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Journal of Clinical Microbiology Jan 2018species are a complex group of organisms considered to belong to the aerobic actinomycetes. Of the validly described species, many have been implicated as the cause of... (Review)
Review
species are a complex group of organisms considered to belong to the aerobic actinomycetes. Of the validly described species, many have been implicated as the cause of serious human infections, especially in immunocompromised patients. The genus has a complicated taxonomic history; this is especially true for , the type species of the genus and previously the most frequently reported nocardial taxon from human specimens. We provide background on the current taxonomy of , with a focus on clinically relevant species, and discuss the currently available methods used to accurately identify isolates to the species, complex, or group level.
Topics: Algorithms; Bacteriological Techniques; Humans; Multilocus Sequence Typing; Nocardia; Nocardia Infections; Nocardia asteroides; Phylogeny; Species Specificity; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
PubMed: 29118169
DOI: 10.1128/JCM.01419-17 -
Clinical Microbiology Reviews Dec 2022This review serves as an update to the previous review by Brown-Elliott et al. published in 2006 (B. A. Brown-Elliott, J. M. Brown, P. S. Conville, and R. J. Wallace.... (Review)
Review
This review serves as an update to the previous review by Brown-Elliott et al. published in 2006 (B. A. Brown-Elliott, J. M. Brown, P. S. Conville, and R. J. Wallace. Jr., Clin Microbiol Rev 19:259-282, 2006, https://doi.org/10.1128/CMR.19.2.259-282.2006). Included is a discussion on the taxonomic expansion of the genus, current identification methods, and the impact of new technology (including matrix-assisted laser desorption ionization-time of flight [MALDI-TOF] and whole genome sequencing) on diagnosis and treatment. Clinical manifestations, the epidemiology, and geographic distribution are briefly discussed. An additional section on actinomycotic mycetoma is added to address this often-neglected disease.
Topics: Nocardia; Bacterial Typing Techniques; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
PubMed: 36314911
DOI: 10.1128/cmr.00027-21 -
Clinical Microbiology Reviews Apr 2006The recent explosion of newly described species of Nocardia results from the impact in the last decade of newer molecular technology, including PCR restriction enzyme... (Review)
Review
The recent explosion of newly described species of Nocardia results from the impact in the last decade of newer molecular technology, including PCR restriction enzyme analysis and 16S rRNA sequencing. These molecular techniques have revolutionized the identification of the nocardiae by providing rapid and accurate identification of recognized nocardiae and, at the same time, revealing new species and a number of yet-to-be-described species. There are currently more than 30 species of nocardiae of human clinical significance, with the majority of isolates being N. nova complex, N. abscessus, N. transvalensis complex, N. farcinica, N. asteroides type VI (N. cyriacigeorgica), and N. brasiliensis. These species cause a wide variety of diseases and have variable drug susceptibilities. Accurate identification often requires referral to a reference laboratory with molecular capabilities, as many newer species are genetically distinct from established species yet have few or no distinguishing phenotypic characteristics. Correct identification is important in deciding the clinical relevance of a species and in the clinical management and treatment of patients with nocardial disease. This review characterizes the currently known pathogenic species of Nocardia, including clinical disease, drug susceptibility, and methods of identification.
Topics: Anti-Bacterial Agents; Bacteriological Techniques; Culture Media; DNA, Bacterial; Humans; Lung Diseases; Microbial Sensitivity Tests; Nocardia; Nocardia Infections; Polymerase Chain Reaction; Polymorphism, Restriction Fragment Length; RNA, Bacterial; RNA, Ribosomal, 16S; Skin Diseases; Species Specificity
PubMed: 16614249
DOI: 10.1128/CMR.19.2.259-282.2006 -
Microbial Physiology 2021Nocardia spp. are filamentous Actinobacteria of the order Corynebacteriales and mostly known for their ability to cause localized and systemic infections in humans.... (Review)
Review
Nocardia spp. are filamentous Actinobacteria of the order Corynebacteriales and mostly known for their ability to cause localized and systemic infections in humans. However, the onset and progression of nocardiosis is only poorly understood, in particular the mechanisms of strain-specific presentations. Recent genome sequencing has revealed an extraordinary capacity for the production of specialized small molecules. Such secondary metabolites are often crucial for the producing microbe to survive the challenges of different environmental conditions. An interesting question thus concerns the role of these natural products in Nocardia-associated pathogenicity and immune evasion in a human host. In this review, a summary and discussion of Nocardia metabolites is presented, which may play a part in nocardiosis because of their cytotoxic, immunosuppressive and metal-chelating properties or otherwise vitally important functions. This review also contains so far unpublished data concerning the biosynthesis of these molecules that were obtained by detailed bioinformatic analyses.
Topics: Actinobacteria; Biological Products; Humans; Nocardia; Nocardia Infections; Virulence
PubMed: 34139700
DOI: 10.1159/000516864 -
Revista Do Instituto de Medicina... 2014New methodologies were developed for the identification of Nocardia but the initial diagnosis still requires a fast and accurate method, mainly due to the similarity to...
New methodologies were developed for the identification of Nocardia but the initial diagnosis still requires a fast and accurate method, mainly due to the similarity to Mycobacterium, both clinical and bacteriologically. Growth on Löwenstein-Jensen (LJ) medium, presence of acid-fast bacilli through Ziehl-Neelsen staining, and colony morphology can be confusing aspects between Nocardia and Mycobacterium. This study describes the occurrence of Nocardia spp. in a mycobacterial-reference laboratory, observing the main difficulties in differentiating Nocardia spp. from Mycobacterium spp., and correlating isolates with nocardiosis cases. Laboratory records for the period between 2008 and 2012 were analyzed, and the isolates identified as Nocardia sp. or as non-acid-fast filamentous bacilli were selected. Epidemiological and bacteriological data were analyzed as well. Thirty-three isolates identified as Nocardia sp. and 22 as non-acid-fast bacilli were selected for this study, and represented 0.12% of isolates during the study period. The presumptive identification was based on macroscopic and microscopic morphology, resistance to lysozyme and restriction profiles using the PRA-hsp65 method. Nocardia spp. can grow on media for mycobacteria isolation (LJ and BBL MGIT™) and microscopy and colony morphology are very similar to some mycobacteria species. Seventeen patients (54.8%) were reported and treated for tuberculosis, but presented signs and symptoms of nocardiosis. It was concluded that the occurrence of Nocardia sp. during the study period was 0.12%. Isolates with characteristics of filamentous bacilli, forming aerial hyphae, with colonies that may be pigmented, rough and without the BstEII digestion pattern in PRA-hsp65 method are suggestive of Nocardia spp. For a mycobacterial routine laboratory, a flow for the presumptive identification of Nocardia is essential, allowing the use of more accurate techniques for the correct identification, proper treatment and better quality of life for patients.
Topics: Adult; Bacteriological Techniques; Female; Humans; Male; Mycobacterium; Mycobacterium Infections; Nocardia; Nocardia Infections; Retrospective Studies; Sensitivity and Specificity
PubMed: 25229219
DOI: 10.1590/s0036-46652014000500005 -
International Journal of Systematic and... Oct 2020The taxonomic positions of two novel aerobic, Gram-stain-positive Actinobacteria, designated RB20 and RB56, were determined using a polyphasic approach. Both were...
The taxonomic positions of two novel aerobic, Gram-stain-positive Actinobacteria, designated RB20 and RB56, were determined using a polyphasic approach. Both were isolated from the fungus-farming termite . Results of 16S rRNA gene sequence analysis revealed that both strains are members of the genus with the closest phylogenetic neighbours JCM12860 (98.9 %) and DSM44481 (98.5 %) for RB20 and DSM 44801 (98.3 %), DSM 44290 (98.3 %) and JCM 19832 (98.2 %) for RB56. Digital DNA-DNA hybridization (DDH) between RB20 and JCM12860 and DSM 44481 resulted in similarity values of 33.9 and 22.0 %, respectively. DDH between RB56 and DSM44801 and DSM44290 showed similarity values of 20.7 and 22.3 %, respectively. In addition, wet-lab DDH between RB56 and JCM19832 resulted in 10.2 % (14.5 %) similarity. Both strains showed morphological and chemotaxonomic features typical for the genus , such as the presence of -diaminopimelic acid (Apm) within the cell wall, arabinose and galactose as major sugar components within whole cell-wall hydrolysates, the presence of mycolic acids and major phospholipids (diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol), and the predominant menaquinone MK-8 (H, ω-cyclo). The main fatty acids for both strains were hexadecanoic acid (C), 10-methyloctadecanoic acid (10-methyl C) and -9-octadecenoic acid (C ω9). We propose two novel species within the genus : sp. nov. with the type strain RB20 (=VKM Ac-2841=NRRL B65541) and sp. nov. with the type strain RB56 (=VKM Ac-2842=NRRL B65542).
Topics: Animals; Bacterial Typing Techniques; Base Composition; DNA, Bacterial; Diaminopimelic Acid; Fatty Acids; Gastrointestinal Microbiome; Isoptera; Nocardia; Phospholipids; Phylogeny; RNA, Ribosomal, 16S; South Africa; Vitamin K 2
PubMed: 32815801
DOI: 10.1099/ijsem.0.004398 -
BMC Biology Nov 2022Nocardia is a facultative intracellular pathogen that infects the lungs and brains of immunocompromised patients with consequences that can be fatal. The incidence of...
BACKGROUND
Nocardia is a facultative intracellular pathogen that infects the lungs and brains of immunocompromised patients with consequences that can be fatal. The incidence of such infections is rising, immunocompetent individuals are also being infected, and there is a need to learn more about this neglected bacterial pathogen and the interaction with its human host.
RESULTS
We have applied dual RNA-seq to assess the global transcriptome changes that occur simultaneously in Nocardia farcinica (N. farcinica) and infected human epithelial alveolar host cells, and have tested a series of mutants in this in vitro system to identify candidate determinants of virulence. Using a mouse model, we revealed the profiles of inflammation-related factors in the lung after intranasal infection and confirmed that nbtB and nbtS are key virulence genes for Nocardia infection in vivo. Regarding the host response to infection, we found that the expression of many histones was dysregulated during the infection of lung cells, indicating that epigenetic modification might play a crucial role in the host during Nocardia infection. In our mouse model, Nocardia infection led to neurological symptoms and we found that 15 of 22 Nocardia clinical strains tested could cause obvious PD-like symptoms. Further experiments indicated that Nocardia infection could activate microglia and drive M1 microglial polarization, promote iNOS and CXCL-10 production, and cause neuroinflammation in the substantia nigra, all of which may be involved in causing PD-like symptoms. Importantly, the deletion of nbtS in N. farcinica completely attenuated the neurological symptoms.
CONCLUSIONS
Our data contribute to an in-depth understanding of the characteristics of both the host and Nocardia during infection and provide valuable clues for future studies of this neglected human pathogen, especially those addressing the underlying causes of infection-related neurological symptoms.
Topics: Humans; Nocardia; Nocardia Infections; Immunocompromised Host; Virulence
PubMed: 36352407
DOI: 10.1186/s12915-022-01452-7 -
Journal of Bacteriology Apr 1967Shadowed motile elements from actinomycetes were observed with an electron microscope. Included were three strains of Actinoplanes, two of Ampullariella, two of...
Shadowed motile elements from actinomycetes were observed with an electron microscope. Included were three strains of Actinoplanes, two of Ampullariella, two of Dermatophilus, two of Spirillospora, and four of "Nocardia" turbata. In addition, three types of previously undescribed actionmycetes were represented: (i) the C(4) group (four strains) forming substrate mycelium breaking into motile rods; (ii) strain 9-41, forming Microellobosporia-like sporangia with motile spores; and (iii) strain P(2), forming aerial hyphae releasing motile cocci when put in water. All the known chemical cell wall types of actinomycetes except the Nocardia asteroides type and the Actinomyces israeli type were represented in this array of motile actinomycetes. Motile elements were, depending on the genus, cocci, rods (often curved), or pyriform. Flagella were always in tufts (or single), never peritrichous. A relationship seems to exist between the location of the tuft and the cell wall composition. The spores of one strain of Actinoplanes were herniated, thus resembling plasmoptysis forms of bacteria.
Topics: Actinomycetales; Amino Acids; Carbohydrates; Cell Wall; Flagella; Microscopy, Electron; Nocardia; Pimelic Acids
PubMed: 6032515
DOI: 10.1128/jb.93.4.1446-1451.1967 -
Drug Discoveries & Therapeutics May 2021Nocardia is a ubiquitous environmental microbe that causes nocardiosis against immunosuppressed and immunocompromised hosts. The assay system for the quantitative... (Comparative Study)
Comparative Study
Nocardia is a ubiquitous environmental microbe that causes nocardiosis against immunosuppressed and immunocompromised hosts. The assay system for the quantitative evaluation of virulence of Nocardia sp. or therapeutic effectiveness of antimicrobials for treatment of nocardiosis is not established so far. In this study, we established an infection model of Nocardia sp. using silkworm as an alternative animal model. We found that all tested Nocardia sp. such as Nocardia asiatica, Nocardia elegans, Nocardia exalbida, Nocardia farcinica, and Nocardia nova killed silkworm and their killing ability were different by species. N. farcinica showed higher pathogenicity among tested strain, similar to the mouse model as previously reported. In addition, we found that antimicrobials such as amikacin and minocycline showed therapeutic effectiveness in silkworms infected with N. farcinica, and we could determine effective doses 50 (ED₅₀) values. These results suggest that silkworm is a useful alternative animal to evaluate the pathogenicity of Nocardia pathogen and the therapeutic effects of antimicrobials against Nocardia sp. in a quantitative manner.
Topics: Animals; Anti-Bacterial Agents; Bombyx; Dose-Response Relationship, Drug; Humans; Immunocompromised Host; Japan; Mice; Models, Animal; Nocardia; Nocardia Infections; Treatment Outcome; Virulence
PubMed: 33952779
DOI: 10.5582/ddt.2021.01035 -
Clinical Microbiology Reviews Apr 1994The nocardiae are bacteria belonging to the aerobic actinomycetes. They are an important part of the normal soil microflora worldwide. The type species, Nocardia... (Review)
Review
The nocardiae are bacteria belonging to the aerobic actinomycetes. They are an important part of the normal soil microflora worldwide. The type species, Nocardia asteroides, and N. brasiliensis, N. farcinica, N. otitidiscaviarum, N. nova, and N. transvalensis cause a variety of diseases in both normal and immunocompromised humans and animals. The mechanisms of pathogenesis are complex, not fully understood, and include the capacity to evade or neutralize the myriad microbicidal activities of the host. The relative virulence of N. asteroides correlates with the ability to inhibit phagosome-lysosome fusion in phagocytes; to neutralize phagosomal acidification; to detoxify the microbicidal products of oxidative metabolism; to modify phagocyte function; to grow within phagocytic cells; and to attach to, penetrate, and grow within host cells. Both activated macrophages and immunologically specific T lymphocytes constitute the major mechanisms for host resistance to nocardial infection, whereas B lymphocytes and humoral immunity do not appear to be as important in protecting the host. Thus, the nocardiae are facultative intracellular pathogens that can persist within the host, probably in a cryptic form (L-form), for life. Silent invasion of brain cells by some Nocardia strains can induce neurodegeneration in experimental animals; however, the role of nocardiae in neurodegenerative diseases in humans needs to be investigated.
Topics: AIDS-Related Opportunistic Infections; Animals; Brain Diseases; Humans; Nocardia; Nocardia Infections; Phagocytosis
PubMed: 8055469
DOI: 10.1128/CMR.7.2.213