Nontuberculous Mycobacteria Infection Research Articles

Risk Factors for Treatment Failure in Skin and Soft Tissue Infections Caused by Nontuberculous Mycobacteria

This study investigated the characteristics of patients with skin and soft tissue infections (SSTIs) caused by nontuberculous mycobacteria (NTM) and identified the risk factors for treatment failure in these patients. Data of patients with NTM SSTIs who received treatment between January 2014 and December 2019 at Taipei Veterans General Hospital were collected retrospectively. Possible risk factors were determined using univariate and multivariate analysis with logistic regression models. A total of 47 patients (24 male, 23 female; age, 57.1 ± 15.2 years) were enrolled. Type 2 diabetes mellitus was the most common comorbidity. The most common mycobacterial species was the Mycobacterium abscessus complex, and the most commonly affected site was the axial trunk. Treatment was successful in 38 patients (81%). Six patients had recurrent infections (13%) after the treatment course was completed, and 3 patients (6.4%) died of NTM-related infection. Delayed treatment for more than 2 months and antibiotic-alone treatment were 2 independent risk factors for treatment failure of NTM SSTIs. Delayed treatment for more than 2 months and antibiotic-alone treatment were associated with a higher failure rate in patients with NTM SSTIs. Therefore, the differential diagnosis of NTM infection should always be considered when the treatment course is prolonged but not effective. Early identification of causative NTM species and appropriate antibiotic treatment may lower the risk of treatment failure. Prompt surgical treatment is suggested if available.

Nontuberculous Mycobacterial Infection of Larynx and Cervical Trachea.

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. Case report and review of the literature. 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. 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.

Cutaneous non-tuberculous mycobacterial infections: An update

Non-tuberculous mycobacteria (NTM) are increasingly recognized as causes of skin and soft-tissue infections. They include rapid-growing and slow-growing species. Hospital outbreaks related to contaminated water and in association with surgical and cosmetic procedures have been described. Infections are also associated with immunosuppression. NTM infections have a wide spectrum of clinical manifestations, though Mycobacterium marinum and Mycobacterium ulcerans manifest characteristic lesions – swimming pool granuloma and Buruli ulcer, respectively. NTM infection should be suspected when the skin infection (especially those following trauma or invasive procedure or in a patient with immunosuppression) does not respond to antibiotics. NTM are acid fast, but will be negative on cartridge based nucleic acid amplification tests for Mycobacterium tuberculosis. Diagnosis is confirmed by polymerase chain reaction test which is the gold standard. NTM show variable susceptibility to antimicrobials and no clear treatment guidelines are available. Surgical treatment may also be needed in some cases.

Emergence of Nontuberculous Mycobacteria at the Human–Livestock–Environment Interface in Zambia

The prevalence of nontuberculous mycobacteria (NTM) infections and disease is rising worldwide due to increased research, diagnostics capabilities, and awareness of the disease. There is limited prevalence data for NTM from different sources in Zambia. The aim of this study was to determine the prevalence and species distribution of NTM at the human–livestock–environment interface. A cross-section study was conducted in Namwala, Chipata, and Lundazi Districts of Zambia from April 2020 to December 2021. Sputum samples were collected from tuberculosis presumptive patients from different health centers, cattle tissues were collected from different abattoirs during routine post-mortem, and water samples were collected from different drinking points for humans and animals such as taps, boreholes, wells, rivers, dams and ponds, and then cultured following standard mycobacteriology procedures. Capilia TB-Neo assay was used to identify NTM from the positive cultures. DNA was extracted and the 16S to 23S rRNA (internal transcribed spacer region) (ITS) was amplified and sequenced to identify the species. The overall prevalence of NTM from humans, cattle, and water was 9.1% (72/794, 95% CI 7.2–11.3). The prevalence in humans was 7.8% (33/421, 95% CI 5.54–10.94), in cattle it was 10.6% (15/142, 95% CI 6.2–17.1), and in water it was 10.4% (24/231, 95% CI 6.9–15.2). Our study has shown, for the first time in Zambia, simultaneous isolation of NTM at the human–livestock–environment interface; M. avium complex and M. fortuitum were the most commonly isolated species. M. fortuitum and M. gordonae were isolated from all three sources, while M. abscessus was isolated from humans and water. The isolation of similar NTM species at the interface which are potentially pathogenic is a public health problem which merits further investigation.

Successful Treatment of Nasal and Parotid Mycobacterium avium Complex Infection in Adult-Onset Immunodeficiency: A Case Report with Literature Review

Non-tuberculous mycobacteria (NTM) infection has increasingly been reported throughout the world, especially in Asia. Autoantibodies to interferon-γ are implicated in the pathogenesis of adult-onset immunodeficiency resulting in multiple opportunistic infections, in particular NTM infection. There are few reports regarding Mycobacterium avium complex infection of the nasal cavity or parotid gland in this condition. The authors reported the first case of nasal and parotid Mycobacterium avium complex presenting with recurrent epistaxis, nasal mass, and parotitis successfully treated with combined systemic and topical anti-mycobacterial agents in Thailand. Keywords: Nasal and parotid Mycobacterium avium complex; Nontuberculous mycobacteria; Autoantibody to interferon-γ; Nasal mass; Epistaxis; Parotitis

Disseminated Mycobacterium haemophilum Infection Mimicking Rheumatoid Nodules.

Disseminated nontuberculous mycobacterium (NTM) infection is rare in the differential diagnosis of rheumatoid nodules. The infection is seen primarily in immunosuppressed patients and has been reported in patients with rheumatoid arthritis.

Inactivation of nontuberculous mycobacteria by gaseous ozone treatment

Nontuberculous mycobacteria (NTM) are environmental bacteria resistant to many common disinfectants and ultraviolet radiation. Inhalation of aerosols generated from NTM-containing water and soil causes NTM lung disease, especially in people with underlying lung diseases and decreased immunity. To prevent healthcare-acquired NTM infections, it is important to eradicate NTM living in hospital environments. Therefore, we evaluated the efficacy of gaseous ozone for the inactivation of NTM, namely Mycobacterium (M.) avium, M. intracellulare, M. kansasii, M. abscessus subsp. abscessus and M.abscessus subsp. massiliense. Gaseous ozone treatment at 1 ppm for 3 h reduced the bacterial number of all strains by more than 97%. Gaseous ozone treatment could be a practical, effective and convenient disinfection method for NTM living in hospital environments.

Evaluation of the anti-mycobacterial activity and composition of Carlina acaulis L. root extracts.

Nontuberculous mycobacteria (NTM) have recently emerged as important bacterial pathogens of animals and humans. Of particular concern is the high level of antimicrobial resistance displayed by these organisms, which complicates treatment and potential successful outcomes. Here, we evaluated the potential of Carlina acaulis L. as a source of novel anti-mycobacterial agents. Our goal was to measure the activity of aqueous, ethanol, and chloroform C. acaulis root extracts against 99 NTM strains. GC-MS spectroscopy analyses were performed to deliver qualitative and quantitative data on the composition of C. acaulis extract. In our study, we have shown for the first time the activity of C. acaulis extracts against NTM. The highest activity was exhibited by the chloroform extract, which inhibited the growth of more than 90% of the strains at the dose of 100 μg/mL (MIC90 = 100 μg/mL). The results of the GC-MS analysis of the C. acaulis chloroform extract contributed to the identification of 37 compounds, with carlina oxide as the most representative compound (69.52%) followed by 3,4-dihydro-2H-phenanthren- -1-one (6.54%) and stigmast-5-en-3-ol (4.14%). Our results indicate that C. acaulis chloroform and ethanol extracts have potential for treatment of NTM infections and that this plant contains anti-mycobacterial compounds.

Клиническое наблюдение микст-инфекции туберкулеза и нетуберкулезного микобактериоза легких

nontuberculous mycobacteriosis is an infectious disease caused by nontuberculous mycobacteria (nTm) with the development of granulomatous inflammation in affected organs and tissues. By now more than 200 nTm species persisting in the environment have been described. According to different authors, 30 to 60 of strains are able to cause disease in humans. It was established that patients with different chronic lung diseases: chronic bronchitis, chronic obstructive pulmonary disease, and bronchiectatic lung disease are predisposed to mycobacteriosis. recently, cases of pulmonary TB/nTm infection have been reported more and more frequently, which impedes timely verification of both diseases. diagnosis of coinfection is essentially facilitated by morphological studies of lung tissue, which can simultaneously assess signs of TB and/or nTm infection. The article describes a clinical case of mixed pulmonary infection with nTm and mycobacterium tuberculosis

Unusual prophages in Mycobacterium abscessus genomes and strain variations in phage susceptibilities.

Mycobacterium abscessus infections are relatively common in patients with cystic fibrosis and are clinically challenging, with frequent intrinsic resistance to antibiotics. Therapeutic treatment with bacteriophages offers some promise but faces many challenges including substantial variation in phage susceptibilities among clinical isolates, and the need to personalize therapies for individual patients. Many strains are not susceptible to any phages or are not efficiently killed by lytic phages, including all smooth colony morphotype strains tested to-date. Here, we analyze a set of new M. abscessus isolates for the genomic relationships, prophage content, spontaneous phage release, and phage susceptibilities. We find that prophages are common in these M. abscessus genomes, but some have unusual arrangements, including tandemly integrated prophages, internal duplications, and they participate in active exchange of polymorphic toxin-immunity cassettes secreted by ESX systems. Relatively few strains are efficiently infected by any mycobacteriophages, and the infection patterns do not reflect the overall phylogenetic relationships of the strains. Characterization of these strains and their phage susceptibility profiles will help to advance the broader application of phage therapies for NTM infections.

Adult-onset immunodeficiency induced by anti-interferon-γ autoantibodies: report of 13 cases

Objective: To investigate the clinical characteristics of a group of patients with adult-onset immunodeficiency (AOID) induced by anti-interferon-γ autoantibodies (AIGA). Methods: Thirteen cases of AOID in a northern China medical center (Peking Union Medical College Hospital) from October 2020 to April 2022 were included. Data comprising clinical manifestations, laboratory results, infection sites and pathogens were collected. Results: Among the 13 patients, 5 were male. The median age of disease onset was 47 (14 to 71) years. The median time from symptom onset to diagnosis was 4 years (1 to 8 years). Four patients were from northern China, and 9 from southern China. Common symptoms included lymphadenopathy (13/13), fever (12/13), respiratory tract symptoms (12/13), and weight loss (11/13). Laboratory tests showed increased levels of white blood cell count (9/13), neutrophil count and proportion (9/13), erythrocyte sedimentation rate (ESR) (12/13), and C reactive protein (CRP) (11/13). The median plasma titers of AIGA upon diagnosis were 5681(3194, 13246). Sites of infection included lungs (12/13), lymph nodes (9/13), bones and joints (9/13), skin and soft tissue (7/13), blood flow and bone marrow (4/13), and glands (3/13). Most patients had nontuberculous mycobacteria (NTM) (12/13) infection. Seven patients had more than one pathogen. Conclusions: AOID also affects patients visiting northern China hospitals. AIGA screening is recommended among patients with disseminated NTM infections or recurrent infections.

Hematological profiles of patients with tuberculosis and nontuberculous mycobacteria infections in Bamako, Mali.

Pulmonary tuberculosis (TB) remains one of the main causes of morbidity and mortality in Mali. Nontuberculous mycobacteria (NTM) infections are very common but are often cofounded with TB because of the similarity of symptoms, which makes the diagnosis difficult. Hematological abnormalities associated with TB have been described, but not with NTM. Therefore, the goal of this study was to compare the hematological parameters of patients infected with TB and NTM infections. A cross-sectional study enrolling TB and NTM participants was conducted in 2018-2020. Five milliliters of venous blood and sputum samples were collected from each participant to determine the hematological parameters using the RUBY CELL-DYN Ruby Version 2.2 ML. A BACTEC MGIT 960 and multiplex reverse transcription-polymerase chain reaction were used to distinguish Mycobacterium tuberculosis from NTM, respectively. Of the total 90 patients enrolled, there was a decrease in hemoglobin and hematocrit levels in both the groups (P = 0.05). In addition, we found that the percentages of basophil cells (P = 0.01) and mean values of platelets (P = 0.04) were significantly higher in TB patients than those of NTMs. Moreover, the mean of absolute values of eosinophil cells of TB patients was significantly lower than those of NTMs (P = 0.03). We found significant statistical differences in basophils, platelets, and eosinophils in differentiating TB and NTM in this pilot study. Future studies with patients at different clinical stages are needed to confirm the hematological profiles of TB and NTM patients.

Risk factors and outcomes of non-tuberculous mycobacteria infection in lung transplant recipients: A systematic review and meta-analysis

Patients with structural lung disease and immunocompromised status are at increased risk of pulmonary non-tuberculous mycobacteria (NTM) infection. However, literature on NTM in lung transplant recipients (LTR) is limited. We sought to systematically review the literature and perform a meta-analysis to examine associations with NTM disease and isolation in LTRs and their influence on mortality and chronic lung allograft dysfunction (CLAD). A literature search of MEDLINE and Embase was performed on February 23, 2022. NTM disease was defined according to international guidelines. Isolation was defined as any growth of NTM in culture. Odds ratios (OR) were pooled for risk factors of NTM disease or isolation, and hazard ratios (HR) were pooled for mortality or CLAD. Eleven studies totaling 3,371 patients were eligible for inclusion, 10 of which underwent meta-analysis. Cystic fibrosis (OR 1.84, 95% confidence interval [CI] 1.03-3.30; I2=0%) and pre-transplant NTM isolation (OR 2.40, 95% CI 1.20-4.83; I2=0%) were associated with NTM disease. Only male sex was associated with NTM isolation (OR 1.45, 95% CI 1.01-2.10; I2=0%). NTM disease was associated with increased mortality (HR 2.69, 95% CI 1.70-4.26; I2=0%) and CLAD (HR 2.11, 95% CI 1.03-4.35; I2=44%). NTM isolation was not associated with mortality in pooled analysis or CLAD in 1 included study. NTM disease, but not isolation, is associated with worse outcomes. Several factors were associated with development of NTM disease, including cystic fibrosis and pretransplant NTM isolation. Strategies to optimize prevention and treatment of NTM disease in lung transplant recipients are needed.

Cumulative antimicrobial susceptibilities for respiratory clinical isolates of Mycobacterium avium Complex, Mycobacterium kansasii, and Mycobacterium abscessus from Pakistan 2018 to 2022.

Nontuberculous mycobacteria (NTM) are increasingly identified as causes of protracted pulmonary infections. Antibiotic susceptibility testing requires microdilution methods, which are often unavailable in laboratories in resource-poor settings. We report cumulative antibiograms for the most frequently isolated clinical pulmonary NTM from Pakistan to inform empiric antibiotic management of initial NTM infections. We analyzed data from 2018 to 2022 for the most frequently isolated and clinically relevant NTM isolated from respiratory specimens, i.e., Mycobacterium avium complex (MAC), Mycobacterium abscessus group (MAG), and Mycobacterium kansasii (MK). Antibiograms were developed using the Clinical Laboratory Standards Institute's M39ED5 standard. Percentage susceptibilities and 95% confidence intervals (CI) were calculated. Over 4 years, 529 NTM, comprising 209 MAC, 249 MAG, and 71 MK were analyzed. For MAC and MAG, where clarithromycin (CLR)-based regimens are recommended, CLR was active for 94.8% (95% CI 91.3-96.9), and 77.5% (95% CI 71.4-82.7) isolates, respectively. Combination regimens comprising 3 active drugs CLR + linezolid (LZD) + moxifloxacin for MAC and CLR + LZD + Amikacin for MAG had 98.4% (95% CI 95.9-99.4) and 68.9% (95% CI 62.3-74.8) coverage for pulmonary disease, respectively. For MK, 91.5% (95% CI 82.8-96.1) isolates were susceptible to rifampin (RIF), with a combination of RIF + CLR covering 88.7% (95% CI 79.3-94.2) of MK pulmonary infections, respectively. These data can inform empiric treatment guidance for the most common NTM pulmonary infections, i.e., for MAC, MAG, and MK disease in Pakistan.

Epidemiological trends in nontuberculous mycobacterial infection among people with cystic fibrosis in Germany

ObjectivesPeople with cystic fibrosis (pwCF) are at risk for infection with nontuberculous mycobacteria (NTM). The epidemiology and screening practice of NTM among pwCF in Germany are largely unknown and require investigation. MethodsWe analyzed the data of the German Cystic Fibrosis Registry from 2016 to 2020 for NTM. The annual prevalence and incidence of any NTM, Mycobacterium abscessus complex (MABC), Mycobacterium avium complex (MAC), Mycobacterium gordonae, and other mycobacteria were determined and correlated to patient characteristics. Patients with incident MABC and MAC infection were compared. ResultsThe annual NTM prevalence and incidence remained stable between 7.53% and 8.76%, as well as 3.31% and 4.95%, respectively, among the approximately 6000 registry participants. MABC was the most common NTM, whereas only the prevalence of MAC increased slightly. In each year, only about one-third of all patients were screened for NTM. An association between NTM infections and Aspergillus fumigatus infection and/or allergic bronchopulmonary aspergillosis was observed. On average, patients with incident MAC infection were older than patients with MABC infection. ConclusionThe NTM burden in pwCF in Germany remained unchanged between 2016 and 2020. MABC was the dominant species detected, whereas only MAC infections increased with time and patient age. The previously observed association of Aspergillus fumigatus and NTM was reaffirmed. Awareness of NTM needs to be improved.

Self-recycling and partially conservative replication of mycobacterial methylmannose polysaccharides

The steep increase in nontuberculous mycobacteria (NTM) infections makes understanding their unique physiology an urgent health priority. NTM synthesize two polysaccharides proposed to modulate fatty acid metabolism: the ubiquitous 6-O-methylglucose lipopolysaccharide, and the 3-O-methylmannose polysaccharide (MMP) so far detected in rapidly growing mycobacteria. The recent identification of a unique MMP methyltransferase implicated the adjacent genes in MMP biosynthesis. We report a wide distribution of this gene cluster in NTM, including slowly growing mycobacteria such as Mycobacterium avium, which we reveal to produce MMP. Using a combination of MMP purification and chemoenzymatic syntheses of intermediates, we identified the biosynthetic mechanism of MMP, relying on two enzymes that we characterized biochemically and structurally: a previously undescribed α–endomannosidase that hydrolyses MMP into defined-sized mannoligosaccharides that prime the elongation of new daughter MMP chains by a rare α-(1→4)-mannosyltransferase. Therefore, MMP biogenesis occurs through a partially conservative replication mechanism, whose disruption affected mycobacterial growth rate at low temperature.

Management of nontuberculous mycobacteria in lung transplant cases: an international Delphi study.

Nontuberculous mycobacterial (NTM) diseases are difficult-to-treat infections, especially in lung transplant (LTx) candidates. Currently, there is a paucity of recommendations on the management of NTM infections in LTx, focusing on Mycobacterium avium complex (MAC), M. abscessus and M. kansasii. Pulmonologists, infectious disease specialists, LTx surgeons and Delphi experts with expertise in NTM were recruited. A patient representative was also invited. Three questionnaires comprising questions with multiple response statements were distributed to panellists. Delphi methodology with a Likert scale of 11 points (5 to -5) was applied to define the agreement between experts. Responses from the first two questionnaires were collated to develop a final questionnaire. The consensus was described as a median rating >4 or <-4 indicating for or against the given statement. After the last round of questionnaires, a cumulative report was generated. Panellists recommend performing sputum cultures and a chest computed tomography scan for NTM screening in LTx candidates. Panellists recommend against absolute contraindication to LTx even with multiple positive sputum cultures for MAC, M. abscessus or M. kansasii. Panellists recommend MAC patients on antimicrobial treatment and culture negative can be listed for LTx without further delay. Panellists recommend 6 months of culture-negative for M. kansasii, but 12 months of further treatment from the time of culture-negative for M. abscessus before listing for LTx. This NTM LTx study consensus statement provides essential recommendations for NTM management in LTx and can be utilised as an expert opinion while awaiting evidence-based contributions.

Reactive Neutrophilic Dermatoses in Adult-Onset Immunodeficiency due to Interferon-Gamma Autoantibody and Their Associated Factors

Background: Adult-onset immunodeficiency (AOID) due to interferon-gamma autoantibody is a rare, acquired immunodeficiency disease. Reactive neutrophilic dermatoses (RND), predominantly Sweet syndrome (SS), and generalized pustular eruption have been reported repeatedly. Objectives: The aims of this study were to describe the cutaneous manifestations in AOID patients and determine the incidence of RND and associated factors using a larger population size than have been previously reported. Methods: A retrospective chart review of all confirmed AOID cases in Chiang Mai University Hospital from January 2006 to June 2020 was conducted. The demographics and characteristics of RND including type, onset, and laboratory information in every episode of cutaneous manifestations were collected. Generalized estimating equations of binary logistic regression were used to determine the indicators of RND. Results: A total of 146 patients with confirmed AOID were identified. Of these, 57 cases (39%) developed at least one episode of RND. Thirteen cases (23%) of the patients experienced RND twice during the follow-up period. All recurrence of RND displayed the same cutaneous phenotype, with the exception of 2 cases who had both SS and generalized pustular eruption. Finally, 49 episodes of SS and 22 episodes of generalized pustular eruption were included in the analysis. All patients with RND had concomitant active opportunistic infections, of which most were non-tuberculous mycobacterium (NTM) infection. NTM infection (prevalence odds ratio [POR] 2.87), lymphadenopathy (POR 3.30) as well as lower serum alkaline phosphatase (ALP) level (POR 0.71 for every 100-unit increment in ALP) were found to be significantly associated with RND occurrence. Conclusions: 39% of our AOID patients experienced RND once during the course of the disease. Notable factors associated with RND occurrence were concomitant NTM infection, lymphadenopathy, and lower level of ALP.

Deficient Complement Opsonization Impairs Mycobacterium avium Killing by Neutrophils in Cystic Fibrosis.

Nontuberculous mycobacteria (NTM), including Mycobacterium avium, are clinically important pathogens in cystic fibrosis (CF). The innate immune response to M. avium remains incompletely understood. We evaluated the role of complement opsonization in neutrophil-mediated killing of M. avium. Killing assays were performed using neutrophils from healthy donors (HDs) and persons with CF (pwCF). Clinical isolates of M. avium were opsonized with plasma from HDs or pwCF, which was intact or heat-treated to inactivate complement. HD neutrophils had killing activity against M. avium opsonized with intact HD plasma and killing was significantly reduced when M. avium was opsonized with heat-inactivated HD plasma. When opsonized with HD plasma, CF neutrophils had killing activity against M. avium that was not different than HD neutrophils. When opsonized with intact plasma from pwCF, HD neutrophil killing of M. avium was significantly reduced. Opsonization of M. avium with C3-depleted serum or IgM-depleted plasma resulted in significantly reduced killing. Plasma C3 levels were elevated in pwCF with NTM infection compared to pwCF without NTM infection. These studies demonstrate that human neutrophils efficiently kill M. avium when opsonized in the presence of plasma factors from HD that include C3 and IgM. Killing efficiency is significantly lower when the bacteria are opsonized with plasma from pwCF. This indicates a novel role for opsonization in neutrophil killing of M. avium and a deficiency in complement opsonization as a mechanism of impaired M. avium killing in CF. IMPORTANCE Mycobacterium avium is a member of a group of bacterial species termed nontuberculous mycobacteria (NTM) that cause lung disease in certain populations, including persons with cystic fibrosis (CF). NTM infections are challenging to diagnose and can be even more difficult to treat. This study investigated how the immune system responds to M. avium infection in CF. We found that neutrophils, the most abundant immune cell in the lungs in CF, can effectively kill M. avium in individuals both with and without CF. Another component of the immune response called the complement system is also required for this process. Levels of complement proteins are altered in persons with CF who have a history of NTM compared to those without a history of NTM infection. These results add to our understanding of how the immune system responds to M. avium, which can help pave the way toward better diagnostic and treatment strategies.

Clofazimine Inhalation Suspension Demonstrates Promising Toxicokinetics in Canines for Treating Pulmonary Nontuberculous Mycobacteria Infection.

Pulmonary nontuberculous mycobacteria (NTM) infection is recognized as a major global health concern due to its rising prevalence worldwide. As an opportunistic pathogen with increasing antibiotics resistance, prolonged systemic dosing with multiple antibiotics remains the primary treatment paradigm. These prolonged treatments, administered predominantly by oral or parenteral routes, often lead to systemic toxicity. A novel inhaled formulation of clofazimine may finally resolve issues of toxicity, thereby providing for improved NTM therapy. Clofazimine inhalation suspension was evaluated in canines to determine toxicity over 28 days of once-a-day dosing. The good laboratory practice (GLP) repeat dosing study evaluated low, mid, and high dosing (2.72 mg/kg and 2.95 mg/kg; 5.45 mg/kg and 5.91 mg/kg; and 10.87 mg/kg and 10.07 mg/kg, average male versus female dosing) of nebulized clofazimine over 30, 60, and 120 min using a jet nebulizer. Toxicokinetic analyses were performed on study days 29, 56, and 84. All three dose levels showed significant residual drug in lung tissue, demonstrating impressive lung loading and long lung residence. Drug concentrations in the lung remained well above the average NTM MIC at all time points, with measurable clofazimine levels at 28 and 56 days postdosing. In contrast, plasma levels of clofazimine were consistently measurable only through 14 days postdosing, with measurements below the limit of quantitation at 56 days postdosing. Clofazimine inhalation suspension may provide an effective therapy for the treatment of NTM infections through direct delivery of antibiotic to the lungs, overcoming the systemic toxicity seen in oral clofazimine treatment for NTM.