Mycobacterium tuberculosis: Difference between revisions

Jump to navigation Jump to search
No edit summary
 
(35 intermediate revisions by 8 users not shown)
Line 1: Line 1:
__NOTOC__
__NOTOC__
{{Tuberculosis}}
{{Tuberculosis}}
{{CMG}}; {{AE}} {{JS}}
{{CMG}}; {{AE}} {{Mashal Awais}}; {{JS}}
{{About0|Tuberculosis}}
{{SK}} M. Tuberculosis


==Overview==
==Overview==
'''''Mycobacterium tuberculosis''''' is the [[bacterium]] responsible for [[tuberculosis]]. It is an [[aerobic]], [[capsule|non-encapsulated]], [[motility|non-motile]], [[acid-fast]] [[bacillus]].  M. tuberculosis belongs to the Mycobacterium tuberculosis complex, that also includes [[bacteria]], such as ''M. bovis'' and ''M. africanum''.  The bacterium has a very slow rate of [[replication]], and its [[genetic]] variations account for the geographical distribution of different [[strains]], and are involved in [[drug resistance]].  M. tuberculosis has [[tropism]] for different kinds of human cells, with preference for [[lung]] cells. It may infect different species, yet human beings are its most frequent [[natural reservoir]].
[[Mycobacterium tuberculosis]] is the [[bacterium]] responsible for [[tuberculosis]]. M. tuberculosis is an [[obligate aerobe]], [[capsule|non-encapsulated]], [[motility|non-motile]], [[acid-fast]] [[bacillus]]. .  M. tuberculosis is one of the '''Mycobacterium tuberculosis''' complex, which also includes [[bacteria]], such as [[Mycobacterium bovis|M. bovis]] and M. africanum.  The bacterium has a very slow rate of [[replication]], and its [[genetic]] variations account for the different [[strains]] and the growing [[drug resistance]].  M. tuberculosis has [[tropism]] for different kinds of human cells, with preference for cells of the [[lung]]. The main [[natural reservoir]] for ''M. [[tuberculosis]] are'' [[Human]] beings'';'' however, the [[bacteria]] can also [[Infection|infect]] other [[species]].


==Taxonomy==
==Taxonomy==
Cellular organisms; [[Bacteria]]; [[Actinobacteria]]; [[Actinobacteria]]; [[Actinobacteridae]]; [[Actinomycetales]]; [[Corynebacterineae]]; [[Mycobacteriaceae]]; ''[[Mycobacterium]]'';  Mycobacterium tuberculosis complex; ''M. tuberculosis''<ref name=NCBI>{{cite web | title = Poliovirus | url = http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=1773 }}</ref>
==Biology==
{| style="float: right;"
{| style="float: right;"
| [[File:M.tuberculosis1.jpg|200px|thumb|none|Computer-generated image of a cluster of rod-shaped drug-resistant Mycobacterium tuberculosis bacteria.<SMALL> ''Image provided by the CDC [http://phil.cdc.gov/phil/details.asp Centers for Disease Control and Prevention] ''<ref>{{Cite web | title = http://phil.cdc.gov/phil/details.asp | url = http://phil.cdc.gov/phil/details.asp}}</ref></SMALL>]]
|[[File:M.tuberculosis1.jpg|200px|thumb|none|Computer-generated image of a cluster of rod-shaped drug-resistant Mycobacterium tuberculosis bacteria.<SMALL> ''Image provided by the CDC [http://phil.cdc.gov/phil/details.asp Centers for Disease Control and Prevention] ''<ref>{{Cite web | title = http://phil.cdc.gov/phil/details.asp | url = http://phil.cdc.gov/phil/details.asp}}</ref></SMALL>]]
|-
|-
| [[File:M. tuberculosis2.jpg|200px|thumb|none|Thin agar culture plates reveal the results of a drug susceptibility test on Mycobacterium tuberculosis bacteria <SMALL> ''Image provided by the CDC [http://phil.cdc.gov/phil/details.asp Centers for Disease Control and Prevention] ''<ref>{{Cite web | title = http://phil.cdc.gov/phil/details.asp | url = http://phil.cdc.gov/phil/details.asp}}</ref></SMALL>]]
|[[File:M. tuberculosis2.jpg|200px|thumb|none|Thin agar culture plates reveal the results of a drug susceptibility test on Mycobacterium tuberculosis bacteria <SMALL> ''Image provided by the CDC [http://phil.cdc.gov/phil/details.asp Centers for Disease Control and Prevention] ''<ref>{{Cite web | title = http://phil.cdc.gov/phil/details.asp | url = http://phil.cdc.gov/phil/details.asp}}</ref></SMALL>]]
|}
|}
''Mycobacterium tuberculosis'' belongs to the Mycobacterium tuberculosis complex.  This complex includes ''M. tuberculosis'', ''M. bovis'', ''M. africanum'', ''M. canetti'', and ''M. microti''.<ref name="pmid21420161">{{cite journal| author=Lawn SD, Zumla AI| title=Tuberculosis. | journal=Lancet | year= 2011 | volume= 378 | issue= 9785 | pages= 57-72 | pmid=21420161 | doi=10.1016/S0140-6736(10)62173-3 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21420161  }} </ref>  
Cellular organisms; [[bacteria]]; [[Actinobacteria]]; [[Actinobacteria]]; [[Actinobacteridae]]; [[Actinomycetales]]; [[Corynebacterineae]]; [[Mycobacteriaceae]]; ''[[Mycobacterium]]''Mycobacterium tuberculosis complex; ''M. tuberculosis''<ref name="NCBI">{{cite web | title = Mycobacterium tuberculosis | url = http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=1773 }}</ref>
 
==Biology==


''M. tuberculosis'' is an [[obligate aerobe]], [[capsule|non-encapsulated]], [[motility|non-motile]], [[acid-fast]] [[bacillus]]. Slender, straight or slightly curved [[bacillus]] with rounded ends, occuring singly, in pairs or in small clumps. It does not form [[spores]] and its ideal growing environment includes tissues with high levels of oxygen. It cannot be considered gram positive or gram negative due to its high lipid cell wall, that is impermeable to the dyes until combined with an alcohol. On microscopic examination of [[sputum]] samples, the bacteria cannot be distinguished from other [[acid-fast]] bacteria, such as [[Nocardia]] app.<ref name="pmid21420161">{{cite journal| author=Lawn SD, Zumla AI| title=Tuberculosis. | journal=Lancet | year= 2011 | volume= 378 | issue= 9785 | pages= 57-72 | pmid=21420161 | doi=10.1016/S0140-6736(10)62173-3 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21420161  }} </ref>
* ''[[Mycobacterium tuberculosis]]'' belongs to the Mycobacterium tuberculosis complex.  This complex includes ''M. tuberculosis'', ''[[Mycobacterium bovis|M. bovis]]'', ''[[M. africanum]]'', ''M. canetti'', and [[M. microti.|''M. microti''.]]<ref name="pmid21420161">{{cite journal| author=Lawn SD, Zumla AI| title=Tuberculosis. | journal=Lancet | year= 2011 | volume= 378 | issue= 9785 | pages= 57-72 | pmid=21420161 | doi=10.1016/S0140-6736(10)62173-3 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21420161  }} </ref>


''M. tuberculosis'' has a very slow rate of replication, taking about 15 to 20 hours to divide. This characteristic, added to its ability to remain in latent state for long periods of time, account for the treatment duration required for infected patients.<ref name="pmid21420161">{{cite journal| author=Lawn SD, Zumla AI| title=Tuberculosis. | journal=Lancet | year= 2011 | volume= 378 | issue= 9785 | pages= 57-72 | pmid=21420161 | doi=10.1016/S0140-6736(10)62173-3 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21420161  }} </ref>
* ''M. tuberculosis'' is an [[obligate aerobe]], [[capsule|non-encapsulated]], [[motility|non-motile]], [[acid-fast]] [[bacillus]].
* Its shape is [[slender]], straight or slightly [[curved]] [[bacillus]] with rounded ends.
* It can be present [[singly]], in pairs or in small groups or [[clumps]].
* It cannot form [[spores]].
* It favors [[Tissue (biology)|tissues]] with high [[oxygen]] levels. 
* Due to the high [[lipid]] and [[mycolic acid]] content of its [[cell wall]], It stains weakly [[gram-positive]] or does not retain the [[dye]]. 
* [[Microscopic examination]] of [[sputum]] [[samples]] cannot differentiate it  from other [[acid-fast]] bacteria, such as [[Nocardia]] spp.<ref name="pmid21420161">{{cite journal| author=Lawn SD, Zumla AI| title=Tuberculosis. | journal=Lancet | year= 2011 | volume= 378 | issue= 9785 | pages= 57-72 | pmid=21420161 | doi=10.1016/S0140-6736(10)62173-3 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21420161  }} </ref> 
* ''M. [[tuberculosis]]'' [[divides]] every 15-20 hours which is considered an extremely low rate of [[Division (biology)|division]]. This feature, in addition to its ability to remain latent for long time, are responsible for the long [[treatment]] duration needed.<ref name="pmid21420161">{{cite journal| author=Lawn SD, Zumla AI| title=Tuberculosis. | journal=Lancet | year= 2011 | volume= 378 | issue= 9785 | pages= 57-72 | pmid=21420161 | doi=10.1016/S0140-6736(10)62173-3 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21420161  }} </ref>
* It can withstand dryness for weeks and also weak [[Disinfectant|disinfectants]].


Genetic variances in the genome of ''M. tuberculosis'' lead to important phenotypical changes. There are many different [[strains]] of the bacteria, however, 6 of them were noted to be associated with specific geographic areas. This data is important since 3 [[strains]], the Beijing family, strain W and the W-like strains, were noted to be associated with resistance to treatment drugs.<ref name="pmid19483712">{{cite journal| author=Smith NH, Hewinson RG, Kremer K, Brosch R, Gordon SV| title=Myths and misconceptions: the origin and evolution of Mycobacterium tuberculosis. | journal=Nat Rev Microbiol | year= 2009 | volume= 7 | issue= 7 | pages= 537-44 | pmid=19483712 | doi=10.1038/nrmicro2165 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19483712  }} </ref><ref name="pmid17448936">{{cite journal| author=Gagneux S, Small PM| title=Global phylogeography of Mycobacterium tuberculosis and implications for tuberculosis product development. | journal=Lancet Infect Dis | year= 2007 | volume= 7 | issue= 5 | pages= 328-37 | pmid=17448936 | doi=10.1016/S1473-3099(07)70108-1 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17448936  }} </ref>
* Genetic variations in the ''M. tuberculosis'' [[genome]] lead to important [[phenotypical]] changes. As a result, there are several variable [[strains]] of the [[bacteria]], six of which have particular [[Geographical isolation|geographical]] distribution. Three [[strains]], the ''[[Beijing family]]'', ''strain W'' and the ''W-like strains'', were reported to be associated with higher [[Incidence (epidemiology)|incidence]] of [[multi-drug resistance]].<ref name="pmid19483712">{{cite journal| author=Smith NH, Hewinson RG, Kremer K, Brosch R, Gordon SV| title=Myths and misconceptions: the origin and evolution of Mycobacterium tuberculosis. | journal=Nat Rev Microbiol | year= 2009 | volume= 7 | issue= 7 | pages= 537-44 | pmid=19483712 | doi=10.1038/nrmicro2165 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19483712  }} </ref><ref name="pmid17448936">{{cite journal| author=Gagneux S, Small PM| title=Global phylogeography of Mycobacterium tuberculosis and implications for tuberculosis product development. | journal=Lancet Infect Dis | year= 2007 | volume= 7 | issue= 5 | pages= 328-37 | pmid=17448936 | doi=10.1016/S1473-3099(07)70108-1 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17448936  }} </ref>


==Tropism==
==Tropism==
''M. tuberculosis'' can infect different cells of the human body, however, due to its preference for tissues with high oxygen levels, its cellular tropism is mostly directed towards lung cells.<ref name="pmid21420161">{{cite journal| author=Lawn SD, Zumla AI| title=Tuberculosis. | journal=Lancet | year= 2011 | volume= 378 | issue= 9785 | pages= 57-72 | pmid=21420161 | doi=10.1016/S0140-6736(10)62173-3 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21420161  }} </ref>
There is no particular tissue [[tropism]] for M. [[tuberculosis]] and it can infect almost all human tissues. However, M. [[tuberculosis]] prefers tissues with high levels of [[oxygen]] , hence, [[pulmonary tuberculosis]] has the highest rate. <ref name="pmid21420161">{{cite journal| author=Lawn SD, Zumla AI| title=Tuberculosis. | journal=Lancet | year= 2011 | volume= 378 | issue= 9785 | pages= 57-72 | pmid=21420161 | doi=10.1016/S0140-6736(10)62173-3 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21420161  }} </ref>
 
==Natural Reservoir==
==Natural Reservoir==
Human beings are the main [[natural reservoir]] for ''M. tuberculosis'', however, the bacteria may infect other [[species]].<ref name="pmid21420161">{{cite journal| author=Lawn SD, Zumla AI| title=Tuberculosis. | journal=Lancet | year= 2011 | volume= 378 | issue= 9785 | pages= 57-72 | pmid=21420161 | doi=10.1016/S0140-6736(10)62173-3 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21420161  }} </ref>
The main [[natural reservoir]] for ''M. [[tuberculosis]] are [[Human]] beings;'' however, the [[bacteria]] can also [[Infection|infect]] other [[species]].<ref name="pmid21420161">{{cite journal| author=Lawn SD, Zumla AI| title=Tuberculosis. | journal=Lancet | year= 2011 | volume= 378 | issue= 9785 | pages= 57-72 | pmid=21420161 | doi=10.1016/S0140-6736(10)62173-3 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21420161  }} </ref>
 
==Resistance==
Mycobacteria are killed at 60 degree celsius in 15-20 minutes.
They are sensitive to UV rays and sunlight.
They are relatively resistant to 5% phenol, 15% sulphuric acid, 5% oxalic acid, 4% sodium hydroxide.
The bacillus are destroyed by tincture of sodium in five minutes and by 80% ethanol in 2-10 minutes.


==References==
==References==
{{reflist|2}}
{{reflist|2}}
[[Category:Acid fast bacilli]]
[[Category:Acid fast bacilli]]
[[Category:Actinobacteria]]
[[Category:Actinobacteria]]
[[Category:Gram positive bacteria]]
[[Category:Gram positive bacteria]]
[[Category:Infectious disease]]

Latest revision as of 06:17, 1 March 2021

Tuberculosis Microchapters

Home

Patient Information

Overview

Historical Perspective

Classification

Pathophysiology

Causes

Differentiating Tuberculosis from other Diseases

Epidemiology and Demographics

Risk Factors

Screening

Natural History, Complications and Prognosis

Children

HIV Coinfection

Diagnosis

History and Symptoms

Physical Examination

Laboratory Findings

Electrocardiogram

Chest X Ray

CT

MRI

Echocardiography or Ultrasound

Other Imaging Findings

Other Diagnostic Studies

Treatment

Medical Therapy

Special Conditions
Drug-resistant

Surgery

Primary Prevention

Secondary Prevention

Cost-Effectiveness of Therapy

Future or Investigational Therapies

Case Studies

Case #1

Mycobacterium tuberculosis On the Web

Most recent articles

Most cited articles

Review articles

CME Programs

Powerpoint slides

Images

American Roentgen Ray Society Images of Mycobacterium tuberculosis

All Images
X-rays
Echo & Ultrasound
CT Images
MRI

Ongoing Trials at Clinical Trials.gov

US National Guidelines Clearinghouse

NICE Guidance

FDA on Mycobacterium tuberculosis

CDC on Mycobacterium tuberculosis

Mycobacterium tuberculosis in the news

Blogs on Mycobacterium tuberculosis

Directions to Hospitals Treating Tuberculosis

Risk calculators and risk factors for Mycobacterium tuberculosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mashal Awais, M.D.[2]; João André Alves Silva, M.D. [3]

This page is about microbiologic aspects of the organism(s).  For clinical aspects of the disease, see Tuberculosis.

Synonyms and keywords: M. Tuberculosis

Overview

Mycobacterium tuberculosis is the bacterium responsible for tuberculosis. M. tuberculosis is an obligate aerobe, non-encapsulated, non-motile, acid-fast bacillus. . M. tuberculosis is one of the Mycobacterium tuberculosis complex, which also includes bacteria, such as M. bovis and M. africanum. The bacterium has a very slow rate of replication, and its genetic variations account for the different strains and the growing drug resistance. M. tuberculosis has tropism for different kinds of human cells, with preference for cells of the lung. The main natural reservoir for M. tuberculosis are Human beings; however, the bacteria can also infect other species.

Taxonomy

Computer-generated image of a cluster of rod-shaped drug-resistant Mycobacterium tuberculosis bacteria. Image provided by the CDC Centers for Disease Control and Prevention [1]
Thin agar culture plates reveal the results of a drug susceptibility test on Mycobacterium tuberculosis bacteria Image provided by the CDC Centers for Disease Control and Prevention [2]

Cellular organisms; bacteria; Actinobacteria; Actinobacteria; Actinobacteridae; Actinomycetales; Corynebacterineae; Mycobacteriaceae; Mycobacterium; Mycobacterium tuberculosis complex; M. tuberculosis[3]

Biology

Tropism

There is no particular tissue tropism for M. tuberculosis and it can infect almost all human tissues. However, M. tuberculosis prefers tissues with high levels of oxygen , hence, pulmonary tuberculosis has the highest rate. [4]

Natural Reservoir

The main natural reservoir for M. tuberculosis are Human beings; however, the bacteria can also infect other species.[4]

References

  1. "http://phil.cdc.gov/phil/details.asp". External link in |title= (help)
  2. "http://phil.cdc.gov/phil/details.asp". External link in |title= (help)
  3. "Mycobacterium tuberculosis".
  4. 4.0 4.1 4.2 4.3 4.4 Lawn SD, Zumla AI (2011). "Tuberculosis". Lancet. 378 (9785): 57–72. doi:10.1016/S0140-6736(10)62173-3. PMID 21420161.
  5. Smith NH, Hewinson RG, Kremer K, Brosch R, Gordon SV (2009). "Myths and misconceptions: the origin and evolution of Mycobacterium tuberculosis". Nat Rev Microbiol. 7 (7): 537–44. doi:10.1038/nrmicro2165. PMID 19483712.
  6. Gagneux S, Small PM (2007). "Global phylogeography of Mycobacterium tuberculosis and implications for tuberculosis product development". Lancet Infect Dis. 7 (5): 328–37. doi:10.1016/S1473-3099(07)70108-1. PMID 17448936.