Mycobacterium tuberculosis: Difference between revisions

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__NOTOC__
__NOTOC__
{{Tuberculosis}}
{{Tuberculosis}}
{{CMG}}; {{AE}} {{JS}}
{{CMG}}; {{AE}} {{Mashal Awais}}; {{JS}}
 
{{About0|Tuberculosis}}
{{SK}} M. 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 different [[strains]] and the growing [[drug resistance]].  M. tuberculosis has [[tropism]] for different kinds of human cells, with preference for cells of the [[lung]]. It may infect different species, yet human beings are its 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==
{| 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>]]
|}
|}
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>
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==
==Biology==
''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>


''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 the high lipid content of the [[cell wall]], which is impermeable to the dyes used until combined with an alcohol.  On microscopic examination of [[sputum]] samples, the bacteria cannot be distinguished 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'' has a very slow rate of replication, taking about 15 to 20 hours to divide. This characteristic, added to its ability to remain in the latent state for long periods of time, account for the long treatment duration required.<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'' 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 ''M. tuberculosis'' [[genome]] lead to important [[phenotypical]] changes. There are many different [[strains]] of the bacteria, 6 of which have specific geographical distribution. Three [[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'' does not have specific tissue tropism and is capable of infecting almost all human tissues. However, ''M. tuberculosis'' strives most in tissues with high oxygen levels, hence the high rate of pulmonary tuberculosis. <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>
 
==Treatment==
===Antimicrobial regimen===
* Standard Regimens for New Patients <ref>{{cite book | title = Treatment of tuberculosis guidelines | publisher = World Health Organization | location = Geneva | year = 2010 | isbn = 9789241547833 }}</ref>
:* Adult
::* Initial phase
:::* Preferred regimen: [[Isoniazid]] 300 mg PO (5 mg/kg/day) {{and}} [[Rifampicin]] 600 mg PO (10 mg/kg/day) {{and}} [[Pyrazinamide]] 2 g PO (25 mg/kg/day) {{and}} [[Ethambutol]] 1.6 g PO (15 mg/kg/day), each drug daily for 8 weeks
:::* Alternative regimen (1): [[Isoniazid]] 300 mg/day PO for 2 weeks (5 mg/kg/day) {{and}} [[Rifampicin]] 600 mg/day PO for 2 weeks (10 mg/kg/day) {{and}} [[Pyrazinamide]] 2 g/day PO for 2 weeks (25 mg/kg/day) {{and}} [[Ethambutol]] 1.6 g PO for 2 weeks (15 mg/kg/day), followed by [[Isoniazid]] 300 mg/day PO twice weekly for 6 weeks (5 mg/kg/day) {{and}} [[Rifampicin]] 600 mg/day PO twice weekly for 6 weeks (10 mg/kg/day) {{and}} [[Pyrazinamide]] 2 g/day PO twice weekly for 6 weeks {{and}} [[Ethambutol]] 1.6 g PO for 2 weeks (15 mg/kg/day)
:::* Alternative regimen (2): [[Isoniazid]] 300 mg/day PO thrice weekly for 8 weeks (5 mg/kg/day) {{and}} [[Rifampicin]] 600 mg/day P.O thrice weekly for 8 weeks (10 mg/kg/day) {{and}} [[Pyrazinamide]] 2g/day PO thrice weekly for 8 week (25 mg/kg/day) {{and}} [[Ethambutol]] 1.6 g PO thrice weekly for 8 weeks (15 mg/kg/day)
::* Continuation phase
:::* Preferred regimen (1): [[Isoniazid]] 300 mg daily PO (5 mg/kg/day) {{and}} [[Rifampicin]] 600 mg daily PO (10 mg/kg/day) for 18 weeks
 
:::* Preferred regimen (2): [[Isoniazid]] 300 mg PO twice weekly (5 mg/kg/day) {{and}} [[Rifampicin]] 600 mg/day PO twice weekly (10 mg/kg/day) for 18 weeks
:::* Alternative regimen (1): [[Isoniazid]] 300 mg/day PO biweekly for 18 weeks (5 mg/kg/day) {{and}} [[Rifampicin]] 600 mg/day PO biweekly for 18 weeks (10 mg/kg/day)
:::* Alternative regimen (2): [[Isoniazid]] 300 mg/day PO thrice weekly for 18 weeks (5 mg/kg/day) {{and}} [[Rifampicin]] 600 mg/day PO thrice weekly for 18 weeks (10 mg/kg/day)
:* Pediatric
::* Initial phase 
:::* Preferred regimen: [[Isoniazid]] 10 mg/kg PO (Max: 300 mg/day) {{and}} [[Rifampicin]] 15 mg/kg PO (Max: 600 mg/day) {{and}} [[Pyrazinamide]] 35 mg/kg PO (Max: 2 g/day) {{and}} [[Ethambutol]] 20 mg/kg PO (Max: 1.6 g/day), each for 8 weeks
::* Continuation phase
:::* Preferred regimen: [[Isoniazid]] 10 mg/kg PO (Max: 300 mg/day) {{and}} [[Rifampicin]] 15 mg/kg PO (Max: 600 mg/day), each drug daily for 18 weeks
 
* MDR Tuberculosis <ref name=WHO>{{cite web | title = The use of delamanid in the treatment of multidrug-resistant tuberculosis| url =http://apps.who.int/iris/bitstream/10665/137334/1/WHO_HTM_TB_2014.23_eng.pdf?ua=1 }}</ref>
:* Adult
::* Preferred regimen: [[Pyrazinamide]] 20–30 mg/kg {{or}} [[Ethambutol]] 15–25 mg/kg {{or}} [[Rifabutin]] 5 mg/kg {{and}} [[Capreomycin]] 15 mg/kg {{or}} [[Kanamycin]] 15 mg/kg {{or}} [[Amikacin]] 7.5-10 mg/kg {{or}} [[Streptomycin]] 12–18 mg/kg {{and}} [[Levofloxacin]] 500-1000 mg {{or}} [[Moxifloxacin]] 400 mg {{or}} [[Ofloxacin]] 400 mg {{and}} [[Ethionamide]] 15-20 mg/kg {{or}} [[Protionamide]] 15-20 mg/kg {{or}} [[Cycloserine]] 10-15 mg/kg {{or}} [[Terizidone]] 10-20 mg/kg {{or}} Para-aminosalicylic acid 8-12 g/d divided q8-12h
 
:* Pediatric
::* Preferred regimen: [[Pyrazinamide]] 20-30 mg/kg (Max: 600 mg) {{or}} [[Ethambutol]] 15-20 mg/kg {{or}} [[Rifabutin]] 5 mg/kg {{and}} [[Capreomycin]] 15-30 mg/kg (Max: 1000 mg) {{or}} [[Kanamycin]] 15-30 mg/kg (Max: 1000 mg) {{or}} [[Amikacin]] 15-22.5 mg/kg (Max: 1000 mg) {{or}} [[Streptomycin]] 12-18 mg/kg {{and}} [[Levofloxacin]] 7.5-10 mg/kg {{or}} [[Moxifloxacin]] 7.5-10 mg/kg {{or}} [[Ofloxacin]] 15-20 mg/kg divided q12h (Max:800 mg) {{and}} [[Ethionamide]] 15-20 mg/kg divided q12h (Max: 1000 mg) {{or}} [[Protionamide]] 15-20 mg/kg divided q12h (Max: 1000 mg) {{or}} [[Cycloserine]] 10-20 mg/kg (Max: 1000 mg) {{or}} [[Terizidone]] 10-20 mg/kg (Max: 1000 mg) {{or}} Para-aminosalicylic acid 150 mg/kg divided q8-12h(Max: 12 000 mg)
 
* XDR Tuberculosis
:* Adult
::* Preferred regimen: [[Pyrazinamide]] 20–30 mg/kg {{or}} [[Ethambutol]] 15–25 mg/kg {{or}} [[Rifabutin]] 5 mg/kg {{and}} [[Ethionamide]] 15-20 mg/kg {{or}} [[Protionamide]] 15-20 mg/kg {{or}} [[Cycloserine]] 10-15 mg/kg {{or}} [[Terizidone]] 10-20 kg/mg {{or}} Para-aminosalicylic acid 8-12 g/d divided q8-12h {{and}} [[Clofazimine]] 50 mg/d AND 300 mg once a month {{or}} [[Amoxicillin]]/clavulanate 500 mg/125 mg q12h {{or}} [[Linezolid]] 300-600 mg {{or}} [[Imipenem]] 500mg q6h {{or}} [[Clarithromycin]] 500-1000 mg q12h {{or}} [[Thioacetazone]] 2.5 mg/kg {{or}} [[Isoniazid]] (high-dose) 16–20 mg/kg
:* Pediatric
::* Preferred regimen: [[Pyrazinamide]] 20-30 mg/kg (Max: 600 mg) {{or}} [[Ethambutol]] 15 mg/kg {{or}} [[Rifabutin]] 5 mg/kg {{and}} [[Ethionamide]] 15-20 mg/kg (Max: 1000 mg) {{or}} [[Protionamide]] 15-20 mg/kg (Max: 1000 mg) {{or}} [[Cycloserine]] 10-20 mg/kg (Max: 1000 mg) {{or}} [[Terizidone]] 10-20 mg/kg (Max: 1000 mg) {{or}} Para-aminosalicylic acid 150 mg/kg/d divided q8-12h {{and}} [[Clofazimine]] 50 mg/d AND 300 mg once a month {{or}} [[Amoxicillin]]/clavulanate {{or}} [[Linezolid]] 300-600 mg {{or}} [[Imipenem]] 500mg q6h {{or}} [[Clarithromycin]] 500-1000 mg q12h {{or}} [[Thioacetazone]] 2.5 mg/kg {{or}} [[Isoniazid]] (high-dose) 16–20 mg/kg


==References==
==References==
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[[Category:Actinobacteria]]
[[Category:Actinobacteria]]
[[Category:Gram positive bacteria]]
[[Category:Gram positive bacteria]]
[[Category:Infectious Disease Project]]
[[Category:Infectious disease]]

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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.
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