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

Cyclohexyl-griselimycin is active against Mycobacterium abscessus in mice

Cyclohexyl-griselimycin is a preclinical candidate for use against tuberculosis (TB). Here, we show that this oral cyclodepsipeptide is also active against the intrinsically drug-resistant nontuberculous mycobacterium Mycobacterium abscessusin vitro and in a mouse model of infection. This adds a novel advanced lead compound to the M. abscessus drug pipeline and supports a strategy of screening chemical matter generated in TB drug discovery efforts to fast-track the discovery of novel antibiotics against M. abscessus.

Molecular epidemiology and phylogenomic analysis of Mycobacterium abscessus clinical isolates in an Asian population

Mycobacterium abscessus comprises three subspecies: M. abscessus subsp. abscessus, M. abscessus subsp. bolletii, and M. abscessus subsp. massiliense. These closely related strains are typically multi-drug-resistant and can cause difficult-to-treat infections. Dominant clusters of isolates with increased pathogenic potential have been demonstrated in pulmonary infections in the global cystic fibrosis (CF) population. An investigation was performed on isolates cultured from an Asian, predominantly non-CF population to explore the phylogenomic relationships within our population and compare it to global M. abscessus isolates. Whole-genome-sequencing was performed on M. abscessus isolates between 2017 and 2019. Bioinformatic analysis was performed to determine multi-locus-sequence-type, to establish the phylogenetic relationships between isolates, and to identify virulence and resistance determinants in these isolates. A total of 210 isolates were included, of which 68.5 % (144/210) were respiratory samples. These isolates consisted of 140 (66.6 %) M. abscessus subsp. massiliense, 67 (31.9 %) M. abscessus subsp. abscessus, and three (1.4 %) M. abscessus subsp. bolletii. Dominant sequence-types in our population were similar to those of global CF isolates, but SNP differences in our population were comparatively wider despite the isolates being from the same geographical region. ESX (ESAT-6 secretory) cluster three appeared to occur most commonly in ST4 and ST6 M. abscessus subsp. massiliense, but other virulence factors did not demonstrate an association with isolate subspecies or sample source. We demonstrate that although similar predominant sequence-types are seen in our patient population, cross-transmission is absent. The risk of patient-to-patient transmission appears to be largely limited to the vulnerable CF population, indicating infection from environmental sources remains more common than human-to-human transmission. Resistance and virulence factors are largely consistent across the subspecies with the exception of clarithromycin susceptibility and ESX-3.

Anxiety and depression in patients with nontuberculous mycobacterial pulmonary disease: a prospective cohort study in South Korea

BACKGROUND

The mental health of patients with nontuberculous mycobacterial pulmonary disease (NTM-PD) has been underestimated.

RESEARCH QUESTION

What is the prevalence of, associated factors for, and clinical impact of anxiety and depression in patients with NTM-PD?

STUDY DESIGN AND METHODS

Among the patients diagnosed with NTM-PD between July 1, 2011 and December 31, 2019, who were a part of Seoul National University Hospital's prospective cohort, we included those who completed the Hospital Anxiety and Depression Scale (HADS) at least twice. Multivariable logistic regression analysis was used to identify the factors associated with anxiety and depression. Multilevel mixed-effects regression was used to analyze the HADS scores' longitudinal trends.

RESULTS

A total of 368 patients were included in this study, including 84 (22.8%) with anxiety (HADS-A score ≥8) and 83 (22.5%) with depression (HADS-D score ≥8). The presence of cough (adjusted odds ratio [aOR] 2.01, 95% confidence interval [CI] 1.19-3.39) and febrile sensation (aOR 4.45, 95% CI 2.13-9.30) were associated with anxiety, whereas dyspnea (aOR 4.13, 95% CI 1.38-12.37) and febrile sensation (aOR 2.91, 95% CI 1.38-6.13) were associated with depression. Although the HADS scores of patients with anxiety or depression at the time of enrollment and throughout the follow-up period were higher than those without, these scores declined significantly within one year after enrollment. Patients with anxiety (P=0.006) or depression (P=0.004) received antibiotic treatment more frequently than those without. Treatment outcomes did not differ depending on the initial anxiety or depression status.

INTERPRETATION

Anxiety and depression were common in patients with NTM-PD and were associated with patient-reported symptoms. While these persisted over time, the treatment outcomes did not differ.

The Role of Biofilms, Bacterial Phenotypes, and Innate Immune Response in Mycobacterium avium Colonization to Infection

Mycobacterium avium complex (MAC), is known for colonizing and infecting humans following inhalation of the bacteria. MAC pulmonary disease is notoriously difficult to treat and prone to recurrence. Both the incidence and prevalence MAC pulmonary disease have been increasing globally. MAC is well known to form biofilms in the environment, and in vitro, these biofilms have been shown to aid MAC in epithelial cell invasion, protect MAC from phagocytosis, and cause premature apoptosis in macrophages. In vivo, the system of interactions between MAC, biofilms and host macrophages is complex, difficult to replicate in vitro and in animal models, has not been fully characterized. Here we present a three-dimensional agent-based model of a lung airway to help understand how these interactions evolve in the first 14 days post-bacterial inhalation. We parameterized the model using published data and performed uncertainty analysis to characterize outcomes and parameters' effects on those outcomes. Model results show diverse outcomes, including wide ranges of macrophage recruitment levels, and bacterial loads and phenotype distribution. Though most bacteria are phagocytosed by macrophages and remain intracellular, there are also many simulations in which extracellular bacteria continue to drive the colonization and infection. Initial parameters dictating host immune levels, bacterial loads introduced to the airway, and biofilm conditions have significant and lasting impacts on the course of these results. Additionally, though macrophage recruitment is key for suppressing bacterial loads, there is evidence of significant excess recruitment that fail to impact bacterial numbers. These results highlight a need and identify a path for further exploration into the inhalation events in MAC infection. Early infection dynamics could have lasting impacts on the development of nodular bronchiectatic or fibrocavitary disease as well as inform possible preventative and treatment intervention targeting biofilm-macrophage interactions.

TREATMENT OF MYCOBACTERIOSIS CAUSED BY MYCOBACTERIUM AVIUM SSP. HOMINISSUIS IN A GROUP OF CAPTIVE LOWLAND TAPIRS (TAPIRUS TERRESTRIS)

Tapirs are a taxonomic group with a high susceptibility to mycobacterial diseases. However, successful therapy has only been documented sporadically. Here treatment of mycobacteriosis diagnosed in three, one male and two female, lowland tapirs (Tapirus terrestris) in a zoo in Germany is reported. Two of the animals showed chronic mild respiratory signs, and conventional therapy did not improve the condition. Culture of broncho-alveolar lavage (BAL) samples was positive for Mycobacterium avium ssp. hominissuis. Upon airway endoscopy, bronchial edema and increased mucus production were visible. Initially, all three infected tapirs received oral antimycobacterial therapy consisting of 5 mg/kg body weight isoniazid, 10 mg/kg rifampicin, and 10 mg/kg clarithromycin q24h. Based on therapeutic drug level monitoring, the doses of rifampicin were adjusted to 12 and 15 mg/kg in the females and the male, respectively. The treatment with all three drugs was continued for 11 mon. Six months into treatment, the clinical condition resolved, and repeated BAL samples of all three tapirs tested negative for mycobacteria by culture. Here the approach for a treatment protocol with minimal side effects suitable to control infections with nontuberculous mycobacteria in lowland tapirs is reported.

Mycobacteria avium-related peritonitis in a patient undergoing peritoneal dialysis: case report and review of the literature

BACKGROUND

Mycobacteria avium (M. avium) is a species of ubiquitous slowly growing nontuberculous mycobacteria. It causes opportunistic infections. However, M. avium-related peritonitis in peritoneal dialysis (PD) patients is rare.

CASE PRESENTATION

A 51-year-old female end-stage kidney disease patient undergoing PD was admitted for a noninfectious complication. She presented catheter exit site drainage and slightly increased PD effluent white cell count (WCC) with polymorphonuclear predominance on admission. Exit site infection and PD-related peritonitis were diagnosed. Repeated cultures of effluent and drainage were negative. Initial empirical antibiotics and further adjustment were not rewarding. PD was terminated 2 weeks later, however, shortly the patient developed stupor, high fever, peritoneal irritation, and spontaneous chylous ascites, and showed elevated ascitic adenosine deaminase (ADA). The manifestations persisted and the patient's general condition deteriorated despite intensified antibiotic therapy. Massive parallel sequencing identified M. avium in ascites on hospital day 25, and 4-drug treatment with azithromycin, amikacin, rifampin, and ethambutol was initiated. Nevertheless, the patient died from sepsis on hospital day 30.

CONCLUSIONS

We report a case of PD-related M. avium peritonitis. Prolonged culture-negative peritonitis, chylous ascites, and elevated ascitic ADA may hint the possibility of mycobacterial infections. Diagnostic method allowing prompt identification of the pathogen is warranted. The prognosis can be extremely poor, and the prophylaxis and treatment should be better defined.

A Novel Oxazolidinone, Contezolid (MRX-I), Expresses Anti-Mycobacterium abscessus Activity In Vitro

An evaluation of the anti-Mycobacterium abscessus activity expressed by a novel oxazolidinone, contezolid (MRX-I), toward 12 reference strains and 194 clinical isolates was conducted. Contezolid was active against M. abscessusin vitro, with effects comparable to the anti-M. abscessus effects of linezolid both extracellularly and intracellularly. Contezolid did not antagonize the most frequently used anti-M. abscessus drugs, and preexposure to contezolid did not induce drug resistance. These results provide a novel approach to treating M. abscessus infections.

Potency of omadacycline against Mycobacteroides abscessus clinical isolates in vitro and in a mouse model of pulmonary infection

The incidence of nontuberculous mycobacterial diseases in the United States is rising and has surpassed that of tuberculosis. Most notable among the nontuberculous mycobacteria is Mycobacteroides abscessus, an emerging environmental opportunistic pathogen capable of causing chronic infections. M. abscessus disease is difficult to treat, and the current treatment recommendations include repurposed antibiotics, several of which are associated with undesirable side effects. In this study, we have evaluated the activity of omadacycline, a new tetracycline derivative, against M. abscessus using in vitro and in vivo approaches. Omadacycline exhibited an MIC₉₀ of 0.5 µg/mL against a panel of 32 contemporary M. abscessus clinical isolates, several of which were resistant to antibiotics that are commonly used for treatment of M. abscessus disease. Omadacycline combined with clarithromycin, azithromycin, cefdinir, rifabutin, or linezolid also exhibited synergism against several M. abscessus strains and did not exhibit antagonism when combined with an additional nine antibiotics also commonly considered to treat M. abscessus disease. Concentration-dependent activity of omadacycline was observed in time-kill assessments. Efficacy of omadacycline was evaluated in a mouse model of lung infection against four M. abscessus strains. A dose equivalent to the 300-mg standard oral human dose was used. Compared to the untreated control group, within 4 weeks of treatment, 1 to 3 log₁₀ fewer M. abscessus CFU were observed in the lungs of mice treated with omadacycline. Treatment outcome was biphasic, with bactericidal activity observed after the first 2 weeks of treatment against all four M. abscessus strains.

Clinical Considerations for Routine Auditory and Vestibular Monitoring in Patients With Cystic Fibrosis

Purpose Specific classes of antibiotics, such as aminoglycosides, have well-established adverse events producing permanent hearing loss, tinnitus, and balance and/or vestibular problems (i.e., ototoxicity). Although these antibiotics are frequently used to treat pseudomonas and other bacterial infections in patients with cystic fibrosis (CF), there are no formalized recommendations describing approaches to implementation of guideline adherent ototoxicity monitoring as part of CF clinical care. Method This consensus statement was developed by the International Ototoxicity Management Working Group (IOMG) Ad Hoc Committee on Aminoglycoside Antibiotics to address the clinical need for ototoxicity management in CF patients treated with known ototoxic medications. These clinical protocol considerations were created using consensus opinion from a community of international experts and available evidence specific to patients with CF, as well as published national and international guidelines on ototoxicity monitoring. Results The IOMG advocates four clinical recommendations for implementing routine and guideline adherent ototoxicity management in patients with CF. These are (a) including questions about hearing, tinnitus, and balance/vestibular problems as part of the routine CF case history for all patients; (b) utilizing timely point-of-care measures; (c) establishing a baseline and conducting posttreatment evaluations for each course of intravenous ototoxic drug treatment; and (d) repeating annual hearing and vestibular evaluations for all patients with a history of ototoxic antibiotic exposure. Conclusion Increased efforts for implementation of an ototoxicity management program in the CF care team model will improve identification of ototoxicity signs and symptoms, allow for timely therapeutic follow-up, and provide the clinician and patient an opportunity to make an informed decision about potential treatment modifications to minimize adverse events. Supplemental Material https://doi.org/10.23641/asha.16624366.

Nontuberculous mycobacterial lung disease caused by Mycobacterium avium complex - disease burden, unmet needs, and advances in treatment developments

INTRODUCTION

Nontuberculous mycobacterial (NTM) lung disease (LD) is the most common clinical manifestation of NTM infection and is a growing health concern. Up to 85% of NTM-LD cases are caused by Mycobacterium avium complex (MAC). Increased awareness of NTM-LD caused by MAC is needed as patients with this disease experience substantial burden and unmet treatment needs.

AREAS COVERED

This review provides clinicians and regulatory and healthcare decision makers an overview of the clinical, economic, and humanistic burden of NTM-LD and the unmet treatment needs faced by patients and clinicians. The review focuses on NTM-LD caused by MAC. A summary of the 2020 NTM guidelines specifically for MAC-LD and an overview of novel treatment options, including amikacin liposome inhalation suspension (ALIS) as the first approved therapy for refractory MAC-LD, and investigational drugs in testing phase are provided.

EXPERT OPINION

Key advancements in NTM-LD management include recent updates to clinical practice guidelines, approval of ALIS for the treatment of refractory MAC-LD, and ongoing clinical trials of investigational treatments. Yet opportunities still exist to improve patient outcomes, including development of better screening tools, such as reliable and responsive biomarkers to help identify high-risk patients, and addressing unmet treatment needs.

Outcomes of adjunctive surgery for nontuberculous mycobacterial pulmonary disease

Background

Owing to the unsatisfactory results of antibiotic treatment alone, surgical resection is currently considered as adjunctive therapy in patients with nontuberculous mycobacterial pulmonary disease (NTM-PD). However, reports regarding the outcomes of surgery vary considerably by institution. Here, we investigated the surgical outcomes and risk factors associated with unfavorable outcomes after surgery.

Methods

We analyzed patients with NTM-PD who underwent pulmonary resection at Seoul National University Hospital between January 1, 2006, and December 31, 2020, and assessed the types of surgical procedures, complications, and long-term outcomes. Multivariate logistic regression analysis was used to identify the risk factors associated with treatment refractoriness or recurrence after surgery.

Results

Among 67 patients who underwent surgery during the study period, the most common indication for surgery was persistent culture positivity despite rigorous medical treatment (80.6%), followed by longstanding cavitary lesions or radiographic aggravation (10.4%) and massive hemoptysis (4.5%). Among 53 patients with positive mycobacterial cultures at the time of surgery, 38 (71.7%) achieved initial negative culture conversion, 9 (17.0%) of whom experienced recurrence. Nine (13.4%) patients experienced postoperative complications, which were managed without lasting morbidity and mortality. Female sex (adjusted odds ratio [aOR] 6.63; 95% confidence interval [CI] 1.04–42.4; P = .046), preoperative positive mycobacterial culture (aOR 5.87; 95 %CI 1.04–33.08; P = .045), and residual lesions (aOR 6.86; 95 %CI 1.49–31.56; P = .013) were associated with refractoriness or recurrence.

Conclusions

Pulmonary resection is a reasonable treatment modality for patients with refractory NTM-PD or major complications such as massive hemoptysis. The potential risk factors associated with unfavorable outcomes included female sex, preoperative positive mycobacterial culture, and residual lesions after surgery.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01679-0.

Multidrug Antibiotic Therapy for a Non-Human Immunodeficiency Virus-Infected Patient With Clarithromycin-Resistant Disseminated Mycobacterium avium Complex Disease

The management of macrolide-resistant Mycobacterium avium complex (MAC) disease is challenging. It is extremely rare for non-human immunodeficiency virus (HIV)-infected patients to develop disseminated MAC disease. A 73-year-old non-HIV-infected woman was diagnosed with MAC lung disease (MAC-LD) for 20 years and subsequently chronic necrotizing pulmonary aspergillosis for three years. To avoid drug interaction between rifampicin and voriconazole, MAC-LD was treated with clarithromycin (CLR) alone. The results of the bone biopsy and bone marrow culture conducted for back pain were compatible with CLR-resistant MAC vertebral osteomyelitis. The clinical management of CLR-resistant disseminated MAC disease consisting of lung and spinal lesions with no established treatment and a poor prognosis is challenging. In this case, the patient was treated with multidrug antibiotic therapy, including CLR, ethambutol, rifampicin, amikacin, and moxifloxacin. The results show the effectiveness of multidrug antibiotic therapy in treating CLR-resistant disseminated MAC disease.

Mycobacterium chimaera as an Underestimated Cause of NTM Lung Diseases in Patients Hospitalized in Pulmonary Wards

Mycobacterium chimaera is the newly described species belonging to Mycobacterium avium complex (MAC), with morphology and growth characteristics closely related to Mycobacterium intracellulare. The aim of this retrospective study was to analyze the frequency and clinical significance of M. chimaera identification in the population of patients with previous positive respiratory cultures for M. intracellulare or MAC. 200 strains of M. intracellulare or MAC, isolated from respiratory specimens of patients hospitalized in pulmonary wards, between 2011 and 2020, were retrospectively analyzed with GenoType NTM-DR test. 88 (44%) of strains were re-classified to M. chimaera species. Analysis of clinical data in 30 patients with positive M. chimaera isolates revealed that they were diagnosed with chronic obstructive pulmonary disease (COPD) – 27%, past tuberculosis – 20%, or interstitial lung diseases – 17%, respectively. Non-tuberculous mycobacterial lung disease (NTMLD) caused by M. chimaera has been recognized in 53% of patients, most often in those presenting with post-tuberculous lung lesions. M. chimaera was almost exclusively isolated from respiratory specimens of patients with underlying lung diseases, especially those with COPD and/or past tuberculosis. NTMLD due to M. chimaera was diagnosed predominantly in patients with past tuberculosis.

NTM Infection Risk and Trace Metals in Surface Water: A Population-Based Ecologic Epidemiologic Study in Oregon

RATIONALE

Nontuberculous mycobacteria (NTM) are ubiquitous environmental bacteria, and some pathogenic species cause lung disease. Environmental factors contribute to increased NTM abundance, with higher potential for exposure and infection.

OBJECTIVE

To identify water-quality constituents that influence the risk of NTM infection in Oregon.

METHODS

We conducted a population-based cohort study using patient incidence data from the Oregon statewide NTM laboratory data collected as part of a public health surveillance project from 2007 through 2012. To estimate the risk of NTM Pulmonary Infection (PI) from exposure to water constituents, we extracted water-quality data from the Water Quality Portal and associated these data with corresponding patient county of residence. Using generalized linear models, we modeled two outcomes: Mycobacterium avium complex species PI and Mycobacterium abscessus group species PI.

RESULTS

For every 1-unit increase in the log concentration of vanadium in surface water, infection risk increased by 49% among persons with Mycobacterium avium complex PI. Among those with Mycobacterium abscessus PI, we observed that for every 1-unit increase in the log concentration of molybdenum in surface water, infection risk increased by 41%. The highest risk of infection due to Mycobacterium abscessus group infection was concentrated in counties within the Northwestern region of Oregon. High infection risk associated with Mycobacterium avium complex species did not show any geographic pattern.

CONCLUSIONS

Concentrations of the trace metals molybdenum and vanadium in surface water sources were associated with NTM infection in Oregon. These findings may help identify regions at higher risk of NTM infection to guide risk reduction strategies.

Challenges of diagnosing and treating non-tuberculous mycobacterial pulmonary disease [NTM-PD]: A case series

Non-tuberculous mycobacterial pulmonary disease (NTM-PD) may simulate Pulmonary Tuberculosis (PTB) in its clinical and radiological expression posing a diagnostic dilemma and challenge to the treating physician, especially in high TB prevalent countries. Though recent emerging data indicates inter-human transmission, infection with non-tuberculous mycobacteria (NTM) is commonly acquired from the environmental sources [1]. NTM can produce disease not only in immunocompromised populations but also in healthy individuals leading to significant morbidity and mortality [2]. Unlike PTB, NTM-PD is usually difficult to confirm and speciate in resource limited clinical settings and high TB endemic countries due to non-availability, poor accessibility and affordability to a specific culture facility. Apart from diagnostic challenges, adverse drug effects with treatment leading to non-adherence are another vexing problem. We present here case descriptions of four patients of NTM-PD, confirmed by culture isolates, one was a rapid grower and the other three were slow growers. All four patients were treated with available guideline-based treatment protocols and followed up.

Disseminated Coinfection by Mycobacterium fortuitum and Talaromyces marneffei in a Non-HIV Case

Background

Mycobacterium fortuitum is a rapidly growing non-tuberculous mycobacterium (NTM) with weak pathogenicity. Here, we present a rare case of disseminated M. fortuitum and Talaromyces marneffei coinfection in a human immunodeficiency virus (HIV) negative patient.

Case Presentation

A 28-year-old female was admitted to our hospital due to 2 months of swelling of lymph nodes on the right side of her cervix, accompanied by repeated low fever for more than 1 month. Biopsy of the right cervical lymph node and endobronchial ultrasound-guided transbronchial fine needle aspiration (EBUS-TBNA) both suggested granulomatous inflammation. The bacterial culture and mycobacteria examination of the lesion as well as HIV antibody test were all negative. Disseminated T. marneffei infection was diagnosed by the quantitative polymerase chain reaction (qPCR) results from the blood showing 1798 copies/ul. In the meantime, treatment with amphotericin B combined with cefoxitin was administered for suspected NTM infection. However, the once-dropped fever recurred and the lymph nodes continued to swell. Metagenomics next-generation sequencing (mNGS) detection of the lymph nodes indicated M. fortuitum. After combination treatment with amphotericin B, voriconazole, linazolamide, and imipenem, the patient's body temperature returned to normal, the lymph node swelling was gradually reduced, and the lung lesion was absorbed.

Conclusion

We report the first case of an HIV-negative patient diagnosed with disseminated M. fortuitum and T. marneffei coinfection with nonspecific clinical manifestation, in order to heighten awareness of these infections.

Challenges in Drug Discovery for Intracellular Bacteria

Novel drugs are needed to treat a variety of persistent diseases caused by intracellular bacterial pathogens. Virulence pathways enable many functions required for the survival of these pathogens, including invasion, nutrient acquisition, and immune evasion. Inhibition of virulence pathways is an established route for drug discovery; however, many challenges remain. Here, we propose the biggest problems that must be solved to advance the field meaningfully. While it is established that we do not yet understand the nature of chemicals capable of permeating into the bacterial cell, this problem is compounded when targeting intracellular bacteria because we are limited to only those chemicals that can permeate through both human and bacterial outer envelopes. Unfortunately, many chemicals that permeate through the outer layers of mammalian cells fail to penetrate the bacterial cytoplasm. Another challenge is the lack of publicly available information on virulence factors. It is virtually impossible to know which virulence factors are clinically relevant and have broad cross-species and cross-strain distribution. In other words, we have yet to identify the best drug targets. Yes, standard genomics databases have much of the information necessary for short-term studies, but the connections with patient outcomes are yet to be established. Without comprehensive data on matters such as these, it is difficult to devise broad-spectrum, effective anti-virulence agents. Furthermore, anti-virulence drug discovery is hindered by the current state of technologies available for experimental investigation. Antimicrobial drug discovery was greatly advanced by the establishment and standardization of broth microdilution assays to measure the effectiveness of antimicrobials. However, the currently available models used for anti-virulence drug discovery are too broad, as they must address varied phenotypes, and too expensive to be generally adopted by many research groups. Therefore, we believe drug discovery against intracellular bacterial pathogens can be advanced significantly by overcoming the above hurdles.

Clinical course of peritoneal dialysis-related peritonitis due to non-tuberculosis mycobacterium - A single centre experience spanning 20 years

BACKGROUND

Peritoneal dialysis (PD)-related peritonitis caused by non-tuberculous mycobacteria (NTM) are difficult to diagnose, is associated with significant morbidity and mortality, and clinical course remains unclear. We determined the prevalence and clinical course of peritonitis caused by these organisms through our kidney registry over 20-year period.

METHOD

We reviewed all patients with NTM peritonitis identified in our tertiary centre between July 2000 and July 2020. The demographic characteristics, microbiological and clinical outcomes were examined.

RESULT

Among 27 patients identified, 20 patients presented with abdominal pain and all had cloudy peritoneal fluid. Twenty-one cases had concomitant exit site infection and 14 cases had prior antibiotic use. The majority of the cases are caused by Mycobacterium chelonae (37%) and Mycobacterium fortuitum (29.7%), with most being resistant to fluoroquinolones (59.3%) and cefoxitin (73.1%). They are all sensitive to amikacin otherwise. None of the cases achieve primary response at day 10 and 20 cases resulted in Tenckhoff catheter removal. Only two of them were able to resume PD. Eight patients died in our cohort. The presence of exit site infection, the use of prior antibiotics and topical disinfectants did not associate with a poorer outcome.

CONCLUSION

NTM peritonitis remains difficult to treat and often with a delay in diagnosis. Refractory peritonitis with negative culture and a poor response to standard antibiotics should raise a possibility of NTM infection and prompt catheter removal and an expert with experience treating NTM infections should be consulted.

Administration and monitoring of clofazimine for NTM infections in children with and without cystic fibrosis

Few studies have evaluated clofazimine (CLOF) drug monitoring and safety in children. We treated 10 children, 8 with CF, for NTM infection with multiple antimicrobials, including CLOF. All had serial blood CLOF concentrations measured and were followed for adverse events. Despite CLOF dose escalation, most children with CF did not reach a target CLOF concentration. Our data suggest that children with CF may require earlier initiation of CLOF at higher doses than is currently recommended.

Outcome and prognostic factors after lung transplantation for bronchiectasis other than cystic fibrosis

BACKGROUND

While lung transplant (LTX) can be an effective therapy to provide the survival benefit in selected populations, post-transplant outcome in LTX recipients with bronchiectasis other than cystic fibrosis (CF) has been less studied. Pseudomonas aeruginosa, often associated with exacerbations in bronchiectasis, is the most common micro-organism isolated from LTX recipients. We aimed to see the outcomes of patients with bronchiectasis other than CF after LTX and seek the risk factors associated with pre- and post-transplant Pseudomonas status.

METHODS

Patients who underwent LTX at Tohoku University Hospital between January 2000 and December 2020 were consecutively included into the retrospective cohort study. Pre- and post-transplant prevalence of Pseudomonas colonization between bronchiectasis and other diseases was reviewed. Post-transplant outcomes (mortality and the development of chronic lung allograft dysfunction (CLAD)) were assessed using a Cox proportional hazards and time-to-event outcomes were estimated using the Kaplan-Meier method.

RESULTS

LTX recipients with bronchiectasis experienced a high rate of pre- and post-transplant Pseudomonas colonization compared to other diseases with statistical significance (p < 0.001 and p < 0.001, respectively). Nevertheless, long-term survival in bronchiectasis was as great as non-bronchiectasis (Log-rank p = 0.522), and the bronchiectasis was not a trigger for death (HR 1.62, 95% CI 0.63-4.19). On the other hand, the chance of CLAD onset in bronchiectasis was comparable to non-bronchiectasis (Log-rank p = 0.221), and bronchiectasis was not a predictor of the development of CLAD (HR 1.88, 95% CI 0.65-5.40).

CONCLUSIONS

Despite high prevalence of pre- and post-transplant Pseudomonas colonization, the outcome in LTX recipients with bronchiectasis other than CF was comparable to those without bronchiectasis.

Recurrence of Disseminated Mycobacterium avium intracellulare Presenting as Spondylodiscitis and Epidural Abscess in a Patient with Acquired Immune Deficiency Syndrome (AIDS)

Patient: Male, 65-year-old

Final Diagnosis: Mycobacterium avium intracellulare epidural abscess

Symptoms: Back pain • flank pain

Medication: —

Clinical Procedure: Debridement • evacuation of epidural abscess • laminectomy

Specialty: Infectious Diseases • Neurosurgery

Lymphocutaneous spread of Mycobacterium elephantis in an immunocompetent individual: A case report

Mycobacterium elephantis was first described when isolated from an elephant that succumbed to lung abscess. However, despite this namesake, it is not associated with animals and has been described most often as a probable colonizer rather than pathogen in humans with chronic lung disease. In this report, we describe the first case of lymphocutaneous infection from M. elephantis, likely as a result of cutaneous inoculation with contaminated soil. This offers further evidence to its capabilities as a pathogen. We provide a review of the limited prior reports of M. elephantis and outline the available in vitro data on efficacy of various antimycobacterial agents.

Treatment of Mycobacterium abscessus Pulmonary Disease

Mycobacterium abscessus is the second most common nontuberculous mycobacterial lung disease pathogen and comprises three subspecies: abscessus, massiliense, and bolletii. Subspecies identification is critical for disease management, as subspecies abscessus and bolletii have an inducible macrolide resistance gene [erm(41)] that results in clinical macrolide resistance. In contrast, subspecies massiliense does not have an active erm(41) gene and is therefore susceptible in vitro and clinically to macrolide-containing regimens. M abscessus is also vulnerable to acquired mutational macrolide resistance. Macrolide resistance has such a profoundly negative impact on M abscessus treatment response that preserving macrolide susceptibility with adequate companion drugs for macrolides is among the highest treatment priorities. After the macrolides, amikacin is regarded as the next most important drug for M abscessus treatment, although data validating that assertion are lacking. The considerations for preventing acquired macrolide resistance also apply to amikacin. Recent guidelines suggest that treatment should be guided by in vitro susceptibilities but, aside from macrolides and amikacin, no other antibiotics have a validated minimum inhibitory concentration for M abscessus. Currently, phase therapy (intensive and continuation) is recommended for M abscessus. This approach is successful with macrolide-susceptible M abscessus but not with macrolide-resistant M abscessus, in which even more aggressive therapy is not predictably successful. Newer drugs have become available, with encouraging in vitro activity against M abscessus, but in vivo validation of their superiority to current agents is not yet available. In the absence of unequivocally effective regimens, we offer suggestions for managing this treatment-refractory organism.

Epetraborole is Active against Mycobacterium abscessus

Benzoxaboroles are a new class of leucyl-tRNA synthetase inhibitors. We recently reported that the antitubercular 4-halogenated benzoxaboroles are active against Mycobacterium abscessus. Here, we find that the nonhalogenated benzoxaborole epetraborole, a clinical candidate developed for Gram-negative infections, is also active against M. abscessusin vitro and in a mouse model of infection. This expands the repertoire of advanced lead compounds for the discovery of a benzoxaborole-based candidate to treat M. abscessus lung disease.

A Molecular-Beacon-Based Multiplex Real-Time PCR Assay To Distinguish Mycobacterium abscessus Subspecies and Determine Macrolide Susceptibility

Mycobacterium abscessus is a rapidly growing nontuberculous mycobacterial species that comprises three subspecies: M. abscessus subsp. abscessus, M. abscessus subsp. massiliense, and M. abscessus subsp. bolletii. These predominantly environmental microorganisms have emerged as life-threatening chronic pulmonary pathogens in both immunocompetent and immunocompromised patients, and their acquisition of macrolide resistance due to the erm(41) gene and mutations in the 23S rrl gene has dramatically impacted patient outcome. However, standard microbiology laboratories typically have limited diagnostic tools to distinguish M. abscessus subspecies, and the testing for macrolide resistance is often not done. Here, we describe the development of a real-time multiplex assay using molecular beacons to establish a robust, rapid, and highly accurate method to both distinguish M. abscessus subspecies and to determine which strains are susceptible to macrolides. We report a bioinformatic approach to identify robust subspecies sequence targets, the design and optimization of six molecular beacons to identify all genotypes, and the development and application of a 2-tube 3-color multiplex assay that can provide clinically significant treatment information in less than 3 h.

An In Vitro Perspective on What Individual Antimicrobials Add to Mycobacterium avium Complex Therapies

For Mycobacterium avium complex pulmonary disease (MAC-PD), current treatment regimens yield low cure rates. To obtain an evidence-based combination therapy, we assessed the in vitro activity of six drugs, namely, clarithromycin (CLR), rifampin (RIF), ethambutol (EMB), amikacin (AMK), clofazimine (CLO), and minocycline (MIN), alone and in combination, against Mycobacterium avium and studied the contributions of individual antibiotics to efficacy. The MICs of all antibiotics against M. avium ATCC 700898 were determined by broth microdilution. We performed kinetic time-kill assays of all single drugs and clinically relevant two-, three-, four-, and five-drug combinations against M. avium. Pharmacodynamic interactions of these combinations were assessed using area under the time-kill curve-derived effect size and Bliss independence. Adding a second drug yielded an average increase of the effect size (E) of 18.7% ± 32.9%, although antagonism was seen in some combinations. Adding a third drug showed a smaller increase in effect size (+12.2% ± 11.5%). The RIF-CLO-CLR (E of 102 log₁₀ CFU/ml · day), RIF-AMK-CLR (E of 101 log₁₀ CFU/ml · day), and AMK-MIN-EMB (E of 97.8 log₁₀ CFU/ml · day) regimens proved more active than the recommended RIF-EMB-CLR regimen (E of 89.1 log₁₀ CFU/ml · day). The addition of a fourth drug had little impact on effect size (+4.54% ± 3.08%). In vitro, several two- and three-drug regimens are as effective as the currently recommended regimen for MAC-PD. Adding a fourth drug to any regimen had little additional effect. In vitro, the most promising regimen would be RIF-AMK-macrolide or RIF-CLO-macrolide.

Severe Pulmonary Mycobacterium abscessus Cases Due to Co-Infection with Other Microorganisms Well Treated by Clarithromycin and Sitafloxacin in Japan

Background

Mycobacterium abscessus frequently causes severe infections, yet its pathophysiological features and treatment regimens have not been established.

Case Report

We present five cases of severe pneumonia due to Mycobacterium abscessus infection in Japan. All cases were diabetic patients, with possible acceleration to pneumonia due to co-infection with other microorganisms. However, following a short period of hospitalization and combination therapy with intravenous imipenem/cilastatin and amikacin, all the cases were successfully treated as outpatients with oral clarithromycin and sitafloxacin.

Conclusion

M. abscessus infections can become severe in the presence of diabetes mellitus and co-infection with other chronic infectious organisms. Sitafloxacin might be a key drug in the treatment of M. abscessus infection in future.

Targeting emerging Mycobacterium avium infections: perspectives into pathways and antimicrobials for future interventions

Mycobacterium avium is an emerging opportunistic pathogen, globally. Infections caused by M. avium are laborious to treat and could result in drug resistance. This review discusses the importance of many factors including the cell wall in M. avium pathogenesis, since this unique structure modulates the pathogen's ability to thrive in various hosts and environmental niches including conferring resistance to killing by antimicrobials. More research efforts in future are solicited to develop novel therapeutics targeting M. avium. The complete eradication of M. avium infection in immunocompromised individuals would need a deeper understanding of the source of infection, unique underlying mechanisms and its uncharacterized pathways. This could, perhaps in future, hold the key to target and treat M. avium more effectively.

Treatment outcomes of nontuberculous mycobacterial pulmonary disease in lung transplant recipients

BACKGROUND

Lung transplant (LTX) recipients are at risk miscellaneous infections, among whom the clinical significance of nontuberculous mycobacteria (NTM) is increasingly recognized. Despite anti-mycobacterial therapy becoming standardized worldwide, there is a lack of data on treatment outcomes in LTX recipients who develop NTM-pulmonary disease (PD). We aimed to review the treatment outcomes of NTM-PD among LTX recipients in our center.

METHODS

Patients who underwent LTX from January 2013 to December 2014 were consecutively enrolled in the retrospective cohort, with follow-up of data retrieved to December 2017. Clinical and radiological improvement and culture conversion after anti-mycobacterial therapy were reviewed in those who developed post-transplant NTM-PD.

RESULTS

Sixteen of 230 LTX recipients developed post-transplant NTM-PD. Ten of 16 patients with post-transplant NTM-PD were treated with macrolide-containing anti-mycobacterial therapy, leading to clinical improvement in 5/10 (50%), radiological improvement in 5/10 (50%) and culture conversion in 6/10 (60%) patients.

CONCLUSION

Anti-mycobacterial therapy may relieve pulmonary symptoms and reduce microbial load among individuals with post-transplant NTM-PD.

DNA Methylation Profiling for the Diagnosis and Prognosis of Patients with Nontuberculous Mycobacterium Lung Disease

The incidence of nontuberculous Mycobacterium (NTM) lung disease is rapidly increasing; however, its diagnosis and prognosis remain unclear while selecting patients who will respond to appropriate treatment. Differences in DNA methylation patterns between NTM patients with good or poor prognosis could provide important therapeutic targets. We used the Illumina MethylationEPIC (850k) DNA methylation microarray to determine the pattern between differentially methylated regions (DMRs) in NTM patients with good or poor prognosis (n = 4/group). Moreover, we merged and compared 20 healthy controls from previous Illumina Methylation450k DNA methylation microarray data. We selected and visualized the DMRs in the form of heatmaps, and enriched terms associated with these DMRs were identified by functional annotation with the “pathfinder” package. In total, 461 and 293 DMRs (|Log2 fold change| > 0.1 and P < 0.03) were more methylated in patients with four poor and four good prognoses, respectively. Furthermore, 337 and 771 DMRs (|Log2 fold change| > 0.08 and P < 0.001) were more methylated in eight NTM patients and 20 healthy controls, respectively. TGFBr1 was significantly less methylated, whereas HLA-DR1 and HLA-DR5 were more methylated in patients with poor prognosis (compared to those with good prognosis). LRP5, E2F1, and ADCY3 were the top three less-methylated genes in NTM patients (compared with the controls). The mTOR and Wnt signaling pathway-related genes were less methylated in patients with NTM. Collectively, genes related to Th1- cell differentiation, such as TGFBr1 and HLA-DR, may be used as biomarkers for predicting the treatment response in patients with NTM lung disease.

Computed Tomography in Adults with Bronchiectasis and Nontuberculous Mycobacterial Pulmonary Disease: Typical Imaging Findings

Among patients with bronchiectasis, nontuberculous mycobacterial pulmonary disease (NTM-PD) ranged between 1 and 6% and it is suspected that its prevalence is underestimated. Our aim was to evaluate differences in computed tomography (CT) features in patients with bronchiectasis, with and without NTM-PD, in order to facilitate earlier diagnosis in the future. In addition, we evaluated longitudinal changes after successful NTM-PD treatment. One hundred and twenty-eight CTs performed in adults with bronchiectasis were scored for the involvement, type, and lobar distribution of bronchiectasis, bronchial dilatation, and bronchial wall thickening according to Reiff. In addition, associated findings, such as mucus plugging, tree-in-bud, consolidations, ground-glass opacities, interlobular thickening, intralobular lines, cavities, and atelectasis, were registered. Patients with NTM-PD (n = 36), as defined by ATS/IDSA diagnostic criteria, were compared to bronchiectasis patients without NTM-PD (n = 92). In twelve patients with an available consecutive CT scan after microbiological cure of NTM-PD imaging findings were also scored according to Kim and compared in the course. In patients with NTM-PD, there was a higher prevalence of bronchiectasis in the middle lobes (p < 0.001), extended bronchiolitis (p = 0.032) and more small and large nodules (p < 0.001). Furthermore, cavities turned out to be larger (p = 0.038), and walls thickened (p = 0.019) and extended (p = 0.016). Patients without NTM more often showed peripheral ground-glass opacities (0.003) and interstitial changes (p = 0.001). CT findings decreased after successful NTM-PD treatment in the follow-up CT; however, without statistical significance for most features (p = 0.056), but bronchiolitis was the only significantly reduced score item (p = 0.043). CT patterns in patients with bronchiectasis and NTM-PD differ from those of patients with bronchiectasis without NTM-PD, although the findings are non-specific radiological features. Follow-up CT findings after microbiological cure differed interindividual regarding the decline in imaging features. Our findings may help practitioners to identify NTM-PD in patients with bronchiectasis. Further research is needed regarding the use of CT as a potential imaging biomarker for the evaluation of treatment response.

Longitudinal validity and prognostic significance of the St George's Respiratory Questionnaire in Mycobacterium avium complex pulmonary disease

BACKGROUND

Although previous cross-sectional studies showed the feasibility and clinical association of the St. George's Respiratory Questionnaire (SGRQ) in Mycobacterium avium complex pulmonary disease (MAC-PD), its longitudinal validity is poorly understood. We aimed to determine the longitudinal validity and prognostic significance of SGRQ.

METHODS

In this prospective observational study conducted between May 2012 and August 2018, we evaluated 269 enrolled patients with MAC-PD and examined associations between baseline SGRQ total scores and mortality or clinical variables (anchors), including serum C-reactive protein levels and pulmonary function test results.

RESULTS

Age- and sex-matched SGRQ scores indicated significantly greater impairment in patients with MAC-PD than in the general population (P < 0.001). On multivariable Cox proportional hazards regression analysis, the SGRQ total score ≥25 was an independent risk factor for mortality (adjusted hazard ratio, 5.90; 95% confidence interval, 1.65-37.7) as well as age, body mass index, and forced vital capacity (FVC). Mixed-effect model results showed a significant association between SGRQ symptom/total scores and forced expiratory volume in 1 s (FEV₁), FVC, and diffusing carbon monoxide capacity. Older age, a positive smear, non-nodular/bronchiectatic form, and cavity regions were associated with SGRQ total score deterioration. Patients with a greater decline from baseline FEV₁ (% predicted) exhibited significantly worse impairment in the SGRQ total score (mean ± SE, 4.69 ± 10.9 points, P = 0.001).

CONCLUSIONS

SGRQ showed longitudinal validity in assessing disease severity and was sensitive to changes in patients with MAC-PD, especially changes in %FEV_1. The SGRQ total score may be an important prognostic factor.

Activity of Oritavancin and Its Synergy with Other Antibiotics against Mycobacterium abscessus Infection In Vitro and In Vivo

Background: Pulmonary disease caused by Mycobacterium abscessus (M. abscessus) spreads around the world, and this disease is extremely difficult to treat due to intrinsic and acquired resistance of the pathogen to many approved antibiotics. M. abscessus is regarded as one of the most drug-resistant mycobacteria, with very limited therapeutic options. Methods: Whole-cell growth inhibition assays was performed to screen and identify novel inhibitors. The IC₅₀ of the target compounds were tested against THP-1 cells was determined to calculate the selectivity index, and then time–kill kinetics assay was performed against M. abscessus. Subsequently, the synergy of oritavancin with other antibiotics was evaluated by using checkerboard method. Finally, in vivo efficacy was determined in an immunosuppressive murine model simulating M. abscessus infection. Results: We have identified oritavancin as a potential agent against M. abscessus. Oritavancin exhibited time-concentration dependent bactericidal activity against M. abscessus and it also displayed synergy with clarithromycin, tigecycline, cefoxitin, moxifloxacin, and meropenem in vitro. Additionally, oritavancin had bactericidal effect on intracellular M. abscessus. Oritavancin significantly reduced bacterial load in lung when it was used alone or in combination with cefoxitin and meropenem. Conclusions: Our in vitro and in vivo assay results indicated that oritavancin may be a viable treatment option against M. abscessus infection.

Population Pharmacokinetic Analysis of Bedaquiline-Clarithromycin for Dose Selection Against Pulmonary Nontuberculous Mycobacteria Based on a Phase 1, Randomized, Pharmacokinetic Study

Based on the in vitro profile of bedaquiline against mycobacterial species, it is being investigated for clinical efficacy against pulmonary nontuberculous mycobacteria (PNTM). Being a cytochrome P450 3A substrate, pharmacokinetic interactions of bedaquiline are anticipated with clarithromycin (a cytochrome P450 3A inhibitor), which is routinely used in pulmonary nontuberculous mycobacteria treatment. This phase 1, randomized, crossover study assessed the impact of steady-state clarithromycin (500 mg every 12 hours for 14 days) on the pharmacokinetics of bedaquiline and its metabolite (M2) after single-dose bedaquiline (100 mg; n  =  16). Using these data, population pharmacokinetic modeling and simulation analyses were performed to determine the effect of clarithromycin on steady-state bedaquiline exposure. Although no effect was observed on maximum plasma concentration of bedaquiline and time to achieve maximum plasma concentration, its mean plasma exposure increased by 14% after 10 days of clarithromycin coadministration, with slower formation of M2. Simulations showed that bedaquiline plasma trough concentration at steady state was higher (up to 41% until week 48) with clarithromycin coadministration as compared to its monotherapy (400 mg once daily for 2 weeks, followed by 200 mg 3 times a week for 46 weeks; reference regimen). The overall exposure of a simulated bedaquiline regimen (400 mg once dialy for 2 weeks, followed by 200 mg twice a week for 46 weeks) with clarithromycin was comparable (<15% difference) to the monotherapy. Overall, combination of bedaquiline (400 mg once daily for 2 weeks, followed by 200 mg twice a week for 46 weeks) with clarithromycin seems a suitable regimen to be explored for efficacy and safety against pulmonary nontuberculous mycobacteria.

Effects of pain on depression, sleep, exercise tolerance, and quality of life in patients with nontuberculous mycobacterial pulmonary disease

The experience and causes of pain in patients with nontuberculous mycobacterial pulmonary disease (NTM-PD) have not been clarified.This study aimed to determine the prevalence and severity of bodily pain (BP) in patients with NTM-PD. We also investigated the clinical indicators that contribute to pain.We used a retrospective cross-sectional study design. The participants were 114 NTM-PD patients (109 women) with a mean age of 65 years. The prevalence and severity of pain were measured using 2 items from the 36-Item Short Form Survey version 2 (SF-36), and the BP score was calculated. Functional limitation due to dyspnea was quantified using the Modified Medical Research Council Dyspnea Scale (mMRC), depression was assessed using the Center for Epidemiological Studies Depression Scale (CES-D), sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI); health-related quality of life was assessed using the Leicester Cough Questionnaire (LCQ), and exercise tolerance was measured using the Incremental Shuttle Walk Test (ISWT).Pain was reported by 70.2% of the patients (n = 80), and of these, 35.7% (n = 25) reported moderate to very severe pain. NTM-PD patients with high levels of pain had significantly higher scores on the mMRC, CES-D, and PSQI scores, and significantly lower performance on the ISWT and LCQ. Multiple regression analysis identified ISWT, CES-D, and PSQI as independent factors that affected BP scores.Our findings suggest that pain significantly impacts daily life associated with reduced exercise tolerance, the presence of depressive symptoms, and poor sleep quality in patients with NTM-PD.

"One-two Punch": Synergistic β-lactam Combinations for Mycobacterium abscessus and Target Redundancy in the Inhibition of Peptidoglycan Synthesis Enzymes

Mycobacterium abscessus subsp. abscessus is one of the most difficult pathogens to treat and its incidence in disease is increasing. Dual β-lactam combinations act synergistically in vitro, but are not widely employed in practice. A recent study shows that a combination of imipenem and ceftaroline significantly lowers the minimum inhibitory concentration (MIC) of clinical isolates despite both drugs targeting the same peptidoglycan synthesis enzymes. The underlying mechanism of this effect provides a basis for further investigations of dual β-lactam combinations in the treatment of M. abscessus subsp. abscessus eventually leading to a clinical trial. Furthermore, dual β-lactam strategies may be explored for other difficult mycobacterial infections.

Robustness of aerosol delivery of amikacin liposome inhalation suspension using the eFlow® Technology

The purpose of these studies was to understand the effect on product performance of batch-to-batch variability in both the amikacin liposome inhalation suspension (ALIS) formulation and its delivery device, the Lamira® nebulizer system, designed and manufactured by PARI (PARI Pharma GmbH, Munich, Germany). Three batches of ALIS spanning a range of lipid concentrations (43, 48 and 54 mg/mL) were tested with nine PARI inhalation devices that varied within the production process of the vibrating membrane with respect to hole geometry. Three hole geometry clusters were built including a geometry close to the mean geometry (median) and two geometries deviating from the mean geometry with smaller (smaller) and larger (larger) holes. The output parameters included the nebulization rate, the aerosol droplet size distribution, the liposome vesicle size post-nebulization, and the fraction of amikacin that remained encapsulated post-nebulization. Across the 27 experimental combinations of three formulation batches and nine devices, the nebulization time varied between 12 and 15 min with the fastest nebulization rate occurring with the combination of low lipid concentration and larger hole geometry (0.68 g/min) and the slowest nebulization rate occurring with the combination of high lipid concentration and the smaller hole geometry (0.59 g/min). The mean liposome vesicle size post-nebulization ranged from 269 to 296 nm across all experimental combinations which was unchanged from the control samples (276-292 nm). While all three batches contained > 99% encapsulated amikacin prior to nebulization, the nebulization process resulted in a consistent generation of ~ 35% unencapsulated amikacin (range: 33.8% to 37.6%). There was no statistically significant difference in the generated aerosol particle size distributions. The mass median aerodynamic diameters (MMAD) ranged from 4.78 µm to 4.98 µm, the geometric standard deviations (GSD) ranged from 1.61 to 1.66, and the aerosol fine particle fraction (FPF < 5 µm) ranged from 50.3 to 53.5%. The emitted dose (ED) of amikacin ranged from 473 to 523 mg (80.2 to 89.3% of loaded dose (LD)) and the fine particle dose (FPD < 5 µm) ranged from 244 to 278 mg (41.4 to 47.1% of label claim (LC)). In conclusion, while variations in the lipid concentration of the ALIS formulation and the device hole geometry had a small but significant impact on nebulization time, the critical aerosol performance parameters were maintained and remained within acceptable limits.

Atypical presentation of nontuberculous mycobacterial pulmonary infection in a patient with interstitial lung abnormality: A case report

Nontuberculous mycobacterial (NTM) infection is a common and important cause of chronic pulmonary disease, typically characterized by fibrocavitary and nodular-bronchiectatic forms on computed tomography (CT) of the chest. Structural lung disease and the host’s immune status can affect NTM pulmonary infections. Herein, we report a rare case of an NTM pulmonary infection with multiple nodules and masses (with internal cavitation) in an immunocompetent patient exhibiting interstitial lung abnormality on a chest CT.

Amikacin liposome inhalation suspension as a treatment for patients with refractory mycobacterium avium complex lung infection

Introduction: Amikacin liposome inhalation suspension (ALIS) contains amikacin sulfate, an aminoglycoside antibacterial drug. It has been approved in the US as a combined antibiotic treatment for refractory MAC lung disease patients. ALIS, as an inhaled antibiotic, can deliver amikacin to the infected site effectively and reduce systemic toxicity.Areas covered: This article gives a summated review of the pharmacodynamics, pharmacokinetics, therapeutic efficacy, post-marketing surveillance, and regulatory affairs of ALIS as an add-on therapy for MAC lung disease in adults by analyzing data from preclinical studies, clinical trials and original studies. We systematically searched Medline/PubMed through October 2020.Expert opinion: Studies demonstrate that ALIS as an add-on treatment significantly improve the rate of sputum culture conversion in MAC lung disease patients compare to guideline-recommended therapy only. The ALIS treatment showed a similar risk of serious adverse events and a low chance of renal adverse events. However, ALIS was associated with more respiratory adverse events than guideline-recommended therapy only. There was not sufficient data to conclude that ALIS treatment can improve clinical outcomes; however, with the significant improvement in the microbiology outcome in MAC lung disease patients, ALIS showed its potential use as an adjunct treatment for treating MAC lung disease.

Nontuberculous mycobacterial pulmonary disease and associated risk factors in China: A prospective surveillance study

BACKGROUND

We aimed to address the knowledge gap that exists regarding the epidemiological, demographic, and clinical characteristics of nontuberculous mycobacterial pulmonary diseases (NTM-PDs) among smear-positive patients with symptoms suggestive of pulmonary tuberculosis (PTB) in China.

METHODS

Prospective and national surveillance of NTM-PD was performed from 17 hospitals within the China Nontuberculous Mycobacteria Surveillance Study (CNTMS). Patients were eligible for inclusion if they had positive smears during hospitalization. Sputum specimens were collected for molecular species identification.

RESULTS

6,766 patients with valid results were included, consisting of 6,236 (92.2%) with PTB, 458 (6.8%) with NTM-PD, and 72 (1.0%) with colonization. The proportion of NTM-PD in PTB patients exhibited significant geographic diversity, ranging from 3.2% in the northwest to 9.2% in the south. The most prevalent species was Mycobacterium intracellulare, followed by Mycobacterium abscessus complex. Females, elderly people, and patients with bronchiectasis or COPD are at high risk for developing NTM-PD, while patients with diabetes have a lower risk of NTM-PD when compared with non-diabetic patients. Regarding clinical symptoms, lower rates of persistent cough and weight loss were noted in NTM-PD patients than in PTB patients.

CONCLUSIONS

Approximately one-fifteenth of PTB patients are afflicted with nontuberculous mycobacterial infections in China. The prevalence of NTM shows geographic diversity across the country, and it showed a gradual increase from north to south and from west to east. NTM-PD patients are prone to exhibit less severe clinical symptoms than PTB patients, highlighting the importance of raising awareness of NTM diseases to improve decision making on how to best screen, diagnose, and treat NTM in TB-endemic settings.

Mycobacteria: Selection of Transplant Candidates and Post-lung Transplant Outcomes

Mycobacterium is a large, clinically relevant bacterial genus made up of the agents of tuberculosis and leprosy and hundreds of species of saprophytic nontuberculous mycobacteria (NTM). Pathogenicity, clinical presentation, epidemiology, and antimicrobial susceptibilities are exceptionally diverse between species. Patients with end-stage lung disease and recipients of lung transplants are at a higher risk of developing NTM colonization and disease and of severe manifestations and outcomes of tuberculosis. Data from the past three decades have increased our knowledge of these infections in lung transplant recipients. Still, there are knowledge gaps to be addressed to further our understanding of risk factors and optimal treatments for mycobacterial infections in this population.

Isolation of non-tuberculous mycobacteria among tuberculosis patients, a study from a tertiary care hospital in Lahore, Pakistan

BACKGROUND

There is scarce knowledge on the prevalence of diseases caused by non-tuberculous mycobacteria (NTM) in Pakistan. In the absence of culture and identification, acid-fast bacilli (AFB) causing NTM disease are liable to be misinterpreted as tuberculosis (TB). Introduction of nucleic acid amplification testing for Mycobacterium tuberculosis complex (MTBC) offers improved diagnostic accuracy, compared with smear microscopy, and also assists in differentiating MTBC from other mycobacteria. This study aimed to investigate the prevalence of NTM among patients investigated for TB and describe NTM disease and treatment outcomes at a tertiary care hospital in Pakistan.

METHODS

This is a retrospective study, data on NTM isolates among culture-positive clinical samples over 4 years (2016-19) was retrieved from laboratory records. Information on clinical specimens processed, AFB smear results, and for the AFB positive isolates, results of species identification for MTBC, and for NTM isolates, results of species characterization and drug susceptibility testing was collected. Additional clinical data including patient characteristics, treatment regimens, and outcomes were collected for patients with NTM disease treated at Gulab Devi Hospital, Lahore.

RESULTS

During the study period, 12,561 clinical specimens were processed for mycobacterial culture and 3673 (29%) were reported positive for AFB. Among these 3482 (95%) were identified as MTBC and 191 (5%) as NTM. Among NTM, 169 (88%) were isolated from pulmonary and 22 (12%) from extrapulmonary specimens. Results of NTM speciation were available for 60 isolates and included 55% (n = 33) M. avium complex and 25% (n = 15) M. abscesses. Among these patients, complete clinical records were retrieved for 12 patients with pulmonary disease including nine infected with M. avium complex and three with M. abscessus. All 12 patients had a history of poor response to standard first-line anti-TB treatment. Ten patients were cured after 18 months of treatment, whereas, one with M. abscessus infection died and another was lost to follow up.

CONCLUSION

In TB endemic areas, NTM can be misdiagnosed as pulmonary TB leading to repeated failed anti-TB treatment and increased morbidity, emphasizing the need for improved diagnosis.

Amikacin Liposome Inhalation Suspension for Refractory Mycobacterium avium Complex Lung Disease: Sustainability and Durability of Culture Conversion and Safety of Long-term Exposure

BACKGROUND

In the CONVERT study, treatment with amikacin liposome inhalation suspension (ALIS) added to guideline-based therapy (GBT) met the primary end point of increased culture conversion by month 6 in patients with treatment-refractory Mycobacterium avium complex lung disease (ALIS plus GBT, 29% [65/224] vs GBT alone, 8.9% [10/112]; P < .0001).

RESEARCH QUESTION

In patients who achieved culture conversion by month 6 in the CONVERT study, was conversion sustained (negative sputum culture results for 12 months with treatment) and durable (negative sputum culture results for 3 months after treatment) and were there any additional safety signals associated with a full treatment course of 12 months after conversion?

STUDY DESIGN AND METHODS

Adults were randomized 2:1 to receive ALIS plus GBT or GBT alone. Patients achieving culture conversion by month 6 continued therapy for 12 months followed by off-treatment observation.

RESULTS

More patients randomized to ALIS plus GBT (intention-to-treat population) achieved conversion that was both sustained and durable 3 months after treatment vs patients randomized to GBT alone (ALIS plus GBT, 16.1% [36/224] vs GBT alone, 0% [0/112]; P < .0001). Of the patients who achieved culture conversion by month 6, 55.4% of converters (36/65) in the ALIS plus GBT treated arm vs no converters (0/10) in the GBT alone arm achieved sustained and durable conversion (P = .0017). Relapse rates through 3 months after treatment were 9.2% (6/65) in the ALIS plus GBT arm and 30.0% (3/10) in the GBT alone arm. Common adverse events among ALIS plus GBT-treated patients (dysphonia, cough, dyspnea, hemoptysis) occurred mainly within the first 8 months of treatment.

INTERPRETATION

In a refractory population, conversion was sustained and durable in more patients treated with ALIS plus GBT for 12 months after conversion than in those treated with GBT alone. No new safety signals were associated with 12 months of treatment after conversion.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT02344004; URL: www.clinicaltrials.gov.

Comparative genomic analysis of Mycobacterium intracellulare: implications for clinical taxonomic classification in pulmonary Mycobacterium avium-intracellulare complex disease

BACKGROUND

Mycobacterium intracellulare is a representative etiological agent of emerging pulmonary M. avium-intracellulare complex disease in the industrialized countries worldwide. The recent genome sequencing of clinical strains isolated from pulmonary M. avium-intracellulare complex disease has provided insight into the genomic characteristics of pathogenic mycobacteria, especially for M. avium; however, the genomic characteristics of M. intracellulare remain to be elucidated.

RESULTS

In this study, we performed comparative genomic analysis of 55 M. intracellulare and related strains such as M. paraintracellulare (MP), M. indicus pranii (MIP) and M. yonogonense. Based on the average nucleotide identity, the clinical M. intracellulare strains were phylogenetically grouped in two clusters: (1) the typical M. intracellulare (TMI) group, including ATCC13950 and virulent M.i.27 and M.i.198 that we previously reported, and (2) the MP-MIP group. The alignment of the genomic regions was mostly preserved between groups. Plasmids were identified between groups and subgroups, including a plasmid common among some strains of the M.i.27 subgroup. Several genomic regions including those encoding factors involved in lipid metabolism (e.g., fadE3, fadE33), transporters (e.g., mce3), and type VII secretion system (genes of ESX-2 system) were shown to be hypermutated in the clinical strains. M. intracellulare was shown to be pan-genomic at the species and subspecies levels. The mce genes were specific to particular subspecies, suggesting that these genes may be helpful in discriminating virulence phenotypes between subspecies.

CONCLUSIONS

Our data suggest that genomic diversity among M. intracellulare, M. paraintracellulare, M. indicus pranii and M. yonogonense remains at the subspecies or genovar levels and does not reach the species level. Genetic components such as mce genes revealed by the comparative genomic analysis could be the novel focus for further insight into the mechanism of human pathogenesis for M. intracellulare and related strains.

Non tuberculous mycobacteria pulmonary disease: patients and clinicians working together to improve the evidence base for care

Non-tuberculous mycobacterial pulmonary disease is on the rise globally. It is often missed, and causes significant morbidity and even mortality. Here, members of a clinical research network and a patient support group discuss some of the current key issues in NTM management. In addition to the need for research into epidemiology, immunology and treatment, we recommend greater use of patient and clinician networks to: (i) educate primary and secondary care clinicians to develop a high index of suspicion when investigating and treating at risk populations. (ii) promote a multidisciplinary team. (iii) promote shared patient-clinician decision making throughout care. (iv) incorporate use of patient self-report measures to assess progress and outcomes. (v) increase education of patients on their illness and its management. (vi) recruit patients into research projects and registries to improve the clinical evidence base. (vii) increase co-production of research with key stakeholders such as patients and their families, using expert patients and patient groups. (viii) understand more about the psychological, social and economic consequences of the disease.

Amikacin Liposome Inhalation Suspension in Refractory Mycobacterium avium Complex Lung Disease: A Profile of Its Use

Amikacin liposome inhalation suspension (ALIS) [Arikayce^® Liposomal (EU); Arikayce^® (USA)], a liposomal suspension of the aminoglycoside amikacin (590 mg) for nebulization via the Lamira^® Nebulizer System, is available as add-on therapy for treatment-refractory Mycobacterium avium complex (MAC) lung disease in adults who have little or no alternative treatment options. Its addition to guideline-based therapy (GBT) significantly improved the likelihood of achieving sputum culture conversion (defined as three consecutive monthly MAC-negative sputum cultures) by month 6 relative to GBT alone in adults with treatment-refractory MAC lung disease, with the conversion response maintained over up to 12 months' therapy and at 3 months' post treatment in significantly higher proportions of ALIS plus GBT than GBT alone recipients. ALIS as an add-on therapy to GBT was associated with an increased risk of respiratory adverse reactions compared with GBT alone, but treatment-emergent adverse events associated with systemic amikacin exposure were uncommon.

Pipeline of anti-Mycobacterium abscessus small molecules: Repurposable drugs and promising novel chemical entities

The Mycobacterium abscessus complex is a group of emerging pathogens that are difficult to treat. There are no effective drugs for successful M. abscessus pulmonary infection therapy, and existing drug regimens recommended by the British or the American Thoracic Societies are associated with poor clinical outcomes. Therefore, novel antibacterial drugs are urgently needed to contain this global threat. The current anti-M. abscessus small-molecule drug development process can be enhanced by two parallel strategies-discovery of compounds from new chemical classes and commercial drug repurposing. This review focuses on recent advances in the finding of novel small-molecule agents, and more particularly focuses on the activity, mode of action and structure-activity relationship of promising inhibitors from five different chemical classes-benzimidazoles, indole-2-carboxamides, benzothiazoles, 4-piperidinoles, and oxazolidionones. We further discuss some other interesting small molecules, such as thiacetazone derivatives and benzoboroxoles, that are in the early stages of drug development, and summarize current knowledge about the efficacy of repurposable drugs, such as rifabutin, tedizolid, bedaquiline, and others. We finally review targets of therapeutic interest in M. abscessus that may be worthy of future drug and adjunct therapeutic development.

A multidisciplinary approach to the management of nontuberculous mycobacterial lung disease: a clinical perspective

INTRODUCTION

Management of nontuberculous mycobacterial lung disease (NTM-LD) can be encumbered by difficult diagnostic criteria and complex treatment decisions. As prevalence of this debilitating, often refractory, progressive lung disease increases globally, management must evolve beyond antimicrobials to encompass holistic and customized treatments coordinated by practitioners across various specialties.

AREAS COVERED

This review aims to complement the recently updated NTM-LD treatment guidelines and expand current approaches to diagnosis, treatment, and disease management in a multidisciplinary dimension. The foundation of effective long-term management of NTM-LD is awareness of diagnostic criteria, individual patient risk factors, and the importance of managing underlying pulmonary and nonpulmonary comorbidities. The value of adopting all available pharmacological and nonpharmacological treatment modalities with a patient-centered approach to address the needs of long-term patient care cannot be minimized.

EXPERT OPINION

This section, while acknowledging the limited advances in understanding of NTM-LD and the availability of newer diagnostic and therapeutic tools over the last decade, underscores the need for a programmatic approach to this chronic, debilitating pulmonary infection. This will not only lead to more comprehensive patient care with better outcomes, but will also inspire and activate robust networks of research and public health initiatives in this field.

Efficacy estimation of a combination of triple antimicrobial agents against clinical isolates of Mycobacterium abscessus subsp. abscessus in vitro

Background

Mycobacterium abscessus subsp. abscessus (M. abscessus) is a rapidly growing mycobacterium that is resistant to most antibiotics. The number of patients with pulmonary disease caused by M. abscessus is increasing in several regions, and therapy involves long-term antibiotic combination treatments, although no standard treatment regimen has been established.

Objectives

To examine candidate regimens for maintenance of antimicrobial treatment against M. abscessus by measuring MIC using the three-drug chequerboard method.

Methods

We evaluated the drug susceptibility of 70 clinical isolates of M. abscessus using the three-drug chequerboard method. We tested the antimycobacterial agents bedaquiline, clofazimine, amikacin, and sitafloxacin (which showed a relatively low MIC range when used as single agents) alone and in combinations.

Results

The three-drug combinations of bedaquiline/clofazimine/amikacin, and bedaquiline/clofazimine/sitafloxacin were studied. Among isolates for which the fractional inhibitory concentration index (FICI) could be calculated, 29/70 isolates (41%) and 11/70 isolates (16%) showed a synergistic response (FICI ≤0.75) with combined use of bedaquiline/clofazimine/amikacin, or with bedaquiline/clofazimine/sitafloxacin, respectively.

Conclusions

The combination of bedaquiline with clofazimine plus either amikacin or sitafloxacin may be useful as maintenance regimens when treating pulmonary disease caused by M. abscessus.