Search Results (115)

Anticytokine autoantibodies (AAbs), particularly anti-interferon-gamma (anti-IFN-γ) AAbs, disrupt cytokine functions, leading to infections, autoimmune-like diseases, and conditions resembling interleukin-12 (IL-12)/IFN-γ pathway defects. Advances in genetic testing have clarified overlaps between autoinflammatory, autoimmune disorders, and primary immunodeficiencies but reveal complex phenotypes and pathways. While these insights deepen our understanding of immune mechanisms, they also complicate diagnosis and treatment, with limited options for IFN-γ deficiencies caused by genetic mutations. The adult-onset immunodeficiency with disseminated lymphadenitis due to nontuberculous mycobacteria (NTM) and other opportunistic infections has been linked to high levels of anti-IFN-γ AAbs. This syndrome, initially identified in HIV-negative Asian patients, frequently affects individuals of Asian descent and may be associated with specific human leukocyte antigen (HLA) alleles. The presence of neutralizing anti-IFN-γ AAbs impairs the IFN-γ-dependent immune response, likely contributing to the persistent NTM infection. This study underscores the potential for late-onset anti-IFN-γ AAb syndrome to manifest with disseminated NTM (dNTM) infections, highlights the importance of timely diagnosis and considers rituximab as a potential therapeutic option. Full article

Background/Objectives: Mycobacterium avium, a member of Mycobacterium avium complex (MAC), is an emerging opportunistic pathogen causing MAC-pulmonary disease (PD). Fluoroquinolones (FQs), along with ethambutol (EMB) and rifampicin, are recommended for macrolide-resistant MAC-PD; however, FQ-resistant M. avium have been reported worldwide. WQ-3810 is an FQ with high potency against FQ-resistant pathogens; however, its activity against M. avium has not yet been studied. Methods: In this study, we conducted a DNA supercoiling inhibitory assay to evaluate the inhibitory effect of WQ-3810 on recombinant wild-type (WT) and four mutant DNA gyrases of M. avium and compared the IC₅₀s of WQ-3810 with those of ciprofloxacin (CIP), levofloxacin (LVX), and moxifloxacin (MXF). In addition, we examined WQ-3810’s antimicrobial activity against 11 M. avium clinical isolates, including FQ-resistant isolates, with that of other FQs. Furthermore, we assessed the synergistic action of WQ-3810 with the combination of either EMB or isoniazid (INH). Results: In a DNA supercoiling inhibitory assay, WQ-3810 showed 1.8 to 13.7-fold higher efficacy than LVX and CIP. In the MIC assay, WQ-3810 showed 4 to 8-fold, 2 to 16-fold, and 2 to 4-fold higher antimicrobial activity against FQ-resistant isolates than CIP, LVX, and MXF, respectively. The combination of WQ-3810 and INH exhibited a synergistic relationship. Conclusions: The overall characteristics of WQ-3810 demonstrated greater effectiveness than three other FQs, suggesting that it is a promising option for treating FQ-resistant M. avium infections. Full article

Worldwide, several million people are infected with mycobacteria such as Mycobacterium tuberculosis (M. tb) or non-tuberculous mycobacteria (NTM). In 2023, 10.8 million cases and 1.25 million deaths due to M. tb were recorded. In Europe and North America, the emergence of NTM is tending to outstrip that of M. tb. Among pulmonary NTM, Mycobacterium avium complex (MAC) is the most common, accounting for 80% of NTM infections. First-line treatment requires the combination of at least three antibiotics over a long period and with different mechanisms of action to limit cross-resistance. The challenge is to discover more effective new anti-MAC molecules to reduce the duration of treatment and to overcome resistant strains. The aim of this review is to present an overview of the challenges posed by MAC infection such as side effects, reinfections and resistance mechanisms. The latest therapeutic options such as the optimized combination therapy, drug repurposing and the development of new formulations, as well as new anti-MAC compounds currently in (pre)clinical trials will also be discussed. Full article

The treatment of Mycobacterium avium complex (MAC) remains a clinical challenge as multidrug regimens are needed and may be limited by treatment-related toxicity. The Clinical and Laboratory Standards Institute (CLSI) endorses breakpoints for several agents used for MAC infection treatment. Amikacin has distinct breakpoints for intravenous (IV) therapy and inhaled therapy using amikacin liposome inhalation suspension (ALIS) for MAC pulmonary disease. The purpose of the present retrospective cohort study of MAC pulmonary isolates was to assess the number of amikacin non-susceptible isolates by the IV breakpoints that remain susceptible to the inhaled breakpoints. One isolate per patient per year was assessed and susceptibility was described for amikacin IV, amikacin inhaled, clarithromycin, moxifloxacin, and linezolid per the CLSI. Of the 218 isolates, 94% [204/218] tested as susceptible to amikacin per the IV breakpoints compared with 99.5% [217/218] to the inhaled breakpoints. Of the amikacin IV non-susceptible isolates, 93% [13/14] were susceptible by the inhaled breakpoints. For comparison, clarithromycin was the next most active agent followed by moxifloxacin and linezolid with 97% [211/218], 82% [178/218], and 66% [143/218] of isolates testing as susceptible to each, respectively. These data highlight the importance of laboratories to report both the IV and inhaled amikacin interpretive criteria so that clinicians do not disregard potential therapeutic options for the treatment of MAC pulmonary disease. Full article

Background: The prevalence of pulmonary nontuberculous mycobacteria (NTM) is increasing in Europe and North America. Most pulmonary NTM cases are caused by Mycobacterium avium complex (MAC). The treatment of pulmonary MAC is suboptimal with failure rates ranging from 30% to 40% and there is a need to develop new vaccines. Methods: We tested the ability of two whole-cell vaccines, DAR-901 (heat-killed M. obuense) and BCG (live-attenuated M. bovis), to induce MAC cross-reactive immunity by first immunizing BALB/c mice and then performing IFN-γ ELISPOT assays after overnight stimulation of splenocytes with live MAC. To study the ability of these vaccines to protect against MAC infection, BALB/c mice were vaccinated with DAR-901 (intradermal) or BCG (subcutaneous or intranasal) and challenged with aerosolized MAC 4 weeks later. A group of mice vaccinated with BCG were also treated with clarithromycin via gavage. Lung colony-forming units (CFU) in immunized mice and unvaccinated controls were quantified 4 weeks after infection. Histopathology was used to quantify lung inflammation and flow cytometry was used to study lung immunity in BCG-vaccinated and unvaccinated mice following MAC infection. To increase the safety profile of mucosal BCG vaccination, we studied BCG with a “kill switch” (tetR BCG) in scnn1b-transgenic mice (i.e., mice prone to cystic fibrosis-type lung diseases). Results: Our results showed that (i) DAR-901 induced cross-reactive immunity to MAC to a similar level as BCG, (ii) DAR-901 and BCG protected against aerosol MAC challenge, (iii) mucosal BCG vaccination, compared to systemic BCG and DAR-901 vaccinations, provided the best protection against MAC challenge, (iv) BCG vaccination did not interfere with anti-MAC activities of clarithromycin, (v) BCG-vaccinated mice had increased inflammation and increased frequencies of activated CD4 and CD8 T cells following MAC infection, and (vi) doxycycline treatment of tetR BCG-vaccinated mice decreased lung BCG CFU without affecting MAC immunity. Conclusions: Both DAR-901 and BCG vaccinations induce MAC cross-reactive immunity and protect against aerosolized MAC challenges. Mucosal BCG vaccination provides the best protection and TetR BCG could enhance the safety of mucosal BCG vaccination. Full article

Rapid and accurate diagnosis of mycobacterial infections is crucial for guiding therapeutic decisions. This study presents the first evaluation of a novel molecular assay, the Mycobacterium RealTime PCR Kit Vircell (MRTVircell), a real-time PCR-based test designed for the specific detection of Mycobacterium tuberculosis complex (MTBC), Mycobacterium avium complex (MAC), Mycobacterium abscessus complex (MABC), and other nontuberculous mycobacteria (NTM) in both respiratory and non-respiratory samples. The evaluation was conducted under routine workflow conditions using 721 clinical specimens, including 559 respiratory and 162 non-respiratory samples. Among these, 5.69% were smear-positive, 6.38% were culture-positive for MTBC, and 9.85% were culture-positive for NTM. The performance of the MRTVircell was compared to both culture results and the Anyplex MTB/NTM real-time PCR assay. The two PCR systems demonstrated a 96.95% overall concordance rate for the detection of MTBC, NTM, and negative specimens. Based on culture as the reference method, the sensitivity, specificity, positive predictive value, and negative predictive value of the MRTVircell for MTBC detection were 80.43%, 99.64%, 94.87%, and 98.41%, respectively, while for Anyplex MTB/NTM (Seegene), these values were 76.09%, 99.64%, 94.59%, and 98.06%, respectively. For NTM detection, the sensitivity, specificity, positive predictive value, and negative predictive values were 28.17%, 99.29%, 83.33% and 91.63% for MRTVircell and 21.13%, 99.11%, 75%, and 91.67% for Anyplex MTB/NTM, respectively. MRTVircell is a rapid and reliable tool for the detection and differentiation of MTBC, MAC, MABC, and other NTM in clinical samples. Full article

Background Members of the Mycobacterium avium complex (MAC) have been documented to cause severe and disseminated infections in dogs, although such cases are sporadically reported. In this study, a comprehensive account of a rare case of generalised lymphadenomegaly caused by a mixed-strain infection with drug- and multidrug-resistant Mycobacterium avium subspecies hominissuis (Mah) in a Maremma sheepdog is presented. Methods Laboratory investigations, as well as the monitoring of the clinical signs displayed by the animal, were conducted throughout the course of a two-year drug therapy (based on rifampicin, azithromycin, and ciprofloxacin) and a two-year post-treatment follow-up period, until the death of the dog. Laboratory examinations included both solid and broth cultures from fine-needle aspiration samples of lymph nodes, molecular typing by 8-locus MIRUVNTR analysis and SNPs typing of five genetic regions (gyrB, rpsA, 3′hsp65, ITS and rpoB), and drug susceptibility testing towards seven antimycobacterial drugs. Results The results indicated the presence of two distinct genotypes of Mah, which exhibited different phenotypic characteristics, such as different drug susceptibility profiles and growth abilities in broth and solid media, suggesting a mixed-strain infection. Resistances to ethambutol alone, to ethambutol and clarithromycin, and to ethambutol, clarithromycin, rifampicin, and doxycycline were detected over the study. Conclusions Although the Mah strains isolated during the course of therapy showed sensitivity to the regiment, the complete eradication of the infection was never achieved. It has been hypothesised that the presence of drug-resistant and multidrug-resistant Mah strains in the animal may have been established at the onset of the infection or soon thereafter. The exposure to therapy has been suggested as a potential factor that could have favoured the growth of resistant strains, thereby rendering the therapy ineffective. The implications that the distinct phenotypic and genotypic profiles of Mah described here may have had for disease dynamics and control are discussed. Full article

Background/Objectives: Nontuberculous mycobacteria (NTM) infections are rising, particularly those by Mycobacterium avium complex (MAC) and Mycobacterium abscessus complex (MAB). Treating NTM infections is challenging due to their poor response to antibiotics. This study aimed to optimize the treatment of NTM infection by selecting antibiotics with bactericidal activity for combination therapy. To do this, we used the minimum bactericidal concentration (MBC) determination approach to define bactericidal or bacteriostatic activity. We developed three main objectives: validate a new method to determine MBC based on a reincubation method, determine MBC values of 229 NTM clinical isolates using the reincubation method, and evaluate antibiotic stability in preincubated microtiter plates. Methods: First, we assessed the stability of the antibiotics included in SLOWMYCOI Sensititre™ microtiter plates. Five strains of MAC were studied comparing the minimum inhibitory concentrations (MICs) of those preincubated for seven days vs. non-incubated plates. Then, we evaluated the percentage of reproducibility of MBC values using two methods, reincubation and subculturing (standard or traditional method) in 30 MAC isolates. Finally, we validated the reincubation method and prospectively determined the MBC values of the 229 NTM clinical strains. Results: Antibiotic stability: The MIC was equivalent after 7 and 14 days for all the antibiotics, except rifampicin, for which the MIC increased by 2- to 3-fold after preincubation. Reincubation method: The percentage of reproducibility of the MBC values between the two methods was 95.2% (range 76.6% to 100%). Prospective validation: MBC/MIC ratios revealed differential bactericidal activity for most antibiotics according to the different species, being bactericidal in M. avium and Mycobacterium xenopi, and predominantly bacteriostatic in MAB. Conclusions: Preincubation of Sensititre™ microtiter plates did not alter the MIC values of the antibiotics included except for rifampicin, suggesting a loss of activity. MBC determination can be easily performed by the Reincubation method presented. MBC values provide useful additional information regarding MIC values since the MBC/MIC ratio reveals whether antibiotics have bactericidal or bacteriostatic activity according to the species, which is pivotal for selecting the most adequate antibiotic combination to ensure efficient treatment management. Full article

Nontuberculous mycobacterial pulmonary disease (NTM-PD), mainly caused by Mycobacterium avium complex (MAC), and pulmonary tuberculosis (TB) are emerging health problems worldwide. However, because their clinical features are often similar, it remains difficult to differentiate NTM-PD from TB when the diagnosis cannot be made by sputum culture. To investigate potential serum biomarkers, we conducted non-targeted proteome analysis on serum extracellular vesicles (EVs) collected from 10 patients with MAC pulmonary disease (MAC-PD), 7 patients with TB, and 10 healthy controls. A total of 2614 proteins were identified in the discovery cohort. The EV protein signature from patients with NTM-PD and TB reflected infectious diseases and inflammatory response pathways. Among the identified proteins, the expression of Na⁺/H⁺ exchanger regulatory factor 2 (NHERF2) was significantly elevated in patients with MAC-PD compared with healthy controls and patients with TB. Moreover, upregulation of NHERF2 was confirmed by immunoblotting of serum EVs and immunohistochemistry of lungs with mycobacterial infection. Our findings highlight that NHERF2 in serum EVs might be a potential biomarker for distinguishing MAC-PD from TB, possibly reflecting the pathogenesis of MAC-PD. Full article

Background: Accurate and timely diagnosis of mycobacterial infections, including Mycobacterium tuberculosis complex (MTBC) and nontuberculous mycobacteria (NTM), is crucial for effective disease management. Methods: This study evaluated the performance of the NeoPlex TB/NTM-5 Detection Kit (NeoPlex assay, Seongnam, Republic of Korea), a multiplex real-time PCR assay that incorporates melting curve analysis, compared with the line-probe assay (LPA). The NeoPlex assay could simultaneously detect and differentiate MTBC from five other NTM species: Mycobacterium intracellulare, Mycobacterium avium, Mycobacterium kansasii, Mycobacterium abscessus, and Mycobacterium massiliense. A total of 91 acid-fast bacillus culture-positive samples, comprising 36 MTBC and 55 NTM isolates, were collected from the Korea University Anam Hospital. Results: The NeoPlex assay successfully detected nucleic acids in 87 of the 91 isolates (95.6%). Notably, it identified additional mycobacterial nucleic acids not detected by the LPA in eight isolates. These findings were confirmed via DNA sequencing. The assay had 100% sensitivity and specificity for M. intracellulare, M. abscessus, M. massilense, NTM, and MTBC, whereas it had 100% specificity and sensitivity of 90.9% and 75.0% for M. avium and M. kansasii, respectively. Conclusions: These results highlight the potential of the NeoPlex assay to enhance rapid and accurate diagnosis of mycobacterial infections, particularly in settings in which prompt treatment initiation is essential. Full article

The incidence of infections caused by the Mycobacterium avium complex (MAC) has risen significantly, posing diagnostic and therapeutic challenges. This study analyzed 134 clinical isolates of the Mycobacterium avium complex from southern Spain, performing in vitro antimicrobial susceptibility testing using a commercial microdilution technique to generate additional data, refine treatment strategies, and improve patient outcomes. Phenotypic susceptibility testing revealed clarithromycin and amikacin as the most effective antibiotics, with susceptibility rates exceeding 90%, while linezolid and moxifloxacin exhibited limited activity, with resistance rates of 49.3% and 41.8%. A comparative analysis between M. avium and M. intracellulare showed significant differences in resistance to amikacin and linezolid, with M. avium exhibiting higher resistance rates. Additionally, species-specific differences were observed in MIC distributions for ethionamide, ciprofloxacin, and streptomycin. Our data reveal regional variability in resistance patterns, particularly for moxifloxacin and linezolid, which exhibit differing resistance rates compared to studies from other regions. The significant MIC differences for several antibiotics between M. avium and M. intracellulare underscore the importance of species-level identification and the heterogeneity in resistance mechanisms within MAC. Full article

Background/Objectives: In sub-Saharan Africa, there is paucity of data regarding non-tuberculous mycobacterial (NTM) infections, leading to underappreciation of disease burden. Consequently, fewer resources are allocated, leading to potential adverse outcomes. This study examines long-term mortality and risk factors of South African patients with positive NTM samples. Methods: We conducted a retrospective analysis of clinical isolates of NTMs between 1 January 2010 and 30 June 2017. We retrieved and thoroughly reviewed the corresponding medical records of patients treated at Charlotte Maxeke Johannesburg Academic Hospital. Outcomes were compared between patients who underwent different therapy regimens, including macrolide-based regimens and ‘watchful waiting’. Results: A total of 123 patients were followed for a median of 1 year (interquartile range [IQR], 0.5–4.5). The median age was 39 years (IQR, 31–51) with male predominance, 58%. The common comorbid conditions were HIV (encountered in 78%) and previous TB (58%). Pulmonary disease due to Mycobacterium avium complex (MAC-PD) was found in 74% of patients, M. fortiutum in 5%, and M. gordonae in 4%. The mortality relative risk for patients on initial macrolide-containing therapy was 0.54 (95% confidence interval [CI], 0.22–1.36), p = 0.194, while that for macrolide-free antimicrobials was 1.38 (95% CI, 0.57–3.34), p = 0.471. The adjusted hazard rate for mortality with low CD4 counts < 50 cells/mm³ was 2.79 (95%, 1.20–6.50), while that for unknown CD4 counts was 4.01 (95% CI, 1.17–13.77), compared to CD4 counts > 50 cells/mm³. Conclusions: Among HIV patients, NTM-PD predominated, and not disseminated disease. MAC-PD was the most common infection. Low CD4 counts was a significant risk factor for early death, while sex, NTM species, macrolide therapy, and previous TB were not. Full article

Background/Objectives: Developing interventions for Johne’s disease, which focuses on controlling Mycobacterium avium subsp. paratuberculosis (MAP) in contaminated environments by treating infected cows and preventing transmission from diseased animals, is a critical priority. Bacteriophage (phage) therapy, an emerging biological intervention, offers a promising alternative for the treatment and management of MAP infections. Methods: In this study, we generated an MAP-specific lytic phage library aimed at characterizing the therapeutic potential of phages under environmental and biological conditions that mimic those encountered in infected cattle such as ruminal fluid, milk, colostrum, and the bovine intestinal epithelium, a key site of MAP colonization and, later, transmission. Results: Our library contains a diverse collection of phages that have demonstrated robust lytic activity against MAP. The host range of these phages was thoroughly assessed, revealing that several isolates produce clear plaques on a range of MAP strains, as well as other pathogenic non-tuberculous mycobacterial (NTM) species and M. tuberculosis strains. This broad host range expands the therapeutic potential of the phage collection, positioning it as a potential cross-species antimicrobial tool. In vitro tests under conditions replicating the rumen, milk, and colostrum environments show that selected phages maintain stability and lytic efficacy, even in the presence of complex biological fluids. Furthermore, a subset of these phages was capable of preventing MAP colonization and invasion in cultured bovine epithelial cells, suggesting their potential for direct prophylactic application in cattle. Conclusions. Our collection of MAP phages represents a valuable source that can be developed into probiotic-like preparations, offering a cost-effective solution for prophylaxis and control of Johne’s disease. Full article

Background/Objectives: In this study, the efficacy of benzo[h]chromene derivatives as antiprotozoal and antimycobacterial agents was explored. Methods: A total of twenty compounds, including benzo[h]chromene alkyl diesters and benzo[h]chromene-triazole derivatives, were synthesized and tested against Trypanosoma cruzi, Leishmania braziliensis, L. infantum, and strains of Mycobacterium abscessus and Mycobacterium intracellulare LIID-01. Notably, compounds 1a, 1b, 2a, and 3f exhibited superior activity against Trypanosoma cruzi, with IC₅₀ values of 19.2, 37.3, 68.7, and 24.7 µM, respectively, outperforming the reference drug benznidazole (IC₅₀: 54.7 µM). Results: Compounds 1b and 3f showed excellent selectivity indices against Leishmania braziliensis, with SI values of 19 and 18, respectively, suggesting they could be potential alternatives to the commonly used, but more selective, miltefosine (IC₅₀: 64.0 µM, SI: 43.0). Additionally, compounds 1a, 1b, and 3f were most effective against Leishmania infantum, with IC₅₀ values of 24.9, 30.5, and 46.6 µM, respectively. Compounds 3f and 3h were particularly potent against various Mycobacterium abscessus strains, highlighting their significance given the inherent resistance of these bacteria to standard antimicrobials. Conclusions: The sensitivity of Mycobacterium intracellulare LIID-01 to these compounds also underscored their potential in managing infections by the Mycobacterium avium–intracellulare complex. Full article

In Europe and North America, the prevalence of pulmonary nontuberculous mycobacteria (NTM) is increasing. Most pulmonary NTM infections are caused by the Mycobacterium avium complex (MAC). Sadly, the treatment of pulmonary MAC is suboptimal with failure rates ranging from 37% to 58%. Therefore, there is a need to develop new therapeutics. Developing new immunotherapies and studying their interaction with standard or new drugs requires reliable assays. Four different assays including CFSE-based flow cytometry, in vitro protection assays, IFN-γ ELISPOT, and murine infection models were optimized using a reference strain of MAC (ATCC 700898) to help with the development of immunotherapies for MAC. Expansion of proliferating and IFN-γ producing human T cells is optimal after 7 days of stimulation with MAC at a multiplicity of infection (MOI) of 0.1, achieving a stimulation index of 26.5 ± 11.6 (mean ± SE). The in vitro protection assay for MAC works best by co-culturing T cells expanded for 7 days with MAC (MOI 1)-infected autologous macrophages. Aerosol MAC infection of mice allows measurement of the effects of the BCG vaccine and clarithromycin. IFN-γ ELISPOT assays with live MAC (MOI 3) stimulation of splenocytes from mice immunized with BCG help identify differences between unimmunized mice and mice immunized with BCG. In conclusion, multiple assays are available for use to identify MAC-specific effector T cells, which will help in the development of new therapeutics or vaccines against pulmonary MAC. Full article