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{{CMG}}; {{AE}} {{AL}}; {{JS}}; {{Ammu}}


==Overview==
==Overview==
Tuberculosis (abbreviated as TB for 'Tubercle bacillus' or Tuberculosis<!-- Do not link to the genus [[Bacillus]] -->) is a common and deadly [[infectious disease]] caused by [[mycobacterium|mycobacteria]], mainly ''[[Mycobacterium tuberculosis]]''. Tuberculosis most commonly attacks the lungs (as [[Lung|pulmonary]] TB) but can also affect the [[central nervous system]], the [[lymphatic system]], the [[circulatory system]], the [[genitourinary system]], [[bone]]s, [[joint]]s and even the [[skin]]. Other mycobacteria such as ''[[Mycobacterium bovis]]'', ''[[Mycobacterium africanum]]'', ''[[Mycobacterium canetti]]'', and ''[[Mycobacterium microti]]'' can also cause tuberculosis, but these species do not usually infect healthy adults.<ref name="Harrison">{{cite book | author = Raviglione MC, O'Brien RJ | chapter = Tuberculosis | title = Harrison's Principles of Internal Medicine | editor = Kasper DL, Braunwald E, Fauci AS, Hauser SL, Longo DL, Jameson JL, Isselbacher KJ, eds. | edition = 16th ed. | publisher = McGraw-Hill Professional | year = 2004 | pages = 953–66 | doi =10.1036/0071402357 | isbn = 0071402357 }}</ref> Over one-third of the world's population has been exposed to the TB bacterium, and new infections occur at a rate of one per second.<ref name="WHO2004data">[[World Health Organization]] (WHO). [http://www.who.int/mediacentre/factsheets/fs104/en/index.html Tuberculosis Fact sheet N°104 - Global and regional incidence.] March 2006, Retrieved on 6 October 2006.</ref> Not everyone infected develops the full-blown disease; [[asymptomatic]], latent TB infection is most common. However, one in ten latent infections will progress to active TB disease, which, if left untreated, kills more than half of its victims.
Tuberculosis (abbreviated as TB or Tuberculosis) is a common [[infectious disease]] caused by ''[[Mycobacterium tuberculosis]]''. Tuberculosis most commonly involves the [[lungs]] as the [[organism]] thrives in high [[oxygen]] environments, but it can also cause [[disease]] in the [[central nervous system]], the [[lymphatic system]], the [[circulatory system]], the [[genitourinary system]], [[bone]]s, [[joint]]s and even the [[skin]]. Over one-third of the world's [[population]] has been [[exposed]] to ''[[M. tuberculosis]]'', and new [[infections]] occur at a [[rate]] of one per second. Not all individuals exposed to the [[bacterium]] develop [[clinically]] overt tuberculosis [[infection]]; in fact, [[asymptomatic]], [[Latent|latent TB]] infection discovered by [[screening]] is more [[common]]. Approximately, one in ten latent infections progresses to active ([[symptomatic]]) TB disease, which, if left untreated, carries [[mortality]] rates of up to 50%.  [[Symptoms]] include [[shortness of breath]], [[hemoptysis]], [[fever]], [[chills]], [[night sweats]], and [[weight loss]].  Several treatment regimens are available for the latent and active forms of TB. Classically, a prolonged course of 6-9 months of a single agent ([[rifampin]] or [[isoniazid]]) is administered to patients with latent TB, while a more [[aggressive]] course that consists of 4 major anti-tuberculous [[agents]] [[(rifampin]], [[isoniazid]], [[ethambutol]], [[pyrazinamide]]) is reserved for patients with active disease.


==Historical Perspective==
==Historical Perspective==  
[[Tuberculosis]] has been present in humans since antiquity. The earliest unambiguous detection of ''[[Mycobacterium tuberculosis]]'' was in the remains of bison, dated 18,000 BC.<ref name=Rothschild_2001>{{cite journal |author=Rothschild B, Martin L, Lev G, Bercovier H, Bar-Gal G, Greenblatt C, Donoghue H, Spigelman M, Brittain D |title=Mycobacterium tuberculosis complex DNA from an extinct bison dated 17,000 years before the present |journal=Clin Infect Dis |volume=33 |issue=3 |pages=305-11 |year=2001 | pmid = 11438894}}</ref> However, whether [[tuberculosis]] originated in cattle and then transferred to humans, or diverged from a common ancestor, is currently unclear.<ref name=Pearce-Duvet_2006>{{cite journal |author=Pearce-Duvet J |title=The origin of human pathogens: evaluating the role of agriculture and domestic animals in the evolution of human disease |journal=Biol Rev Camb Philos Soc |volume=81 |issue=3 |pages=369-82 |year=2006 | pmid = 16672105}}</ref> Through history [[tuberculosis]] had many names, such as ''phthisis'' and ''Wasting disease'', which were mostly derived from its [[symptoms]]. The ''[[Mycobacterium tuberculosis]]'' was only identified in 1882 by [[Robert Koch]]. In the 19th and early 20th centuries, [[tuberculosis]] caused the most widespread public concern, being considered an endemic disease of the urban poor. It was only in 1946, with the development of the [[antibiotic]] [[streptomycin]], that effective treatment and cure became possible. Since the rise of [[Antibiotic resistant|drug-resistant]] strains in the 1980s, hopes that the disease could be completely eliminated have been dashed.
*[[Tuberculosis]] has been present in humans for thousands of years.  
*The earliest unambiguous detection of ''[[Mycobacterium tuberculosis]]'' was in the [[remains]] of [[bison]], dated 18,000 BC.  
*[[Tuberculosis]] originated in [[cattle]] and then transferred to humans, or diverged from a common [[ancestor]].  
*[[Tuberculosis]] has had many names including ''[[phthisis]]'' and ''[[Wasting]] disease''.
*Some [[hypotheses]] demonstrate that the origin of the [[genus]]''[[Mycobacterium tuberculosis]],'' was more than 150 million years ago.
*TB with its different names and [[presentations]] throughout its [[history]] was detected on [[skeletal]] [[deformities]] of Ancient Egyptian [[mummies]], dating back to 2400 BC.
*The first written record of TB, found in [[India]] and [[China]], dated back to 3300 and 2300 years ago.
*In the Middle Ages as well as during the [[Renaissance]], TB was [[referenced]] to as the “[[King’s]] Evil”.
*During this period if time, the [[contagious]] nature, [[pathology]] and [[anatomical]] afflictions were described.
*An English physician named [[Benjamin Marten]], supposed the anticipated [[origins]] for this [[disease]] by 1720.
*Years later, there were a number of proposed [[cures]] but the most [[significant]] [[milestone]] in the [[fight]] against TB was achieved by renowned [[scientist]], [[Robert Koch]].  
*[[Robert Koch]] discovered the ''[[Mycobacterium tuberculosis]]'' in 1882.
*In the 19th and early 20th centuries, [[tuberculosis]] caused the most widespread [[public]] concern, being considered an [[endemic]] disease of the [[urban]] poor.  
*An effective therapy became possible with the development of the [[antibiotic]] [[streptomycin]] in 1946.  
*The [[Antibiotic resistant|drug-resistant]] strains began to increase in the 1980s.


==Classification==
==Classification==
Tuberculosis may be classified according to its [[pathogenesis]] into 6 categoriesThis classification divides patients from "class 0", in which the person hasn't had previous exposure to [[TB]], and has a negative [[TST]] and [[IGRA]], to "class 5", in which [[TB]] is suspected, there are [[signs]] and [[symptoms]] of the disease, but the evaluation is not complete to confirm the [[diagnosis]]. According to the U.S. Citizenship and Immigration Services, immigrants and refugees have a special classification system. This last classifies immigrants and refugees from "no class", in which the person has normal screening tests, to "class B3", in which the person is a recent contact of a known tuberculosis case.
*According to [[exposure]], [[clinical]] [[symptoms]], and [[adjunct]] [[diagnostic]] [[testing]] tuberculosis is classified into 6 main [[classes]] .   
*The [[classification]] ranges from ''Class 0'', in people without previous [[exposure]] to [[TB]] and negative [[PPD|tuberculin skin testing]] and/or [[interferon-gamma release assay]]s (2 methods of [[screening]] for [[TB]]), to ''Class 3'' for [[active]] TB and ''Class 5'' for [[suspected]] TB based on [[signs]] and [[symptoms]] of the disease.
*The U.S. [[Citizenship]] and [[Immigration]] [[Services]] also made a special classification for immigrants and [[refugees]] according to the risk of infection.
 
===TB Classification System===
 
*As per [[CDC]] ([[Centers of Disease Control and Prevention]]), the clinical classification system for [[TB]] used in the United States is based on the [[pathogenesis]] of the disease.  
*This [[classification]] system provides clinicians the opportunity to keep an eye on the development of TB in their patients.  
*Health care providers should follow with state and local laws and regulations requiring the reporting of TB disease.
*All persons with Class 3 or Class 5 TB should be reported directly to the local or state health department.
*A patient should not have a Class 5 classification for more than 3 months.
{| style="border: 2px solid #4479BA; align="left"
! style="width: 200px; background: #4479BA;" | {{fontcolor|#FFF|Class}}
! style="width: 300px; background: #4479BA;" | {{fontcolor|#FFF|Type}}
! style="width: 400px; background: #4479BA;" | {{fontcolor|#FFF|Description}}
|-
| style="padding: 0 5px; background: #F5F5F5; text-align: left;" | 0
| style="padding: 0 5px; background: #F5F5F5; text-align: left;" | *No TB exposure<br>*Not infected
| style="padding: 0 5px; background: #F5F5F5; text-align: left;" | *No history of TB exposure and no evidence of [[M. tuberculosis]] [[infection]] or [[disease]]<br>*Negative reaction to [[TST]] or [[IGRA]]
|-
| style="padding: 0 5px; background: #F5F5F5; text-align: left;" | 1
| style="padding: 0 5px; background: #F5F5F5; text-align: left;" | *[[TB]] exposure<br>*No evidence of [[infection]]
| style="padding: 0 5px; background: #F5F5F5; text-align: left;" | *History of exposure to [[M. tuberculosis]]<br>*Negative reaction to [[TST]] (Tuberculin skin tests) or [[IGRA]] (an interferon gamma release assay blood test) (given at least 8 to 10 weeks after exposure)
|-
| style="padding: 0 5px; background: #F5F5F5; text-align: left;" | 2
| style="padding: 0 5px; background: #F5F5F5; text-align: left;" | *[[TB]] infection<br>*No TB disease
| style="padding: 0 5px; background: #F5F5F5; text-align: left;" | *Positive reaction to TST or IGRA<br>*Negative bacteriological studies (smear and cultures)<br>*No bacteriological or radiographic evidence of active TB disease
|-
| style="padding: 0 5px; background: #F5F5F5; text-align: left;" | 3
| style="padding: 0 5px; background: #F5F5F5; text-align: left;" | *[[TB]] clinically active
| style="padding: 0 5px; background: #F5F5F5; text-align: left;" | *Positive culture for [[M. tuberculosis]] OR<br>*Positive reaction to [[TST]] or [[IGRA]], plus clinical, bacteriological, or radiographic evidence of current active TB
|-
| style="padding: 0 5px; background: #F5F5F5; text-align: left;" | 4
| style="padding: 0 5px; background: #F5F5F5; text-align: left;" | *Previous TB disease (not clinically active)
| style="padding: 0 5px; background: #F5F5F5; text-align: left;" | *May have past medical history of [[TB]] disease<br>*Abnormal but stable radiographic findings<br>*Positive reaction to the [[TST]] or [[IGRA]]<br>*Negative bacteriologic studies (smear and cultures)<br>*No clinical or radiographic evidence of current active TB disease
|-
| style="padding: 0 5px; background: #F5F5F5; text-align: left;" | 5
| style="padding: 0 5px; background: #F5F5F5; text-align: left;" | *[[TB]] suspected
| style="padding: 0 5px; background: #F5F5F5; text-align: left;" | *[[Signs]] and [[symptoms]] of active [[TB]] disease, but medical evaluation not complete
|-
|}


==Pathophysiology==
==Pathophysiology==
Tuberculosis is a granulomatous infection which is chiefly transmitted through droplets. The [[granuloma]] prevents the dissemination of [[M. tuberculosis|mycobacteria]] and provides a pathway for [[immune cell]] communication. Within the [[granuloma]], [[CD4|T lymphocytes]] (CD4) secrete [[cytokines]], such as [[interferon gamma]], which activate local [[macrophages]] to kill the bacteria with which they are infected It is asymptomatic in 90% of immunocompetent individuals. In symptomatic patients it can present as pulmonary or extra pulmonary manifestations. The primary infection can progress to certain complications like disseminated infection. Tuberculosis can influence the progression of HIV if concomitantly present. Depending on the age of the patient, tuberculosis may have different clinical manifestations, progression, and prognosis.
*Tuberculosis is a [[granulomatous]] [[infection]] that is chiefly transmitted through [[droplets]].
*The [https://www.wikidoc.org/index.php/Granuloma granuloma] encloses mycobacteria and prevents their spreading and facilitates immune [https://www.wikidoc.org/index.php/Immune_cell immune cell] communication.  
*Within the [[granuloma]], [[CD4|T lymphocytes]] (CD4) releases [[cytokines]], such as [[interferon gamma]], that [[Activate|activates]] local [[macrophages]].
*It is [[asymptomatic]] in 90% of [[immunocompetent]] individuals.  
*In [[symptomatic]] patients, it can present as [[pulmonary]] or [[extrapulmonary]] [[manifestations]]. The primary infection may turn into [[disseminated]] infection.
*[[Tuberculosis]] usually has an impact the [[progression]] of [[HIV]] if present together. Depending on the [[age]] of the [[patient]], [[tuberculosis]] may have different [[clinical]] [[manifestations]], [[progression]], and [[prognosis]].


==Causes==
==Causes==
'''''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 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]].  
*It is an [[aerobic]], [[capsule|non-encapsulated]], [[motility|non-motile]], [[acid-fast]] [[bacillus]].   
*[[M. tuberculosis]] is one of the [[Mycobacterium]] [[tuberculosis]] [[complex]], which also includes [[bacteria]], such as [[Bovis|''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 [[Cells (biology)|cells]] of the [[lung]].   
*It may [[infect]] different [[species]], but human [[beings]] are its frequent [[natural reservoir]].


==Epidemiology and Demographics==
==Epidemiology and Demographics==
Tuberculosis is a [[bacterial infection]] that constitutes one of the world's deadliest diseases.  In 2012, about 8.6 million people developed symptomatic TB and 1.3 million died from the disease. In 2013 there were 9 582 reported cases in the United States, with an [[incidence]] of 3.0 per 100 000 persons. Since 1990, the [[mortality rate]] of TB has been decreasing towards the goal of 50% reduction, planed for 2015. The prevalence of TB increases with age and is superior in older men. Racial and ethnic minorities have a higher prevalence of TB than non-Hispanic whites.  TB is an important cause of death in people who are [[coinfection|coinfected]] with [[HIV]], with approximately 1/5 of deaths among these patients being due to TB.
*In 2015, about 10.4 million people developed [[symptomatic]] TB and 1.8 million [[died]] from the [[disease]].  
*There were 9,421 [[reported]] [[cases]] in the [[United|United States]] in 2014  with an [[incidence]] of 3.0 per 100,000 persons.  
*Since 1990, the [[mortality rate]] was steadily [[decreasing]].  
*The [[prevalence]] of TB increases with [[age]] and it is higher in [[older]] men. TB is more [[Prevalence|prevalent]] in [[racial]] and [[Ethnic group|ethnic]] minorities than non-[[Hispanic]] whites.   
*[[TB]] is an major cause of [[Death-associated protein 6|death]] in people [[coinfection|coinfected]] with [[HIV]].
*A third of [[deaths]] among these [[patients]] is due to TB.
*In 2015, 60% of TB cases [[worldwide]] occurred in 6 [[countries]]: [[South Africa]], [[Indonesia]], Nigeria, Pakistan, India, and [[China]].
*The [[WHO]] has [[identified]] 24 other high-burden TB countries including Bangladesh, Congo, Columbia, Lesotho, Cambodia, Korea, [[Brazil]], Ethiopia, Myanmar, Mozambique, Thailand, [[Angola]], Zambia, Vietnam, Kenya, Central Africa, Russia, Liberia, Tanzania, Zimbabwe, Namibia, Philippines,  Sierra Leone, Papua New Guinea.


==Risk Factors==
==Risk Factors==
The [[risk factor]]s for the development of [[tuberculosis]] include: weakened [[immune system]] (patients taking [[immunosuppressive]] medication or with [[immunosuppressive]] diseases, such as [[HIV]] or [[diabetes]]); history of contact with [[infected]] patients, bad hygiene conditions, and evidence of previous tuberculosis.
*The [[risk factor]]s for the [[development]] of [[tuberculosis]] include:  
Risk factors for [[multidrug-resistant TB]] include: non-adherence to treatment regimen, inadequate medication for that [[strain]] of [[bacteria]], and contact with patients with [[multidrug-resistant TB]].
**[[weakened]] [[immune system]] (patients taking [[immunosuppressive]] [[medication]] or with [[immunosuppressive]] [[diseases]], such as [[HIV]] or [[diabetes]]
**History of contact with [[infected]] patients
**Bad hygiene conditions
**Evidence of previous tuberculosis.
*[[Risk|Risk factors]] for [[multidrug-resistant TB]] include:
**Non-adherence to the [[treatment]] [[regimen]]
**Insufficient [[medication]] for that [[strain]] of [[bacteria]]
**[[Contact]] with [[patients]] with [[multidrug-resistant TB]].


==Screening==
==Screening==
Screening for tuberculosis is generally done with using a [[mantoux tuberculin skin test]], also known as a tuberculin skin test or a [[PPD]]. The test involves injecting a small amount of a purified protein derivative of the tuberculosis bacterium intradermally, and watching for a reaction in the following days.
*[[Screening]] for [[tuberculosis]] is generally done by using a [[mantoux tuberculin skin test]], also known as a [[tuberculin]] [[skin]] [[test]] or a [[PPD]].  
*The test involves [[injecting]] a small amount of a [[purified protein derivative]] of the [[tuberculosis]] [[bacterium]] [[intradermally]] and watching for a [[reaction]] in the following days.


==Natural history, complications and prognosis==
==Natural history, complications and prognosis==
Tuberculosis has been classified as primary or secondary (post primary) infection. It can have pulmonary and extra pulmonary manifestations as well as severe parenchymal, vascular, pleural and chest wall complications. Pulmonary complications include pleural effusions, cavitations, lymphadenopathy, airway obstruction, pneumonia and bronchietasis. The hematogenous dissemination of infection can lead to miliary tuberculosis. The post primary infection can be due to a recent infection or reactivation of an old infection. Without treatment, 1/3 of patients with active tuberculosis dies within 1 year of the diagnosis, and more than 50% during the first 5 years. But with early diagnosis and treatment it has a good prognosis.
*[[Tuberculosis]] has been [[classified]] as a [[primary]] or [[secondary]] (post-primary) [[infection]].  
*It can have [[pulmonary]] and extra pulmonary [[manifestations]] as well as severe [[parenchymal]], vascular, pleural, and chest wall complications.  
*Pulmonary complications include [[pleural effusions]], [[cavitations]], [[lymphadenopathy]], airway obstruction, [[pneumonia]] and [[bronchietasis|bronchiectasis]].  
*The [[hematogenous]] [[dissemination]] of [[infection]] can lead to [[miliary tuberculosis]].  
*The post-primary [[infection]] can be due to a [[recent]] infection or [[reactivation]] of an old infection. Without [[treatment]], 1/3 of patients with active [[tuberculosis]] dies within 1 year of the [[diagnosis]], and more than 50% during the first 5 years.  
*But with early [[diagnosis]] and [[treatment]], it has a good [[prognosis]].


==Diagnosis==
==Diagnosis==
===History and Symptoms===
===History and Symptoms===
The general symptoms of tuberculosis include [[weakness]], [[weight loss]], [[fever]], and [[night sweats]]. Symptoms of pulmonary tuberculosis include [[cough]], [[chest pain]], and [[hemoptysis]].  Tuberculosis is particularly difficult to diagnose in children, as these may not present with common findings.
*The [[general]] [[symptoms]] of tuberculosis include [[weakness]], [[weight loss]], [[fever]], and [[night sweats]].  
*[[Symptoms]] of pulmonary tuberculosis include [[cough]], [[chest pain]], and [[hemoptysis]].   
*[[Tuberculosis]] is particularly difficult to [[diagnose]] in [[children]], as these may not present with [[Common Atrium|common]] [[Findings on urinalysis|findings]].


===Physical Examination===
===Physical Examination===
A physical examination can provide valuable information about the patient’s overall condition and other factors that may affect how tuberculosis is treated, such as [[HIV]] infection or other illnesses. The most common physical findings include [[fever]], [[decreased breath sounds]], [[tachypnea]] and [[tachycardia]].  Physical findings will depend on the location of the tuberculosis infection.
*A [[physical]] [[examination]] can give an [[overview]] about the [[Overall|general]] [[condition]] and other [[factors]] that may influence the [[tuberculosis]] response to treatment, such as [[HIV]] [[infection]] or other diseases.  
*The most common [[physical]] findings include [[fever]], [[decreased breath sounds]], [[tachypnea]] and [[tachycardia]].   
*Physical findings will depend on the location of the tuberculosis infection.


===Laboratory findings===
===Laboratory findings===
Routine laboratory exams are usually in the normal ranges. The presence of [[acid-fast-bacilli]] (AFB) on a [[sputum]] smear or other specimen often indicates TB disease and a positive culture for [[M. tuberculosis]] confirms the diagnosis.  Other laboratory test include [[peritoneal fluid]] or [[CSF]] analysis, [[urinalysis]], and Interferon-Gamma release assays.
*[[Routine]] [[laboratory]] exams are usually in the [[normal]] [[ranges]].  
*The presence of [[acid-fast-bacilli]] ([[AFB]]) on a [[sputum]] [[smear]] or another [[specimen]] often indicates TB disease and a positive [[culture]] for [[M. tuberculosis]] confirms the [[diagnosis]].   
*Other [[laboratory]] tests include [[peritoneal fluid]] or [[CSF]] analysis, [[urinalysis]], and [[Interferon]]-[[Gamma]] [[release]] [[assays]].


===Electrocardiogram===
===Electrocardiogram===
Patients can develop a [[pericardial effusion]] secondary to TB and this might be manifested as low voltage and [[tachycardia]] on an EKG.
*[[Echocardiography]] or [[Ultrasound]] can be helpful in patients who develop [[pericardial effusion]] secondary to TB. In rare occasions TB may lead to [[congestive heart failure]], in which case [[echocardiograph]] may also help in the diagnosis. 
*Common findings in [[CHF]] on the [[echocardiogram]] include: [[hypokinesia]]; [[valvular insufficiency]]; and [[enlargement]] of all [[heart]] [[chambers]].


===Chest X-Ray===
===Chest X-Ray===
A chest X ray is one of the important diagnostic tools in [[tuberculosis]]. A chest radiograph may be used to rule out the possibility of pulmonary TB in a person who are symptomatic or had a positive reaction to a [[tuberculin test]] or QFT-G and no symptoms of disease. The findings on chest x ray can be divided into [[parenchymal]] and [[pleural]]. The early parenchmal findings can be infiltrates, and cavity. A healed tuberculotic lesion can present as [[fibrosis]], and [[calcification]]. Pleural lesions in form of [[pleral effusion]] can also be seen. An advanced tuberculosis lesion can present as combination of these early lesions and termed as fibrocavitatory lesions.
*A [[chest X-ray]] is one of the important [[diagnostic]] tools in [[tuberculosis]].  
*A [[chest]] [[radiograph]] may be used to rule out the possibility of [[pulmonary]] TB in a person who are [[symptomatic]] or had a positive reaction to a [[tuberculin test]] or QFT-G and no symptoms of the disease.  
*The findings on chest x-ray can be divided into [[parenchymal]] and [[pleural]].  
*The early [[Parenchyma|parenchymal]] findings can be infiltrated, and cavity.  
*A healed tuberculotic lesion can present as [[fibrosis]], and [[calcification]].  
*[[Pleural]] [[lesions]] in form of [[pleural effusion]] can also be seen.  
*An [[advanced]] [[tuberculosis]] lesion can present a combination of these early lesions and termed [[fibrocavitary]] [[lesions]].
 
===CT===
*The majority of patients with [[pulmonary]] [[tuberculosis]] will have [[abnormal]] findings in a [[chest]] [[CT]], which include [[micronodules]], [[interlobular]] [[septal]] [[thickening]], [[cavitation]] and [[Consolidation (medicine)|consolidation]]. 
*[[CT scan]] is more [[sensitive]] than an [[X-ray]] to detect [[lymphadenopathy|lymphadenopathies]].
 
===MRI===
*MRI is used for the [[Assessment and Plan|assessment]] of [[extrapulmonary]] tuberculosis, such as [[Tuberculous meningitis|CNS tuberculosis]], [[Pott's disease]], and [[parotid gland]] tuberculosis.


===Echocardiography or Ultrasound===
===Echocardiography or Ultrasound===
[[Echocardiography]] or [[ultrasound]]: Patients can develop a [[pericardial effusion]] secondary to TB.
*[[Echocardiography]] or [[Ultrasound]] can be helpful in patients who develop [[pericardial effusion]] secondary to TB.
*In [[rare]] occasions TB may lead to [[congestive heart failure]], in which case [[echocardiograph]] may also help in the [[diagnosis]]. 
*Common findings in [[CHF]] on the [[echocardiogram]] include: [[hypokinesia]]; [[valvular]] [[insufficiency]]; and enlargement of all [[heart chambers]].
 
===Other Imaging findings===
*The [[abreugraphy]] is a smaller [[variant]] of the [[chest X-ray]] that allows the [[Identification of sites|identification]] of [[lung]] [[abnormalities]] that may suggest the [[diagnosis]] of TB. 
*With the decrease of [[incidence]] of TB, the [[abreugraphy]] is no longer recommended in most countries for low-risk populations. 
*However, depending on the [[screening]] resources of each country, it may be used for the [[screening]] of [[high-risk]] groups, such as [[HIV]]-positive patients and [[alcoholics]].


===Other Diagnostic Studies===
===Other Diagnostic Studies===
Because of difficulties with the [[Tuberculin skin test]], many laboratory methods of diagnosis are emerging <ref name="pmid12614730">{{cite journal |author=Drobniewski F, Caws M, Gibson A, Young D |title=Modern laboratory diagnosis of tuberculosis |journal=Lancet Infect Dis |volume=3 |issue=3 |pages=141-7 |year=2003 |id=PMID 12614730}}</REF> <REF NAME="pmid17266837">{{cite journal |author=Dinnes J, Deeks J, Kunst H, Gibson A, Cummins E, Waugh N, Drobniewski F, Lalvani A |title=A systematic review of rapid diagnostic tests for the detection of tuberculosis infection |journal=Health Technol Assess |volume=11 |issue=3 |pages=1-314 |year=2007 |id=PMID 17266837 | url = http://www.hta.nhsweb.nhs.uk/project/1247.asp}}</ref>.
*Because of difficulties with the [[Tuberculin skin test]], many [[laboratory]] methods of [[diagnosis]] are [[emerging]].


==Treatment==
==Treatment==
===Medical Therapy===
===Medical Therapy===
If there is a high probability of infection, presumptively treat the patient even if the stain is negative, while waiting for the culture results.  The patient should be brought back in few weeks.  Patients usually feel better a few weeks post-treatment. In the U.S., all TB is tested for [[drug resistance]].  [[Isoniazid]] (INH) resistant TB can be treated in same way as non-MDR TB.
*If there is a high [[probability]] of [[infection]], presumptively [[treat]] the patient even if the stain is [[negative]], while waiting for the [[culture]] [[results]].   
*The patient should be brought back in a few weeks.   
*Patients usually feel better a few weeks post-treatment.  
*Patients must be [[monitored]] for [[Adverse effect (medicine)|adverse effects]] and treatment [[failure]].
*In the U.S., all TB is tested for [[drug resistance]].
 
====Special conditions====
*[[Medical]] [[therapy]] for tuberculosis in special conditions include [[HIV]] co-infection and extra pulmonary [[manifestations]].
*Different approaches are taken for [[patients]] taking [[AIDS antiretroviral drugs|ART]] and those who do not take [[AIDS antiretroviral drugs|ART]].
*Although [[World Health Organization|WHO]] recommends the same drug regimen for pulmonary and extrapulmonary [[manifestations]], various stages of [[skeletal]] tuberculosis are managed differently.
*For patients with [[renal]] or [[liver]] diseases, the first line of drugs are substituted with second-line drugs to prevent [[Complication (medicine)|complications]].
 
====Drug-resistant====
*[[Drug resistance|Drug-resistant]] tuberculosis is caused by M. tuberculosis [[organisms]] that are [[resistant]] to at least one first-line anti-TB drug.   
*[[Multi-drug-resistant tuberculosis|Multidrug-resistant TB]] (MDR TB) is resistant to more than one [[anti-TB drug]] and at least [[isoniazid]] ([[INH]]) and [[rifampin]] ([[RIF]])
*Treatment should be started with an [[empirical]] treatment of at least 4 drugs based on expert advice as soon as [[Multi-drug-resistant tuberculosis|drug-resistant TB]] disease is suspected.
 
====Children====
*[[Tuberculosis]] in children aged 15 years or younger is a [[public health problem]] of special [[significance]] because it is a marker for recent [[transmission]] of TB. *Infants and young [[children]] are more likely to develop life-threatening forms of tuberculosis, such as [[miliary TB]] or [[TB meningitis]].
*[[Screening]] in children is very important, as the [[clinical manifestations]] are usually poor or [[non-specific]]. 
*History of close contact with tuberculosis patients has an important role in the [[diagnosis]] of TB in children. 
*The [[treatment]] is similar to adults, with adjusted [[dosing]] according to the child's weight.


===Surgery===
===Surgery===
[[Surgery]] may be necessary, especially to drain spinal [[abscess]]es or to stabilize the spine in case of [[Pott's disease]].
*[[Surgery]] may be necessary, especially to [[Drain (surgery)|drain]]  [[abscess]]es , [[empyema]], [[venticular shun]]<nowiki/>t in [[tubercular meningitis]], [[surgical resection]] of [[tissues]] affected in [[abdominal tuberculosis]], stabilize the [[spine]] in case of [[Pott's disease]], [[lobectomy]], [[pneumonectomy]], [[pericardiocentesis]] or surgical repair of [[pericardium]].


=== Primary Prevention ===
===Primary Prevention===
Many countries use [[Bacillus Calmette-Guérin|BCG]] vaccine as part of their TB control programs, especially for infants. This was the first vaccine for TB and developed at the [[Pasteur Institute]] in France between 1905 and 1921.<ref name=Bonah>{{cite journal |author=Bonah C |title=The 'experimental stable' of the BCG vaccine: safety, efficacy, proof, and standards, 1921–1933 |journal=Stud Hist Philos Biol Biomed Sci |volume=36 |issue=4 |pages=696–721 |year=2005 | pmid = 16337557}}</ref> However, mass [[vaccination]] with BCG did not start until after World War II.<ref name=Comstock>{{cite journal |author=Comstock G |title=The International Tuberculosis Campaign: a pioneering venture in mass vaccination and research |journal=Clin Infect Dis |volume=19 |issue=3 |pages=528-40 |year=1994 | pmid = 7811874}}</ref> The protective efficacy of BCG for preventing serious forms of TB (e.g. [[meningitis]]) in children is greater than 80%; its protective efficacy for preventing pulmonary TB in adolescents and adults is variable, ranging from 0 to 80%.<ref name=Bannon_1999>{{cite journal |author=Bannon M |title=BCG and tuberculosis |journal=Arch Dis Child |volume=80 |issue=1 |pages=80-3 |year=1999 | pmid = 10325767}}</ref>
*[[Primary prevention]] in tuberculosis is targeted to avoid disease [[Transmission (medicine)|transmission]] and infection of [[healthy]] individuals. The [[BCG]] [[vaccine]] is used in children [[Susceptible individual|susceptible]] to TB infections, such as children living in [[Endemic (epidemiology)|endemic]] areas or having [[close contact]] with a confirmed [[case]] of TB.
*Several [[Preventive medicine|preventive]] [[measures]] are used to avoid the [[transmission]] of the [[mycobacteria]], such as [[respiratory]] [[Isolation (health care)|isolation]], use of respiratory [[masks]] among [[health-care professionals]], and advising [[respiratory hygiene]] and [[cough]] etiquette.


===Secondary Prevention===
===Secondary Prevention===
All health-care settings need an infection-control program designed to ensure prompt 1) detection, 2) airborne precautions and 3) treatment of persons who have suspected or confirmed tuberculosis (TB) disease (or prompt referral of persons who have suspected TB disease for settings where persons with TB disease are not expected to be encountered). In order to be effective, the primary emphasis of the TB infection-control program should be on achieving these three goals.  
*[[Secondary prevention]] for tuberculosis includes [[methods]] for [[screening]] and early [[diagnosis]], such as [[tuberculin skin test]] (TST) and [[IGRAs]]; and to guarantee the correct [[treatment]] [[regimen]] at the right time to prevent [[disease]] [[progression]].
 
===Cost effectiveness of therapy===
*Treatment of [[tuberculosis]] must be [[analyzed]] for relative [[Cost-effectiveness|cost]] [[effectiveness]] of [[inpatient]] and [[outpatient]] models of [[care]] as it will [[benefit]] regions where [[tuberculosis]] is highly [[prevalent]].
*Unless there is severe [[Complication (medicine)|complications]] it is highly recommended to treat the TB patient in [[ambulatory care]] rather than [[inpatient]] services.


In all health-care settings, particularly those in which persons who are at high risk for exposure to Mycobacterium tuberculosis work or receive care, policies and procedures for TB control should be developed, reviewed periodically, and evaluated for effectiveness to determine the actions necessary to minimize the risk for transmission of ''M. tuberculosis''.
===Future or investigational therapy===
*Since new [[drug-resistant tuberculosis]] has been emerging, the role of future [[therapies]] is [[vital]] in curbing [[outbreaks]].
*The new [[:Category:Drugs|drugs]] should be more effective than the current [[regimen]] and a few drugs in [[clinical]] trials have been showing good [[results]].


==References==
==References==
{{Reflist|2}}
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[[Category:Bacterial diseases]]
[[Category:Bacterial diseases]]
[[Category:Disease]]
[[Category:Disease]]
[[Category:Infectious disease]]
[[Category:Pulmonology]]{{Reflist|2}}
[[Category:Pulmonology]]
[[Category:Primary care]]
 
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Latest revision as of 21:55, 26 June 2021

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Tuberculosis Microchapters

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Alejandro Lemor, M.D. [2]; João André Alves Silva, M.D. [3]; Ammu Susheela, M.D. [4]

Overview

Tuberculosis (abbreviated as TB or Tuberculosis) is a common infectious disease caused by Mycobacterium tuberculosis. Tuberculosis most commonly involves the lungs as the organism thrives in high oxygen environments, but it can also cause disease in the central nervous system, the lymphatic system, the circulatory system, the genitourinary system, bones, joints and even the skin. Over one-third of the world's population has been exposed to M. tuberculosis, and new infections occur at a rate of one per second. Not all individuals exposed to the bacterium develop clinically overt tuberculosis infection; in fact, asymptomatic, latent TB infection discovered by screening is more common. Approximately, one in ten latent infections progresses to active (symptomatic) TB disease, which, if left untreated, carries mortality rates of up to 50%. Symptoms include shortness of breath, hemoptysis, fever, chills, night sweats, and weight loss. Several treatment regimens are available for the latent and active forms of TB. Classically, a prolonged course of 6-9 months of a single agent (rifampin or isoniazid) is administered to patients with latent TB, while a more aggressive course that consists of 4 major anti-tuberculous agents (rifampin, isoniazid, ethambutol, pyrazinamide) is reserved for patients with active disease.

Historical Perspective

Classification

TB Classification System

  • As per CDC (Centers of Disease Control and Prevention), the clinical classification system for TB used in the United States is based on the pathogenesis of the disease.
  • This classification system provides clinicians the opportunity to keep an eye on the development of TB in their patients.
  • Health care providers should follow with state and local laws and regulations requiring the reporting of TB disease.
  • All persons with Class 3 or Class 5 TB should be reported directly to the local or state health department.
  • A patient should not have a Class 5 classification for more than 3 months.
Class Type Description
0 *No TB exposure
*Not infected
*No history of TB exposure and no evidence of M. tuberculosis infection or disease
*Negative reaction to TST or IGRA
1 *TB exposure
*No evidence of infection
*History of exposure to M. tuberculosis
*Negative reaction to TST (Tuberculin skin tests) or IGRA (an interferon gamma release assay blood test) (given at least 8 to 10 weeks after exposure)
2 *TB infection
*No TB disease
*Positive reaction to TST or IGRA
*Negative bacteriological studies (smear and cultures)
*No bacteriological or radiographic evidence of active TB disease
3 *TB clinically active *Positive culture for M. tuberculosis OR
*Positive reaction to TST or IGRA, plus clinical, bacteriological, or radiographic evidence of current active TB
4 *Previous TB disease (not clinically active) *May have past medical history of TB disease
*Abnormal but stable radiographic findings
*Positive reaction to the TST or IGRA
*Negative bacteriologic studies (smear and cultures)
*No clinical or radiographic evidence of current active TB disease
5 *TB suspected *Signs and symptoms of active TB disease, but medical evaluation not complete

Pathophysiology

Causes

Epidemiology and Demographics

Risk Factors

Screening

Natural history, complications and prognosis

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

  • Medical therapy for tuberculosis in special conditions include HIV co-infection and extra pulmonary manifestations.
  • Different approaches are taken for patients taking ART and those who do not take ART.
  • Although WHO recommends the same drug regimen for pulmonary and extrapulmonary manifestations, various stages of skeletal tuberculosis are managed differently.
  • For patients with renal or liver diseases, the first line of drugs are substituted with second-line drugs to prevent complications.

Drug-resistant

Children

Surgery

Primary Prevention

Secondary Prevention

Cost effectiveness of therapy

Future or investigational therapy

References

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