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Journal of Clinical Microbiology Jan 2023Mycobacterium abscessus is one of the most common and pathogenic nontuberculous mycobacteria (NTM) isolated in clinical laboratories. It consists of three subspecies: M....
Mycobacterium abscessus is one of the most common and pathogenic nontuberculous mycobacteria (NTM) isolated in clinical laboratories. It consists of three subspecies: M. abscessus subsp. , M. abscessus subsp. , and M. abscessus subsp. . Due to their different antibiotic susceptibility pattern, a rapid and accurate identification method is necessary for their differentiation. Although matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) has proven useful for NTM identification, the differentiation of M. abscessus subspecies is challenging. In this study, a collection of 325 clinical isolates of M. abscessus was used for MALDI-TOF MS analysis and for the development of machine learning predictive models based on MALDI-TOF MS protein spectra. Overall, using a random forest model with several confidence criteria (samples by triplicate and similarity values >60%), a total of 96.5% of isolates were correctly identified at the subspecies level. Moreover, an improved model with Spanish isolates was able to identify 88.9% of strains collected in other countries. In addition, differences in culture media, colony morphology, and geographic origin of the strains were evaluated, showing that the latter had an impact on the protein spectra. Finally, after studying all protein peaks previously reported for this species, two novel peaks with potential for subspecies differentiation were found. Therefore, machine learning methodology has proven to be a promising approach for rapid and accurate identification of subspecies of M. abscessus using MALDI-TOF MS.
Topics: Humans; Mycobacterium; Mycobacterium abscessus; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Nontuberculous Mycobacteria; Mycobacterium Infections, Nontuberculous
PubMed: 36602341
DOI: 10.1128/jcm.01110-22 -
Microbiology Spectrum Apr 2022Pathogenic intracellular mycobacteria, such as Mycobacterium tuberculosis and Mycobacterium avium, which cause lung diseases, can grow in macrophages. Extracellular...
Pathogenic intracellular mycobacteria, such as Mycobacterium tuberculosis and Mycobacterium avium, which cause lung diseases, can grow in macrophages. Extracellular mycobacteria have been reported in the lungs, blood, and sputum of patients, indicating the involvement of these pathogens in disease progression. Erythrocytes are involved in the symptoms associated with pulmonary mycobacterial diseases, such as bloody sputum and hemoptysis; however, little attention has been paid to the role of erythrocytes in mycobacterial diseases. Herein, we found that Mycobacterium avium subsp. (MAH) and Mycobacterium intracellulare colocalized with erythrocytes at the sites of lung infection, inside capillaries and necrotic areas of granulomas, using histopathological examinations. Electron microscopy showed that MAH adhered and entered human erythrocytes when they were cocultured . MAH adhered to erythrocytes through complement receptor 1 and cell-surface sialo-glycoproteins. Importantly, MAH grew vigorously without causing any pronounced damage to erythrocytes. This erythrocyte-mediated enhancement of MAH growth occurred extracellularly depending on its direct attachment to erythrocytes. In contrast, MAH failed to multiply inside erythrocytes. Similarly, erythrocytes augmented the growth of other pathogenic mycobacteria, such as M. intracellulare and M. tuberculosis. THP-1 cell-derived human macrophages preferentially phagocytosed erythrocytes that were attached to mycobacteria (compared to bacteria alone), suggesting that erythrocyte-attached mycobacteria are an efficient infectious source for macrophages. Our findings provide new insights into the pathogenesis of mycobacterial diseases and offer an alternative and useful strategy for treating mycobacterial disease. Pathogenic mycobacteria, such as Mycobacterium tuberculosis, Mycobacterium avium subsp. (MAH), and Mycobacterium intracellulare, cause pulmonary infections as intracellular parasites of lung macrophages and epithelial cells. Here, using histopathological examinations we found that MAH and M. intracellulare colocalized with erythrocytes in lung infection sites. Subsequent studies demonstrated that direct interaction with erythrocytes enhances the extracellular proliferation of mycobacteria based on the following results: 1. MAH adhered and invaded human erythrocytes upon coculture ; 2. MAH adhered to erythrocytes through complement receptor 1 and cell-surface sialo-glycoproteins; 3. MAH rapidly proliferated when directly attached to erythrocytes but not within them; 4. other mycobacteria, such as M. intracellulare and M. tuberculosis, also proliferated in the same way as MAH. The finding that pathogenic mycobacteria grow extracellularly in an erythrocyte-dependent manner is of considerable clinical importance for understanding disease progression and latent infection.
Topics: Disease Progression; Erythrocytes; Glycoproteins; Humans; Mycobacterium; Mycobacterium avium Complex; Mycobacterium avium-intracellulare Infection; Mycobacterium tuberculosis; Receptors, Complement; Tuberculosis
PubMed: 35293805
DOI: 10.1128/spectrum.02454-21 -
Human Genetics Jun 2020Mendelian susceptibility to mycobacterial disease (MSMD) is caused by inborn errors of IFN-γ immunity. Affected patients are highly and selectively susceptible to... (Review)
Review
Mendelian susceptibility to mycobacterial disease (MSMD) is caused by inborn errors of IFN-γ immunity. Affected patients are highly and selectively susceptible to weakly virulent mycobacteria, such as environmental mycobacteria and Bacillus Calmette-Guérin vaccines. Since 1996, disease-causing mutations have been reported in 15 genes, with allelic heterogeneity leading to 30 genetic disorders. Here, we briefly review the progress made in molecular, cellular, immunological, and clinical studies of MSMD since the last review published in 2018. Highlights include the discoveries of new genetic etiologies of MSMD: autosomal recessive (AR) complete deficiencies of (1) SPPL2a, (2) IL-12Rβ2, and (3) IL-23R, and (4) homozygosity for TYK2 P1104A, resulting in selective impairment of responses to IL-23. The penetrance of SPPL2a deficiency for MSMD is high, probably complete, whereas that of IL-12Rβ2 and IL-23R deficiencies, and TYK2 P1104A homozygosity, is incomplete, and probably low. SPPL2a deficiency has added weight to the notion that human cDC2 and Th1* cells are important for antimycobacterial immunity. Studies of IL-12Rβ2 and IL-23R deficiencies, and of homozygosity for P1104A TYK2, have shown that both IL-12 and IL-23 are required for optimal levels of IFN-γ. These recent findings illustrate how forward genetic studies of MSMD are continuing to shed light on the mechanisms of protective immunity to mycobacteria in humans.
Topics: Genetic Diseases, Inborn; Genetic Heterogeneity; Genetic Predisposition to Disease; Host-Pathogen Interactions; Humans; Interferon-gamma; Mycobacterium; Mycobacterium Infections
PubMed: 32025907
DOI: 10.1007/s00439-020-02120-y -
Emerging Infectious Diseases Mar 2022The treatment of leprosy is long and complex, benefiting from the development of sterilizing, rapidly-acting drugs. Reductive evolution made Mycobacterium leprae...
The treatment of leprosy is long and complex, benefiting from the development of sterilizing, rapidly-acting drugs. Reductive evolution made Mycobacterium leprae exquisitely sensitive to Telacebec, a phase 2 drug candidate for tuberculosis The unprecedented potency of Telacebec against M. leprae warrants further validation in clinical trials.
Topics: Imidazoles; Mycobacterium leprae; Piperidines; Pyridines
PubMed: 35202539
DOI: 10.3201/eid2803.210394 -
Emerging Microbes & Infections 2019Of the more than 190 distinct species of Mycobacterium genus, many are economically and clinically important pathogens of humans or animals. Among those mycobacteria... (Review)
Review
Of the more than 190 distinct species of Mycobacterium genus, many are economically and clinically important pathogens of humans or animals. Among those mycobacteria that infect humans, three species namely Mycobacterium tuberculosis (causative agent of tuberculosis), Mycobacterium leprae (causative agent of leprosy) and Mycobacterium abscessus (causative agent of chronic pulmonary infections) pose concern to global public health. Although antibiotics have been successfully developed to combat each of these, the emergence of drug-resistant strains is an increasing challenge for treatment and drug discovery. Here we describe the impact of the rapid expansion of genome sequencing and genome/pathway annotations that have greatly improved the progress of structure-guided drug discovery. We focus on the applications of comparative genomics, metabolomics, evolutionary bioinformatics and structural proteomics to identify potential drug targets. The opportunities and challenges for the design of drugs for M. tuberculosis, M. leprae and M. abscessus to combat resistance are discussed.
Topics: Animals; Bacterial Proteins; Computational Biology; Drug Discovery; Drug Resistance, Bacterial; Genome, Bacterial; Humans; Molecular Sequence Annotation; Mycobacterium; Mycobacterium abscessus; Mycobacterium leprae; Mycobacterium tuberculosis; Protein Conformation; Proteomics; Sequence Analysis, DNA
PubMed: 30866765
DOI: 10.1080/22221751.2018.1561158 -
Clinical Microbiology Reviews Apr 2016Molecular typing has revolutionized epidemiological studies of infectious diseases, including those of a mycobacterial etiology. With the advent of fingerprinting... (Review)
Review
Molecular typing has revolutionized epidemiological studies of infectious diseases, including those of a mycobacterial etiology. With the advent of fingerprinting techniques, many traditional concepts regarding transmission, infectivity, or pathogenicity of mycobacterial bacilli have been revisited, and their conventional interpretations have been challenged. Since the mid-1990s, when the first typing methods were introduced, a plethora of other modalities have been proposed. So-called molecular epidemiology has become an essential subdiscipline of modern mycobacteriology. It serves as a resource for understanding the key issues in the epidemiology of tuberculosis and other mycobacterial diseases. Among these issues are disclosing sources of infection, quantifying recent transmission, identifying transmission links, discerning reinfection from relapse, tracking the geographic distribution and clonal expansion of specific strains, and exploring the genetic mechanisms underlying specific phenotypic traits, including virulence, organ tropism, transmissibility, or drug resistance. Since genotyping continues to unravel the biology of mycobacteria, it offers enormous promise in the fight against and prevention of the diseases caused by these pathogens. In this review, molecular typing methods for Mycobacterium tuberculosis and nontuberculous mycobacteria elaborated over the last 2 decades are summarized. The relevance of these methods to the epidemiological investigation, diagnosis, evolution, and control of mycobacterial diseases is discussed.
Topics: Bacterial Typing Techniques; Humans; Molecular Epidemiology; Molecular Typing; Mycobacterium; Mycobacterium Infections; Mycobacterium tuberculosis
PubMed: 26912567
DOI: 10.1128/CMR.00055-15 -
G3 (Bethesda, Md.) Aug 2022Mycobacterium abscessus is an emerging pathogen of concern in cystic fibrosis and immunocompromised patients and is considered one of the most drug-resistant...
Mycobacterium abscessus is an emerging pathogen of concern in cystic fibrosis and immunocompromised patients and is considered one of the most drug-resistant mycobacteria. The majority of clinical Mycobacterium abscessus isolates carry 1 or more prophages that are hypothesized to contribute to virulence and bacterial fitness. The prophage McProf was identified in the genome of the Bergey strain of Mycobacterium chelonae and is distinct from previously described prophages of Mycobacterium abscessus. The McProf genome increases intrinsic antibiotic resistance of Mycobacterium chelonae and drives expression of the intrinsic antibiotic resistance gene, whiB7, when superinfected by a second phage. The prevalence of McProf-like genomes was determined in sequenced mycobacterial genomes. Related prophage genomes were identified in the genomes of 25 clinical isolates of Mycobacterium abscessus and assigned to the novel cluster, MabR. They share less than 10% gene content with previously described prophages; however, they share features typical of prophages, including polymorphic toxin-immunity systems.
Topics: Anti-Bacterial Agents; Humans; Mycobacterium; Mycobacterium abscessus; Mycobacterium chelonae; Prophages
PubMed: 35894699
DOI: 10.1093/g3journal/jkac188 -
Microbiology Spectrum Aug 2014The cell wall of Mycobacterium tuberculosis is unique in that it differs significantly from those of both Gram-negative and Gram-positive bacteria. The thick,... (Review)
Review
The cell wall of Mycobacterium tuberculosis is unique in that it differs significantly from those of both Gram-negative and Gram-positive bacteria. The thick, carbohydrate- and lipid-rich cell wall with distinct lipoglycans enables mycobacteria to survive under hostile conditions such as shortage of nutrients and antimicrobial exposure. The key features of this highly complex cell wall are the mycolyl-arabinogalactan-peptidoglycan (mAGP)-based and phosphatidyl-myo-inositol-based macromolecular structures, with the latter possessing potent immunomodulatory properties. These structures are crucial for the growth, viability, and virulence of M. tuberculosis and therefore are often the targets of effective chemotherapeutic agents against tuberculosis. Over the past decade, sophisticated genomic and molecular tools have advanced our understanding of the primary structure and biosynthesis of these macromolecules. The availability of the full genome sequences of various mycobacterial species, including M. tuberculosis, Mycobacterium marinum, and Mycobacterium bovis BCG, have greatly facilitated the identification of large numbers of drug targets and antigens specific to tuberculosis. Techniques to manipulate mycobacteria have also improved extensively; the conditional expression-specialized transduction essentiality test (CESTET) is currently used to determine the essentiality of individual genes. Finally, various biosynthetic assays using either purified proteins or synthetic cell wall acceptors have been developed to study enzyme function. This article focuses on the recent advances in determining the structural details and biosynthesis of arabinogalactan, lipoarabinomannan, and related glycoconjugates.
Topics: Antitubercular Agents; Biosynthetic Pathways; Galactans; Genome, Bacterial; Lipopolysaccharides; Molecular Biology; Mycobacterium
PubMed: 26104198
DOI: 10.1128/microbiolspec.MGM2-0013-2013 -
Journal of Clinical Microbiology Oct 2023Macrolides, such as clarithromycin, are crucial in the treatment of nontuberculous mycobacteria (NTM). NTM are notoriously innately drug resistant, which has made the...
Macrolides, such as clarithromycin, are crucial in the treatment of nontuberculous mycobacteria (NTM). NTM are notoriously innately drug resistant, which has made the dependence on macrolides for their treatment even more important. Not surprisingly, resistance to macrolides has been documented in some NTM, including and , which are the two NTM species most often identified in clinical isolates. Resistance is mediated by point mutations in the 23S ribosomal RNA or by methylation of the rRNA by a methylase (encoded by an gene). Chromosomally encoded genes have been identified in many of the macrolide-resistant isolates, but not in . Now, Brown-Elliott et al. (J Clin Microbiol 61:e00428-23, 2023, https://doi.org/10.1128/JCM.00428-23) describe the identification of a new variant, (55) which was found either on the chromosome or on a plasmid in highly macrolide-resistant clinical isolates of . The chromosomal (55) gene appears to be associated with mobile elements; one gene is within a putative transposon and the second is in a large (37 kb) insertion/deletion. The plasmid carrying (55) also encodes type IV and type VII secretion systems, which are often linked on large mycobacterial plasmids and are hypothesized to mediate plasmid transfer. While the conjugative transfer of the (55)-containing plasmid between NTM has yet to be demonstrated, the inferences are clear, as evidenced by the dissemination of plasmid-mediated drug resistance in other medically important bacteria. Here, we discuss the findings of Brown-Elliott et al. and the potential ramifications on treatment of NTM infections.
Topics: Humans; Anti-Bacterial Agents; Mycobacterium chelonae; Macrolides; Drug Resistance, Bacterial; Clarithromycin; Mycobacterium; Mycobacterium Infections, Nontuberculous; Nontuberculous Mycobacteria; Chromosomes
PubMed: 37724858
DOI: 10.1128/jcm.00628-23 -
Epidemiology and Infection Dec 2022A cross-sectional and retrospective study of patients with spp. in a Portuguese tertiary hospital, in 2009 and 2019, was performed to understand better the rise in...
A cross-sectional and retrospective study of patients with spp. in a Portuguese tertiary hospital, in 2009 and 2019, was performed to understand better the rise in isolations of nontuberculous mycobacteria (NTM). The number of patients with positive samples for spp. grew from 56 in 2009 to 83 in 2019. The proportion of NTM rose from 39.3% to 49.4% ( = 0.240), with being more frequent in 2009 and in 2019, and decreased from 60.7% to 50.6%. Higher age was associated with NTM in both years, and pulmonary disease and immunosuppression were associated with NTM in 2019 ( < 0.05), with weak to moderate correlation ( = 0.231-0.343). The overall rise of NTM, allied to their known capacity to resist antimicrobial therapy, alerts clinicians to the importance of recognising potential risk factors for infection and improving future prevention strategies.
Topics: Humans; Nontuberculous Mycobacteria; Mycobacterium Infections, Nontuberculous; Retrospective Studies; Cross-Sectional Studies; Mycobacterium avium Complex; Mycobacterium
PubMed: 36503567
DOI: 10.1017/S0950268822000899