 %, p = 0.008) and treatment >12 months (62.1 % vs. 42.5 %, p = 0.07) had higher proportion of favorable outcomes than unfavorable outcomes. Multivariable logistic regression analysis showed that age >65, comorbidities of COPD and prior tuberculosis, low hemoglobin, and high MAC burden were independent risk factors of unfavorable outcome. In contrast, triple therapy (OR: 0.018, 95 % CI: 0.04-0.78, p = 0.022) and treatment duration >12 months (OR: 0.20, 95 % CI: 0.055-0.69, p = 0.012) were protective factors against unfavorable outcome.

CONCLUSIONS

Triple therapy including GBT, and treatment more than 12 months achieved more favorable outcome. Maintenance of triple therapy, but not reducing the number of active drugs, might be an acceptable alternative of GBT.

Mycobacterium gordonae Infection in a Patient With Non-small Cell Lung Cancer

Mycobacterium gordonae (MG) is one of the least pathogenic nontuberculous mycobacteria (NTM). We report an unusual case of MG infection in a patient with newly diagnosed lung cancer. A 61-year-old woman presented with shortness of breath and weight loss. Six months prior to admission, she was diagnosed with MG infection based on positive sputum cultures and bronchioalveolar lavage. Despite anti-mycobacterial therapy, her symptoms worsened and she lost approximately 100 pounds. A transbronchial biopsy obtained one week prior to admission revealed adenocarcinoma of the lung. At admission, vital signs were normal, and a physical exam revealed bilateral crackles. Computed tomography (CT) scan of the chest revealed infiltrates with ground-glass opacity. The patient was admitted to the oncology service for evaluation. Our findings suggest that symptomatic individuals with positive cultures of MG should proceed with extensive workup for possible underlying lung cancer especially if not responding to anti-mycobacterial therapy.

Challenges and knowledge gaps in the management of non-tuberculous mycobacterial pulmonary disease in sub-Saharan African countries with a high tuberculosis burden: a scoping review

INTRODUCTION

In sub-Saharan African (SSA) countries endemic for tuberculosis (TB), previous TB is a significant risk factor for non-tuberculous mycobacterial pulmonary disease (NTM-PD). The deployment of GeneXpert MTB/RIF in pulmonary TB diagnostic work-up regularly identifies symptomatic patients with a positive smear microscopy but negative GeneXpert, indicative of NTM presence. This scoping review outlines recent evidence for NTM-PD diagnosis and management in SSA.

OBJECTIVE

The review's objective was to outline the risk factors, available diagnostics, management options and outcomes of NTM-PD in high-burden TB settings in SSA using the population-concept-context framework.

DESIGN AND DATA SOURCES

We searched existing literature from PubMed, Web of Science, African Journals Online, Google Scholar and grey literature. Studies published between January 2005 and December 2022 were retained. Data were extracted into Rayyan software and Mendeley and summarised using Excel.

RESULTS

We identified 785 potential articles, of which 105 were included in the full-text review, with 7 papers retained. Included articles used international criteria for diagnosing NTM-PD. Multiple papers were excluded due to non-application of the criteria, suggesting challenging application in the SSA setting. Identified risk factors include previous TB, smoking and mining. Most commonly, chest radiography and not CT was used for the radiological diagnosis of PD, which may miss early changes related to NTM-PD. Molecular methods for NTM species identification were employed in research settings, usually at referral centres, but were unavailable for routine care. Most studies did not report a standardised approach to treatment and they were not offered treatment for the specific disease, marking a lack of guidance in treatment decision-making. When treatment was provided, the outcome was often not reported due to the lack of implementation of standardised outcome definitions.

CONCLUSIONS

These outlined challenges present a unique opportunity for researchers to undertake further studies in NTM-PD and proffer solutions more applicable to SSA.

A case report of atypical anti-glomerular basement membrane nephritis associated with Mycobacterium Avium

We present the case of a woman with atypical anti-glomerular basement membrane (anti-GBM) nephritis associated with concurrent pulmonary infection with Mycobacterium avium. A kidney biopsy showed crescentic glomerulonephritis with 50% active crescents and linear IgG staining, but no circulating anti-GBM antibodies were detected, and the patient did not have pulmonary hemorrhage. Despite treatment with a triple-regimen of antibiotics, corticosteroids, and plasmapheresis, the patient did not regain kidney function. One year later she is on maintenance dialysis and has still not cleared the infection with M. avium.

Development of 2nd generation aminomethyl spectinomycins that overcome native efflux in Mycobacterium abscessus

Mycobacterium abscessus (Mab), a nontuberculous mycobacterial (NTM) species, is an emerging pathogen with high intrinsic drug resistance. Current standard-of-care therapy results in poor outcomes, demonstrating the urgent need to develop effective antimycobacterial regimens. Through synthetic modification of spectinomycin (SPC), we have identified a distinct structural subclass of N-ethylene linked aminomethyl SPCs (eAmSPCs) that are up to 64-fold more potent against Mab over the parent SPC. Mechanism of action and crystallography studies demonstrate that the eAmSPCs display a mode of ribosomal inhibition consistent with SPC. However, they exert their increased antimicrobial activity through enhanced accumulation, largely by circumventing efflux mechanisms. The N-ethylene linkage within this series plays a critical role in avoiding TetV-mediated efflux, as lead eAmSPC 2593 displays a mere fourfold susceptibility improvement against Mab ΔtetV, in contrast to the 64-fold increase for SPC. Even a minor shortening of the linkage by a single carbon, akin to 1st generation AmSPC 1950, results in a substantial increase in MICs and a 16-fold rise in susceptibility against Mab ΔtetV. These shifts suggest that longer linkages might modify the kinetics of drug expulsion by TetV, ultimately shifting the equilibrium towards heightened intracellular concentrations and enhanced antimicrobial efficacy. Furthermore, lead eAmSPCs were also shown to synergize with various classes of anti-Mab antibiotics and retain activity against clinical isolates and other mycobacterial strains. Encouraging pharmacokinetic profiles coupled with robust efficacy in Mab murine infection models suggest that eAmSPCs hold the potential to be developed into treatments for Mab and other NTM infections.

Characterisation and antimicrobial susceptibility pattern of non-tuberculous mycobacteria

Background

Non-tuberculous mycobacteria (NTM) management comprises prolonged therapy that includes macrolides. Non-tuberculous mycobacteria can cause disease in patients with predisposing conditions such as HIV and structural lung disease. Local data on NTM disease and macrolide resistance are scarce, and routine antimicrobial susceptibility testing is currently not performed for NTM in South Africa.

Objectives

This study aims to characterise NTM isolated at Tshepong National Health Laboratory Service (NHLS) according to species and antimicrobial susceptibility pattern.

Method

A retrospective data analysis of NTM isolates from Tshepong NHLS was performed from January to June 2020. GenoType® NTM-DR was performed on selected isolates where the assay can confirm the species and determine resistance to macrolides and aminoglycosides.

Results

Of the 194 collected NTM isolates, 183 were included in the study. Patients' ages ranged from 1 day to 81 years (median 36 years). The most common specimen was sputum (84.7%), followed by gastric aspirate (6.6%). The most common NTM isolated were Mycobacterium (M.) intracellulare (67.6%), M. fortuitum (12.6%), M. species (4.3%), M. kansasii (3.9%), and M. scrofulaceum (3.9%). Macrolide resistance occurred in 2.8% of tested isolates; no aminoglycoside resistance was detected. Although most isolates were from males (62.3%), resistance was observed only in females.

Conclusion

M. intracellulare predominated, with only two M. intracellulare and two M. abscessus isolates showing macrolide resistance; aminoglycoside resistance was absent.

Contribution

This study highlights the need for increased awareness of NTM, regular nationwide NTM surveillance, and monitoring of resistance trends to guide future patient management and ensure good treatment outcomes.

In Vitro Activity of Benzimidazole (SPR719) Against Clinical Isolates of Nontuberculous Mycobacteria With and Without Clarithromycin or Amikacin Resistance

Limited data are available regarding the in vitro activity of SPR719, a derivative of benzimidazole, against diverse nontuberculous mycobacteria (NTM) species. We investigated the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of SPR719 against clinical NTM isolates, including clarithromycin- and amikacin-resistant strains. NTM isolates were obtained from patients with NTM-pulmonary disease caused by various NTM species, including Mycobacterium avium complex, M. abscessus (subspecies abscessus and massiliense), M. kansasii, and M. fortuitum. Regardless of clarithromycin or amikacin resistance, the MIC and MBC values of SPR719 were comparable among these major pathogenic NTM species. In over 70% of the isolates, the MIC values were ≤2 μg/mL with MBC values of ≤4 μg/mL. The MIC and MBC values of M. kansasii were relatively lower than those of the other species with little difference between them, demonstrating the bactericidal properties of SPR719. The in vitro activity of SPR719 against major clinical NTM species suggests that SPR719 can serve as a novel treatment option for NTM-pulmonary disease.