An official ATS/IDSA statement: diagnosis, treatment, and prevention of nontuberculous mycobacterial diseases

Disasters pile up on the rubbing heel: Sporothrix globosa as secondary infection to Mycobacterium chelonae infection

Mycobacterium chelonae and Sporothrix globosa, both of which are opportunistic pathogens, have been proved to be possible multidrug resistant. However, are all recurring symptoms in chronic infections related to decreasing susceptibility? Here we report a case of sporotrichosis secondary to M. chelonae infection. In addition, we find that the blackish-red spots under the dermoscopic view can be employed as a signal for the early identification and regression of subcutaneous fungal infection.

The clinical features and prognostic factors of miliary tuberculosis in a high tuberculosis burden area

BACKGROUND

Miliary Tuberculosis (TB) remains an important infectious disease that threatens human health. The clinical characteristics and prognostic factors of miliary TB are summarized in this study.

METHODS

The clinical information of miliary TB patients between 2010 and 2022 was retrospectively analyzed. Patients with miliary TB were characterized and compared to adverse outcomes cases. Factors independently associated with adverse outcomes were determined via multivariate logistic regression analysis.

RESULTS

A total of 288 patients were analyzed, including 181 with adverse outcomes. The clinical manifestations are atypical. 88.54% Of them experienced systemic symptoms, whilst 69.79% manifested respiratory symptoms. 40.97% Presented with neurologic symptoms, while 35.07% reported gastrointestinal symptoms. The major comorbidities were pharmacological immunosuppression (21.53%), pneumoconiosis (15.28%), diabetes (10.76%), and pregnancy or postpartum (7.29%). Regarding microbiology, most patients were diagnosed via sputum or Bronchoalveolar Lavage Fluid (BALF), pleural effusion, ascites, cerebrospinal fluid, urine TB-DNA, and tuberculosis culture. Meanwhile, 2.43% of patients were diagnosed via cerebrospinal fluid NGS. Independent risk factors predictive of adverse outcomes were current smoking, leukocytosis, elevated alanine aminotransferase (ALT) levels, and the combination of lymphopenia with bone marrow tuberculosis or tuberculous lymphadenitis. The accuracy of the model was validated by an area under the ROC curve of 0.753 (95% IC 0.697-0.810).

CONCLUSIONS

The clinical manifestations of miliary TB are atypical, and early diagnosis is challenging. The major comorbidities in miliary TB patients were pharmacological immunosuppression, pneumoconiosis, diabetes, pregnancy, and postpartum. Regarding etiological detection, multi-site and multi-type specimens should be collected for a timely diagnosis. Cerebrospinal fluid mNGS test may be a viable choice in some cases. Finally, current smoking, leukocytosis, elevated ALT levels, and the combination of lymphopenia with bone marrow tuberculosis or tuberculous lymphadenitis were identified as independent risk factors for adverse outcomes.

Successful management of surgical site infection caused by Mycobacterium mageritense in a breast cancer patient

Mycobacterium mageritense (M. mageritense), a nontuberculous mycobacterium, is classified as a rapidly growing mycobacterium, class IV in the Runyon Classification. This bacterium is found in soil, water, and other habitats. Infections caused by M. mageritense are relatively rare and no treatment protocol has been established. Herein, we report a case of skin and soft tissue infection caused by M. mageritense. A 49-year-old woman underwent surgery for right breast cancer. Four months after surgery, a surgical site infection was found, and M. mageritense was identified in the wound culture using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Based on the sensitivity results, the patient was treated with levofloxacin and doxycycline for 4 months. In addition to antimicrobial agents, aggressive surgical interventions led to a favorable course of treatment. In conclusion, successful treatment of skin and soft tissue infections with M. mageritense requires surgical intervention whenever possible, aggressive susceptibility testing, and appropriate antimicrobial therapy.

Is there a role for lung or bronchial biopsies for the diagnosis of mycobacterial pulmonary disease in patients with bronchiectasis?

Background

Workup of bronchiectasis patients mandates microbiological characterization often being sought via Bronchoscopy. However, whether to perform bronchial or lung biopsies, is unknown, especially for the diagnosis of NTM pulmonary disease. We aimed to assess the current practice and yield of the different bronchoscopic procedures in this setting.

Methods

Data from an adult cohort with bronchiectasis referred for bronchoscopy for microbiologic sampling was reviewed, including demographics, etiology, imaging and results of the different bronchoscopic procedures performed.

Results

127 subjects were analyzed (mean age 61, 56% female). BAL culture was positive in 44%. Frequent pathogens were Hemophilus Influenza (20%), pseudomonas aeruginosa (8%) and Staphylococcus aureus (7%). NTM and tuberculosis were found in 6% and 1.5% respectively. BAL cytology was sent in 125 procedures, EBB was performed in 51 patients (40%) and TBLB in 38 patients (30%). BAL cytology and both EBB and TBB (including tissue cultures) had no benefit over BAL with respect to microbiological diagnosis, including identification of mycobacterial disease.

Conclusions

In adult subjects with Non-CF bronchiectasis requiring bronchoscopy for microbiological characterization, BAL cytology and lung tissue biopsies were frequently performed but were of minimal additional benefit over BAL culture (including for mycobacterial pulmonary disease), and are most likely futile.

Attenuated tuberculin skin test responses associated with Mycobacterium intracellulare sputum colonization in an adolescent TB prevalence survey in Western Kenya

INTRODUCTION

Exposure to Non-tuberculous Mycobacteria (NTM) varies regionally and may partly explain the disparate outcomes of BCG vaccination and tuberculosis (TB) susceptibility.

METHODS

We examined NTM sputum colonization, associations with clinical characteristics, and tuberculin skin test (TST) responses in an adolescent TB prevalence survey.

RESULTS

Among 5004 adolescents screened, 2281 (45.5 %) were evaluated further. TB and NTM prevalence rates were 0.3 % and 8.0 %, respectively. Among 418 NTM isolates, 103 were unidentifiable, and 315 (75 %) comprised 15 species, the most frequent being M. intracellulare (MAC) (108, 26 %), M. scrofulaceum (96, 23 %) and M. fortuitum (51, 12 %). "NTM colonized" adolescents had less frequent chronic cough and night sweats (adjusted odds ratio [aOR] 0.62, 95 % confidence interval [CI] 0.44-0.87and aOR 0.61, CI 0.42-0.89 respectively), and lower TST induration (median 11 mm (interquartile range [IQR] 0-16) vs 13 mm (IQR 6-17; p = 0.006)) when compared to "NTM not colonized" participants. MAC, but not M. scrofulaceum or M. fortuitum, was associated with decreased TST induration (median 7.5 mm (IQR 0-15) vs 13 mm (IQR 6-17) among "MAC colonized" vs "not colonized", p = 0.001).

CONCLUSION

We observed high NTM prevalence rates with species-specific associations with TST induration, consistent with a model of species-dependent heterologous immunity among mycobacteria.

New liposidomycin congeners produced by Streptomyces sp. TMPU-20A065, anti-Mycobacterium avium complex agents with therapeutic efficacy in a silkworm infection model

Three new liposidomycin congeners (1, 2, and 4), together with 14 known liposidomycins (3 and 5-17), were isolated from the culture broth of Streptomyces sp. TMPU-20A065 as anti-Mycobacterium avium complex agents. The structures of liposidomycins were elucidated by spectroscopic analyses, including NMR and MS. Compounds 1, 2, and 4 belong to type-I liposidomycin-containing sulfate groups and methylglutaric acid, each with a different acyl side chain in the structure. Compounds 1-17 exhibited in vitro anti-M. avium and M. intracellulare activities with MIC values ranging between 2.0 and 64 μg ml-1. Furthermore, 1-17 exerted potent therapeutic effects in an in vivo-mimic silkworm infection model with ED50 values ranging between 0.12 and 3.7 μg larva-1 g-1.

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

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

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.

Drug-related pneumonitis caused by amikacin liposome inhalation suspension: One pathologically proven case and single-center experience

Amikacin liposome inhalation suspension (ALIS) is known to cause drug-related pneumonitis, which has been described as "hypersensitivity pneumonitis (HP)". However, its clinical and pathological characteristics have never been reported. We retrospectively evaluated 18 patients treated with ALIS. Three (16.7%) patients developed HP-pattern pneumonitis on high-resolution computed tomography. Serum eosinophil counts were elevated up to above 1000/μL in these three patients, which decreased with ALIS discontinuation only. Of note, the specimen obtained by transbronchial lung cryobiopsy in one patient revealed a mild degree of lymphocyte and eosinophil infiltration. Rather, the findings of acute lung injury such as an edematous thickening of the alveolar walls, and an accumulation of foamy degenerative macrophages in the alveolar lumina was prominent. A pulmonary alveolar proteinosis reaction was also observed. HP-pattern pneumonitis due to ALIS may pathologically correspond to acute lung injury and a pulmonary alveolar proteinosis reaction despite increasing serum eosinophil counts.

Histologic Features of Mycobacterial Spindle Cell Pseudotumors: A Multi-institutional Clinicopathologic Analysis of 14 Cases

Mycobacterial spindle cell pseudotumors (MSPs) are a rare and diagnostically challenging manifestation of non-tuberculous mycobacterial (NTM) infections. Proper recognition of these pseudotumors is important because they are treatable and benign. In this study, we evaluated the morphologic patterns of MSPs to improve their pathologic identification. Clinical and morphologic features of 14 MSPs were analyzed. Histologic factors evaluated included the architectural growth pattern of spindled or epithelioid macrophages, granulomas and their location within the lesion, neutrophilic microabscesses, multinucleated giant cells, necrosis, and effacement of background tissue. The composition of inflammatory infiltrates, organism density by acid-fast staining, and stromal changes were also assessed. In addition, 8 of 14 cases underwent molecular microbiology identification by a clinical amplicon-sequencing assay for non-tuberculous mycobacteria. MSP sites included 2 bowel, 10 lymph nodes, 1 liver, and 1 extremity. Cases with available clinical history (n=10) all occurred in immunocompromised patients. All demonstrated effacement of normal structures with spindled cells arranged in a storiform or fascicular architectural pattern. In addition, all cases showed lymphocytic inflammation, with prominent concurrent neutrophilic inflammation in 50% (7/14) of cases. Other morphologic findings included foamy histiocytes (64%, 9/14), peripherally situated granulomas (21%, 3/14), and neutrophilic microabscesses (21%, 3/14). All tested cases were positive for NTM by PCR methods. Mycobacterium avium was the most commonly isolated pathogen (6/8). Mycobacterial spindle cell pseudotumors show predominantly spindled morphology that may be mistaken as a neoplasm. Surgical pathologists who evaluate lymph nodes, soft tissue, and gastrointestinal tissues should be aware of this spindled tumefactive phenomenon in the setting of immunocompromised patients. Recognition of key morphologic features of neutrophilic inflammation, peripheral granulomas, or foamy histiocytes within a spindled lesion can help guide the pathologist to a correct diagnosis of an inflammatory process secondary to infection rather than a spindle cell neoplasm. Accurate diagnosis to facilitate appropriate antimicrobial and/or surgical therapy requires a comprehensive evaluation combining clinical, histopathologic, and microbiological findings.

Anti-biofilm activities and antibiotic synergy of naturally occurring compounds against drug-resistant rapidly growing mycobacteria

Some naturally occurring compounds, known for their antimicrobial activities, have been employed as food additives. However, their efficacy in treating infections caused by antibiotic-resistant bacteria is yet to be fully explored. Rapidly growing mycobacteria (RGM), a category within nontuberculous mycobacteria (NTM), are prevalent in various environments and can lead to infections in humans. The rise of antimicrobial resistance within RGM is a documented concern. In this study, we reported that four specific natural compounds effectively inhibited the growth and biofilm formation of three key RGM pathogens M. abscessus, M. fortuitum, and M. chelonae. We screened 12 natural compounds for their effectiveness against antibiotic-resistant clinical strains of RGM. Four compounds showed significant inhibitory effects from the most effective to least: trans-cinnamaldehyde, carvacrol, gentisaldehyde, and phloroglucinaldehyde. In the analysis of time-killing kinetics, gentisaldehyde and phloroglucinaldehyde displayed bactericidal activity while trans-cinnamaldehyde and carvacrol exhibited bacteriostatic effects. At 1× minimal inhibition concentrations, these compounds significantly reduced biofilm formation in all three RGM species to levels between 2.9% and 20.5% relative to controls. Checkerboard assays indicated synergistic interactions between these four compounds and antibiotics such as amikacin, clarithromycin, and linezolid. Of these 12 compound-antibiotic combinations, the pairs of carvacrol-linezolid, carvacrol-amikacin, and gentisaldehyde-clarithromycin demonstrated the most synergy against multiple RGM strains. Moreover, two other compounds citral and geraniol showed synergism with all three test antibiotics. Time-killing assays further confirmed most of synergistic combinations identified in the checkerboard tests. Our research suggests the potential of these essential oils and phenolic aldehydes, both individually and in combination with antibiotics, in treating RGM infections. In addition, this work illuminates applications of these natural compounds in environmental remediation to mitigate bacterial persistence for the control of infectious diseases.

IMPORTANCE

The emergence of antimicrobial resistance within rapidly growing mycobacteria (RGM) poses a significant threat to public health. This study investigates the potential of naturally occurring compounds to combat infections caused by antibiotic-resistant RGM including M. abscessus, M. fortuitum, and M. chelonae. We identified four specific natural compounds showing impressive inhibitory effects against antibiotic-resistant clinical strains. These compounds not only inhibited the growth and biofilm formation but also exhibited synergistic interactions with antibiotics against key RGM pathogens. Our findings highlight the alternative treatment strategies for RGM infections and potential environmental applications of these natural compounds in mitigating microbial persistence and controlling infectious diseases.

Discovery of 2-phenylquinazolines as potent Mycobacterium avium efflux pump inhibitors able to synergize with clarithromycin against clinical isolate

Nontuberculous mycobacteria (NTM), which include the Mycobacterium avium complex, are classified as difficult-to-treat pathogens due to their ability to quickly develop drug resistance against the most common antibiotics used to treat NTM infections. The overexpression of efflux pumps (EPs) was demonstrated to be a key mechanism of clarithromycin (CLA) resistance in NTM. Therefore, in this work, 24 compounds from an in-house library, characterized by chemical diversity, were tested as potential NTM EP inhibitors (EPIs) against Mycobacterium smegmatis mc2 155 and M. avium clinical isolates. Based on the acquired results, 12 novel analogs of the best derivatives 1b and 7b were designed and synthesized to improve the NTM EP inhibition activity. Among the second set of compounds, 13b emerged as the most potent NTM EPI. At a concentration of 4 µg/mL, it reduced the CLA minimum inhibitory concentration by 16-fold against the clinical isolate M. avium 2373 overexpressing EPs as primary mechanism of CLA resistance.

Clinical spectrum and relevance of Mycobacterium malmoense: Systematic review and meta-analysis of 859 patients

INTRODUCTION

The clinical relevance of Mycobacterium malmoense isolation from pulmonary specimens has been considered high compared with other non-tuberculous mycobacteria. In this study, we aimed to analyse all published clinical data of patients with M. malmoense isolation to investigate the clinical spectrum, relevance, and outcomes of infections with this uncommon mycobacterium.

METHODS

A systematic review of PubMed, Web of Science, Embase, and Scopus was performed to identify all clinical data about M. malmoense. Random effects meta-analyses of proportions were calculated for clinical relevance, treatment success, and mortality, as well as for other clinical characteristics. A logistic regression analysis, investigating predictors of mortality, as well as Kaplan-Meier survival analyses, were performed.

RESULTS

One hundred and eighty eight patients with individual data from 112 articles and 671 patients with pooled data from 12 articles were included in the meta-analyses. Of patients with individual data, pulmonary infection was the most common manifestation (n = 106/188, 56.4%). One third (n = 61/188, 32.4%) suffered from isolated extra-pulmonary and 21/188 (11.2%) from disseminated disease. In 288 patients with pooled data and pulmonary affection, clinical relevance was high with 68% (95% CI 44-85%) of patients fulfilling criteria for clinical disease. Macrolide and rifamycin-containing regimens were associated with improved survival (adjusted OR 0.12, 95% CI 0.03-0.42, p = 0.002, and 0.23, 95% CI 0.04-0.86, p = 0.03, for lethal events, respectively).

CONCLUSION

In this study, we provide a detailed clinical description of M. malmoense infections. The pathogen is of high clinical relevance for the individual patient with more than 2 out of 3 patients having relevant disease and >40% of manifestations being extra-pulmonary or disseminated. Macrolide and rifamycin-containing regimens are associated with improved survival.

Single-cell transcriptomics of blood identified IFIT1+ neutrophil subcluster expansion in NTM-PD patients

OBJECTIVE

Non-tuberculous mycobacterial pulmonary disease (NTM-PD) is caused by an imbalance between pathogens and impaired host immune responses. Mycobacterium avium complex (MAC) and Mycobacterium abscessus (MAB) are the two major pathogens that cause NTM-PD. In this study, we sought to dissect the transcriptomes of peripheral blood immune cells at the single-cell resolution in NTM-PD patients and explore potential clinical markers for NTM-PD diagnosis and treatment.

METHODS

Peripheral blood samples were collected from six NTM-PD patients, including three MAB-PD patients, three MAC-PD patients, and two healthy controls. We employed single-cell RNA sequencing (scRNA-seq) to define the transcriptomic landscape at a single-cell resolution. A comprehensive scRNA-seq analysis was performed, and flow cytometry was conducted to validate the results of scRNA-seq.

RESULTS

A total of 27,898 cells were analyzed. Nine T-cells, six mononuclear phagocytes (MPs), and four neutrophil subclusters were defined. During NTM infection, naïve T-cells were reduced, and effector T-cells increased. High cytotoxic activities were shown in T-cells of NTM-PD patients. The proportion of inflammatory and activated MPs subclusters was enriched in NTM-PD patients. Among neutrophil subclusters, an IFIT1+ neutrophil subcluster was expanded in NTM-PD compared to healthy controls. This suggests that IFIT1+ neutrophil subcluster might play an important role in host defense against NTM. Functional enrichment analysis of this subcluster suggested that it is related to interferon response. Cell-cell interaction analysis revealed enhanced CXCL8-CXCR1/2 interactions between the IFIT1+ neutrophil subcluster and NK cells, NKT cells, classical mononuclear phagocytes subcluster 1 (classical Mo1), classical mononuclear phagocytes subcluster 2 (classical Mo2) in NTM-PD patients compared to healthy controls.

CONCLUSIONS

Our data revealed disease-specific immune cell subclusters and provided potential new targets of NTM-PD. Specific expansion of IFIT1+ neutrophil subclusters and the CXCL8-CXCR1/2 axis may be involved in the pathogenesis of NTM-PD. These insights may have implications for the diagnosis and treatment of NTM-PD.

Usefulness of the mini nutritional assessment short-form for evaluating nutritional status in patients with nontuberculous mycobacterial pulmonary disease: a prospective cross-sectional study

BACKGROUND

Although the Mini Nutritional Assessment (MNA) is recognized as a useful tool for evaluating nutritional status in patients with various diseases, its applicability in patients with nontuberculous mycobacterial pulmonary disease (NTM-PD) remains undetermined.

METHODS

We designed a prospective cross-sectional study to investigate whether the MNA Short-Form (MNA-SF) score can serve as a screening tool to assess the nutritional status of patients with NTM-PD. The MNA-SF was conducted upon patient enrollment, and correlation analyses were performed to compare MNA-SF scores with other nutritional measurements and disease severity. Multivariable logistic regression analyses were conducted to evaluate the association between MNA-SF scores and NTM-PD severity.

RESULTS

The 194 patients with NTM-PD included in the analysis had a median age of 65.0 (59.0-69.0) years; 59.3% (n = 115) had low MNA-SF scores (< 12). The low MNA-SF group exhibited a lower body mass index (19.7 vs. 22.4 kg/m2, p < 0.001) and fat-free mass index (14.7 vs. 15.6 kg/m2, p < 0.001) than the normal MNA-SF group, as well as higher incidences of sarcopenia (20.0% vs. 6.3%, p = 0.008) and adipopenia (35.7% vs. 5.1%, p < 0.001). However, no significant differences in calorie and protein intakes were observed between the two groups. Low MNA-SF scores were associated with radiographic severity (adjusted odds ratio 2.72, 95% confidence interval 1.38-5.36) but not with forced vital capacity.

CONCLUSIONS

The MNA-SF can effectively assess the nutritional status of patients with NTM-PD and can serve as an important clinical indicator in NTM-PD where treatment timing is determined by clinical judgment.

Protein-energy restriction-induced lipid metabolism disruption causes stable-to-progressive disease shift in Mycobacterium avium-infected female mice

BACKGROUND

Disease susceptibility and progression of Mycobacterium avium complex pulmonary disease (MAC-PD) is associated with multiple factors, including low body mass index (BMI). However, the specific impact of low BMI on MAC-PD progression remains poorly understood. This study aims to examine the progression of MAC-PD in the context of low BMI, utilising a disease-resistant mouse model.

METHODS

We employed a MAC infection-resistant female A/J mouse model to compare the progression of MAC-PD under two dietary conditions: one group was fed a standard protein diet, representing protein-energy unrestricted conditions, and the other was fed a low protein diet (LPD), representing protein-energy restriction.

FINDINGS

Our results reveal that protein-energy restriction significantly exacerbates MAC-PD progression by disrupting lipid metabolism. Mice fed an LPD showed elevated fatty acid levels and related gene expressions in lung tissues, similar to findings of increased fatty acids in the serum of patients who exhibited the MAC-PD progression. These mice also exhibited increased CD36 expression and lipid accumulation in macrophages upon MAC infection. In vitro experiments emphasised the crucial role of CD36-mediated palmitic acid uptake in bacterial proliferation. Importantly, in vivo studies demonstrated that administering anti-CD36 antibody to LPD-fed A/J mice reduced macrophage lipid accumulation and impeded bacterial growth, resulting in remarkable slowing disease progression.

INTERPRETATION

Our findings indicate that the metabolic status of host immune cells critically influences MAC-PD progression. This study highlights the potential of adequate nutrient intake in preventing MAC-PD progression, suggesting that targeting CD36-mediated pathways might be a host-directed therapeutic strategy to managing MAC infection.

FUNDING

This research was funded by the National Research Foundation of Korea, the Korea Research Institute of Bioscience and Biotechnology, and the Korea National Institute of Health.

Differential radiological features of patients infected or colonised with slow-growing non-tuberculous mycobacteria

Non-tuberculous mycobacterial pulmonary disease (NTM-PD) is considered a growing health concern. The majority of NTM-PD cases in Europe are caused by slow-growing mycobacteria (SGM). However, distinct radiological features of different SGM remain largely uninvestigated. We applied a previously described radiological score to a patient cohort consisting of individuals with isolation of different SGM. Correlations between clinical data, species and computed tomography (CT) features were examined by logistic and linear regression analyses, as well as over the course of time. Overall, 135 pulmonary CT scans from 84 patients were included. The isolated NTM-species were mainly Mycobacterium avium complex (MAC, n = 49), as well as 35 patients with non-MAC-species. Patients with isolation of M. intracellulare had more extensive CT findings compared to all other SGM species (coefficient 3.53, 95% Cl - 0.37 to 7.52, p = 0.075) while patients meeting the ATS criteria and not undergoing therapy exhibited an increase in CT scores over time. This study provides insights into differential radiological features of slow-growing NTM. While M. intracellulare exhibited a tendency towards higher overall CT scores, the radiological features were similar across different SGM. The applied CT score might be a useful instrument for monitoring patients and could help to guide antimycobacterial therapy.

Application of a new designed high resolution melting analysis for mycobacterial species identification

The Non-tuberculous mycobacterial (NTM) isolates should be distinguished from tuberculosis and identified at the species level for choosing an appropriate treatment plan. In this study, two molecular methods were used to differentiate NTM species, including a new designed High Resolution Melting (HRM) and Multilocus Sequence Analysis (MLSA). Seventy-five mycobacterial isolates were evaluated by sequencing four genes ( MLSA) and a HRM assay specifically targeting atpE was designed to rapidly and accurately identify and differentiate mycobacterium species. Out of 70 NTM isolates, 66 (94.3%), 65 (92.9%), 65 (92.9%) and 64 (91.4%) isolates were identified to the species level by PCR of atpE, tuf, rpoB and dnaK genes. We could identify 100% of the isolates to the species level (14 different species) by MLSA. By using HRM assay, all NTM isolates were identified and classified into eight groups, in addition, Mycobacterium tuberculosis and Nocardia were also detected simultaneously. The MLSA technique was able to differentiate all 14 species of NTM isolates. According to the results, the HRM assay is a rapid and beneficial method for identifying NTM, M. tuberculosis (MTB), and Nocardia isolates without sequencing.

Detection of Mtb and NTM: preclinical validation of a new asymmetric PCR-binary deoxyribozyme sensor assay

Tuberculosis (TB) and infectious diseases caused by non-tuberculous mycobacteria (NTM) are global concerns. The development of a rapid and accurate diagnostic method, capable of detecting and identifying different mycobacteria species, is crucial. We propose a molecular approach, the BiDz-TB/NTM, based on the use of binary deoxyribozyme (BiDz) sensors for the detection of Mycobacterium tuberculosis (Mtb) and NTM of clinical interest. A panel of DNA samples was used to evaluate Mtb-BiDz, Mycobacterium abscessus/Mycobacterium chelonae-BiDz, Mycobacterium avium-BiDz, Mycobacterium intracellulare/Mycobacterium chimaera-BiDz, and Mycobacterium kansasii-BiDz sensors in terms of specificity, sensitivity, accuracy, and limit of detection. The BiDz sensors were designed to hybridize specifically with the genetic signatures of the target species. To obtain the BiDz sensor targets, amplification of a fragment containing the hypervariable region 2 of the 16S rRNA was performed, under asymmetric PCR conditions using the reverse primer designed based on linear-after-the-exponential principles. The BiDz-TB/NTM was able to correctly identify 99.6% of the samples, with 100% sensitivity and 0.99 accuracy. The individual values of specificity, sensitivity, and accuracy, obtained for each BiDz sensor, satisfied the recommendations for new diagnostic methods, with sensitivity of 100%, specificity and accuracy ranging from 98% to 100% and from 0.98 to 1.0, respectively. The limit of detection of BiDz sensors ranged from 12 genome copies (Mtb-BiDz) to 2,110 genome copies (Mkan-BiDz). The BiDz-TB/NTM platform would be able to generate results rapidly, allowing the implementation of the appropriate therapeutic regimen and, consequently, the reduction of morbidity and mortality of patients.IMPORTANCEThis article describes the development and evaluation of a new molecular platform for accurate, sensitive, and specific detection and identification of Mycobacterium tuberculosis and other mycobacteria of clinical importance. Based on BiDz sensor technology, this assay prototype is amenable to implementation at the point of care. Our data demonstrate the feasibility of combining the species specificity of BiDz sensors with the sensitivity afforded by asymmetric PCR amplification of target sequences. Preclinical validation of this assay on a large panel of clinical samples supports the further development of this diagnostic tool for the molecular detection of pathogenic mycobacteria.

Treatment for non-tuberculous mycobacteria: challenges and prospects

Non-Tuberculous mycobacteria (NTM) are opportunistic environmental bacteria. Globally, NTM incidence is increasing and modeling suggests that, without new interventions, numbers will continue to rise. Effective treatments for NTM infections remain suboptimal. Standard therapy for Mycobacterium avium complex, the most commonly isolated NTM, requires a 3-drug regime taken for approximately 18 months, with rates of culture conversion reported between 45 and 70%, and high rates of relapse or reinfection at up to 60%. New therapeutic options for NTM treatment are urgently required. A survey of ongoing clinical trials for new NTM therapy listed on ClinicalTrials.Gov using the terms 'Mycobacterium avium', 'Mycobacterium abscessus', 'Mycobacterium intracellulare', 'Non tuberculous Mycobacteria' and 'Nontuberculous Mycobacteria' and a selection criterion of interventional studies using antibiotics demonstrates that most trials involve dose and combination therapy of the guideline based therapy or including one or more of; Amikacin, Clofazimine, Azithromycin and the anti-TB drugs Bedaquiline and Linezolid. The propensity of NTMs to form biofilms, their unique cell wall and expression of both acquired and intrinsic resistance, are all hampering the development of new anti-NTM therapy. Increased investment in developing targeted treatments, specifically for NTM infections is urgently required.

Epidemiology of Mycobacterium abscessus

BACKGROUND

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

OBJECTIVES

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

SOURCES

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

CONTENT

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

IMPLICATIONS

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

Bronchiectasis management in adults: state of the art and future directions

Formerly regarded as a rare disease, bronchiectasis is increasingly recognised. A renewed interest in this disease has led to significant progress in bronchiectasis research. Randomised clinical trials (RCTs) have demonstrated the benefits of airway clearance techniques, inhaled antibiotics and long-term macrolide therapy in bronchiectasis patients. However, the heterogeneity of bronchiectasis remains one of the most challenging aspects of management. Phenotypes and endotypes of bronchiectasis have been identified to help find "treatable traits" and partially overcome disease complexity. The goals of therapy for bronchiectasis are to reduce the symptom burden, improve quality of life, reduce exacerbations and prevent disease progression. We review the pharmacological and non-pharmacological treatments that can improve mucociliary clearance, reduce airway inflammation and tackle airway infection, the key pathophysiological features of bronchiectasis. There are also promising treatments in development for the management of bronchiectasis, including novel anti-inflammatory therapies. This review provides a critical update on the management of bronchiectasis focusing on treatable traits and recent RCTs.

Dermatology practice updates in mycobacterial disease

Atypical mycobacterial infections are commonly acquired through exposure to water, and tuberculosis remains highly endemic in many parts of the world. In this era of global connection, travel, and immigration, it is more important than ever to maintain a high index of suspicion for infection from cutaneous tuberculosis and atypical mycobacteria. Epidemics related to surgical procedures have been related to inadequate sterilization, as almost 50% of public water supplies harbor mycobacteria. Improved diagnostic techniques for these microbes, including Auramine-Rhodamine staining and rapid detection of mycobacteria and drug susceptibilities through PCR and MALDI-TOF, have improved detection and treatment outcomes. Given an increasing number of patients on immunosuppressive therapies, clinicians must remain vigilant.

Retrospective and prospective evaluation of the FluoroType®-Mycobacteria VER 1.0 assay for the identification of mycobacteria from cultures in a French center

PURPOSE

Rapid, reliable identification of mycobacteria from positive cultures is essential for patient management, particularly for the differential diagnosis of Mycobacterium tuberculosis complex (MTBC) and nontuberculous mycobacteria (NTM) species. The aim of the present study was to evaluate a new "In-Vitro-Diagnostic"-certified PCR kit, FluoroType®-Mycobacteria VER 1.0 (Hain Lifescience GmbH) for NTM and MTBC identification from cultures.

METHODS

Mycobacteria identification isolated from positive cultures during routine practice at the Lyon university hospital mycobacteria laboratory obtained by hsp65 amplification/sequencing were compared retrospectively and prospectively to those obtained by and the FluoroType®-Mycobacteria VER 1.0 kit.

RESULTS

The overall agreement between hsp65 amplification/sequencing and the FluoroType®-Mycobacteria VER 1.0 kit was 88.4% (84/95); 91.2% (52/57) for the retrospective period and 84.2% (32/38) for the prospective period. There were 9 (9.5%) minor discrepancies (species in the FluoroType®-Mycobacteria VER 1.0 database and identified at genus level): 4 during the retrospective period, 5 during the prospective period; and 2 (2.1%) major discrepancies (species in the FluoroType®-Mycobacteria VER 1.0 database and identified incorrectly to species level): 1 during the retrospective period (M. kumamotonense identified as M. abscessus subsp massiliense by the kit) and 1 during the prospective period (M. chimaera identified as M. smegmatis by the kit). Including concordant results at genus level and minor discrepancies, 17.9% (17/95) of strains were identified as Mycobacterium sp. by the FluoroType®-Mycobacteria-VER 1.0 kit.

CONCLUSION

The good performance of the FluoroType®-Mycobacteria-VER 1.0 kit with few major discrepancies could enable its use for first-line identification of positive mycobacteria cultures. However, an alternative identification method at least for reference laboratories is needed owing to the non-negligible proportion of NTM strains were identified at genus level.

Granulomatous Lung Diseases: A Practical Approach and Review of Common Entities

Granulomas are frequently encountered by pathologists in all types of lung specimens and arise from diverse etiologies. They should always be reported as necrotizing or non-necrotizing, with microorganism stains performed to evaluate for infection. With attention to distribution, quality (poorly vs well-formed), associated features, and correlation with clinical, radiologic, and laboratory data, the differential diagnosis for granulomatous lung disease can usually be narrowed to a clinically helpful "short list." This review describes a practical approach to pulmonary granulomas and reviews the clinicopathological aspects of common entities, including infectious (mycobacteria, fungi) and noninfectious (hypersensitivity pneumonitis, sarcoid, and vasculitis) causes.

Spatial Heterogeneity of Nontuberculous Mycobacterial Pulmonary Disease in Shanghai: Insights from a Ten-Year Population-Based Study

OBJECTIVE

To investigate the spatial heterogeneity of nontuberculous mycobacterial pulmonary disease (NTM-PD) in Shanghai.

METHODS

A population-based retrospective study was conducted using presumptive pulmonary tuberculosis surveillance data of Shanghai between 2010 and 2019. The study described the spatial distribution of NTM-PD notification rates, employing hierarchical Bayesian mapping for high-risk areas and the Getis-Ord Gi* statistic to identify hot spots and explore associated factors.

RESULTS

Of 1652 NTM-PD cases, the most common species was Mycobacterium kansasii complex (MKC) (41.9%), followed by Mycobacterium avium complex (MAC) (27.1%) and Mycobacterium abscessus complex (MABC) (16.2%). MKC-PD patients were generally younger males with a higher incidence of pulmonary cavities, while MAC-PD patients were more often farmers or had a history of tuberculosis treatment. MKC-PD hot spots were primarily located in the areas alongside the Huangpu River, while MAC-PD hot spots were mainly in the western agricultural areas. Patients with MKC-PD and MAC-PD exhibited a higher risk of spatial clustering compared to those with MABC-PD.

CONCLUSIONS

Different types of NTM-PD exhibit distinct patterns of spatial clustering and are associated with various factors. These findings underscore the importance of environmental and host factors in the epidemic of NTM-PD.

Clinical Characteristics and Treatment Outcomes of Pulmonary Diseases Caused by Coinfections With Multiple Nontuberculous Mycobacterial Species

BACKGROUND

Coinfections with multiple nontuberculous mycobacterial (NTM) species have not been widely studied. We aimed to evaluate the clinical characteristics and treatment outcomes in patients with NTM-pulmonary disease (PD) caused by coinfection with multiple NTM species.

METHODS

We retrospectively reviewed patients with NTM-PD at a tertiary referral hospital in Korea between March 2012 and December 2018. Coinfection was defined as two or more species of NTM pathogens isolated from the same respiratory specimen or different specimens within three months.

RESULTS

Among 1,009 patients with NTM-PD, 147 (14.6%) NTM coinfections were observed (average age 64.7 years, 69.4% women). NTM species were identified more frequently (median 6 vs. 3 times, P < 0.001) in the coinfection group than in the single species group, and follow-up duration was also longer in the coinfection group (median 44.9 vs. 27.1 months, P < 0.001). Mycobacterium avium complex (MAC) and M. abscessus and M. massiliense (MAB) were the dominant combinations (n = 71, 48.3%). For patients treated for over six months in the MAC plus MAB group (n = 31), sputum culture conversion and microbiological cure were achieved in 67.7% and 41.9% of patients, respectively. We divided the MAC plus MAB coinfection group into three subgroups according to the target mycobacteria; however, no statistical differences were found in the treatment outcomes.

CONCLUSION

In NTM-PD cases, a significant number of multiple NTM species coinfections occurred. Proper identification of all cultured NTM species through follow-up is necessary to detect multispecies coinfections. Further research is needed to understand the nature of NTM-PD in such cases.

Noncanonical mutations in ribosome nascent peptide exit tunnel confer clarithromycin resistance in Mycobacterium abscessus complex

Mycobacterium abscessus is a non-tuberculous mycobacterial pathogen known to cause pulmonary and skin infections worldwide. Renowned for its multidrug resistance, M. abscessus infections often result in unfavorable clinical outcomes. Clarithromycin plays a pivotal role in treating M. abscessus infections, with resistance commonly leads to treatment failure. While canonical mutations in 23S rRNA residue 2270/2271 are recognized as a major mechanism for acquired clarithromycin resistance, resistant isolates devoid of such mutations have been widely reported. In this study, we conducted a comprehensive investigation into acquired clarithromycin resistance using spontaneous mutants derived from two parental strains characterized by erm(41) T28 and C28 sequevars respectively. A total of 135 resistant mutants were selected from the parental strains. Sequencing of the 78 mutants lacking canonical 2270/2271 mutations identified mutations within the peptidyl-transferase center and in hairpin loops 35, 49, and 74 of the 23S rRNA. Moreover, these noncanonical mutations were identified in 57 out of 1875 genomes of clinical isolates. Thirteen representative mutations were introduced into the bacterial genome via site-directed mutagenesis, and their contribution to macrolide resistance was verified. Mapping these mutations onto the three-dimensional structure of 23S rRNA revealed their localization at the entrance of the nascent peptide exit tunnel, potentially contributing to resistance by disrupting the macrolide binding pocket. The identification of these noncanonical 23S rRNA mutations advances our understanding of macrolide resistance in M. abscessus and underscores their importance as potential markers for detecting clarithromycin resistance.

Triple-Antibiotic Combination Exerts Effective Activity against Mycobacterium avium subsp. hominissuis Biofilm and Airway Infection in an In Vivo Murine Model

OBJECTIVES

Slow-growing nontuberculous mycobacteria (NTMs) are highly prevalent and routinely cause opportunistic intracellular infectious disease in immunocompromised hosts.

METHODS

The activity of the triple combination of antibiotics, clarithromycin (CLR), rifabutin (RFB), and clofazimine (CFZ), was evaluated and compared with the activity of single antibiotics as well as with double combinations in an in vitro biofilm assay and an in vivo murine model of Mycobacterium avium subsp. hominissuis (M. avium) lung infection.

RESULTS

Treatment of 1-week-old biofilms with the triple combination exerted the strongest effect of all (0.12 ± 0.5 × 107 CFU/mL) in reducing bacterial growth as compared to the untreated (5.20 ± 0.5 × 107/mL) or any other combination (≥0.75 ± 0.6 × 107/mL) by 7 days. The treatment of mice intranasally infected with M. avium with either CLR and CFZ or the triple combination provided the greatest reduction in CLR-sensitive M. avium bacterial counts in both the lung and spleen compared to any single antibiotic or remaining double combination by 4 weeks posttreatment. After 4 weeks of treatment with the triple combination, there were no resistant colonies detected in mice infected with a CLR-resistant strain. No clear relationships between treatment and spleen or lung organ weights were apparent after triple combination treatment.

CONCLUSIONS

The biofilm assay data and mouse disease model efficacy results support the further investigation of the triple-antibiotic combination.

Disseminated Mycobacterium chimaera infection successfully treated with a clofazimine-containing regimen and long-term follow-up after discontinuing treatment

Mycobacterium chimaera is a slow-growing member of the Mycobacterium avium complex. It can contaminate tap water and has been detected in water tanks of heater-cooler devices used during open-heart surgery. Herein we report a case of a 67-year-old- male with disseminated M. chimaera infection who presented with fevers, significant weight loss and was found to have bacteremia with prosthetic valve endocarditis, chorioretinitis, bone marrow and splenic granulomas two years after an open-heart surgery. He developed multiple drug adverse events over the course of treatment but was successfully treated using a clofazimine containing regimen along with aortic valve replacement. He has remained symptom-free with no signs of recurrence three years after completion of antimicrobials. Clofazimine is an effective alternative that can be used as part of a multi-drug regimen in M. chimaera infection when there is resistance to first-line drugs or when adverse drug reactions occur.

Comparison of the sputum microbiome between patients with stable nontuberculous mycobacterial pulmonary disease and patients requiring treatment

BACKGROUND

We evaluated whether the sputum bacterial microbiome differs between nontuberculous mycobacteria pulmonary disease (NTM-PD) patients with stable disease not requiring antibiotic treatment and those requiring antibiotics.

METHODS

We collected sputum samples from 21 clinically stable NTM-PD patients (stable group) and 14 NTM-PD patients needing antibiotic treatment (treatment group). We also obtained 13 follow-up samples from the stable group. We analyzed the 48 samples using 16S rRNA gene sequencing (V3-V4 region) and compared the groups.

RESULTS

In the linear discriminant analysis effect size (LEfSe) analysis, the species Porphyromonas pasteri, Haemophilus parahaemolyticus, Prevotella nanceiensis, and Gemella haemolysans were significantly more prevalent in the sputum of the stable group compared to the treatment group. No taxa showed significant differences in alpha-/beta-diversity or LEfSe between the 21 baseline and 13 follow-up sputum samples in the stable group. In the stable group, the genus Bergeyella and species Prevotella oris were less common in patients who achieved spontaneous culture conversion (n = 9) compared to those with persistent NTM positivity (n = 12) (effect size 3.04, p = 0.039 for Bergeyella; effect size 3.64, p = 0.033 for P. oris). In the treatment group, H. parainfluenzae was more common in patients with treatment success (n = 7) than in treatment-refractory patients (n = 7) (effect size 4.74, p = 0.013).

CONCLUSIONS

Our study identified distinct bacterial taxa in the sputum of NTM-PD patients based on disease status. These results suggest the presence of a microbial environment that helps maintain disease stability.

Dual β-lactam for treatment of pulmonary Mycobacterium abscessus in a child

Treatment of Mycobacterium abscessus infection presents significant challenges, exacerbated by the emergence of macrolide-resistant strains that necessitate the use of multiple antimicrobials in combination and carry the potential for significant toxic effects. Select dual beta-lactam combinations, with or without beta-lactamase inhibitors, have been shown to be highly active in vitro. Herein, we describe a 6-year-old child with underlying mild bilateral lower lobe cylindrical bronchiectatic lung disease who developed pulmonary Mycobacterium abscessus infection and was treated with a multi-drug regimen including two β-lactam antibiotics, achieving both early clinical and microbiological cure. This case highlights the potential benefit of dual β-lactam therapy for the treatment of drug-resistant Mycobacterium abscessus infection.

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

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

Cu-promoted synthesis of triclosan-Mannich and Glaser adducts: anti-mycobacterial evaluation with in silico validations

Aim: The WHO, Global tuberculosis report 2022 estimated number of tuberculosis (TB) cases reached 10.6 million in 2021, reflecting a 4.5% increase compared with the 10.1 million reported in 2020. The incidence rate of TB showed 3.6% rise from 2020 to 2021. Results/methodology: This manuscript discloses Cu-promoted single pot A3-coupling between triclosan (TCS)-based alkyne, formaldehyde and secondary amines to yield TCS-based Mannich adducts. Additionally, the coupling of TCS-alkynes in the presence of Cu(OAc)2 afforded the corresponding homodimers. Among tested compounds, the most potent one in the series 11 exhibited fourfold higher potency than rifabutin against drug-resistant Mycobacterium abscessus. The selectivity index was also substantially improved, being 26 (day 1) and 15 (day 3), which is four-times better than TCS.

Identification of Mycobacterium abscessus using the peaks of ribosomal protein L29, L30 and hemophore-related protein by MALDI-MS proteotyping

Mycobacteroides (Mycobacterium) abscessus, which causes a variety of infectious diseases in humans, is becoming detected more frequently in clinical specimens as cases are spreading worldwide. Taxonomically, M. abscessus is composed of three subspecies of M. abscessus subsp. abscessus, M. abscessus subsp. bolletii, and M. abscessus subsp. massiliense, with different susceptibilities to macrolides. In order to identify rapidly these three subspecies, we determined useful biomarker proteins, including ribosomal protein L29, L30, and hemophore-related protein, for distinguishing the subspecies of M. abscessus using the matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) profiles. Thirty-three clinical strains of M. abscessus were correctly identified at the subspecies-level by the three biomarker protein peaks. This study ultimately demonstrates the potential of routine MALDI-MS-based laboratory methods for early identification and treatment for M. abscessus infections.

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

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

Toward Characterizing Environmental Sources of Non-tuberculous Mycobacteria (NTM) at the Species Level: A Tutorial Review of NTM Phylogeny and Phylogenetic Classification

Nontuberculous mycobacteria (NTM) are any mycobacteria that do not cause tuberculosis or leprosy. While the majority of NTM are harmless and some of them are considered probiotic, a growing number of people are being diagnosed with NTM infections. Therefore, their detection in the environment is of interest to clinicians, environmental microbiologists, and water quality researchers alike. This review provides a tutorial on the foundational approaches for taxonomic classifications, with a focus on the phylogenetic relationships among NTM revealed by the 16S rRNA gene, rpoB gene, and hsp65 gene, and by genome-based approaches. Recent updates on the Mycobacterium genus taxonomy are also provided. A synthesis on the habitats of 189 mycobacterial species in a genome-based taxonomy framework was performed, with attention paid to environmental sources (e.g., drinking water, aquatic environments, and soil). The 16S rRNA gene-based classification accuracy for various regions was evaluated (V3, V3-V4, V3-V5, V4, V4-V5, and V1-V9), revealing overall excellent genus-level classification (up to 100% accuracy) yet only modest performance (up to 63.5% accuracy) at the species level. Future research quantifying NTM species in water systems, determining the effects of water treatment and plumbing conditions on their variations, developing high throughput species-level characterization tools for use in the environment, and incorporating the characterization of functions in a phylogenetic framework will likely fill critical knowledge gaps. We believe this tutorial will be useful for researchers new to the field of molecular or genome-based taxonomic profiling of environmental microbiomes. Experts may also find this review useful in terms of the selected key findings of the past 30 years, recent updates on phylogenomic analyses, as well as a synthesis of the ecology of NTM in a phylogenetic framework.

Particulate matter deposition and its impact on tuberculosis severity: A cross-sectional study in Taipei

The objective of this study was to examine the association between the lung lobe-deposited dose of inhaled fine particulate matter (PM2.5) and chest X-ray abnormalities in different lung lobes of pulmonary tuberculosis (TB), multidrug-resistant tuberculosis (MDR-TB), and non-tuberculosis mycobacteria infections (NTM). A cross-sectional study was conducted between 2014 and 2022, comprising 1073 patients who were recruited from chest department clinic in a tertial refer hospital in Taipei City, Taiwan. Ambient 1-, 7-, and 30-day PM2.5 exposure and the deposition of PM2.5 in different lung lobes were estimated in each subject. The β coefficient for PM2.5 and deposited PM2.5 in lungs with the outcome variables (pulmonary TB, MDR-TB, and NTM infection) was derived through regression analysis and adjusted for age, gender, BMI, smoking status, and family income. We observed that a 1 μg/m3 increase in ambient PM2.5 was associated with an increase of MDR-TB infections of 0.004 times (95%CI: 0.001-0.007). A 1 μg/m3 increase in 1-day and 7-day PM2.5 deposition in left upper lobe and left lower lobe was associated with an increase in chest X-ray abnormalities of 9.19 % and 1.18 % (95%CI: 0.87-17.51 and 95%CI: 0.08-2.28), and 4.52 % and 5.20 % (95%CI: 0.66-8.38 and 95%CI: 0.51-9.89) in left lung of TB patients, respectively. A 1 μg/m3 increase in 30-day PM2.5 deposition in alveolar region was associated with an increase in percent abnormality of 2.50 % (95%CI: 0.65-4.35) in left upper lobe and 3.33 % (95%CI: 0.65-6.01) in right middle lobe, while in total lung was 0.63 % (95%CI: 0.01-1.27) in right upper lobe and 0.37 % (95%CI, 0.06-0.81) in right lung of MDR-TB patients. Inhaled PM2.5 deposition in lungs was associated with an exacerbation of the radiographic severity of pulmonary TB, particularly in pulmonary MDR-TB patients in upper and middle lobes. Particulate air pollution may potentially exacerbate the radiographic severity and treatment resistance in individuals with pulmonary TB.

Clinical characteristics and antimicrobial susceptibility profiles of Mycobacterium abscessus and Mycobacterium massiliense pulmonary infection

OBJECTIVES

Mycobacterium abscessus complex (MABC) is the most common rapidly growing Mycobacterium species in structural pulmonary diseases and can be life-threatening. This study aimed to assess the clinical characteristics and drug-susceptibility statuses of different M. abscessus (MAB) subspecies in the Zhejiang Province.

METHODS

DNA sequencing was used to differentiate clinical MABC subspecies isolates. The Clinical and Laboratory Standards Institute guidelines were used to determine in vitro susceptibility of imipenem-relebactam (IMP-REL), omadacycline, and other conventional antibiotics. Patient clinical characteristics were collected and analysed.

RESULTS

In total, 139 M. abscessus, 39 Mycobacterium massiliense, and 1 Mycobacterium bolletii isolates were collected, accounting for 77.7%, 21.8%, and 0.5% of the MABC isolates, respectively. Patients with M. abscessus pulmonary disease (M.ab-PD) had higher proportions of older adults, tuberculosis history, chronic pulmonary disease, and malignancy than those with M. massiliense pulmonary disease (M.ma-PD). Patients with M.ab-PD had higher rates of bilateral middle- and lower-lobe involvement than patients with M.ma-PD. Both subspecies showed high resistance rates to doxycycline and moxifloxacin, and clarithromycin-induced resistance was more common in M.ab than in M.ma. IMP-REL resulted in a twofold reduction in the minimum inhibitory concentration (MIC) value compared with imipenem alone among MAB; furthermore, the MIC was lower in M.ab than in M.ma. Omadacycline and tigecycline had comparable in vitro susceptibility, and the MIC showed no statistically significant difference between M.ab and M.ma.

CONCLUSIONS

M.ab is the most prevalent MABC subspecies in the Zhejiang Province. Patients with M.ab-PD have complex underlying diseases and broader lobar lesions. IMP-REL and omadacycline are promising antibiotics for MABC infection treatment.

Pulmonary transplant complications: a radiologic review

Lung transplantation has become the definitive treatment for end stage respiratory disease. Numbers and survival rates have increased over the past decade, with transplant recipients living longer and with greater comorbidities, resulting in greater complexity of care. Common and uncommon complications that occur in the immediate, early, intermediate, and late periods can have significant impact on the course of the transplant. Fortunately, advancements in surgery, medical care, and imaging as well as other diagnostics work to prevent, identify, and manage complications that would otherwise have a negative impact on survivability. This review will focus on contextualizing complications both categorically and chronologically, with highlights of specific imaging and clinical features in order to inform both radiologists and clinicians involved in post-transplant care.

Targeting intracellular nontuberculous mycobacteria and M. tuberculosis with a bactericidal enzymatic cocktail

To address intracellular mycobacterial infections, we developed a cocktail of four enzymes that catalytically attack three layers of the mycobacterial envelope. This cocktail is delivered to macrophages, through a targeted liposome presented here as ENTX_001. Endolytix Cocktail 1 (EC1) leverages mycobacteriophage lysin enzymes LysA and LysB, while also including α-amylase and isoamylase for degradation of the mycobacterial envelope from outside of the cell. The LysA family of proteins from mycobacteriophages has been shown to cleave the peptidoglycan layer, whereas LysB is an esterase that hydrolyzes the linkage between arabinogalactan and mycolic acids of the mycomembrane. The challenge of gaining access to the substrates of LysA and LysB provided exogenously was addressed by adding amylase enzymes that degrade the extracellular capsule shown to be present in Mycobacterium tuberculosis. This enzybiotic approach avoids antimicrobial resistance, specific receptor-mediated binding, and intracellular DNA surveillance pathways that limit many bacteriophage applications. We show this cocktail of enzymes is bactericidal in vitro against both rapid- and slow-growing nontuberculous mycobacteria (NTM) as well as M. tuberculosis strains. The EC1 cocktail shows superior killing activity when compared to previously characterized LysB alone. EC1 is also powerfully synergistic with standard-of-care antibiotics. In addition to in vitro killing of NTM, ENTX_001 demonstrates the rescue of infected macrophages from necrotic death by Mycobacteroides abscessus and Mycobacterium avium. Here, we demonstrate shredding of mycobacterial cells by EC1 into cellular debris as a mechanism of bactericide.IMPORTANCEThe world needs entirely new forms of antibiotics as resistance to chemical antibiotics is a critical problem facing society. We addressed this need by developing a targeted enzyme therapy for a broad range of species and strains within mycobacteria and highly related genera including nontuberculous mycobacteria such as Mycobacteroides abscessus, Mycobacterium avium, Mycobacterium intracellulare, as well as Mycobacterium tuberculosis. One advantage of this approach is the ability to drive our lytic enzymes through encapsulation into macrophage-targeted liposomes resulting in attack of mycobacteria in the cells that harbor them where they hide from the adaptive immune system and grow. Furthermore, this approach shreds mycobacteria independent of cell physiology as the drug targets the mycobacterial envelope while sidestepping the host range limitations observed with phage therapy and resistance to chemical antibiotics.

An early and trustable indicator suggestive of non-tuberculosis mycobacteria isolation in a high tuberculosis burden setting

BACKGROUND

Distinguishing between nontuberculous mycobacterial (NTM) lung infections and pulmonary tuberculosis becomes challenging due to their similar clinical manifestations and radiological images. Consequently, instances of delayed diagnosis or misdiagnosis are highly frequent. A feasible and reliable indicator of the existence of NTM in the early stages of the disease would help to solve this dilemma.

METHODS

In this study, we evaluated the potential of smear-positive and Xpert assay (Cepheid, USA) negative outcomes as an early indicator of possible NTM infection in a high TB-burden setting retrospectively and prospectively.

RESULTS

During the study period, 12·77% (138/1081) of the smear-positive cases yielded negative outcomes with the simultaneous Xpert assay. From the 110 patients who yielded smear-positive/Xpert-negative outcomes and cultivated strain as well, 105 (95·45%) were proved to have NTM isolated. By incorporating an additional criterion of a negative result from the Interferon-gamma release assay, the accuracy of the screening method reached 100%. Regarding the NTM presence prediction value, smear-positive/Xpert-negative has a sensitivity of 24·86% (45/181) in all NTM isolated cases but 93·75-96·55% accuracy in retrospective study or 93·75% accuracy in prospective study in smear-positive NTM isolated cases. In addition, the specificity was ∼99·47% (943/948) in smear-positive tuberculosis cases.

CONCLUSION

The clue of the presence of NTM could be obtained on the first day of the hospital visit due to the point of care (POC) feature of smear testing and Xpert assay. About one-fourth of the NTM-isolated patients would benefit from this rapid, convenient, and reliable screening strategy in the given circumstance. Smear-positive/Xpert-negative outcome is an early, trustable indicator that is indicative of NTM isolation.

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.

Peritoneal Dialysis-Related Infections

Peritoneal dialysis (PD) represents an important treatment choice for patients with kidney failure. It allows them to dialyze outside the hospital setting, facilitating enhanced opportunities to participate in life-related activities, flexibility in schedules, time and cost savings from reduced travel to dialysis centers, and improved quality of life. Despite its numerous advantages, PD utilization has been static or diminishing in parts of the world. PD-related infection, such as peritonitis, exit-site infection, or tunnel infection, is a major concern for patients, caregivers, and health professionals-which may result in hesitation to consider this as treatment or to cease therapy when these complications take place. In this review, the definition, epidemiology, risk factors, prevention, and treatment of PD-related infection on the basis of the contemporary evidence will be described.

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.

Polypropylene Mesh Infection From Surgical Site Infections Caused by Mycobacterium fortuitum

This report highlights two cases of surgical site infections (SSIs) caused by Mycobacterium fortuitum (Mf) following abdominal mesh implantation. The first case involved an 83-year-old male experiencing non-healing erythema and wounds post-operation, which persisted despite multiple treatments, until effective management was achieved with targeted antibiotics after Mf identification. The second case concerned a female patient with a gynecological postoperative hernia, where Mf was quickly detected following SSI onset three weeks after surgery. Prompt mesh removal and appropriate antibiotic treatment led to a rapid and full recovery. These cases emphasize the importance of early detection and intervention in managing Mf infections effectively, illustrating how the timing of diagnosis can significantly influence treatment outcomes.