Nontuberculous Mycobacteria Research Articles

Antibiotic Resistance in Mycobacterium Tuberculosis and Non-Tuberculous Mycobacteria

Mycobacterium tuberculosis (MTB) and non-tuberculous mycobacteria (NTM) antibiotic resistance presents an important challenge to the treatment of mycobacterial infections. The therapeutic approaches are complicated by the resistance of both MTB and NTM to a variety of antibiotics. Resistance to first-line drugs such as isoniazid, rifampicin, ethambutol, and streptomycin has been consistently increasing in MTB, underscoring the necessity of effective treatment strategies. Conversely, the necessity of species-specific treatment regimens is underscored by the high resistance rates of NTM species, such as Mycobacterium avium complex, M. kansasii, and M. abscessus complex, to commonly used anti-tuberculosis pharmaceuticals. A combination of intrinsic and acquired factors are involved in the mechanisms of antibiotic resistance in these mycobacteria. Features such as biofilm formation, thick cell walls, and reduced drug uptake are responsible for intrinsic resistance in NTM, whereas acquired resistance can develop as a result of protracted antibiotic exposure. Understanding these resistance mechanisms is essential for the development of new therapies and the prevention of the increasing prevalence of drug resistance in mycobacterial infections. The significance of continuous surveillance, species-specific treatment protocols, and the development of novel antimicrobial agents to effectively manage mycobacterial diseases is emphasized by the prevalence of antibiotic resistance in MTB and NTM. This review article focuses on the molecular mechanisms that have resulted in the development of resistance in both MTB and NTMs, as well as the extent to which various classes of antimycobacterial drugs act.

Comparison of molecular testing methods for diagnosing non-tuberculous mycobacterial infections.

Rapid and accurate identification of non-tuberculous mycobacteria (NTM) is crucial yet challenging, promoting the development of novel molecular techniques such as amplification-based targeted high-throughput sequencing and metagenomic unbiased high-throughput sequencing. We aimed to evaluate the diagnostic value of these molecular techniques for NTM infection. A total of 115 clinical specimens from patients with confirmed NTM infection were subjected to multiplex polymerase chain reaction detection techniques (multi-PCR), metagenomic Next-Generation Sequencing (mNGS), targeted Next-Generation Sequencing (tNGS), and targeted Nanopore sequencing (tNanopore). Positivity rates and species identification were compared among these techniques. The sensitivity of mNGS, tNGS, and multi-PCR in NTM-infection diagnosis was 44.3%, 42.6%, and 36.5%, respectively, while the sensitivity of the three methods in combination increased to 54.8%. The pathogen identification results of mNGS, tNGS and multi-PCR were matched in 80.6% (25/31) samples at the species level, among which 14 samples (45.2%) was completely matched at the subspecies level. The results of tNanopore, tNGS and mNGS at the species level were completely matched in 73.3% (22/30) samples. These molecular assays demonstrated comparable performance in precisely identifying NTM species in clinical specimens, showing their promising potential as efficient and alternative tools for the rapid diagnosis of NTM disease.

Novel Synthetic Peptide Agelaia-12 Has Improved Activity Against Mycobacterium abscessus Complex

Fast-growing mycobacteria cause difficult-to-treat infections due to their high intrinsic resistance to antibiotics as well as disinfectant agents. Mycobacterium abscessus complex (MAC) is the main cause of nontuberculous mycobacteria diseases. In this work, we evaluated the activity of the novel synthetic antimicrobial peptide, Agelaia-12, against Mycobacterium abscessus and M. massiliense. Agelaia-12 showed a minimum inhibitory concentration (MIC) of 25 μM detected against M. abscessus and M. massiliense with no cytotoxicity. The scanning electronic microscopy analysis of mycobacterial treated with Agelaia-12 demonstrated the presence of filamentous structures and aggregation of the cells. Congo red binding assay of M. abscessus exhibited altered dye accumulation after treatment with Agelaia-12. Treatment of M. abscessus- or M. massiliense-infected murine macrophages with Agelaia-12 decreased the mycobacterial load by 92% for the tested strains. Additionally, IFN-y KO mice infected with M. abscessus or M. massiliense and treated with Agelaia-12 showed a 98% reduction in lung bacterial load. Thus, the synthetic peptide Agelaia-12 may be a promising biomolecule for the treatment of mycobacteriosis, and its structural properties may serve as a foundational model for the design and development of novel pharmaceutical agents aimed at combating this disease.

Biofilm formation and polar lipid biosynthesis in Mycobacterium abscessus are inhibited by naphthylmethylpiperazine.

Mycobacterium abscessus is a biofilm-forming, non-tuberculous mycobacterium that is highly resistant to antibiotics. Bacterial efflux pumps contribute to biofilm formation, export of biofilm-associated lipids and antibiotic tolerance. The Resistance Nodulation Cell Division (RND) and ATP-Binding Cassette (ABC) families of efflux pumps export lipids to the mycobacterial cell surface. 1-(1-naphthyl methyl)-piperazine (NMP) is a chemosensitizer that causes membrane destabilization and is an inhibitor of RND efflux pumps. The effects of NMP on biofilm formation and lipid metabolism in M. abscessus biofilms have not been investigated. Plumbagin (PLU) is an inhibitor of ABC efflux pumps that has not been studied for its effects on antibiotic tolerance in M. abscessus biofilms. In this study, we report that the efflux pump inhibitors NMP and PLU inhibit biofilm formation by 50% at sub-MIC levels. We show that NMP inhibits the incorporation of the radiolabeled long-chain fatty acid 14C-palmitate into glycopeptidolipids in cell surface lipids of log-phase M. abscessus. NMP also inhibits the utilization of the radiolabel in the biosynthesis of phosphatidylethanolamine in the cell surface and cellular lipids of M. abscessus cells in log-phase and in biofilms. Incorporation of the radiolabel into cardiolipin in the cellular lipids of M. abscessus biofilms was inhibited by NMP. The incorporation of 14C-acetate into cell surface phosphatidylethanolamine in log-phase and biofilm cells was also inhibited by NMP. Triacylglycerol biosynthesis using 14C-palmitate and 14C-acetate in cellular lipids of log-phase and biofilm cells was increased several folds by NMP. Efflux pump activity in M. abscessus cells was inhibited by 97% and 68% by NMP and PLU respectively. NMP and PLU caused 5-fold decreases in the minimum inhibitory concentrations of ciprofloxacin and clarithromycin against M. abscessus. Our results demonstrate that NMP and PLU affect important physiological processes in M. abscessus associated with its pathogenesis.

Relationship between age, sex, geography and incidence of nontuberculous mycobacteria in Denmark from 1991–2022

Relationship between age, sex, geography and incidence of nontuberculous mycobacteria in Denmark from 1991–2022

SQ31f is a potent non-tuberculous mycobacteria antibiotic by specifically targeting the mycobacterial F-ATP synthase.

Non-tuberculous mycobacteria (NTM) infection presents a growing global health problem and requires new antibiotics targeting enzymes that are essential for the pathogens under various metabolic conditions, with high target specificity, good solubility and with attractive combinatory potency. SQ31f was synthesized by a simplified synthesis protocol, and its effect on growth inhibition of fast- and slow-growing NTM and clinical isolates, whole-cell ATP depletion, ex vivo macrophages and its potency in combination with other antibiotics were evaluated. Molecular docking studies were employed to assess SQ31f's binding mode. We present- squaramide SQ31f as a novel anti-NTM inhibitor targeting the NTM F1FO-ATP synthase, essential for ATP formation, regulation of ATP homeostasis and proton motive force under multiple growth conditions. The potency of SQ31f in growth inhibition of fast- and slow-growing NTM and clinical isolates correlates with whole-cell ATP depletion, which is not caused by altered oxygen consumption. SQ31f's high aqueous solubility enables binding to the waterfilled cytosolic proton half channel in the subunits a-c interface of the FO domain. As presented for the fast-growing Mycobacterium abscessus, the compound is active against intracellular-residing M. abscessus. Importantly, SQ31f shows an additive effect of the anti-M. abscessus drugs clofazimine, rifabutin or amikacin, and an attractive potentiation of linezolid, clarithromycin, or the oral pair tebipenem and avibactam. SQ31f represents an attractive inhibitor to tackle the issues associated with NTM drug tolerance and toxicity. Its combinatory potency with anti-M. abscessus drugs holds potential for overcoming resistance, while also reducing intensive compound synthesis and associated costs.

Optimal incubation duration of liquid cultures for assessing culture negative conversion in patients with Mycobacterium avium complex and Mycobacterium abscessus pulmonary diseases.

Mycobacterial liquid culturing typically requires six weeks or longer, primarily because of the slow growth rate of Mycobacterium tuberculosis. This study aimed to evaluate the potential of shortening the duration of mycobacterial liquid culturing in healthcare settings with high prevalence rates of non-tuberculous mycobacteria. We retrospectively analyzed the relationship between mycobacterial species and time to positive testing of liquid cultures from sputum samples using the Mycobacteria Growth Indicator Tube system over a 3.5-year period beginning in July 2020 at a university hospital in Japan. We analyzed 15,147 sputum culture samples and found a 1.1% positivity rate for Mycobacterium tuberculosis complex, while the rates for Mycobacterium avium complex and Mycobacterium abscessus were 17.6% and 2.1%, respectively. The median time to positivity was 17 days for Mycobacterium tuberculosis complex, 9 days for Mycobacterium avium complex, and 4 days for Mycobacterium abscessus. Comparing a 4-week culture period with an eight-week period, the positivity rates for Mycobacterium avium complex and Mycobacterium abscessus were 97.0% and 99.4%, respectively. In settings with a high incidence of non-tuberculous mycobacteria, the basic liquid culturing period can be safely shortened to 4 weeks without significantly compromising detection sensitivity, except for the samples that are highly suspected to contain tuberculosis, extremely slow-growing mycobacteria, smear-positive, or nucleic acid amplification testing positive.

Primary cutaneous infections with non-tuberculous mycobacteria: a report of 6 cases

BackgroundThe incidence of non-tuberculous mycobacterium infection has shown a gradual increasing trend in recent years, among which cutaneous manifestations as an important aspect. This study aimed to describe the clinical features and microbiological findings in 6 cases of primary cutaneous nontuberculous mycobacterium infection.MethodsIn this retrospective study from June 2021 to June 2022, the clinical data and microbiological results of six cases diagnosed with primary cutaneous non-tuberculous mycobacterium infection in department of dermatology, Hangzhou Third People’s Hospital were analyzed.ResultsAll six cases were primary cutaneous non-tuberculous mycobacterium infections, four of which had a history of trauma or exposure, and two had an underlying disease that could lead to compromised immunity. All patients presented with erythema nodular skin lesions, four on the upper or lower extremities, one on the face, and one on the right hip. The histopathological findings of five patients who underwent biopsy were granulomatous inflammatory changes with mixed infiltration. Laboratory cultures using tissue or tissue fluid were all successful, including four Mycobacterium marinum, one Mycobacterium abscessus, and one Mycobacterium avium. Metagenomics next-generation sequencing detected results consistent with culture colonies in only two cases. With the exception of case 4, all patients responded well to oral medication, with a course of treatment ranging from 4 months to 1 year, and the prognosis was good.ConclusionsThe clinical features of primary cutaneous non-tuberculous mycobacterium infection are often lacking in specificity, and the identification of related strains is difficult for a variety of reasons. Although the results of metagenomics next-generation sequencing are useful for pathogen spectrum identification, its diagnostic value should be carefully reevaluated under certain circumstances. Patients with suspected triggers who do not respond well to conventional treatments should be suspected as atypical infection and potential immunosuppression. If diagnosed and treated promptly, the prognosis of primary cutaneous non-tuberculous mycobacterium infection is generally good.

Structural Studies on Mycobacterial NudC Reveal a Class of Zinc Independent NADH Pyrophosphatase

Non-tuberculous mycobacteria (NTM) have emerged as an increasing threat to public health, due to the extreme antibiotic resistance. NADH pyrophosphatase (NudC) was proposed involving in mycobacterial resistance to the first line anti-tubercular drug isoniazid (INH) or its analog ethionamide (ETH), by hydrolyzing their NAD modified active forms (NAD-INH and NAD-ETH). In this study, we performed enzymatic and structural studies on NudC from M. abscessus (NudCMab), which is highly resistant to isoniazid and emerging as the most worrisome NTM. We determined the crystal structures of NudCMab in apo form, substrate NAD-bound form and product AMP-bound form. We observed the mode for the Nudix motif of NudCMab capturing the pyrophosphate group of NAD mediated by three divalent cation ions, which provides details for understanding the mechanism on NudC hydrolyzing NAD(H) or NAD-capped substrate. Interestingly, our structures revealed a novel subclass NudC from mycobacteria characterized by a unique arginine residue on the conserved QPWPFPxS motif, as well as a unique tower domain that replaces a well-defined zinc-binding motif in E.coli NudC and catalytic domain of mammalian Nudt12. Thus, our structural studies on NudCMab not only present a class of zinc independent NADH pyrophosphatase in mycobacteria, but also may facilitate the design of NudC inhibitors for the treatment of mycobacteria infections in combination with INH or ETH.

The inflammasome-activating poxvirus peptide IAMP29 promotes antimicrobial and anticancer responses.

Poxviruses are implicated in a variety of infectious diseases; however, little is known about the molecular mechanisms that underlie the immune response during poxvirus infection. We investigated the function and mechanisms of the monkeypox virus envelope protein (A30L) and its core peptide (IAMP29) during the activation of innate immune responses. The A30L protein and its core peptide, IAMP29 (a 29-amino-acid inflammasome-activating peptide encompassing His40 to Asp69 of A30L), strongly activated the nucleotide-binding oligomerization domain, leucine rich repeat and pyrin domain-containing 3 (NLRP3) inflammasome by inducing the production of mitochondrial reactive oxygen species in human monocytes. Specifically, IAMP29 triggered metabolic reprogramming toward glycolysis and interacted with pyruvate kinase M isoforms (PKM1 and PKM2), thus activating the NLRP3 inflammasome and interleukin (IL)-1β production in human monocytes and murine macrophages. In human primary monocyte-derived macrophages, IAMP29-induced inflammasome activation promoted an antimicrobial response to rapidly growing non-tuberculous mycobacteria. Furthermore, IAMP29 exhibited cytotoxic activity against leukemia cells, which was mediated by pyroptosis and apoptosis. These findings provide insights into the immunological function of the poxvirus envelope peptide and suggest its therapeutic potential.

Synthesis, Biological Evaluation, Molecular Docking Studies and ADMET Prediction of Oxindole-Based Hybrids for the Treatment of Tuberculosis.

With a projected mortality toll of 1.4 million in 2019, tuberculosis (TB) continues to be a significant public health concern around the world. Studies of novel treatments are required due to decreased bioavailability, increased toxicity, increased side effects, and resistance of several first- and second-line TB therapies, including isoniazid and ethionamide. This study reports the synthesis of oxindole-based hybrids as potent InhA inhibitors targeting Mycobacterium tuberculosis. The synthesized compounds (5a-5e and 8a-8c) were evaluated for their anti-mycobacterial activity against Mycobacterium tuberculosis and nontuberculous mycobacteria (NTMs), viz. M. abscessus (ATCC 19977), M. fortuitum (ATCC 6841), and M. chelonae (ATCC 35752) using the Microplate Alamar Blue Assay (MABA). Molecular docking studies were performed using AutoDock Vina to explore the binding interactions of these compounds with the InhA enzyme (PDB: 2NSD). Additionally, biochemical and histopathological studies were conducted to assess the hepatotoxicity of the lead compounds. Insilico molecular properties and ADMET properties of the synthesized compounds were predicted using SwissADME and Deep-PK online tools to assess their drug-likeness. Among the tested compounds, 8b exhibited significant anti-mycobacterial activity with a minimum inhibitory concentration (MIC = 1 μg/mL) comparable to the reference drug ethambutol. Further, the compound demonstrated a binding affinity and orientation similar to the reference inhibitor 4PI, indicating its potential as a potent InhA inhibitor, and was found to be stabilized within the binding pocket of InhA through H-bonding, hydrophobic and van der Waal's interactions. Besides, the compounds hepatotoxicity assessment studies depicted that 8b showed no significant liver dysfunction or damage to liver tissues. Additionally, 8b adhered to Lipinski's rule of five and Veber's rule, displaying favourable pharmacokinetic and drug-like properties, including high human intestinal absorption, distribution, and acceptable metabolic stability and excretion. Compound 8b emerged as a promising candidate for further optimization and development as a therapeutic agent for tuberculosis, offering a new avenue for tackling tuberculosis.

Pathogen spectrum and microbiome in lower respiratory tract of patients with different pulmonary diseases based on metagenomic next-generation sequencing.

The homeostasis of the microbiome in lower respiratory tract is crucial in sustaining normal physiological functions of the lung. Different pulmonary diseases display varying degrees of microbiome imbalance; however, the specific variability and clinical significance of their microbiomes remain largely unexplored. In this study, we delineated the pathogen spectrum and commensal microorganisms in the lower respiratory tract of various pulmonary diseases using metagenomic sequencing. We analyzed the disparities and commonalities of the microbial features and examined their correlation with disease characteristics. We observed distinct pathogen profiles and a diversity in lower airway microbiome in patients diagnosed with cancer, interstitial lung disease, bronchiectasis, common pneumonia, Nontuberculous mycobacteria (NTM) pneumonia, and severe pneumonia. This study illustrates the utility of Metagenomic Next-generation Sequencing (mNGS) in identifying pathogens and analyzing the lower respiratory microbiome, which is important for understanding the microbiological aspect of pulmonary diseases and essential for their early and precise diagnosis.

Use of BD BACTEC™ MGIT™ for the detection of non-tuberculous mycobacteria in sanitary water samples.

The most commonly used method for the detection of non-tuberculous mycobacteria (NTM) is culture in BD BACTEC™ MGIT™ Mycobacteria Growth Indicator Tubes incubated in an automated growth detection reader BD BACTEC™ MGIT™ 960 Instrument. The system is currently validated for the detection of mycobacteria from clinical specimens but not environmental matrices. From November 2018 to December 2023, 1,369 sanitary water samples from 92 heater-cooler units (HCUs) and 747 sanitary water samples from 489 haemodialysis instruments (dialysis) were concentrated, decontaminated, and cultured on MGIT and solid Lowenstein-Jensen media to evaluate the presence of NTM. NTM-positive cultures (n = 261 HCUs and n = 20 dialysis) were purified by Middlebrook 7H11 agar plate subcultures and identified by MALDI-TOF mass spectrometry technology. The purpose of this study was to evaluate the accuracy and reproducibility of the MGIT system on sanitary water from HCU and dialysis, using the two strains most frequently isolated on these devices as sources of NTM during the Emilia- Romagna surveillance programme: M. chimaera (79%) and M. saskatchewanense (100%), respectively. To evaluate the accuracy, sanitary water was spiked with M. chimaera and M. saskatchewanense at the theoretical concentrations of 100 and 10 CFU/mL, and all resulted positive in MGIT tubes. No significant changes in time to positivity were observed when MGIT tubes were inoculated with NTM at the theoretical concentrations of 10 and 100 CFU/mL on 3 consecutive days, indicating that the detection method is reproducible. The MGIT system is suitable for detecting the presence of NTM in sanitary water samples as it was capable of detecting up to 4 CFU/mL for both M. chimaera and M. saskatchewanense. Our results indicate that the MGIT system can be used for NTM detection not only for clinical samples but also for environmental matrices.

TBAJ-587, a novel diarylquinoline, is active against Mycobacterium abscessus.

Nontuberculous mycobacteria (NTM) infections are extremely difficult to treat due to a natural resistance to many antimicrobials. TBAJ-587 is a novel diarylquinoline, which shows higher anti-tuberculosis activity, lower lipophilicity, and weaker inhibition of hERG channels than bedaquiline (BDQ). The susceptibilities of 11 NTM reference strains and 194 clinical Mycobacterium abscessus isolates to TBAJ-587 were determined by the broth microdilution assay. The activity of TBAJ-587 toward the growth of M. abscessus in macrophages was also evaluated. Minimum bactericidal concentration and time-kill kinetic assays were conducted to distinguish between the bactericidal and bacteriostatic activities of TBAJ-587. The synergy between TBAJ-587 and eight clinically important antibiotics was determined using a checkerboard assay. TBAJ-587 was highly effective against M. abscessus by targeting its F-ATP synthase c chain. The antimicrobial activities of TBAJ-587 and BDQ toward intracellular M. abscessus were comparable. The in vivo activities of TBAJ-587 and BDQ in an immunocompromised mouse model were also comparable. TBAJ-587 expressed bactericidal activity and was compatible with eight anti-NTM drugs commonly used in clinical practice; no antagonism was discovered. As such, TBAJ-587 represents a potential candidate for the treatment of NTM infections.

Development and preliminary assessment of the iFIND TBR: all-in- one molecular diagnostic assay for rapid detection of Mycobacterium tuberculosis and rifampicin resistance.

Early and accurate diagnosis of tuberculosis (TB) is crucial for initiating timely treatment and preventing new infections. In this study, we introduced the iFIND TBR assay, an automated all-in-one tuberculosis detection approach that simultaneously detect Mycobacterium tuberculosis (MTB) and rifampicin (RIF) resistance. The limits of detection (LOD), sensitivity, specificity, and RIF-R rpoB mutation detection of the iFIND TBR were tested on Mycobacterium tuberculosis DNA or sputum samples spiked with known numbers of M.tuberculosis H37Rv. Frozen clinical samples from patients suspected of having TB were also tested. The LOD of the iFIND TBR for MTB detection were 13.34 CFU/ml (95% CI, 11.71-16.47), and for RIF resistance was 109.79CFU/mL (95% CI, 95-138.19). The iFIND TBR assay accurately distinguish MTB strains from non-tuberculous mycobacteria (NTM) without any cross reactivity. Testing on 157 clinical sputum samples, compared with the bacteriologically TB standard, the overall sensitivity and specificity of the iFIND TBR was 100% (95%CI, 94.64, 100) and 85.29% (95% CI, 74.61, 92.72), respectively. When assessing RIF susceptibility, the iFIND TBR achieved a sensitivity of 98.15% (95% CI, 90.11-99.95) and a specificity of 85.71% (95% CI, 67.33-95.97), compared with phenotypic drug susceptibility testing. Discordant RIF susceptibility results were more frequently observed in samples exhibiting heteroresistance. These findings demonstrate that iFIND TBR assay performs well in detecting TB and RIF resistance, and shows promise as a point-of-care tool in resource-limited areas.

Rational Exploration of 2,4-Diaminopyrimidines as DHFR Inhibitors Active against Mycobacterium abscessus and Mycobacterium avium, Two Emerging Human Pathogens.

Nontuberculous mycobacteria (NTM) are emerging human pathogens linked to severe pulmonary diseases. Current treatments involve the prolonged use of multiple drugs and are often ineffective. Bacterial dihydrofolate reductase (DHFR) is a key enzyme targeted by antibiotics in Gram-negative bacterial infections. However, existing DHFR inhibitors designed for Gram-negative bacteria often fail against mycobacterial DHFRs. Here, we detail the rational design of NTM DHFR inhibitors based on P218, a malarial DHFR inhibitor. We identified compound 8, a 2,4-diaminopyrimidine exhibiting improved pharmacological properties and activity against purified DHFR, and whole cell cultures of two predominant NTM species: Mycobacterium avium and Mycobacterium abscessus. This study underscores the potential of compound 8 as a promising candidate for the in vivo validation of DHFR as an effective treatment against NTM infections.

A histopathological study in road-killed European badgers (Meles meles) from the English midlands with isolation of novel non-tuberculous atypical mycobacteria

European badgers (Meles meles) play an important role in the epidemiology of bovine tuberculosis (caused by Mycobacterium bovis) in England, but little is known about the prevalence of atypical mycobacteriosis. Badgers are also known to be infected by other infectious agents, and the relationship between mycobacteriosis and concomitant infections needs further investigation. Overall, 88 badger carcasses from the Midlands of England collected between July 2016-August 2017 were selected for histopathological examination based on the degree of autolysis (mild), mycobacterial culture results and a balanced sex ratio. Mycobacteria were cultured from 44 badgers, of which 31 were mycobacteria belonging to the M. tuberculosis complex (MTBC) (based on IS6110 PCR and Hsp64 and/or rRNA PCR and sequencing) and 13 were non-tuberculous atypical mycobacteria (NTM). Mycobacteria were not cultured from the remaining 44 animals. Histologically, the most common findings were silica-laden macrophages (85%), granulomas (53%), sarcocystosis (47%), nephritis (31%), portal/periportal hepatitis (26%), ulcerative dermatitis (18%). Culturable mycobacteriosis was associated with higher prevalence of granulomas (p < 0.001) and lower prevalence of hepatitis (p = 0.003). NTM (M. nonchromogenicum, M. avium complex, M. hassiacum, M. malmoense, M. vaccae.) infections were associated with granulomatous pneumonia, and M. malmoense was associated with pyogranulomatous and ulcerative dermatitis. In conclusion, this study describes, for the first time, histological lesions associated with NTM in badgers, the histomorphology of which was similar to those caused by MTBC. In addition, the negative relationship between mycobacteriosis and periportal hepatitis may indicate a complex relationship between mycobacteriosis and other diseases, as previously observed with tuberculosis.

Epidemiology of bronchiectasis at a single center in Japan: a retrospective cohort study

BackgroundThe characteristics of bronchiectasis (BE) in Asia, including Japan, remain largely unknown. We aimed to provide insights into the clinical characteristics and treatment outcomes of BE, especially regarding nontuberculous mycobacteria (NTM) infection and its poorly understood impact on prognosis. We also aimed to clarify the effect of long-term macrolide antibiotic use in patients with BE, who had no history of exacerbations.MethodsIn this single-center, retrospective study, the medical records of patients who satisfied the BE criteria between January 1, 2012, and August 31, 2023, were reviewed. Severe exacerbations and mortality during the observation period were recorded. Baseline characteristics and overall survival of patients with and without NTM infection, and factors influencing the time to the first exacerbation and death were analyzed. Additionally, the effects of long-term macrolide antibiotic use in patients without a history of severe exacerbations were estimated.ResultsIn a cohort of 1044 patients with BE, the rate of severe exacerbation was 22.3%, with mortality rates of 3.2% over 3 years. Notably, the high prevalence of NTM infection (n = 410, 39.3%) in this cohort was distinctive. NTM infection was not associated with either the time to first severe exacerbation (p = 0.5676, adjusted hazard ratio = 1.11) or mortality (p = 0.4139, adjusted hazard ratio = 0.78). Compared with the NTM group, the non-NTM group had a higher proportion of elevated inflammatory markers, with significant differences in C-reactive protein levels (p = 0.0301) and blood neutrophil counts (p = 0.0273). Pseudomonas aeruginosa colonization was more frequent in the non-NTM group (p = 0.0003). Among patients with non-NTM infection and without a history of exacerbation in the past 2 years, 38.2% received long-term macrolide antibiotics that did not invariably prolong the time to first severe exacerbation (p = 0.4517, IPW p = 0.3555).ConclusionsThis study highlights BE epidemiology in Japan, noting that the presence of NTM infection may not necessarily worsen the prognostic outcomes and advising caution in the casual use of macrolides for milder cases without a history of exacerbations.Clinical trial registrationUMIN Clinical Trials Registry Number: UMIN000054726 (Registered on 21 June 2024).

Non-tuberculous mycobacterial bone and joint infections - a case series from a tertiary referral centre in Australia.

Non-tuberculous mycobacteria (NTM) are rare causes of bone and joint infection (BJI) and there is limited evidence on which to base management decisions. This study describes 1 year of experience from a multi-disciplinary BJI team which collects data on all cases reviewed at a tertiary referral centre in Queensland, Australia. The database was interrogated for all cases in which NTM were recovered from operative samples. Individual chart review was performed to collect the details of each case. A total of seven cases were managed between 1st February 2021 and 28th February 2022, comprising one patient with chronic osteomyelitis, three with fracture-related infections, two with prosthetic joint infections, and one with infection of a synthetic ligament graft. In contrast to pulmonary NTM infections, most patients were clinically well and immunocompetent, and most infections were propagated by direct inoculation. Time to diagnosis was unknown in three patients, with 1, 2, 2, and 5 months for the remaining four. Rapid growing NTM were diagnosed on routine cultures and specific mycobacterial cultures were confirmatory. Management was characterized by multiple stage surgical procedures and prolonged antimicrobial regimens. Antimicrobial complications were common; however, all patients were infection free at their latest follow up. Despite the inherent limitations, these results suggest that routinely ordering mycobacterial culture is of low yield. There is potential for shorter-term oral antimicrobial treatments. Prospective research is required to optimize treatment regimens and durations.

Challenges in diagnosing bovine tuberculosis through surveillance and characterization of Mycobacterium species in slaughtered cattle in Kolkata

BackgroundTuberculosis in cattle is caused by Mycobacterium tuberculosis complex (MTBC) species. Apart from MTBC, different Nontuberculous Mycobacteria (NTM) species have also been isolated from cattle. The presence of NTM infection in bovines makes the diagnosis of bovine tuberculosis (bTB) a cumbersome task. Therefore, a cross sectional study was conducted to isolate and characterize different Mycobacterium spp. from a slaughterhouse situated in Kolkata, a city in the eastern part of India.ResultsOut of 258 morbid samples, 98 isolates were found to be positive for bacterial growth, and 35% (n = 34) were positive for Mycobacterium. 94% of Mycobacterial cultural isolates were NTM (n = 32), and the rest (n = 2) were found to be MTBC. Species-level identification of the isolates by hsp65 sequencing revealed that out of 32 isolates, 24 were M. fortuitum, three were M. abscessus, two each were M. chelonae and M. parascrofulaceum, and one was M. novocastrense. A phylogenetic tree with partial hsp65 gene sequences was also constructed to determine the relatedness of the unknown isolates to the reference strains.ConclusionBoth NTM species and MTBCs were identified from TB-like lesions in cattle that were slaughtered at the Kolkata abattoir. This discovery may indicate that NTM contributes to the development of lesions in cattle. Also, we recommend implication of more specific diagnostic tests for bTB.