The mycobacteria: an introduction to nomenclature and pathogenesis (original) (raw)
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Overview of Mycobacterium: A Review
European Journal of Molecular & Clinical Medicine, 2021
Mycobacterium is still is one of the major causes of mortality, since two million people die each year from this malady. Currently, there are over 170 recognized species of Mycobacterium, the only genus in the family Mycobacteriaceae. Organisms belonging to this genus are quite diverse with respect to their ability to cause disease in humans; some are strict pathogens, while others are opportunistic pathogens or nonpathogenic. Similar to other major groups of bacteria, the mycobacteria have undergone an extraordinary expansion in the number of different species over the last 2 decades, due in large part to the discriminatory power of gene sequencing, which phenotypic methods cannot achieve. This discriminatory power is such that phenotypic traits, i.e., biochemical and cultural characteristics, are no longer acceptable for the identification of mycobacteria. M. tuberculosis strains are reportedly more virulent than others, as defined by increased transmissibility as well as being associated with higher morbidity and mortality in infected individuals. As more clinical laboratories use molecular or other methods, such as mass spectrometry, for identification, our understanding of clinical significance will change and evolve as the number of case reports regarding the "new" species increase; it may well be that the role of many of the newly described mycobacterial species has been underestimated either because of misidentification or because the species were unrecognized. Molecular typing methods have greatly improved our understanding of the biology of mycobacteria and provide powerful tools to combat the diseases caused by these pathogens. The utility of various typing methods depends on the Mycobacterium species under investigation as well as on the research question.. Within this review, we summarize currently available molecular methods for strain typing of M. tuberculosis. For the various methods, technical practicalities as well as discriminatory power and accomplishments are reviewed. General Description of Taxonomy and Nomenclature The discovery of leprosy bacillus (originally named Bacillus leprosy) in 1880, and of tubercle bacillus (named Bacterium tuberculosis) in 1883, led to the first steps in the classification of mycobacteria. These organisms were renamed Mycobacterium leprae and Mycobacterium tuberculosis by Lehmann and Neumann and grouped within the genus Mycobacterium, which is the single genus within the Mycobacteriaceae family, in the Actinomycetales order and Actinomycetes class. Bacteria were first classified as plants constituting the class Schizomycetes, which along with the Schizophyceae (blue green algae/Cyanobacteria) formed the phylum Schizophyta. Despite there being little agreement
A simple chemical test to distinguish mycobacteria from other mycolic-acid-containing actinomycetes
Journal of general microbiology, 1993
Two hundred and fifty-two representatives of the general Corynebacterium, Gordona, Mycobacterium, Nocardia, Rhodococcus and Tsukamurella were degraded by alkaline hydrolysis and their mycolic acids extracted as methyl esters following phase-transfer-catalysed esterification. When the mycolic acid methyl esters were treated with a mixture of acetonitrile and toluene all mycobacterial mycolates formed copious white precipitates whereas all but 5 out of the 106 non-mycobacterial mycolates remained in solution. The precipitated methyl mycolates and the dried soluble mycolates were compared by pyrolysis gas chromatography and silica gel thin-layer chromatography. On pyrolysis, the precipitated methyl mycolates from mycobacteria yielded fatty acid methyl esters with 20 to 26 carbon atoms whereas those from the remaining taxa produced shorter-chain esters. Mycobacteria and Tsukamurella paurometabola gave multispot mycolic acid patterns on thin-layer chromatography of their methyl esters wh...
European Journal of …, 2008
Recently, the incidence of human mycobacterial infections due to species other than M. tuberculosis has increased worldwide. Since disease control depends on appropriate antimicrobial therapy, the precise identification of these species of clinical importance has become a major public health concern. Identification of mycobacteria has been hampered because of the lack of specific, rapid, and inexpensive methods. Therefore, we aimed at designing and validating a bacterial lysate-based polymerase chain reaction identification scheme. This scheme can classify clinical isolates into: (1) the genus Mycobacterium, (2) the M. tuberculosis complex, (3) the nontuberculous mycobacteria, and (4) the species M. avium, M. intracellulare, M. abscessus, M. chelonae, M. fortuitum and M. bovis of clinical importance, and M. gordonae, the most commonly encountered nonpathogenic species in clinical laboratories. By using M. fortuitum and M. avium lysates as models, the method sensitivity was determined to be 372 pg of DNA. In a blind parallel comparison between our approach and conventional biochemical tests, both assays correctly categorized 75 patient's mycobacterial isolates. However, our approach only required 4-9 h for categorization compared with at least 15 days by conventional tests. Furthermore, our methodology could also detect M. fortuitum and M. avium from liquid cultures, after only 2 and 6 days, respectively, of incubation. Our new identification scheme is therefore sensitive, specific, rapid, and economic. Additionally, it can help to provide proper treatment to patients, to control these diseases, and to improve our knowledge of the epidemiology of mycobacteriosis, all urgently needed, particularly in developing countries. Mycobacterial diseases in humans can be caused by species belonging to the M. tuberculosis complex (MTC, which includes the species M. tuberculosis, M. bovis, M. africanum, M. canetii, and M. microti) and some nontuberculous mycobacteria (NTM) [1]. The HIV epidemic not only revealed that other mycobacteria other than M. tuberculosis can frequently cause pulmonary-[2, 3] and extrapulmonary-mycobacteriosis in HIV-infected patients [2, 4] but in immunocompetent subjects as well [2, 5]. For example, in some developing countries, M. avium complex (MAC) appears to be the second most common group causing pulmonary-mycobacteriosis after M. tuberculosis [2, 3, 5]. Other implicated species include M. bovis, M. kansasii, M. fortuitum, M. abscessus and M. chelonae [4-6], all of which present clinical features that may resemble those of
Clinical Microbiology Reviews, 2001
SUMMARYMycobacterium tuberculosis is the etiologic agent of tuberculosis and can be accurately detected by laboratories using commercial genetic tests. Nontuberculosis mycobacteria (NTM) causing other mycobacterioses can be difficult to identify. The identification processes are confounded by an increasing diversity of newly characterized NTM species. The ubiquitous nature of NTM, combined with their potential to be opportunistic pathogens in immunocompromised as well as nonimmunodeficient patients, further complicates the problem of their identification. Since clinical case management varies depending on the etiologic agent, laboratories must identify the species in a timely manner. However, only a few identification methods can detect the species diversity within the Mycobacterium genus. Over the last decade, high-performance liquid chromatography analysis of the mycolic acids has become an accepted method for identification of mycobacteria. In this review, we assess its developme...
Veterinární medicína, 2001
Molecular biology methods offer new opportunities to differentiate, identify and type bacterial species and strains. These methods use the variability of nucleic sequences of genes such as 16S rDNA, beta subunit RNA-ase (rpoB), gyrase (gyrB), rDNA internal transcribed spacer and other genes. The aim of this paper is to provide comprehensive information about the methods available to differentiate and identify species of mycobacteria at the DNA sequence level. The methods discussed in the review include PCR, PCR-REA, sequencing analysis, spoligotyping and DNA fingerprinting. These methods have been applied to both the “universal” part of the genome and to specific mycobacterial genes.
Simple and rapid identification of different species of Mycobacteria by PCR
Molecular and Cellular Probes, 1999
A simple polymerase chain reaction (PCR) assay for rapid identification of different species of mycobacteria was developed. This PCR is based on the use of conserved sequences to amplify the genome of several mycobacterial species. The amplification patterns obtained were specific and reproducible for the species tested. In particular, we could identifyMycobacterium tuberculosisandMycobacterium bovis(both produced the same pattern),Mycobacterium avium, Mycobacterium kansasii, Mycobacterium xenopi, Mycobacterium chelonae, Mycobacterium peregrinum, Mycobacterium fortuitum, Mycobacterium gordonaeandMycobacterium smegmatis. Moreover, due to the numerous copies of the target sequences present in the genome, the PCR showed a very high level of sensitivity.
Identification of mycobacteria species by molecular methods
International Wound Journal, 2019
In this study, mycobacteria, which were previously identified as Mycobacterium tuberculosis complex (MTC), and mycobacteria other than tuberculosis (MOTT) with cord factor and the p‐nitro‐alpha‐acetyl‐amino‐beta‐hydroxypropiophenone (NAP) test were reanalysed using the polymerase chain reaction—restriction fragment length polymorphism (PCR‐RFLP) analysis method in order to confirm the identification, and at the same time, species accepted as MOTT were identified. Although the results of the NAP test were obtained within 3‐5 days, the PCR‐RFLP results were obtained in 1 day. Ten species identified as MTC with the NAP test and cord factor were confirmed with the PCR‐RFLP method. Fourteen species accepted as MOTT were identified as Mycobacterium species with the evaluation of the bands observed after the restriction of PCR product with the PCR‐RFLP method. These were as follows: three species Mycobacterium intracellulare type I, two species Mycobacterium phlei, two species Mycobacteriu...
INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY, 2009
Mycobacterium riyadhense sp. nov., a nontuberculous species identified as Mycobacterium tuberculosis complex by a commercial line-probe assay A non-chromogenic, slowly growing Mycobacterium strain was isolated from a maxillary sinus lavage from a symptomatic patient in Riyadh, Saudi Arabia. It was initially identified as a member of the Mycobacterium tuberculosis complex by a commercial line-probe assay. Its 16S rRNA, hsp65 and rpoB gene and 16S-23S internal transcribed spacer sequences were unique; phylogenetic analysis based on the 16S rRNA gene sequence groups this organism close to Mycobacterium szulgai and Mycobacterium malmoense. Its unique biochemical properties and mycolic acid profile support separate species status. We propose the name Mycobacterium riyadhense sp. nov. to accommodate this strain. The type strain is NLA000201958 T (5CIP 109808 T 5DSM 45176 T ).
Molecular biology of mycobacteria
British medical bulletin, 1988
MOLECULAR BIOLOGY OF THE MYCOBACTERIA The molecular biology of the mycobacteria is poised at the threshold of making major contributions to the understanding of the biochemistry and pathogenic mechanisms involved in mycobacterial infections. The application of molecular biology to the study of mycobacteria has recently begun, with preliminary studies on the nucleic acids of mycobacteria, cloning and expression of a number of mycobacterial genes and the development of mycobacteria themselves as gene cloning systems. In this review, we will discuss the progress that has been made so far and the likely direction of future work. The nucleic acids of mycobacteria Both DNA and RNA have been isolated from mycobacteria, including armadillo-grown Mycobacterium leprae. They belong to the high guanine plus cytosine (G+C) Gram-positive group of bacteria; the cultivable mycobacteria have G+C in the range 60-67%, while M. leprae's G+C content is somewhat lower, at 56%.1 The genome size for M. tuberculosis is similar to that for Escherichia coli (2' 5 x 109 M,), while that for M. leprae is smaller (1•3-2•2 x 109 M,).2 Plasmids and phages have been isolated from cultivable mycobacteria, but not, probably for technical reasons, from M. leprae. There is a sugestion that plasmids isolated from members of the