Search Results (164)

Immunosuppressive therapies increase the risk of infection, but there is little information regarding their effects on cellular antimycobacterial activity. In this context, the aim was to evaluate in vitro the impact of commonly used immunosuppressive drugs on the ability of peripheral blood mononuclear cells (PBMCs), neutrophils (polymorphonuclear cells, PMNs), and monocyte-derived macrophages (MDMs) to control Mycobacterium abscessus. Biofilm formation was assessed by quantifying bacterial colonies in cellular cultures (BCCCs) and bacterial viability by colony-forming units (CFUs). BCCCs showed significant differences among treatment conditions in PBMCs. The median (interquartile range) BCCC values for tacrolimus (TAC) 16.5 (41), everolimus (EVE) 11 (33), methotrexate (MTX) 12.5 (22) and leflunomide (LEF) 11 (29) were all significantly higher than the negative control (DMSO) 5 (14), indicating that these immunosuppressants impaired the ability of PBMCs to restrict BCCC formation. Log-transformed CFUs also varied across treatments in PMNs. Mycophenolic acid (MPA) 5.98 (2.61) and EVE 5.85 (2.77) increased LogCFU recovery compared with DMSO 5.58 (2.63), whereas MTX 5.18 (2.74) decreased it. In contrast, immunosuppressants had no significant overall effect in MDM cultures. Interestingly, 6-mercaptopurine (6MP) affected the size of colonies. Prednisolone, as expected, but also MTX and LEF, inhibited the expression in infected PBMCs of IL-1β, IL-1Ra, IL-6, CCL3, CCL5, CXCL8 and TIMP-2, whereas IL-10, CCL2 and CXCL7 expression remained essentially unchanged. Unexpectedly, methotrexate promoted CXCL8 expression, a chemokine for PMNs. These results show that commonly used immunosuppressive drugs can differentially modulate the antimycobacterial activity of PBMCs and innate immune cells, affecting both mycobacterial viability and biofilm formation. Full article

Background: Oxygen–ozone (O₂–O₃) therapy is a minimally invasive treatment for discogenic lumbar pain. Although rare, spinal infections—specifically spondylodiscitis—have been reported following intradiscal injections. To date, Lactobacillus iners has not been described as a causative agent in this context. Case Presentation: A 55-year-old immunocompetent woman presented with progressive lumbosciatica and elevated inflammatory markers three months after intradiscal O₂–O₃ therapy. MRI revealed L4–L5 spondylodiscitis with paravertebral involvement. Surgical biopsy confirmed L. iners as the pathogen. She underwent decompression and received targeted intravenous antibiotics, achieving full clinical and radiological recovery. Methods: A systematic literature review was performed using PubMed, MEDLINE, and Scopus to identify reports of spondylodiscitis following oxygen–ozone therapy. Six cases were included based on predefined inclusion criteria. Results: The 8 identified cases involved a range of pathogens, including Staphylococcus aureus, Streptococcus beta-haemolyticus, Escherichia coli, Achromobacter xylosoxidans, Mycobacterium abscessus, and Streptococcus intermedius, and one culture-negative infection. Clinical presentations varied from radiculopathy to sepsis. Management strategies encompassed both conservative (antibiotics alone) and surgical approaches, depending on neurological status and abscess formation. Outcomes were favorable in all cases except one fatality. Conclusions: This report is the first to describe L. iners spondylodiscitis in an immunocompetent patient following O₂–O₃ therapy. Clinicians should vigilantly evaluate post-infiltration spinal infections, maintain a low threshold for imaging and biopsy, and implement pathogen-targeted antibiotic regimens, with surgical intervention as needed. Full article

Background: The incidence of patients with nontuberculous mycobacterial pulmonary disease (NTM-PD) complicated by chronic pulmonary aspergillosis (CPA) has been increasing. CPA is known to be associated with complex treatment regimens and a poor prognosis. However, data from mainland China remain scarce. This single-center retrospective study aimed to evaluate the clinical characteristics, risk factors, and prognoses of patients with concurrent CPA and NTM-PD. Methods: We conducted a retrospective review of the medical records of 248 patients diagnosed with NTM-PD. Risk factors for CPA were analyzed via multiple logistic regression, followed by survival analysis. Results: Among the 248 patients with NTM-PD, 66 (26.6%) were diagnosed with CPA. Independent risk factors for NTM-PD and CPA coinfection included male sex (OR 2.13, 95% CI: 1.03–4.47), dyspnea (OR 27.9, 95% CI: 4.24–570), cavity (OR 5.95, 95% CI: 2.76–13.9), use of oral corticosteroids (OR 4.28, 95% CI: 1.13–16.6), and interstitial lung disease (OR 15.5, 95% CI: 1.89–361). The wide confidence intervals for some risk factors reflect limited precision. The Kaplan–Meier survival curves indicated a significant divergence between the NTM-PD group and the NTM-PD with CPA group (log-rank test, p = 0.00039). However, the adjusted hazard ratio was not statistically significant (HR 2.01, 95% CI: 0.66–6.12, p = 0.217). Conclusions: In patients with NTM-PD, the presence of concurrent CPA was associated with higher unadjusted mortality. Clinicians should maintain a high index of suspicion for CPA to ensure prompt diagnosis and treatment, particularly in high-risk individuals. Full article

Mycobacterium abscessus exhibits intrinsic resistance to conventional antibiotics, significantly limiting treatment options. Our previous studies established that MAB_2362 (SteA) is a key regulator of cell division that contributes to intrinsic resistance and virulence. Considering that SteA-like proteins often act alongside SteB counterparts, we hypothesized that the adjacent gene MAB_2363 encodes the corresponding SteB-like division regulator. In this study, we found that deletion of MAB_2363 significantly increased susceptibility to multiple antibiotics and disrupted cell wall permeability. Microscopy revealed pronounced cell division defects in the mutant, including elongated cell morphology and multiple septa. Subcellular localization of a GFP-MAB_2363 fusion protein demonstrated its enrichment at division septa, confirming its direct involvement in cell division. Furthermore, deletion of MAB_2363 led to attenuated virulence, as evidenced by reduced bacterial survival in macrophages and murine infection models. To assess its functional relation with MAB_2362, we compared the single-deletion mutant of MAB_2363 with the single-deletion mutant of MAB_2362 and the double-deletion mutant of MAB_2362-MAB_2363. Notably, the phenotypes of the MAB_2363 mutant, including cell division defects, antibiotic susceptibility, and virulence, were markedly milder than those of the other two mutants. Collectively, these findings indicate that MAB_2363 functions as a secondary but essential division-associated factor that operates during cell division, thereby influencing intrinsic resistance and virulence in M. abscessus. Full article

Background/Objectives: This study evaluated the concordance between sputum and bronchoscopic specimens in diagnosing nontuberculous mycobacteria (NTM) pulmonary disease. Methods: We retrospectively analyzed patients with NTM isolated from respiratory specimens between 2010 and 2022. Our analysis assessed species concordance across the two diagnostic methods and compared clinical outcomes between patients with multiple positive cultures and those with a single positive culture. Results: A total of 400 patients were included, 100 of whom underwent bronchoscopy. Among these, 61 demonstrated concordant NTM species between sputum and bronchoscopic specimens, while 38 had NTM cultured from only one source. One patient showed a discordant result, with Mycobacterium abscessus isolated from bronchoalveolar lavage and Mycobacterium avium from sputum. Multivariate analysis identified several factors associated with radiologic progression or the need for treatment: body mass index (HR, 0.847; 95% CI, 0.794–0.902; p < 0.001), membership in the single-isolation group (HR, 0.400; 95% CI, 0.184–0.871; p = 0.021), and fibrocavitary radiologic type (HR, 2.318; 95% CI, 1.470–3.655; p < 0.001). Conclusions: Only a small number of cases showed different NTM species identified by sputum and bronchoscopy. Full article

Background: Infections caused by the multidrug-resistant pathogen Mycobacterium abscessus (Mab) are notoriously difficult to treat. The novel β-lactamase inhibitor durlobactam, in combination with β-lactams, shows potent bactericidal activity against Mab, but the potential for acquired resistance remains a clinical concern. Objectives: To identify and characterize mechanisms of acquired resistance to durlobactam in Mab. Methods: In vitro single-step resistance selection was performed by plating wild-type Mab ATCC 19977 and by transcriptional silencing using a CRISPR interference (CRISPRi) system. Minimum inhibitory concentrations (MICs) were determined by both an agar-based method and broth microdilution. Results: Whole-genome sequencing of durlobactam-resistant mutants identified loss-of-function mutations in ponA1, a gene encoding a class A penicillin-binding protein involved in cell wall synthesis. Targeted deletion of ponA1 (ΔponA1) and CRISPRi-mediated knockdown of ponA1 expression both recapitulated the resistance phenotype, resulting in a significant increase in the durlobactam MIC on solid agar media. Strikingly, broth microdilution MICs remained largely unaffected. Conclusions: Inactivation of the peptidoglycan synthase PonA1 is a novel mechanism of resistance to durlobactam in Mab that is phenotypically expressed only during growth on solid surfaces. This finding identifies a specific genetic pathway for resistance and highlights that standard broth-based susceptibility testing could miss clinically relevant resistance mechanisms. Full article

Background: Nontuberculous mycobacterial pulmonary disease (NTM-PD) is a chronic respiratory infection primarily caused by Mycobacterium avium complex (MAC) and Mycobacterium abscessus. These species differ markedly in antibiotic susceptibility and treatment response, yet the contribution of the respiratory microbiome to this clinical variability remains unclear. To date, however, comparative analyses of microbiome differences between MAC-PD and M. abscessus-PD and their associations with disease severity are limited. Methods: We conducted microbiome analysis of sputum from 37 patients with NTM-PD. Patients were antibiotic-naïve and classified into MAC-PD (n = 29) and M. abscessus-PD (n = 8) groups. Disease severity was determined using radiologic extent on chest computed tomography. Bacterial communities were profiled by 16S rRNA gene sequencing, and differential taxa and predicted functional pathways were analyzed using LEfSe and KEGG orthology databases. Results: Distinct microbiome profiles were observed between MAC-PD and M. abscessus-PD. Three anaerobic species—Porphyromonas pasteri, Fusobacterium periodonticum, and Prevotella nanceiensis—were significantly enriched in M. abscessus-PD (LDA effect size > 3, p < 0.05). Functional biomarker analysis revealed significant enrichment of the cobalamin (vitamin B12) biosynthesis pathway in patients with severe disease, while the C19/C18 steroid hormone biosynthesis pathway was enriched in those with mild disease (p < 0.05). Conclusions: In conclusion, our study demonstrates distinct differences in the respiratory microbiome between MAC-PD and M. abscessus-PD and identifies specific functional pathways associated with disease severity in NTM-PD. These findings highlight the potential value of microbial metabolic signatures as biomarkers for disease assessment. Full article

The incidence and prevalence of nontuberculous mycobacterial (NTM) disease are rising. This narrative review examines the evolution of NTM disease trends over the past four decades, in Canada and globally, encompassing changing epidemiology, shifting treatment paradigms, and emerging antimicrobial resistance patterns. Challenges to NTM treatment are explored, and novel and investigational therapies are summarized. Key themes include a significant increase in NTM disease incidence, temporal shifts in the dominant species causing human infections, evolution from single-drug to multi-drug treatment approaches, and growing concerns regarding macrolide resistance. The substantial challenges with treatment tolerability, effectiveness, and access are outlined. This review synthesizes data from multiple sources, including peer-reviewed literature, clinical trials, and public health databases, to provide a comprehensive understanding of the changing NTM disease landscape in Canada and more broadly. There is a need for expanded surveillance, continued innovation, and a multidisciplinary approach to NTM management. Full article

Non-tuberculous mycobacteria (NTM) comprise more than 190 species capable of causing severe pulmonary, lymphatic, cutaneous, and disseminated infections, particularly in immunocompromised populations. Over the past two decades, the global incidence of NTM infections has risen steadily, underscoring an urgent unmet medical need. Treatment remains highly challenging due to intrinsic antimicrobial resistance and the requirement for prolonged multidrug regimens that are often poorly tolerated and associated with unsatisfactory outcomes. At the same time, the development of novel therapies has lagged behind other disease areas, hindered by the high costs of antimicrobial drug discovery and the relatively low commercial return compared with treatments for chronic conditions. Over the past decade, discovery and development have diversified across novel small molecules, next-generation analogues of existing classes, and adjunctive or host-directed strategies. While most candidates remain preclinical, several agents have advanced clinically in other infections, including gepotidacin (topoisomerase inhibitor; FDA-approved 2025 for urinary tract infection (UTI)), sulbactam–durlobactam (DBO β-lactamase inhibitor; FDA-approved 2023 for Acinetobacter baumannii complex), and contezolid, supporting repurposing opportunities for NTM. Conversely, SPR720 (gyrase B prodrug) was suspended after not meeting its Phase 2 endpoint in 2024, underscoring translational risk. Overall, the NTM pipeline is expanding, with near-term progress most likely from repurposed agents and optimised combinations, alongside earlier-stage candidates that target biofilms or resistance mechanisms. This review aims to provide a critical and up-to-date overview of emerging antimicrobial strategies against NTM, highlighting recent advances, translational challenges, and opportunities to accelerate the development of effective therapeutics. Full article

Mycobacterium abscessus (Mab) is a rapidly growing, non-tuberculous mycobacterium and opportunistic pathogen that causes lung and skin infections in immunocompromised individuals. In recent years, Mab has gained attention due to its resistance to multiple antibiotics and its ability to evade the immune response by transitioning into different morphotypes. Macrophages and neutrophils play key roles during the acute phase of infection and granuloma formation, utilising clearance mechanisms that affect the smooth and rough morphotypes differently. Despite considerable research, the inflammatory response elicited by Mab and its impact on disease outcomes remain not well understood. This perspective examines the interactions between Mab and immune cells, proposing potential receptors that may mediate Mab-driven immune communication. By drawing insights from immune evasion and signalling strategies employed by other mycobacterial species, it aims to deepen our understanding of Mab pathogenicity and to outline innovative approaches for infection control. Full article

Carotenoid pigments are widely distributed in nature and play a crucial role in protecting organisms from photodynamic damage. However, the characterization of carotenoid production in clinically relevant mycobacteria has been limited due to the low sensitivity of conventional detection methods. We present a descriptive analysis of carotenoid production in seven mycobacterial isolates from the scotochromogenic, photochromogenic, and non-chromogenic groups. To achieve this, we used a combination of High-performance liquid chromatography with diode-array detection (HPLC-DAD) and Ultra-high performance liquid chromatography–mass spectrometry (UHPLC-MS) to detect carotenoids pigments. Mycobacterium tuberculosis (MTB) and Mycobacterium bovis (MB) (non-chromogenic mycobacteria) produced β-carotene when cultured in the absence of light, at levels comparable to those of photochromogenic mycobacteria such as M. marinum (MM) and M. kansasii (MK). The highest levels of carotenoids were found in scotochromogenic species M. avium (MAV) and M. gordonae (MGOR). Conversely, M. abscessus (MABS), a non-chromogenic species in which no β-carotene was detected, served as a negative control for matrix effects. As expected, the use of highly sensitive analytical techniques such as HPLC-DAD and UHPLC-MS significantly enhanced the detection of β-carotene compared to visual pigment assessment. These methods allowed the detection of basal β-carotene levels even in mycobacteria classified as non-chromogenic. The proposed analytical approach provides a robust research tool to understand the effects of different stimulus that may alter the cell physiology in terms of pigment production. Full article

Nontuberculous mycobacteria (NTM) represent a heterogeneous group of environmental opportunistic pathogens that have emerged particularly in immunocompromised individuals and patients with underlying pulmonary disorders. NTM infections primarily affect the lungs, but can also manifest as lymphadenitis, skin and soft tissue infections, and disseminated disease. This retrospective study took into consideration 425 NTM-positive samples collected between May 2011 and December 2023, analyzed by sample type, sex, and age group (0–17, 18–49, 50–65, >65 years). Antimicrobial susceptibility analysis was performed on the 223 NTM strains with greater pathogenic power and most frequently isolated, from 2016 to 2023. Pulmonary NTM disease (NTM-PD) infections were most prevalent in patients over 65 years (52.1%), while extrapulmonary NTM disease (NTM-EPD) occurred most frequently in the 0–17 age group (56.4%). Women were slightly more affected (54.4%) than men (45.6%), with the highest incidence in female individuals over 65 years old. The most frequently isolated NTM species was the Mycobacterium avium complex (MAC) (47% of isolates). Antimicrobial susceptibility testing of 223 isolates from 2016 to 2023 revealed species-specific resistance patterns, with high susceptibility to clarithromycin in MAC (94.7%) and Mycobacterium chelonae (100%), but notable resistance in Mycobacterium abscessus complex (MABC). The increasing incidence of NTM infections underscores the need for improved diagnostic techniques and targeted treatment strategies. Full article

Background: Nontuberculous mycobacteria (NTM) are opportunistic pathogens responsible for chronic pulmonary infections, primarily affecting individuals with underlying conditions such as cystic fibrosis (CF). The aim of this review is to present the epidemiological profile of NTM in CF patients, with a focus on incidence, prevalence, predominant species, and geographic distribution. Methods: The search included cross-sectional, retrospective, and prospective observational studies published in English that reported epidemiological data concerning the isolation and/or infection of individuals with CF by NTM. NTM infection was defined as the isolation of any NTM species at least once per patient. Out of an initial 1120 references identified in PubMed, and following the application of exclusion criteria based on PRISMA guidelines, a total of 78 studies were included. Results: The reported prevalence of NTM in CF patients ranges globally from 0% to 40.9%. This wide variability is attributed to population heterogeneity, study period, and geographical region. Of the studies included, 30 were conducted in Europe and 25 in the U.S.A. Mycobacterium abscessus and the Mycobacterium avium complex (MAC) were the most commonly isolated species, with MAC being more prevalent in older individuals. The incidence of NTM pulmonary disease was high, with the majority of cases being associated with M. abscessus. Although emerging evidence suggests that CFTR modulator therapy may reduce the risk of NTM isolation and/or disease, current data remain limited. Conclusions: Nontuberculous mycobacteria are significant pathogens in patients with cystic fibrosis, with a negative impact on respiratory health. Full article

Limited data exist regarding lysogenic phages carried by M. abscessus, as well as regarding their roles played in diseases. Strains identified as M. abscessus from patients were collected. Prophages, virulence factors, and antibiotic resistance genes present in genomes were predicted, and correlations between prophages, virulence factors, antibiotic resistance genes, and clinical patient prognoses were analyzed. A total of 145 prophage sequences were detected in 56 M. abscessus strains. Prophages contained more virulence factors and antibiotic resistance genes, compared to known mycobacteriophages. The average sequence similarity among prophage sequences from a single patient was significantly higher than that among prophages from different patients or between prophages and known phages. The study showed that M. abscessus commonly carries prophages, which are enriched in virulence factors and antibiotic resistance genes relative to known phages, but their relationship to clinical prognoses requires further study. Prophages present in strains from different patients were highly diverse and exhibited low similarity with known mycobacterial phages. Full article

Background/Objectives: Mycobacterium abscessus is an opportunistic pathogen causing infections mainly in patients with immunosuppression and chronic pulmonary pathologies. Extended treatment periods are needed to tackle this pathogen, bacterial eradication is rare, and recurrence can take place with time. New alternative treatments are being investigated, such as bacteriophage therapy. This work describes the characterization of the mycobacteriophage P3MA, showing its ability to infect clinical and standard M. abscessus strains. Methods: Phylogenetic analysis, electron microscopy, growth curves, biofilm assays, checkerboard, and granuloma-like medium studies were performed. Results: P3MA inhibited the growth of clinical samples in both planktonic and biofilm states as well as in a granuloma-like model. The study of the interaction with antibiotics revealed that P3MA exhibited an antagonistic effect combined with clarithromycin, indifference with amikacin, and synergy with imipenem. Conclusions: All these results suggest that, after genetic engineering, P3MA could be a promising candidate for phage therapy in combination with imipenem, including lung infections. Full article