Search Results (163)

Background/Objectives: Nontuberculous mycobacteria (NTM) represent a heterogeneous group of pathogens with increasing global prevalence and significant geographical variation in species distribution. NTM infections, often affecting immunocompromised individuals, are difficult to diagnose due to nonspecific clinical presentations and laboratory findings. This case study presents a rare extrapulmonary NTM infection in a 73-year-old man, initially misdiagnosed as sarcoidosis, highlighting the diagnostic and therapeutic challenges posed by such infections. Methods: The patient, a pigeon fancier, presented with recurrent fever and pancytopenia. Extensive diagnostics included blood cultures, bone marrow aspiration, and histopathology. Initial cultures and serological tests remained negative. Results: Bone marrow aspiration revealed epithelioid granulomas, initially leading to the provisional diagnosis of sarcoidosis. However, after six weeks, M. genavense was isolated from mycobacterial blood cultures from bone marrow aspirant. Antimicrobial therapy with azithromycin, rifampicin, and ethambutol was initiated. Following the initiation of appropriate antimycobacterial therapy, the patient developed immune reconstitution inflammatory syndrome (IRIS), which was managed with supportive care. The patient’s condition improved, and no further febrile episodes occurred post-treatment, marking the successful conclusion of NTM therapy. Conclusions: This case underscores the diagnostic complexity of extrapulmonary NTM infections, particularly in immunocompromised patients. Misdiagnosis can delay appropriate treatment. M. genavense, though rare, should be considered in patients with a fever of unknown origin, especially with a background of immunosuppression. Prompt mycobacterial testing and tailored antibiotic therapy are crucial to improving outcomes in NTM infections. Full article

Three isolates of a novel, rapidly growing, non-pigmented Mycobacterium species were recovered from the water and runoff of a public fountain in a rural village in central Portugal, formerly used by the local population as a source of drinking water and not accessible to animals. High-quality draft genome sequencing, in silico DNA–DNA hybridization, and phylogenetic analyses confirmed that isolates 21AC1^T, 21AC14, and 21AC21 represent a previously undescribed species within the genus Mycobacterium, forming a distinct phylogenetic lineage closely related to Mycobacterium wolinskyi, Mycobacterium goodii and Mycobacterium smegmatis. MALDI-TOF MS analysis of the type strain 21AC1^T revealed a unique spectral profile. A comprehensive polyphasic characterization was performed, including chemotaxonomic analyses of fatty acid and mycolic acid composition, as well as an extensive biochemical characterization. Their susceptibility to 12 antimicrobials was also assessed. The identification and characterization of novel nontuberculous mycobacteria species are of increasing environmental and clinical relevance, as infections by these opportunistic pathogens are on the rise globally. Based on our findings, we propose that isolates 21AC1^T, 21AC14, and 21AC21 represent a novel species, for which we propose the name Mycobacterium appelbergii sp. nov., with the type strain designated as 21AC1^T (=BCCM/ITM 501212 = DSM 113570) and the additional two strains as 21AC14 (=BCCM/ITM 501447 = DSM 118402) and 21AC21 (=BCCM/ITM 501448 = DSM 118403). Full article

Since 2013, the World Health Organization has recommended the use of rapid molecular tests as the initial diagnostic step for Mycobacterium tuberculosis (MTB) infection to enhance the control of tuberculosis. In recent years, the prevalence of infections by non-tuberculous mycobacteria (NTM) in humans has also risen, particularly in countries with low tuberculosis incidence, such as Italy. Therefore, the rapid differentiation between NTM and Mycobacterium tuberculosis complex is crucial for timely therapeutic decisions. This study evaluates a new rapid molecular assay, Standard M10 MTB/NTM, designed to detect MTB, NTM, or co-detection in Mycobacteria Growth Indicator Tube cultures from different biological matrices. The assay was validated using 100 positive and 50 negative liquid mycobacteria cultures, already confirmed by specific real-time PCR and Sanger sequencing. Following optimization of assay conditions for culture sample processing and assessment of potential interference, Standard M10 demonstrated excellent sample stability, high specificity, and good sensitivity, identifying all 50 MTB and 49 NTM samples. Some limitations included the non-detection of M. celatum in one case and false positive results (MTB co-infection) in two NTB cases. Nevertheless, overall, the adoption of this test could be considered for laboratory management to enable rapid and effective sample targeting for subsequent diagnostic evaluation and treatment decision-making. Full article

Non-tuberculous mycobacteria (NTM) are saprophytes of both soil and water that may cause infection with a high risk of dissemination, mainly in immunocompromised patients. Most NTM infections occur in the lungs, while uncommon localizations are the skin, soft tissues, musculoskeletal apparatus, and lymphatic system. The possible relationship between NTM infections and dental procedures is still unclear. The authors reported a rare manifestation of NTM infection occurring in a 6-year-old girl who developed sub-mandibular swelling related to a necrotic tooth, thus mimicking an abscess of odontogenic origin. Fine-needle aspiration biopsy of the sub-mandibular swelling and the following microbiologic investigation showed infection sustained by the Mycobacterium fortuitum complex. After the medical and surgical treatment, the patient completely recovered after 8 months. A review of the relevant literature was carried out to deepen the clinical and microbiological aspects of such a rare occurrence. Full article

People with CF (pwCF) have a significant risk for pulmonary infections with non-tuberculous mycobacteria (NTM), particularly Mycobacterium abscessus (Mab). Mab is an emerging pathogen, which causes pulmonary infections in patients with chronic lung diseases, particularly CF; Mab pulmonary disease leads to progressive pulmonary dysfunction and increased morbidity and mortality. Despite advances in CF care, including CFTR modulators (CFTRm), Mab continues to pose a therapeutic challenge, with significant long-term medical burden. This review provides insights into the complex host–pathogen interplay of Mab infections in pwCF. It provides a detailed overview of Mab bacterial virulence factors, including biofilm formation, secretion systems, the virulence-associated rough morphotype, and antibiotic resistance mechanisms. This review also summarizes features conferring susceptibility of the CF host to Mab infections, alongside the contribution of the CF-host environment to the pathogenesis of Mab infection, such as antibiotic-derived microbial selection, within-host mycobacterial evolution, and interactions with co-pathogens such as Pseudomonas aeruginosa (PA). Finally, the therapeutic implications and novel treatments for Mab are discussed, considering the complex host–pathogen interplay. Full article

Nontuberculous mycobacteria (NTMs) are increasingly being recognized as opportunistic pathogens in clinical practice because of their innate resistance to antimicrobial treatment and the widespread increase in multidrug-resistant strains on a global scale. NTMs pose a tremendous infection management challenge, especially in individuals with pre-existing lung conditions, as well as those who are immunocompromised. NTMs’ capability to evade or suppress the immune responses of their host is a key feature that makes them a cause of persistent chronic infection. Autophagy, an essential cellular defense mechanism that delivers and breaks down intracellular materials in lysosomes, protects the host from mycobacterial infection. Initial studies have revealed encouraging therapeutic strategies that augment endogenous autophagic mechanisms or block harmful host responses, thus having the potential to decrease intracellular mycobacterial infection, including that caused by multidrug-resistant strains. This review discusses how NTMs can evade autophagic mechanisms and considers the possibilities of using autophagy-inducing agents to develop novel therapeutic strategies to combat NTM infection. 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

The long regimen of drug therapy, the emergence of drug-resistance (DR), and infections with non-tuberculous mycobacteria (NTMs) are alarming challenges in controlling tuberculosis (TB), a disease caused by Mycobacterium tuberculosis (M.tb), necessitating the pursuit of new, broad-spectrum anti-mycobacterials. With more than two-thirds of the clinically useful antibiotics originating from the bacterial phylum Actinomycetota, and their enormous diversity in India, we explored atypical environments for new bacterial strains with potential anti-M.tb activity. In this study, we the examined the secondary metabolites of soil and endophytic bacterial isolates from the wetland niches of Manipur, India, and determined their anti-mycobacterial properties using viability assays. The ethyl acetate culture filtrate extracts of one of the isolates, named Streptomyces sp. SbAr007, showed broad-spectrum anti-mycobacterial activity against laboratory M.tb strains H37Ra and H37Rv, a clinical drug-resistant M.tb and non-tuberculous mycobacteria (NTM). The isolate was characterized for its phenotype and genetic identity, which indicated its closeness to Streptomyces samsunensis, Streptomyces malaysiensis, and Streptomyces solisilvae. Further, macrophage infection assays showed that the extracts could effectively control the intracellular mycobacterial growth but had negligible cytotoxicity to PBMCs from healthy donors. LC-MS identified an unusual combination of antibiotics in these culture filtrate extracts, which can be further explored for specific active molecules or as a formulation against DR-TB. 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

Infections caused by non-tuberculous mycobacteria (NTM), such as Mycobacterium abscessus, elicit diverse cell death mechanisms including apoptosis, necrosis, and pyroptosis, which play key roles in immunopathogenesis. NTM can manipulate these cell death pathways to evade host immune responses, ensuring their intracellular survival and persistence. Apoptosis may aid in antigen presentation and immune activation, while necrosis and pyroptosis trigger excessive inflammation, leading to tissue damage. Autophagy, a crucial cellular defense mechanism, is often induced in response to NTM infection; however, M. abscessus has evolved mechanisms to inhibit autophagic processes, enhancing its ability to survive within host cells. This manipulation of cell death pathways, particularly the dysregulation of autophagy and ferroptosis, contributes to chronic infection, immune evasion, and tissue damage, complicating disease management. Understanding these mechanisms offers potential therapeutic targets for improving treatment strategies against M. abscessus infections. 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

(1) Background: The treatment of Mycobacterium abscessus (M. abscessus) infections resistant to clarithromycin (CLR) is highly challenging. Traditional non-tuberculous mycobacteria (NTM) chemotherapy may disturb the immune homeostasis of the host by increasing oxidative stress; therefore, host-directed immunotherapy is an alternative option for infections caused by M. abscessus. (2) Method: A clinical isolate of CLR-resistant M. abscessus was screened, and then the therapeutic effects of N-acetylcysteine (NAC) against CLR-resistant M. abscessus infection were evaluated in Tohoku Hospital Pediatrics-1 (THP-1) cells and murine models. RNA sequencing and Western blot were used to profile the protective immune responses induced by NAC. The contribution of candidate signaling pathways was confirmed by the corresponding inhibitor and agonist. (3) Results: NAC immunotherapy led to a significant reduction in bacterial loads both in THP-1 cells and murine infection models, which was associated with enhanced antioxidant effects and downregulation of apoptosis signal-regulating kinase 1 (ASK1)–mitogen-activated protein ki-nase/extracellular signal-regulated kinase 3/6 (MKK3/6)–p38 mitogen-activated protein kinase (MAPK)-mediated inflammatory immune responses. The inhibitor of p38 signaling mimicked the protective effect of NAC, while the agonist attenuated it, suggesting that the p38 pathway is crucial in NAC-mediated immune protection against M. abscessus infection. (4) Conclusion: Our study suggests that NAC could be used as a host-directed therapy agent against drug-resistant M. abscessus infection. Full article

Nontuberculous mycobacteria (NTM) are environmental organisms that can cause opportunistic infections in humans and animals. Mycobacterium abscessus (Mab) is a rapidly growing Mycobacterium known for its resistance to multiple antibiotics and ability to cause respiratory, skin, and mucosal infections. Understanding the distribution and prevalence of NTM, particularly Mab, in cattle farms and slaughterhouses is crucial for developing effective prevention and control measures. We collected environmental swabs from various surfaces (e.g., feed troughs, sinks, walls, floors, feces, and padding) in cattle farms and slaughterhouses across multiple provinces. High-throughput sequencing technology was utilized to analyze the 16S rDNA V3–V4 region of bacterial DNA extracted from the samples, and qPCR methods were employed to detect and quantify Mycobacterium abscessus in the collected samples. Bioinformatics analysis was performed to identify and classify the NTM species present in the samples. This study compared the abundance and diversity of NTM in different environments and assessed the potential zoonotic risk. A total of 1648 environmental swabs were collected from cattle farms and slaughterhouses in 12 provinces of China in 2023, of which 12 samples tested positive for Mab qPCR detection, yielding a detection rate of 0.73% (12/1648). Among them, the detection rate of environmental samples from cattle farms and slaughterhouses was 0.42% (3/720) and 0.87% (9/928), respectively. This study provides valuable information on the epidemiology of NTM in cattle farms and slaughterhouses, contributing to developing effective strategies for preventing and controlling NTM infections. It also enhances our understanding of the zoonotic potential of Mycobacterium abscessus and other NTM species. Full article

Background: The prevalence of nontuberculous mycobacteria (NTM) infection is on the rise, surpassing that of pulmonary tuberculosis in Japan. Current standard therapy for NTM infection involves long-term treatment of at least 1.5 years, with low success rates and a high relapse rate. ^99mTc-diethylenetriaminepentaacetic acid-galactosyl-human serum albumin (^99mTc-GSA) is used for human liver imaging. In this study, we utilized ^99mTc-GSA as a probe to detect Mycobacterium avium (M. avium), a major pathogen in NTM pulmonary diseases (NTM-PDs). Our aim was to investigate the non-invasive detection of M. avium using ^99mTc-GSA on Single-Photon Emission Computed Tomography (SPECT). Methods: The accumulation of ^99mTc-GSA in M. avium was investigated in vitro. In vivo, SPECT images were obtained after the administration of ^99mTc-GSA to an M. avium thigh infection model. Subsequently, the contrast difference in accumulated ^99mTc-GSA between infected and non-infected thighs was calculated using SPECT imaging. Furthermore, SPECT images were obtained for thighs infected with varying bacterial loads, and the accumulation was compared between them. Results: In vitro, we observed that ^99mTc-GSA accumulates in M. avium. In vivo, SPECT images demonstrated the specific accumulation of ^99mTc-GSA at the infection site, with this accumulation being correlated with the bacterial load. Conclusions: ^99mTc-GSA specifically accumulates in M. avium, and SPECT can be used to monitor the distribution and quantity of M. avium in animals. By utilizing these measures, ^99mTc-GSA can be targeted to the site of infection and used as a bacterial probe. Full article