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

Omadacycline drug susceptibility testing for non-tuberculous mycobacteria using oxyrase to overcome challenges with drug degradation

BACKGROUND

Drug susceptibility testing (DST) protocol of omadacycline against non-tuberculous mycobacteria has not yet been established. We developed a method to accurately determine MIC omadacycline MIC against Mycobacterium abscessus (Mab), Mycobacterium avium-complex (MAC), and Mycobacterium kansasii (Mkn).

METHODS

First, we identified the oxyrase concentration not affecting Mab, MAC, and Mkn growth followed by omadacycline MIC experiments with and without oxyrase using reference and clinical strains.

RESULTS

Oxyrase 0.5 % (v/v) stabilized omadacycline in the culture medium. The median omadacycline MIC was 1 mg/L for Mab and 8 mg/L for Mkn. For MAC, the median omadacycline MIC was 2 mg/L for M. avium, 256 mg/L for M. intracellulare, and 4 mg/L for M. chimaera (p < 0.0001). Wilcoxon matched-pairs signed rank test revealed statistically lower MICs with oxyrase for all MAC subspecies (p < 0.0001), all Mab subspecies (p < 0.0001), and Mkn (p = 0.0002). The decrease in MICs with oxyrase was 17/18 of Mab, 14/19 of Mkn, 8/8 of M. avium, 4/5 M. chimera, but only 11/18 of M. intracellulare (p < 0.013).

CONCLUSION

Use of 0.5 % oxyrase could be a potential solution to reliable and reproducible omadacycline MIC of Mab. However, oxyrase demonstrated a variable effect in reducing MICs against MAC and Mkn.

Biofilm prevention concentration of clarithromycin against clinically relevant species of nontuberculous mycobacteria

OBJECTIVE

Mycobacterium avium complex (MAC) and Mycobacterium abscessus are a group of nontuberculous mycobacteria (NTM) that have been described as human pathogens. Their ability to develop biofilms in tissues and medical devices is one of the most important pathogenicity factors, with important implications in diagnosis and treatment. Macrolides are usually considered one of the bases of this treatment.

METHODS

Here we have studied the biofilm prevention concentration (BPC) of 16 strains (n=16) with clarithromycin to avoid the biofilm development by these NTM.

RESULTS

In this study, all M. abscessus strains have similar BPC, while MAC strains showed different values. For MAC the concentrations ranged between 1-16 mg/L, while for M. abscessus the concentration was 32 mg/L for all strains except one that was 64 mg/L.

CONCLUSIONS

These results open the possibility of using macrolides for the prevention of biofilm development in patients with a risk of developing NTM disease.

Ertapenem's therapeutic potential for Mycobacterium avium lung disease in the hollow fiber model

INTRODUCTION

Guideline-based therapy for Mycobacterium avium complex (MAC) pulmonary disease achieves sustained sputum conversion rates in only 43-53% of patients. Repurposing of β-lactam antibiotics such as ertapenem could expedite design of more efficacious regimens, compared to developing new drugs.

METHODS

We performed an ertapenem exposure-response study in the hollow fiber system model of intracellular MAC (HFS-MAC). We recapitulated human-like intrapulmonary concentration-time profiles of eight once-daily intravenous doses of ertapenem over 28 days and performed repetitive sampling for drug concentration-time profiles and MAC burden. The % of time concentration persisted above MIC (%TMIC) mediating either 50% or 80% of maximal effect (E50, EC80) were identified. The EC80 was used as target exposure in a 10,000 subject Monte Carlo experiments for ertapenem doses of 1G, 2G, or 4G administered once versus twice daily.

RESULTS

The ertapenem MIC ranged from 0.5 to 2 mg/L on three occasions. Ertapenem achieved a half-life of 4.04±0.80h in the HFS-MAC and killed a maximum of 2.17 log10 CFU/mL below day 0. The EC50 was %TMIC of 75.9% (95% confidence interval: 68.43% to 86.54%) and the EC80 was %TMIC of 100%. Target attainment probability was >90% for 1G twice daily up to an MIC of 2 mg/L, while for 2G twice daily the susceptibility MIC breakpoint was 4-8 mg/L.

CONCLUSIONS

Ertapenem microbial kill below day 0 burden was better than guideline-based therapy drugs in the HFS-MAC in the past. Ertapenem is a promising drug for novel combination therapies for MAC lung disease.

Tolerability Outcomes of American Thoracic Society/Infectious Diseases Society of America Guideline-Recommended Multidrug Antibiotic Treatment for Mycobacterium avium Complex Pulmonary Disease in US Medicare Beneficiaries With Bronchiectasis

BACKGROUND

Nontuberculous mycobacteria are environmental organisms that are increasingly causing chronic and debilitating pulmonary infections, of which Mycobacterium avium complex (MAC) is the most common pathogen. MAC pulmonary disease (MAC-PD) is often difficult to treat, often requiring long-term multidrug antibiotic therapy.

RESEARCH QUESTION

Is there an association between various guideline-based three-drug therapy (GBT) regimens and (1) therapy-associated adverse events or (2) regimen change/discontinuation, within 12 months of therapy initiation?

STUDY DESIGN AND METHODS

In a retrospective cohort study, we examined tolerability outcomes of GBT regimens for MAC-PD in 4,626 US Medicare beneficiaries with bronchiectasis, who were prescribed a GBT as initial antibiotic treatment for presumed MAC-PD during 2006 to 2014. Using multivariable Cox proportional hazard regression, we estimated adjusted hazard ratios (aHRs) to compare the risk of adverse events and regimen change/discontinuations within 12 months of therapy initiation in various GBT regimens.

RESULTS

The cohort had a mean age ± SD of 77.9 ± 6.1 years at treatment start, were mostly female (77.7%), and were mostly non-Hispanic White (87.2%). The risk of regimen change/discontinuation within 12 months of therapy was higher for clarithromycin-based regimens than azithromycin-based regimens (aHR, 1.12; 95% CI, 1.04-1.20 with rifampin; aHR, 1.11; 95% CI, 0.93-1.32 with rifabutin as the companion rifamycin), and for rifabutin-containing regimens than rifampin-containing regimens (aHR, 1.49; 95% CI, 1.33-1.68 with azithromycin; aHR, 1.47; 95% CI, 1.27-1.70 with clarithromycin as the companion macrolide). The aHR comparing regimen change/discontinuation with clarithromycin-ethambutol-rifabutin and azithromycin-ethambutol-rifampin was 1.64 (95% CI, 1.43-1.64).

INTERPRETATION

Overall, an azithromycin-based regimen was less likely to be changed or discontinued than a clarithromycin-based regimen, and a rifampin-containing regimen was less likely to be changed or discontinued than a rifabutin-containing regimen within 12 months of therapy start. Our work provides a population-based assessment on the tolerability of multidrug antibiotic regimens used for the treatment of MAC-PD.

A health literacy analysis of online patient-directed educational materials about mycobacterium avium complex

Introduction

Mycobacterium avium complex (MAC) is a complex lung infection requiring multi-disciplinary approach and management. Due to limited clinician-patient interactions, clinicians may refer patients to online resources to learn about the diagnosis, prognosis, and treatment of MAC. The American Medical Association (AMA) recommends educational materials be written at a sixth-grade reading level and the National Institutes of Health (NIH) recommends that patient education materials be written at an eighth-grade reading level; however, several evaluations found these materials inaccessible due to high literacy levels. To date, there has never been a health literacy assessment of MAC patient education materials. The study aims to assess the health literacy of online patient education materials about MAC.

Methods

The patient education materials were evaluated for readability, actionability, understandability and clarity. Readability was assessed through the Flesch-Kincaid Grade Level Scale (FkGL), SMOG Index, Coleman Liau Index (CLI), Gunning Fog Index (GFI), and Automated Readability Index (ARI). Actionability and understandability was evaluated using the Patient Education Materials Assessment Tool (PEMAT). The Centers for Disease Control (CDC) Clear Communication Index (CCI) was used to assess clarity.

Results

Ten patient education resources were evaluated: CDC, Cleveland Clinic, Mayo Clinic, JAMA, American Thoracic Society (ATS), National Jewish Health, UpToDate, CHEST, WebMD, and Medline. The mean readability scores were as follows: FkGL (9.76), SMOG index (9.82), CLI (13.54), GFI (11.66), ARI (9.15). Four patient education materials were written at a sixth-grade reading level and eight patient education materials were written at an eighth-grade reading level. The majority of the materials received a passing score for understandability but failed to achieve a passing score for actionability. Cleveland Clinic, JAMA, and ATS all received a passing clarity score, indicating that they are easy to read. No patient education materials were available on UpToDate.

Conclusion

Most patient education materials scored poorly for actionability and clarity while scoring highly for readability and understandability. This study should serve as a guide for clinicians interested in offering online education materials to their patients. Increasing access to readable MAC educational materials should be a priority for those working at the intersection of public health, clinical care, and communications.

Beyond Symptoms: Radiologic identification of asymptomatic Mycobacterium avium complex pulmonary infections

BACKGROUND

Although international nontuberculous mycobacterial pulmonary disease (NTM-PD) guidelines highlight symptom presence at diagnosis, the clinical characteristics of asymptomatic Mycobacterium avium complex pulmonary infection (MAC-PI) patients remain understudied. We clarified the clinical characteristics and course of asymptomatic MAC-PI patients.

METHODS

We retrospectively analyzed 200 consecutive patients with MAC-PIs and adequate available data who newly met the microbiological and radiological criteria for NTM-PD at Fukujuji Hospital from January 2018 to June 2020. We compared the clinical characteristics and course of asymptomatic patients with symptomatic patients and evaluated factors influencing treatment initiation through multivariate analysis.

RESULTS

111 patients were symptomatic and 89 were asymptomatic at diagnosis. While the proportion was significantly lower than that in the symptomatic group (28.8 %), 15.7 % of asymptomatic group patients had cavitary lesions (P = 0.042). In the asymptomatic group, treatments were initiated in 38 (42.7 %) patients, and cavitary lesions, a positive acid-fast bacilli smear, and younger age were independent risk factors for treatment initiation. Among 22 (57.9 %) patients who experienced disease progression necessitating treatment during follow-up, 13 (34.2 %) displayed radiological progression without any worsening of symptoms. Agents used for treatment were consistent across the groups, with no significant differences in culture conversion, microbiological recurrence rates, or spontaneous culture conversion rates.

CONCLUSION

Routine health checkups and radiological examinations can detect clinically important MAC-PIs even in the absence of symptoms. Considering that the clinical course of asymptomatic MAC-PI patients is largely similar to that of symptomatic patients, timely and appropriate management and intervention are essential for all MAC-PI patients.

Management of M. abscessus subsp. abscessus early-onset prosthetic joint infection: Case report and literature review

Nontuberculous mycobacteria are a rare but still emerging cause of difficult-to-treat prosthetic joint infection. To our knowledge only 17 cases of M. abscessus complex prosthetic joint infection are reported in literature, of which only 1 is by M. abscessus subps. abscessus. No guidelines are available for this clinical scenario. We describe a 68-years-old female patient with an early-onset M. abscessus subsp. abscessus prosthetic joint infection, successfully treated with a tailored medical-surgical strategy, and present an overview of cases currently available in the literature to assist physicians in the management of these uncommon infections.

Mycobacterium abscessus extracellular vesicles increase mycobacterial resistance to clarithromycin in vitro

Nontuberculous Mycobacteria (NTM) are a group of emerging bacterial pathogens that have been identified in cystic fibrosis (CF) patients with microbial lung infections. The treatment of NTM infection in CF patients is challenging due to the natural resistance of NTM species to many antibiotics. Mycobacterium abscessus is one of the most common NTM species found in the airways of CF patients. In this study, we characterized the extracellular vesicles (EVs) released by drug-sensitive M. abscessus untreated or treated with clarithromycin (CLR), one of the frontline anti-NTM drugs. Our data show that exposure to CLR increases mycobacterial protein trafficking into EVs as well as the secretion of EVs in culture. Additionally, EVs released by CLR-treated M. abscessus increase M. abscessus resistance to CLR when compared to EVs from untreated M. abscessus. Proteomic analysis further indicates that EVs released by CLR-treated M. abscessus carry an increased level of 50S ribosomal subunits, the target of CLR. Taken together, our results suggest that EVs play an important role in M. abscessus resistance to CLR treatment.

Therapeutic developments for tuberculosis and nontuberculous mycobacterial lung disease

Tuberculosis (TB) drug discovery and development has undergone nothing short of a revolution over the past 20 years. Successful public-private partnerships and sustained funding have delivered a much-improved understanding of mycobacterial disease biology and pharmacology and a healthy pipeline that can tolerate inevitable attrition. Preclinical and clinical development has evolved from decade-old concepts to adaptive designs that permit rapid evaluation of regimens that might greatly shorten treatment duration over the next decade. But the past 20 years also saw the rise of a fatal and difficult-to-cure lung disease caused by nontuberculous mycobacteria (NTM), for which the drug development pipeline is nearly empty. Here, we discuss the similarities and differences between TB and NTM lung diseases, compare the preclinical and clinical advances, and identify major knowledge gaps and areas of cross-fertilization. We argue that applying paradigms and networks that have proved successful for TB, from basic research to clinical trials, will help to populate the pipeline and accelerate curative regimen development for NTM disease.

Neurological manifestations of nontuberculous mycobacteria in adults: case series and review of the literature

Introduction

Nontuberculous mycobacteria (NTM) mediated infections are important to consider in cases with neuroinflammatory presentations. We aimed to characterize cases of NTM with neurological manifestations at the National Institutes of Health (NIH) Clinical Center and review the relevant literature.

Materials and methods

Between January 1995 and December 2020, six cases were identified. Records were reviewed for demographic, clinical, and radiological characteristics. A MEDLINE search found previously reported cases. Data were extracted, followed by statistical analysis to compare two groups [cases with slow-growing mycobacteria (SGM) vs. those with rapidly growing mycobacteria (RGM)] and evaluate for predictors of survival. NIH cases were evaluated for clinical and radiological characteristics. Cases from the literature were reviewed to determine the differences between SGM and RGM cases and to identify predictors of survival.

Results

Six cases from NIH were identified (age 41 ± 13, 83% male). Five cases were caused by SGM [Mycobacterium avium complex (MAC) n = 4; Mycobacterium haemophilum n = 1] and one due to RGM (Mycobacterium abscessus). Underlying immune disorders were identified only in the SGM cases [genetic (n = 2), HIV (n = 1), sarcoidosis (n = 1), and anti-interferon-gamma antibodies (n = 1)]. All cases were diagnosed using tissue analysis. A literature review found 81 reports on 125 cases (SGM n = 85, RGM n = 38, non-identified n = 2). No immune disorder was reported in 26 cases (21%). Within SGM cases, the most common underlying disease was HIV infection (n = 55, 65%), and seizures and focal lesions were more common. In RGM cases, the most common underlying condition was neurosurgical intervention or implants (55%), and headaches and meningeal signs were common. Tissue-based diagnosis was used more for SGM than RGM (39% vs. 13%, p = 0.04). Survival rates were similar in both groups (48% SGM and 55% in RGM). Factors associated with better survival were a solitary CNS lesion (OR 5.9, p = 0.01) and a diagnosis made by CSF sampling only (OR 9.9, p = 0.04).

Discussion

NTM infections cause diverse neurological manifestations, with some distinctions between SGM and RGM infections. Tissue sampling may be necessary to establish the diagnosis, and an effort should be made to identify an underlying immune disorder.

Laboratory tests and analysis of drug resistance in non-tuberculous mycobacteria

Background

This study analyzed the laboratory diagnosis results and drug resistance of patients infected with non-tuberculous mycobacterium (NTM).

Methods

We collected information on patients with positive indicators of NTM infection at the Henan Provincial Chest Hospital from 2020 to 2022. Acid-fast smear, mycobacterium culture, QB-SPOT assay, GeneXpert MTB/RIF assay, immunoglobulin E test, tuberculosis antibody test, and microplate method for drug sensitivity test were analyzed using strain identification as the gold standard.

Results

The 242 cases of NTM infection were predominantly detected with slow-growing mycobacteria (a detection rate of 87.19%), among which Mycobacterium intracellulare (66.53%), Mycobacterium avium (15.70%), and Mycobacterium chelonei/abscessus complex (11.16%) ranked the top three in terms of the isolation rate. Males patients accounted for a higher proportion (58.26%) than females (41.74%), and the majority of them were over 60 years (50.83%). Among laboratory tests for patients with NTM infection, mycobacterium culture showed a highest detected rate (87.20%) among laboratory tests. The results of the drug sensitivity test demonstrated that the resistance rate of NTM was generally high. Moreover, the Mycobacterium avium complex with the highest isolation rate showed 100% resistant to doxycycline and minocycline, but exhibited relatively high sensitivity to moxifloxacin (a resistance rate of 7.89%) and rifabutin (a resistance rate of 13.16%). The Mycobacterium chelonei/abscessus complex was 100% resistant to doxycycline and relatively sensitive to cefoxitin (29.17%) and clarithromycin (37.50%).

Conclusion

The NTM species isolated by the Henan Provincial Chest Hospital is dominated by Mycobacterium intracellulare and the highest positive rate is detected by mycobacterium culture among laboratory tests. NTM infection generally exhibits a high rate of drug resistance. Accordingly, the accurate diagnosis of NTM diseases requires enhanced drug sensitivity testing to provide patients with targeted combination drug treatment.

Intracellular iron accumulation facilitates mycobacterial infection in old mouse macrophages

Aging has a significant impact on the immune system, leading to a gradual decline in immune function and changes in the body's ability to respond to bacterial infections. Non-tuberculous mycobacteria (NTM), also known as atypical mycobacteria or environmental mycobacteria, are commonly found in soil, water, and various environmental sources. While many NTM species are considered opportunistic pathogens, some can cause significant infections, particularly in individuals with compromised immune systems, such as older individuals. When mycobacteria enter the body, macrophages are among the first immune cells to encounter them and attempt to engulf mycobacteria through a process called phagocytosis. Some NTM species, including Mycobacterium avium (M. avium) can survive and replicate within macrophages. However, little is known about the interaction between NTM and macrophages in older individuals. In this study, we investigated the response of bone marrow-derived macrophage (BMMs) isolated from young (5 months) and old (25 months) mice to M. avium serotype 4, one of the main NTM species in patients with pulmonary NTM diseases. Our results demonstrated that BMMs from old mice have an increased level of intracellular iron and are more susceptible to M. avium serotype 4 infection compared to BMMs from young mice. The whole-cell proteomic analysis indicated a dysregulated expression of iron homeostasis-associated proteins in old BMMs regardless of mycobacterial infection. Deferoxamine, an iron chelator, significantly rescued mycobacterial killing and phagolysosome maturation in BMMs from old mice. Therefore, our data for the first time indicate that an intracellular iron accumulation improves NTM survival within macrophages from old mice and suggest a potential application of iron-chelating drugs as a host-directed therapy for pulmonary NTM infection in older individuals.

Bigger problems from smaller colonies: emergence of antibiotic-tolerant small colony variants of Mycobacterium avium complex in MAC-pulmonary disease patients

BACKGROUND

Mycobacterium avium complex (MAC) is a group of slow-growing mycobacteria that includes Mycobacterium avium and Mycobacterium intracellulare. MAC pulmonary disease (MAC-PD) poses a threat to immunocompromised individuals and those with structural pulmonary diseases worldwide. The standard treatment regimen for MAC-PD includes a macrolide in combination with rifampicin and ethambutol. However, the treatment failure and disease recurrence rates after successful treatment remain high.

RESULTS

In the present study, we investigated the unique characteristics of small colony variants (SCVs) isolated from patients with MAC-PD. Furthermore, revertant (RVT) phenotype, emerged from the SCVs after prolonged incubation on 7H10 agar. We observed that SCVs exhibited slower growth rates than wild-type (WT) strains but had higher minimum inhibitory concentrations (MICs) against multiple antibiotics. However, some antibiotics showed low MICs for the WT, SCVs, and RVT phenotypes. Additionally, the genotypes were identical among SCVs, WT, and RVT. Based on the MIC data, we conducted time-kill kinetic experiments using various antibiotic combinations. The response to antibiotics varied among the phenotypes, with RVT being the most susceptible, WT showing intermediate susceptibility, and SCVs displaying the lowest susceptibility.

CONCLUSIONS

In conclusion, the emergence of the SCVs phenotype represents a survival strategy adopted by MAC to adapt to hostile environments and persist during infection within the host. Additionally, combining the current drugs in the treatment regimen with additional drugs that promote the conversion of SCVs to RVT may offer a promising strategy to improve the clinical outcomes of patients with refractory MAC-PD.

Identification of essential oils with strong activity against stationary phase Mycobacterium abscessus

Purpose

To identify essential oils (EOs) active against non-growing stationary phase Mycobacterium abscessus and multidrug-resistant M. abscessus strains.

Methods

The activity of EOs against both stationary and log phase M. abscessus was evaluated by colony forming unit (CFU) assay and minimum inhibitory concentration (MIC) testing.

Results

We assessed the activity of 80 EOs against stationary phase M. abscessus and found 12 EOs (Cinnamon, Satureja montana, Palmarosa, Lemon eucalyptus, Honey myrtle, Combava, Health shield, Mandarin, Thyme, Rosewood, Valerian Root and Basil) at 0.5% concentration to be active against both growing and non-growing stationary phase M. abscessus. Among them, Satureja montana essential oil and Palmarosa essential oil could eliminate all stationary phase M. abscessus at 0.125% and Cinnamon essential oil could eliminate stationary phase bacteria at 0.063% after 1-day treatment. Interestingly, these EOs also exhibited promising activity against multidrug-resistant M. abscessus clinical strains.

Conclusions

Our study indicates that some EOs display outstanding effectiveness against both drug susceptible M. abscessus and multidrug-resistant M. abscessus isolates. These findings may be significant for the treatment of persistent M. abscessus infections.

Variables associated with antibiotic treatment tolerance in patients with Mycobacterium avium complex pulmonary disease

BACKGROUND

Treatment of Mycobacterium avium complex pulmonary disease (MAC-PD) involves prolonged courses of multiple antibiotics that are variably tolerated and commonly cause adverse drug reactions (ADR). The purpose of this retrospective, single-center study was to identify demographic and disease-related variables associated with significant ADRs among patients treated with antibiotics against MAC-PD.

METHODS

We reviewed all patients treated with antibiotic therapy for MAC-PD at a single center from 2000 to 2021. Patients were included if they met diagnostic criteria for MAC-PD, were prescribed targeted antibiotic therapy for any length of time and had their treatment course documented in their health record. We compared patients who completed antibiotics as originally prescribed (tolerant) with those whose antibiotic treatment course was modified or terminated secondary to an ADR (intolerant).

RESULTS

Over the study period, 235 patients were prescribed antibiotic treatment with their clinical course documented in our center's electronic health record, and 246 treatment courses were analyzed. One hundred forty-three (57%) tolerated therapy versus 108 (43%) experienced ADRs. Among the 108 intolerant courses, 67 (63%) required treatment modification and 49 (46%) required premature treatment termination. Treatment intolerance was associated more frequently with smear positive sputum cultures (34% vs. 20%, p = 0.009), a higher Charlson Comorbidity Index (CCI) (4 vs. 6, p = 0.007), and existing liver disease (7% vs. 1%, p = 0.03). There was no between-group difference in BMI (21 vs. 22), fibrocavitary disease (24 vs. 19%), or macrolide sensitivity (94 vs. 80%). The use of daily therapy was not associated with intolerance (77 vs. 79%). Intolerant patients were more likely to be culture positive after 6 months of treatment (44 vs. 25%).

CONCLUSIONS

Patients prescribed antibiotic therapy for MAC-PD are more likely to experience ADRs if they have smear positive sputum cultures at diagnosis, a higher CCI, or existing liver disease. Our study's rate of early treatment cessation due to ADR's was similar to that of other studies (20%) but is the first of its kind to evaluate patient and disease factors associated with ADR's. A systematic approach to classifying and addressing ADRs for patients undergoing treatment for MAC-PD is an area for further investigation.

Amikacin liposome inhalation suspension for Mycobacterium avium complex pulmonary disease: A subgroup analysis of Japanese patients in the randomized, phase 3, CONVERT study

BACKGROUND

CONVERT, a randomized, active-controlled, global, Phase 3 trial demonstrated that patients with treatment-refractory Mycobacterium avium complex (MAC) pulmonary disease were more likely to achieve culture conversion with amikacin liposome inhalation suspension (ALIS) plus guideline-based therapy (GBT) versus those continuing on GBT alone. This subgroup analysis reports the efficacy and safety of ALIS in Japanese patients enrolled in CONVERT.

METHODS

Japanese patients aged ≥20 years with treatment-refractory MAC pulmonary disease from Japanese sites were included. Patients were randomized to receive once-daily 590 mg ALIS + GBT or GBT alone; patients converting by Month 6 remained in the study to complete 12-month treatment followed by a 12-month off-treatment period. Nonconverters exited the study at Month 8. The primary endpoint was the proportion of patients achieving culture conversion by Month 6.

RESULTS

Of the 59 Japanese patients screened, 48 were randomized to receive ALIS + GBT (n = 34) or GBT alone (n = 14), and 41/48 (85.4 %) were women. The mean (standard deviation) age of patients was 64.5 (8.6) years, and 83.3 % of patients had bronchiectasis at baseline. By Month 6, sputum culture conversion was cumulatively achieved in 9/34 (26.5 %) patients receiving ALIS + GBT versus none receiving GBT alone. Treatment-emergent adverse events were reported in 94.1 % and 100.0 % of patients receiving ALIS + GBT and GBT alone, respectively. No deaths were reported.

CONCLUSIONS

The efficacy observed in the Japanese subpopulation was largely consistent with that in the overall CONVERT study population, with more patients achieving culture conversion with ALIS + GBT versus GBT alone. Safety profiles were similar between the overall population and the Japanese subpopulation.

CLINICAL TRIAL REGISTRATION

NCT02344004.

Standards for the care of people with cystic fibrosis (CF); recognising and addressing CF health issues

This is the third in a series of four papers updating the European Cystic Fibrosis Society (ECFS) standards for the care of people with CF. This paper focuses on recognising and addressing CF health issues. The guidance was produced with wide stakeholder engagement, including people from the CF community, using an evidence-based framework. Authors contributed sections, and summary statements which were reviewed by a Delphi consultation. Monitoring and treating airway infection, inflammation and pulmonary exacerbations remains important, despite the widespread availability of CFTR modulators and their accompanying health improvements. Extrapulmonary CF-specific health issues persist, such as diabetes, liver disease, bone disease, stones and other renal issues, and intestinal obstruction. These health issues require multidisciplinary care with input from the relevant specialists. Cancer is more common in people with CF compared to the general population, and requires regular screening. The CF life journey requires mental and emotional adaptation to psychosocial and physical challenges, with support from the CF team and the CF psychologist. This is particularly important when life gets challenging, with disease progression requiring increased treatments, breathing support and potentially transplantation. Planning for end of life remains a necessary aspect of care and should be discussed openly, honestly, with sensitivity and compassion for the person with CF and their family. CF teams should proactively recognise and address CF-specific health issues, and support mental and emotional wellbeing while accompanying people with CF and their families on their life journey.

Prevalence of Mycobacterium kansasii in clinical and environmental isolates, a systematic review and meta-analysis

Background

Mycobacterium kansasii infection is one of the most common causes of non-tuberculosis mycobacterial (NTM) disease worldwide. However, accurate information on the global prevalence of this bacterium is lacking. Therefore, this study was conducted to investigate the prevalence of M. kansasii in clinical and environmental isolates.

Methods

Databases, including PubMed, Scopus, and the Web of Science, were utilized to gather articles on the prevalence of M. kansasii in clinical and environmental isolates. The collected data were analyzed using Comprehensive Meta-Analysis software.

Results

A total of 118 and 16 studies met the inclusion criteria and were used to analyze the prevalence of M. kansasii in clinical and environmental isolates, respectively. The prevalence of M. kansasii in NTM and environmental isolates were 9.4 and 5.8%, respectively. Subsequent analysis showed an increasing prevalence of M. kansasii over the years. Additionally, the results indicated a significant difference in the prevalence of this bacteria among different regions.

Conclusion

The relatively high prevalence of M. kansasii among NTM isolates suggests the need for further implementation of infection control strategies. It is also important to establish appropriate diagnostic criteria and management guidelines for screening this microorganism in environmental samples in order to prevent its spread, given its high prevalence in environmental isolates.

Time-dependent pharmacodynamics of amikacin on Mycobacterium abscessus growth and resistance emergence

Mycobacterium abscessus pulmonary disease is increasing in prevalence globally, particularly for individuals with cystic fibrosis. These infections are challenging to treat due to a high rate of resistance. Amikacin is critical to treatment, but the development of toxicity, amikacin resistance, and treatment failure are significant challenges. Amikacin has been characterized previously as peak-dependent and extended-interval dosing is commonly used. In our hollow fiber infection model of M. abscessus, amikacin exhibited time-dependent rather than the expected peak-dependent pharmacodynamics. Humanized amikacin exposures with more frequent, short-interval dosing (continuous infusion or every 12 hours) yielded improved microbiological response compared to extended-interval dosing (every 24 hours or 1-3 times per week). Short-interval dosing inhibited growth with a mean (SD) maximum Δlog10 colony forming units of -4.06 (0.52), significantly more than extended-interval dosing (P = 0.0013) every 24 hours, -2.40 (0.58), or 1-3 times per week, -2.39 (0.38). Growth recovery, an indicator of resistance emergence, occurred at 6.56 (0.70) days with short-interval dosing but was significantly earlier with extended-interval dosing (P = 0.0032) every 24 hours, 3.88 (0.85) days, and 1-3 times per week, 3.27 (1.72) days. Microbiological response correlated best with the pharmacodynamic index of %T > minimum inhibitory concentration (MIC), with an EC80 for growth inhibition of ~40%T > MIC. We used a previously published population model of amikacin to determine the probability of achieving 40%T > MIC and show that current dosing strategies are far below this target, which may partially explain why treatment failure remains so high for these infections. These data support a cautious approach to infrequent amikacin dosing for the treatment of M. abscessus.IMPORTANCEPulmonary disease caused by Mycobacterium abscessus complex (MABSC) is increasing worldwide, particularly in patients with cystic fibrosis. MABSC is challenging to treat due to high levels of antibiotic resistance. Treatment requires 2-4 antibiotics over more than 12 months and has a significant risk of toxicity but still fails to eradicate infection in over 50% of patients with cystic fibrosis. Antibiotic dosing strategies have been largely informed by common bacteria such as Pseudomonas aeruginosa. The "pharmacodynamic" effects of amikacin, a backbone of MABSC treatment, were thought to be related to maximum "peak" drug concentration, leading to daily or three times weekly dosing. However, we found that amikacin MABSC kill and growth recovery, an indicator of antibiotic resistance, are dependent on how long amikacin concentrations are above the minimum inhibitory concentration, not how high the peak concentration is. Therefore, we recommend a re-evaluation of amikacin dosing to determine if increased frequency can improve efficacy.

Post-treatment Radiographic Severity and Mortality in Mycobacterium avium Complex Pulmonary Disease

Rationale: Imaging studies are widely performed when treating Mycobacterium avium complex pulmonary disease (MAC-PD); however, the clinical significance of post-treatment radiographic change is unknown. Objectives: To determine whether a deep neural network trained with pulmonary tuberculosis could adequately score the radiographic severity of MAC-PD and then to examine relationships between post-treatment radiographic severity and its change from baseline and long-term prognosis. Methods: We retrospectively collected chest radiographs of adult patients with MAC-PD treated for ⩾6 months at baseline and at 3, 6, 9, and 12 months of treatment. We correlated the radiographic severity score generated by a deep neural network with visual and clinical severity as determined by radiologists and mycobacterial culture status, respectively. The associations between the score, improvement from baseline, and mortality were analyzed using Cox proportional hazards regression. Results: In total, 342 and 120 patients were included in the derivation and validation cohorts, respectively. The network's severity score correlated with radiologists' grading (Spearman coefficient, 0.40) and mycobacterial culture results (odds ratio, 1.02; 95% confidence interval [CI], 1.0-1.05). A significant decreasing trend in the severity score was observed over time (P < 0.001). A higher score at 12 months of treatment was independently associated with higher mortality (adjusted hazard ratio, 1.07; 95% CI, 1.03-1.10). Improvements in radiographic scores from baseline were associated with reduced mortality, regardless of culture conversion (adjusted hazard ratio, 0.42; 95% CI, 0.22-0.80). These findings were replicated in the validation cohort. Conclusions: Post-treatment radiographic severity and improvement from baseline in patients with MAC-PD were associated with long-term survival.

Efficacy of clofazimine-containing regimens for treatment of Mycobacterium avium complex-pulmonary disease in patients unsuitable for standard treatment regimen

OBJECTIVES

Patients with Mycobacterium avium complex-pulmonary disease (MAC-PD) can exhibit contraindications in applying the recommended treatment regimens by the guidelines. Clofazimine (CFZ) is considered a promising drug for MAC-PD treatment and is frequently included in alternative regimens; however, its efficacy remains unclear.

METHODS

MAC-PD patients, unsuitable for standard regimens, were enrolled continuously in a prospective study at Beijing Chest Hospital. The treatment response of the CFZ-containing regimen was monitored.

RESULTS

Fifty patients were enrolled in the initial treatment, and 25 patients had a history of anti-TB treatment. Nodular bronchiectasis was observed in 34 patients, while 8 patients exhibited fibrocavitary changes. Additionally, eight patients displayed a combination of both patterns. In a multivariate analysis, MAC-PD patients with CFZ MIC < 0.25 mg/L were significantly associated with culture conversion [OR 8.415, 95% CI (1.983-35.705); P = 0.004]. Among patients who had previous TB treatment history, patients with CFZ MIC < 0.25 mg/L had a higher chance of acquiring culture conversion outcomes [(OR 7.737, 95% CI 1.032-57.989); P = 0.046]. In contrast, among patients with no previous TB treatment history, the RIF-containing regimen had a higher chance of acquiring culture conversion outcomes [(OR 11.038, 95%CI 1.008-120.888); P = 0.049].

CONCLUSION

MAC-PD patients unsuitable for standard regimens could benefit from a CFZ-containing regimen, especially for patients with previous TB treatment history and baseline CFZ MIC values lower than 0.25 mg/L.

In vitro susceptibility of nontuberculous mycobacteria in China

OBJECTIVES

This study aimed to measure the prevalence of resistance to antimicrobial agents, and explore the risk factors associated with drug resistance by using nontuberculous Mycobacteria (NTM) isolates from China.

METHODS

A total of 335 NTM isolates were included in our analysis. Broth dilution method was used to determine in vitro drug susceptibility of NTM isolates.

RESULTS

Clarithromycin (CLA) was the most potent drug for Mycobacterium intracellulare (MI). The resistance rate of 244 MI isolates to CLA was 21%, yielding a minimum inhibitory concentrations (MIC)50 and MIC90 of 8 and 64 mg/L, respectively. 51% of 244 MI isolates exhibited resistance to amikacin (AMK). For 91 Mycobacterium abscessus complex (MABC) isolates, 6 (7%) and 49 (54%) isolates were categorized as resistant to CLA at day 3 and 14, respectively. The resistance rate to CLA for Mycobacterium abscessus subspecies abscessus (MAA) was dramatically higher than that for Mycobacterium abscessus subspecies massiliense (MAM). Additionally, the percentage of patients presenting fever in the CLA-susceptible group was significantly higher than that in the CLA-resistant group.

CONCLUSIONS

Our data demonstrate that approximate one fifth of MI isolates are resistant to CLA. We have identified a higher proportion of CLA-resistant MAA isolates than MAM. The patients caused by CLA-resistant MI are at low risk for presenting with fever relative to CLA-susceptible group.

In Vitro Evaluation of Drug-Drug Interaction Potential of Epetraborole, a Novel Bacterial Leucyl-tRNA Synthetase Inhibitor

Epetraborole (EBO) is a boron-containing inhibitor of bacterial leucyl-tRNA synthetase, with potent activity against nontuberculous mycobacteria (NTM) and Gram-negative bacteria, including Burkholderia pseudomallei. EBO is being developed for the treatment of NTM lung disease and melioidosis, administered in combination with other therapeutic agents in both diseases. Therefore, EBO and its major circulating metabolite M3 were evaluated in comprehensive drug-drug interaction (DDI) in vitro studies. The CYP inhibitory and substrate potential of EBO and M3 were assessed using hepatic microsomes. Stably transfected cells that expressed individual efflux or uptake transporters were used to determine whether EBO or M3 were substrates or inhibitors for these receptors. Stability studies indicated that EBO is a poor substrate for major CYP enzymes. Neither EBO nor M3 was a potent reversible or time-dependent inhibitor of major CYP enzymes. EBO was not an inducer of CYP1A2 mRNA, while it was a weak inducer of CYP2B6 and CYP3A4. EBO was a substrate only for OCT2. At clinically relevant concentrations, neither EBO nor M3 inhibited major human efflux or uptake transporters. Based on these data, at clinically relevant concentrations of EBO and M3, there is a low risk of victim or perpetrator DDI.

Impact of Metagenomic Next-Generation Sequencing of Bronchoalveolar Lavage Fluid on Antimicrobial Stewardship in Patients With Lower Respiratory Tract Infections: A Retrospective Cohort Study

BACKGROUND

The impact of metagenomic next-generation sequencing (mNGS) on antimicrobial stewardship in patients with lower respiratory tract infections (LRTIs) is still unknown.

METHODS

This retrospective cohort study included patients who had LRTIs diagnosed and underwent bronchoalveolar lavage between September 2019 and December 2020. Patients who underwent both mNGS and conventional microbiologic tests were classified as the mNGS group, while those with conventional tests only were included as a control group. A 1:1 propensity score match for baseline variables was conducted, after which changes in antimicrobial stewardship between the 2 groups were assessed.

RESULTS

A total of 681 patients who had an initial diagnosis of LRTIs and underwent bronchoalveolar lavage were evaluated; 306 patients were finally included, with 153 in each group. mNGS was associated with lower rates of antibiotic escalation than in the control group (adjusted odds ratio, 0.466 [95% confidence interval, .237-.919]; P = .02), but there was no association with antibiotic de-escalation. Compared with the control group, more patients discontinued the use of antivirals in the mNGS group.

CONCLUSIONS

The use of mNGS was associated with lower rates of antibiotic escalation and may facilitate the cessation of antivirals, but not contribute to antibiotic de-escalation in patients with LRTIs.

Pharmacological validation of dihydrofolate reductase as a drug target in Mycobacterium abscessus

The Mycobacterium abscessus drug development pipeline is poorly populated, with particularly few validated target-lead couples to initiate de novo drug discovery. Trimethoprim, an inhibitor of dihydrofolate reductase (DHFR) used for the treatment of a range of bacterial infections, is not active against M. abscessus. Thus, evidence that M. abscessus DHFR is vulnerable to pharmacological intervention with a small molecule inhibitor is lacking. Here, we show that the pyrrolo-quinazoline PQD-1, previously identified as a DHFR inhibitor active against Mycobacterium tuberculosis, exerts whole cell activity against M. abscessus. Enzyme inhibition studies showed that PQD-1, in contrast to trimethoprim, is a potent inhibitor of M. abscessus DHFR and over-expression of DHFR causes resistance to PQD-1, providing biochemical and genetic evidence that DHFR is a vulnerable target and mediates PQD-1's growth inhibitory activity in M. abscessus. As observed in M. tuberculosis, PQD-1 resistant mutations mapped to the folate pathway enzyme thymidylate synthase (TYMS) ThyA. Like trimethoprim in other bacteria, PQD-1 synergizes with the dihydropteroate synthase (DHPS) inhibitor sulfamethoxazole (SMX), offering an opportunity to exploit the successful dual inhibition of the folate pathway and develop similarly potent combinations against M. abscessus. PQD-1 is active against subspecies of M. abscessus and a panel of clinical isolates, providing epidemiological validation of the target-lead couple. Leveraging a series of PQD-1 analogs, we have demonstrated a dynamic structure-activity relationship (SAR). Collectively, the results identify M. abscessus DHFR as an attractive target and PQD-1 as a chemical starting point for the discovery of novel drugs and drug combinations that target the folate pathway in M. abscessus.

Prospective evaluation of nontuberculous mycobacteria disease in cystic fibrosis: The design of the PREDICT study

BACKGROUND

Nontuberculous mycobacteria (NTM) are an important cause of airway infections in people with cystic fibrosis (pwCF). Isolation of NTM from respiratory specimens of pwCF do not mandate treatment in the absence of clinical and radiologic features of NTM pulmonary disease (NTM-PD), as some pwCF clear the infection without treatment and others do not appear to progress to NTM-PD despite persistent infection. An evidence-based protocol to standardize diagnosis of NTM-PD is needed to systematically identify pwCF who may benefit from treatment.

METHODS

In this multicenter observational study, eligible pwCF who are 6 years of age and older and who have had a recent positive NTM culture are systematically evaluated for NTM-PD. Participants are identified based on positive NTM culture results obtained during routine clinical care and following enrollment are evaluated for NTM-PD and CF-related comorbidities. Participants are followed in PREDICT until they meet NTM-PD diagnostic criteria and are ready to initiate NTM treatment, or until study termination. Active participants who have not met these criteria are re-consented every 5 years to enable long-term participation.

RESULTS

The primary endpoint will summarize the proportion of participants who meet the NTM-PD diagnosis definition. The time from enrollment to NTM-PD diagnosis will be derived from Kaplan-Meier estimates.

CONCLUSION

A prospective protocol to identify NTM-PD in pwCF will test if this standardized approach defines a cohort with signs and symptoms associated with NTM-PD, to assist with clinical decision making and to build a framework for future therapeutic trials.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02073409.

Non-tuberculous mycobacterial pulmonary disease (NTM-PD): Epidemiology, diagnosis and multidisciplinary management

Non-tuberculous mycobacteria (NTM) are ubiquitous environmental organisms that can cause significant disease in both immunocompromised and immunocompetent individuals. The incidence of NTM pulmonary disease (NTM-PD) is rising globally. Diagnostic challenges persist and treatment efficacy is variable. This article provides an overview of NTM-PD for clinicians. We discuss how common it is, who is at risk, how it is diagnosed and the multidisciplinary approach to its clinical management.

Identification of the Optimal Cultivation Period Required to Isolate Representatives of Mycobacterium abscessus Complex Isolated from Patients with Cystic Fibrosis

BACKGROUND

In patients with cystic fibrosis (CF), representatives of the fast-growing Mycobacterium abscessus complex (MABSc) are often distinguished, but the culture of the material taken from such patients increases the growth time. We analyzed the terms of cultivation of MABSc representatives on dense nutrient media and also evaluated the productivity of a modified nutrient medium based on agar for the isolation of Burkholderia cepacia complex (BCC).

METHODS

Sixty-four strains of MABSc isolated from patients with CF and suspected tuberculosis were analyzed. The material from the patients was cultured on a universal chromogenic medium, 5% blood agar, yolk-salt agar, selective medium for isolation of BCC, and Löwenstein-Jensen medium. The cultures were incubated for 5 days (37°C, aerobic conditions), after for 23 days (28°C, aerobic conditions). The productivity of the developed nutrient medium was evaluated by the number of cells that gave visible growth after culturing 0.1 mL of a bacterial suspension of 103 CFU/mL.

RESULTS

76.8% of the strains grew in a 2-week period, and 23.2% of the strains were obtained at a later date from 18 to 28 days (average: 21.23 days). The modified medium with a concentration of 240 mg of iron (III) polymaltose hydroxide proved to be the most optimal for the isolation of MABSc.

CONCLUSION

When using a chromogenic medium for culture material from patients with CF, it is necessary to extend incubation up to 28 days to increase the probability of MABSc isolation. The modified BCC medium showed a good selectivity result but required further investigation.

Pulmonary Mycobacterium abscessus infection treated in combination with inhaled tigecycline

Pulmonary disease caused by Mycobacterium abscessus is difficult to treat, as there is currently no reliable evidence-based treatment. Treatment is long, complex and has many side effects. In this case, we report a patient with treatment-refractory pulmonary M abscessus disease, treated with inhaled tigecycline. Treatment with inhaled tigecycline lasted 15 months with comparably limited side effects. There were no positive mycobacterial cultures in the follow-up period of 2 years. Inhaled tigecycline is an option in the treatment of pulmonary M. abscessus when first-line treatment fails. Additional research should investigate this further.

Case Commentary: Another prong of attack? Topical antibiotic instillation with negative pressure wound therapy for nontuberculous mycobacterial skin and soft tissue infections

Nontuberculous mycobacteria (NTM) skin infections remain therapeutically challenging. Given the diversity in infections, host responses, and antimicrobials, clinical guidelines are often built on case series and observational studies. In this commentary, we respond to a paper by Stemkens et al. that introduces an emerging strategy: adjunctive negative pressure wound therapy with instillation and dwell time combined with topical antibiotics for refractory NTM skin and soft tissue infections. We delve into the primary considerations surrounding this innovative approach.

Surgical Resection in Nontuberculous Mycobacterial Pulmonary Disease

Rates of nontuberculous mycobacterial pulmonary disease are increasing worldwide, particularly in the United States and other developed countries. While multidrug antimicrobial therapy is the mainstay of treatment, surgical resection has emerged as an important adjunct. In this article, we will review the indications for surgery, preoperative considerations, surgical techniques, and postoperative outcomes.

Culture, Identification, and Antimicrobial Susceptibility Testing of Pulmonary Nontuberculous Mycobacteria

Nontuberculous mycobacteria (NTM) typically cause opportunistic pulmonary infections and reliable laboratory results can assist with diagnosis of disease. Microscopy can detect acid-fast bacilli from specimens though it has poor sensitivity. Solid and liquid culture are used to grow NTM, which are identified by molecular or protein-based assays. Because culture has a long turnaround time, some assays are designed to identify NTM directly from sputum specimens. When indicated, phenotypic susceptibility testing should be performed by broth microdilution as per the guidelines from the Clinical Laboratory Standards Institute. Genotypic susceptibility methods may be used to decrease the turnaround time for some antimicrobials.

In vitro susceptibility patterns for slowly growing non-tuberculous mycobacteria in the USA from 2018 to 2022

BACKGROUND

Treatment of slowly growing non-tuberculous mycobacteria (SGM) is challenging. In vitro antimicrobial susceptibility testing (AST) is needed to optimize a multidrug regimen but requires weeks to result. Aggregated AST patterns, or an antibiogram, of SGM would be helpful to providers.

OBJECTIVES

We aggregated and analysed human SGM isolates sent to our laboratory from across the USA between 2018 and 2022 to describe their in vitro susceptibility patterns and construct an antibiogram.

METHODS

SGM isolates' species/subspecies and mutations in rrs or rrl were identified by a line probe assay. AST was done primarily by broth microdilution and interpreted using the latest CLSI guideline. Mutational and AST results for SGM with ≥15 isolates were collated and analysed with descriptive statistics.

RESULTS

There were 32 different species/subspecies of SGM from 10 131 isolates between January 2018 and December 2022 from across the USA, 80% of which were from organisms in Mycobacterium avium complex (MAC). Most specimens were sputum and came from Florida (2892). MAC ranged from 94% to 100% susceptible to clarithromycin, 64% to 91% to amikacin, 2% to 31% to linezolid, and 4% to 41% to moxifloxacin. Non-MAC SGM ranged from 82% to 100% susceptible to clarithromycin, 49% to 100% to amikacin, and 76% to 100% to rifabutin, but susceptibilities to other antimicrobials varied widely. WT rrs and rrl predicted >96% of phenotypic non-resistance to amikacin and clarithromycin, respectively, whereas mutant genotypes predicted >90% of phenotypic resistance.

CONCLUSIONS

Most SGM are likely to be susceptible to clarithromycin and amikacin, complementing their treatment guidance by mycobacterial experts. Molecular identification of resistant genotypes is accurate and helpful. This antibiogram for SGM will help providers.

Accuracy of QuantiFERON in active tuberculosis suspects with comorbidities and nontuberculous mycobacterial infection in Northern California

The QuantiFERON-TB Gold (QFT) is routinely utilized in North American health systems to detect a cellular immune response to Mycobacterium tuberculosis antigens in symptomatic and asymptomatic patients. The sensitivity of QFT in tuberculosis (TB) patients with comorbidities is not well established and the specificity of QFT in patients with nontuberculous mycobacteria (NTM) infections is incompletely understood. Between 2012 and 2023, all patients with culture-positive TB and patients with NTM infection per the expert diagnostic guidelines or biopsy-proven NTM infection who had a concurrent QFT test were included in this study. The sensitivity and specificity of QFT were measured in TB and NTM patients, respectively. In 109 patients with active TB, the overall sensitivity of QFT was 78.0% (85/109; 95% CI: 70.1, 85.7). The sensitivity was 86.0% (49/57; 95% CI: 76.6, 94.8) and 69.2% (36/52; 95% CI: 56.7, 81.8) in immunocompetent and immunocompromised patients, respectively. The overall specificity of QFT in 88 patients with NTM infection was 76.1% (67/88; 95% CI: 67.2, 85.0). After the exclusion of 17 NTM patients with risk factors for latent TB infection, the specificity was 94.4% (67/71; 95% CI: 89.1, 99.7). Two patients had NTM species known to cross-react with QFT. In two NTM patients infected with species (Mycobacterium intracellulare subsp. intracellulare and Mycobacterium intracellulare subsp. chimaera) not known to cross-react, whole genome sequencing did not detect ESAT-6 or CFP-10. In Northern California, the QFT assay demonstrated moderately low to moderately high sensitivity in TB patients and very high specificity in NTM patients, thus ruling out concerns for cross-reactivity with NTM.

Secondary spontaneous pneumothorax in a patient with resistant Mycobacterium abscessus infection and systemic sclerosis-associated interstitial lung disease: A case report

Mycobacterium abscessus subsp. abscessus (MABA) is refractory and sometimes fatal especially in an immunocompromised patient. Also, MABA-associated pneumothorax is an extremely rare complication. We report a case of MABA pulmonary infection complicated pneumothorax treated successfully. A 69-year-old Japanese female with immunosuppressed systemic sclerosis-associated interstitial lung disease experienced left-sided secondary spontaneous pneumothorax. MABA was detected in the pleural effusion and blood culture. Microbial sensitivity test showed the MABA was sensitive to only amikacin, sitafloxacin, and clofazimine. Combination therapy with these antibiotics including azithromycin achieved remission within three weeks. In the treatment of MABA infection, compliance with microbial sensitivity test is crucial.

Antibacterial and immunological properties of piperine evidenced by preclinical studies: a systematic review

Aim: To review in vitro, in vivo, and in silico studies examining the antibacterial and immunomodulatory properties of piperine (PPN). Methods: This systematic review followed PRISMA guidelines, and five databases were searched. Results: A total of 40 articles were included in this study. Six aspects of PPN activity were identified, including antibacterial spectrum, association with antibiotics, efflux pump inhibition, biofilm effects, protein target binding, and modulation of immune functions/virulence factors. Most studies focused on Mycobacterium spp. and Staphylococcus aureus. Cell lineages and in vivo models were employed to study PPN antibacterial effects. Conclusion: We highlight PPN as a potential adjuvant in the treatment of bacterial infections. PPN possesses several antibacterial properties that need further exploration to determine the mechanisms behind its pharmacological activity.

Building a model for the differential diagnosis of non-tuberculous mycobacterial lung disease and pulmonary tuberculosis: A case-control study based on immunological and radiological features

BACKGROUND

Although the incidence of non-tuberculous mycobacterial pulmonary disease (NTM-PD) is increasing annually, it is easily misdiagnosed as pulmonary tuberculosis (PTB). This study aimed to screen and identify the immunological and radiological characteristics that differentiate NTM-PD from PTB and to construct a discriminatory diagnostic model for NTM-PD, providing new tools for its differential diagnosis.

METHODS

Hospitalised patients diagnosed with NTM-PD or PTB between January 2019 and June 2023 were included in the study. Immunological and radiological characteristics were compared between the two groups. Based on the selected differential features, a logistic regression algorithm was used to construct a discriminatory diagnostic model for NTM-PD, and its diagnostic performance was preliminarily analysed.

RESULTS

Patients with NTM-PD were significantly older than those with PTB and the tuberculosis-specific interferon-gamma release assay (TB-IGRA) positivity rate was significantly lower in the NTM-PD group. Moreover, the absolute counts of total T lymphocytes, CD4+ T lymphocytes, CD8+ T lymphocytes, NK cells, and B lymphocytes were significantly lower in patients with NTM-PD and PTB than in healthy controls. Additionally, patients with NTM-PD had a significantly lower absolute count of B lymphocytes than the PTB group. Radiological analysis revealed significant differences between patients with NTM-PD and PTB in terms of cavity wall thickness, bronchial dilation, lung consolidation, pulmonary nodule size, pulmonary emphysema, lung bullae, lymph node calcification, pleural effusion, mediastinal and hilar lymphadenopathy, and the tree-in-bud sign. Bronchial dilation was identified as the predominant risk factor of NTM-PD, whereas TB-IGRA positivity, lymph node calcification, pleural effusion, and mediastinal and hilar lymphadenopathies were protective factors. Based on this, we constructed a discriminatory diagnostic model for NTM-PD. Its receiver operating characteristic curve demonstrated good diagnostic performance, with an area under the curve of 0.938. At the maximum Youden index of 0.746, the sensitivity and specificity were 0.835 and 0.911, respectively.

CONCLUSIONS

Patients with NTM-PD and PTB exhibited impaired humoral and cellular immune functions as well as significant differences in radiological features. The constructed NTM-PD diagnostic model demonstrated good diagnostic performance. This study provides a new tool for the differential diagnosis of NTM-PD.

Nontuberculous Mycobacterial Infection of Larynx and Cervical Trachea

OBJECTIVES

To present a patient with the first case of NTM (nontuberculous mycobacteria) infection of the larynx extending to cervical trachea, and the first case of subglottic stenosis associated with an NTM infection.

METHODS

Case report and review of the literature.

RESULTS

A 68-year-old female with history of prior smoking, gastroesophageal reflux disease, asthma, bronchiectasis, and tracheobronchomalacia presented with a 3-month history of shortness of breath, exertional inspiratory stridor, and hoarseness. Flexible laryngoscopy demonstrated ulceration of medial aspect of right vocal fold and subglottic tissue abnormality with crusting and ulceration extending through the upper trachea. Microdirect laryngoscopy with tissue biopsies and carbon dioxide (CO2) laser ablation of disease completed, and intraoperative culture revealed positive Aspergillus and acid-fast bacilli with Mycobacterium abscessus (type of NTM). Patient began antimicrobial treatment of cefoxitin, imipenem, amikacin, azithromycin, clofazimine, and itraconazole. Fourteen months after initial presentation, patient developed subglottic stenosis with limited extension into the proximal trachea prompting CO2 laser incision, balloon dilation, and steroid injection of the subglottic stenosis. Patient remains disease free without further subglottic stenosis.

CONCLUSION

Laryngeal NTM infections are exceedingly rare. Failure to consider NTM infection in the differential diagnosis when presented with an ulcerative, exophytic mass in patients with increased risk factors (structural lung disease, Pseudomonas colonization, chronic steroid use, prior NTM positivity) may result in insufficient tissue evaluation, delayed diagnosis, and disease progression.

Nontuberculous mycobacterial infections in patients with hematologic malignancies and recipients of hematopoietic stem cell transplantation

BACKGROUND

The incidence of mycobacterial infections in patients with hematologic malignancies and hematopoietic stem cell transplant (HSCT) recipients is increasing, contributing to significant mortality and morbidity. This review explores the epidemiology, risk factors, clinical presentation, diagnosis, and treatment of nontuberculous mycobacteria (NTM) in this population.

METHODS

A literature search was performed using PubMed with keywords and MeSH terms pertaining to the topics of nontuberculous mycobacteria, hematologic malignancies, hematopoietic stem cell transplant, cellular therapies, chimeric antigen therapies, epidemiology, diagnosis, and treatment. Additionally, we examined the reference lists of the included articles to identify other pertinent studies.

RESULTS

Diagnosing mycobacterial disease among patients with hematologic disease and treatment-associated immunosuppressive conditions is challenging due to the lack of distinctive clinical, radiographic, and laboratory markers, as well as the atypical manifestations compared to immunocompetent patients. Treatment involves using a combination of antibiotics for extended durations, coupled with strategies to achieve source control and reduce immunosuppression when feasible. This is complicated by the absence of clear data correlating in-vitro drug susceptibility and clinical outcome for many antimicrobials use to treat NTM, adverse drug-drug interactions, and the frequent challenges related to poor medication tolerability and toxicities.

CONCLUSION

The rising incidence and corresponding clinical challenges of mycobacterial infections in this unique patient population necessitate a heightened awareness and familiarity of NTM disease by clinicians to achieve timely diagnosis and favorable treatment outcomes.

Improving the identification and diagnostic efficiency of Metagenomic Next-Generation Sequencing for mycobacterial granuloma on postoperative formalin-fixed paraffin-embedded specimens

OBJECTIVE

Metagenomic Next-Generation Sequencing (mNGS) has been validated to have an important role in the diagnosis of mycobacterium infection. The study aimed to further explore the mycobacteria identification ability of mNGS on formalin-fixed paraffin-embedded（FFPE）tissues from postoperative specimens.

METHODS

Patients who underwent surgical biopsy or resection for clarifying the diagnosis and whose initial postoperative pathology indicated granulomatous lesions were included. Fresh tissues were sent for mycobacterium culture and Xpert MTB/RIF (Xpert) to establish the diagnosis. FFPE specimens were sent for mNGS and molecular pathology，the diagnostic values were compared between the two methods.

RESULTS

A total of 65 cases with definite diagnoses were finally included in the study. 31 cases were confirmed as mycobacterium granuloma using the fresh specimen etiology as diagnostic criteria. The overall sensitivity and specificity of mNGS on FFPE specimens in the diagnosis of mycobacterium granuloma were 100% and 88.24%, respectively. In 19 cases diagnosed as tuberculous granulomas, the sensitivity (100% vs47.37%) and negative predictive value (NPV, 100%vs 82.14%) of mNGS were both significantly higher than that of molecular pathology on the FFPE section（both p 0.00）while the positive predictive value (PPV) and specificity were not significantly different. In 12 cases diagnosed as Non-tuberculous mycobacterium (NTM）granuloma, the sensitivity of mNGS was also significantly higher than that of molecular pathology on FFPE section (100% vs 66.67%, p 0.00) while the specificity, PPV and NPV were all not significantly different.

CONCLUSIONS

The mNGS could be used for one-time detection of pathogens on FFPE sections with high sensitivity. It could be recommended as a supplementary method for the identification of pathogenic bacteria in the diagnosis of postoperative granuloma lesions.

Plasmid-mediated drug resistance in mycobacteria: the tip of the iceberg?

Macrolides, such as clarithromycin, are crucial in the treatment of nontuberculous mycobacteria (NTM). NTM are notoriously innately drug resistant, which has made the dependence on macrolides for their treatment even more important. Not surprisingly, resistance to macrolides has been documented in some NTM, including Mycobacterium avium and Mycobacterium abscessus, which are the two NTM species most often identified in clinical isolates. Resistance is mediated by point mutations in the 23S ribosomal RNA or by methylation of the rRNA by a methylase (encoded by an erm gene). Chromosomally encoded erm genes have been identified in many of the macrolide-resistant isolates, but not in Mycobacterium chelonae. Now, Brown-Elliott et al. (J Clin Microbiol 61:e00428-23, 2023, https://doi.org/10.1128/JCM.00428-23) describe the identification of a new erm variant, erm(55), which was found either on the chromosome or on a plasmid in highly macrolide-resistant clinical isolates of M. chelonae. The chromosomal erm(55) gene appears to be associated with mobile elements; one gene is within a putative transposon and the second is in a large (37 kb) insertion/deletion. The plasmid carrying erm(55) also encodes type IV and type VII secretion systems, which are often linked on large mycobacterial plasmids and are hypothesized to mediate plasmid transfer. While the conjugative transfer of the erm(55)-containing plasmid between NTM has yet to be demonstrated, the inferences are clear, as evidenced by the dissemination of plasmid-mediated drug resistance in other medically important bacteria. Here, we discuss the findings of Brown-Elliott et al., and the potential ramifications on treatment of NTM infections.

Genome-Scale Characterization of Mycobacterium abscessus Complex Isolates from Portugal

The Mycobacterium abscessus complex (MABC) is an emerging, difficult to treat, multidrug-resistant nontuberculous mycobacteria responsible for a wide spectrum of infections and associated with an increasing number of cases worldwide. Dominant circulating clones (DCCs) of MABC have been genetically identified as groups of strains associated with higher prevalence, higher levels of antimicrobial resistance, and worse clinical outcomes. To date, little is known about the genomic characteristics of MABC species circulating in Portugal. Here, we examined the genetic diversity and antimicrobial resistance profiles of 30 MABC strains isolated between 2014 and 2022 in Portugal. The genetic diversity of circulating MABC strains was assessed through a gene-by-gene approach (wgMLST), allowing their subspecies differentiation and the classification of isolates into DCCs. Antimicrobial resistance profiles were defined using phenotypic, molecular, and genomic approaches. The majority of isolates were resistant to at least two antimicrobials, although a poor correlation between phenotype and genotype data was observed. Portuguese genomes were highly diverse, and data suggest the existence of MABC lineages with potential international circulation or cross-border transmission. This study highlights the genetic diversity and antimicrobial resistance profile of circulating MABC isolates in Portugal while representing the first step towards the implementation of a genomic-based surveillance system for MABC at the Portuguese NIH.

The in vitro effect of new combinations of carbapenem-β-lactamase inhibitors for Mycobacterium abscessus

As new treatment alternatives for Mycobacterium abscessus complex (MABC) are urgently needed, we determined the minimum inhibitory concentrations (MICs) for novel carbapenem combinations, including imipenem-relebactam and tebipenem-avibactam against 98 MABC isolates by broth microdilution. The MIC50 was reduced from 16 to 8 mg/L by adding relebactam to imipenem, while the addition of avibactam to tebipenem showed a more pronounced reduction from 256 to 16 mg/L, representing a promising non-toxic, oral treatment option for further exploration.