11/14/24, 10\:39 AM Tuberculosis (TB)

Tuberculosis (TB)

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Tuberculosis (TB)\: granulomatous disease caused by M y c o b a c t e r i u m t u b e r c u l o s i s complex; primarily a
can involve any organ.
Transmission\: infection through droplet inhalation, commonly spread by coughing and sneezing.
Primary TB\: may be asymptomatic; if not cleared, leads to latent TB which can reactivate (post-primary TB). Small number
develop primary progressive or extra-pulmonary TB.
Extra-pulmonary TB\: can a
(pericarditis), lymphatics (lymphadenitis), spinal vertebrae (Pott’s disease), miliary TB (disseminated TB with lung nodules).
Risk factors\: close contact with infected person, demographic factors (ethnic minorities, high prevalence areas, age,
homelessness), medical conditions (HIV, immunosuppression, diabetes, malignancy, long-term steroid use, renal disease).
Symptoms\: general (fever, lethargy, anorexia, weight loss), pulmonary (chronic cough, sputum, breathlessness, chest pain),
extra-pulmonary (urinary symptoms, joint pain, headache, chest pain, abdominal pain, rash).
Examination
percussion), extra-pulmonary (depends on a
Di
Investigations\: urine dip, ECG, blood tests (in
microscopy/culture, rapid diagnostic tests, Mantoux and interferon-gamma release assay, chest X-ray (various
appearances including consolidation, nodules, cavitating lesions), CT chest, other imaging based on extra-pulmonary
symptoms.
Management\:
Noti
Antimicrobials\: isoniazid, rifampicin, pyrazinamide, ethambutol (2 months), followed by isoniazid and rifampicin (4 months).
CNS involvement\: isoniazid and rifampicin for 10 months.
Multi-drug resistant TB and TB in HIV patients\: specialist input.
Latent TB\: three months isoniazid and rifampicin or six months isoniazid.
Pyridoxine (vitamin B6) given with isoniazid to prevent peripheral neuropathy.
Complications\: pulmonary (pleurisy, e
quality of life, sepsis, death; adverse e
interactions).
Monitoring\: liver function and visual acuity during treatment.
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Introduction

Tuberculosis (TB) is a granulomatous disease caused by the M y c o b a c t e r i u m t u b e r c u l o s i s complex. TB most commonly
a
After HIV/AIDs, TB is the second most common cause of death from infectious disease and is particularly prevalent in sub-
Saharan Africa.
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Aetiology

The M y c o b a c t e r i u m t u b e r c u l o s i s complex includes M . t u b e r c u l o s i s (majority of cases), M . b o v i s and M . a f r i c a n u m .
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Infection is through droplet inhalation and therefore commonly spread by coughing and sneezing.
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After exposure to TB, the mycobacterium is engulfed by macrophages in the lung. Most people clear the infection at this
point and have a spontaneous recovery. Those who do not clear it develop primary TB (Figure 1).
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Figure 1. Outcomes of TB exposure.
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Primary TB leads to asymptomatic latent TB in most people. Latent TB can re-activate in 10%, causing post-primary TB.
A small number of people with primary TB develop primary progressive pulmonary or extra-pulmonary TB through
haematogenous dissemination.
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Extra-pulmonary TB can a
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Genitourinary (sterile pyuria, pyelonephritis)
Central nervous system (meningitis)
Gastrointestinal system (peritonitis)
Cardiac (pericarditis)
Lymphatics (lymphadenitis)
Spinal vertebrae (Pott’s disease)
Miliary TB is a disseminated form of TB commonly found in the lungs, which can develop from primary progressive or post-
primary TB. The name originates from millet seeds which are said to resemble the lung nodules occurring in miliary TB.
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Figure 2. The extra-pulmonary
manifestations of tuberculosis.
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Risk factors

An important risk factor is close contact with a patient infected with pulmonary TB. It is important to consider exposure at
school and/or work (including healthcare professionals).
Demographic features which confer increased risk of TB are ethnic minorities, those born in or travelling from high
prevalence areas (India and sub-Saharan Africa), extremes of age and homelessness.
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Some medical conditions or medications can increase the risk of contracting TB or reactivation of latent TB. These include
alcohol and drug dependency, immunosuppression (including HIV), malignancy, diabetes, long term steroid use and end-
stage renal disease.
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Clinical features

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Primary TB is often asymptomatic, and symptoms of primary progressive or post-primary TB are varied. A thorough history
and examination are therefore vital when considering TB.

History

Typical symptoms of TB may include\:
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General\: fever, lethargy, anorexia, weight loss, enlarged and tender lymph nodes
Pulmonary\: cough (usually chronic), sputum (initially dry, then purulent or blood-stained), breathlessness, pleuritic chest
pain
Extra-pulmonary\: genitourinary (urinary symptoms), musculoskeletal (joint pain), neurological (headache, reduced GCS,
focal neurology), cardiac (chest pain), gastrointestinal (abdominal pain, bloating), rash
Other important areas to cover in the history include\:
Past medical history\: HIV or other immunosuppressive condition, chronic conditions such as diabetes
Drug history\: immunosuppressive medications including steroids
Social history\: occupation, alcohol or drug dependence, homelessness, country of birth and travel history
TB contacts\: nature and duration of contact

Clinical examination

As 60% of TB cases in the UK are pulmonary, a respiratory examination is essential when suspecting TB.
1
Typical clinical
Sputum pots with purulent or blood-stained sputum
Enlarged, tender lymph nodes
Crackles or bronchial breathing over consolidation
Dullness to percussion and decreased fremitus over pleural e
As extra-pulmonary TB has the potential to aneurological, abdominal,
cardiology, musculoskeletal and skin examinations depending on features in the history.

Di

Important di
Bacterial pneumonia or viral respiratory tract infection
Interstitial lung disease
Malignancy including lymphoma
Sarcoidosis

Investigations

Bedside investigations

Relevant bedside investigations include\:
Urine dip\: sterile pyuria in genitourinary TB
ECG\: small complexes suggestive of pericardial e
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Laboratory investigations

Relevant laboratory investigations include\:
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Basic blood tests\: looking for raised in
Viral screen\: HIV, hepatitis B and C which can increase the risk of TB
Sputum microscopy, culture and sensitivities\: three samples (a least one early morning) prior to starting antimicrobial
treatment. Bronchoscopy with lavage or bronchial washings can be considered if there is no spontaneous sputum
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production.
Rapid diagnostic tests for TB are used in some cases.
Extra-pulmonary sites\: early morning urine or lymph node biopsies can be cultured for TB.
Mantoux and interferon-gamma release assay\: can help to diagnose latent TB.
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Analysing samples for TB1
Samples are stained with Ziehl-Neelson (ZN) stain for acid-fast bacilli.
Samples are cultured on Löwenstein-Jensen media for 4-8 weeks. Sensitivities are complete after a further 3-4
weeks.

Imaging

The most useful initial imaging is a chest X-ray.
Pulmonary TB can have various appearances on chest x-ray\:
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Patchy or lobar consolidation
Linear and nodular opacities
Miliary TB (small, uniformly distributed nodules)
Cavitating lesions (more likely in post-primary TB)
Tuberculoma (a caseating granuloma)
Calci
Lymphadenopathy
Pleural e
A CT chest can be used to further characterise pulmonary lesions or investigate for di
Figure 3. Chest X-ray showing patchy opaci
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Figure 4. Chest X-ray showing the appearance of miliary TB.
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Figure 5. Section of a chest X-ray showing a Ghon focus.
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Other investigations

Further investigations will depend on any features of extra-pulmonary TB identi
Investigations may include CT/MRI brain, lumbar puncture, echocardiogram, ultrasound liver or kidneys and skin biopsy.
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Management

TB is a noti1
any close contacts of a person with active TB.
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Screening should be o
Patients with suspected TB should be managed in a single room or a negative pressure room if they are considered high
risk.
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Medical management

Medical treatment for TB is delivered through several antimicrobials which are usually given daily for a prolonged period.
In exceptional circumstances, three times weekly dosing can be considered. This regimen is particularly useful if there is a
risk of non-adherence, and a patient needs directly observed therapy (i.e. substance misuse, homelessness or major
psychiatric disorder). In directly observed therapy, a healthcare worker administers and observes the patient taking the
medication.
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The treatment for active TB without central nervous system (CNS) involvement is\:
Isoniazid, rifampicin, pyrazinamide and ethambutol for two months, followed by...
Isoniazid and rifampicin for a further four months
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In TB with CNS involvement, treatment is similar, but isoniazid and rifampicin should be continued for ten months rather
than four.
7
Multi-drug resistant TB (resistant to isoniazid and rifampicin) and TB in HIV positive patients should be managed and
treated with close specialist input.
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Latent TB is treated with three months of isoniazid and rifampicin or six months of isoniazid only.
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To avoid peripheral neuropathy, pyridoxine (vitamin B6) is always given with isoniazid.
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Complications

Pulmonary complications of TB include pleurisy, pleural e
respiratory failure.
Other important complications include reduced quality of life (through prolonged treatment and stigmatisation), sepsis and
death.
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In addition to complications relating to TB itself, the medical treatment of TB can have adverse e
1
Hepatitis\: rifampicin, isoniazid and pyrazinamide
Visual disturbance\: ethambutol
Peripheral neuropathy\: isoniazid
Drug interactions\: most notably with anti-retroviral therapy used in HIV
In view of the potential complications, liver function and visual acuity should be monitored during treatment.

References

Patient Info. T u b e r c u l o s i s . Published in 2019. Available from [LINK].
Antimicrobe. M y c o b a c t e r i u m T u b e r c u l o s i s C o m p l e x . Published in 2010. Available from [LINK].
E. Wang, A. Sohoni. T u b e r c u l o s i s \: A P r i m e r f o r t h e E m e r ge n c y P h y s i c i a n . Published in 2006. Available from [LINK].
MSD Manual, Professional Version. E x t r a p u l m o n a r y T u b e r c u l o s i s ( T B ) . Published in 2018. Available from [LINK].
Mikael Häggström. E x t r a p u l m o n a r y t u b e r c u l o s i s s y m p t o m s . Licence\: [Public domain].
B. Mayosi et al. T u b e r c u l o u s P e r i c a r d i t i s . Published in 2005. Available from [LINK].
NICE. T u b e r c u l o s i s . Published in 2016. Available from [LINK].
Radiopaedia. T u b e r c u l o s i s ( p u l m o n a r y m a n i f e s t a t i o n s ) . Published in 2020. Available from [LINK].
Dr Jeremy Jones, Radiopaedia.org. P u l m o n a r y t u b e r c u l o s i s . Licence\: [CC BY-NC-SA 3.0].
Benjamín Herreros, Isabel Plaza, Rebeca García, Marta Chichón, Carmen Guerrero and Emilio Pintor. C h e s t r a d i o g r a p h o f
m i l i a r y t u b e r c u l o s i s . Licence\: [CC BY 4.0].
Basem Abbas Al Ubaidi. C h e s t X -r a y o f a G h o n . Licence\: [CC BY 4.0].
NICE CKS. T u b e r c u l o s i s \: W h a t a r e t h e c o m p l i c a t i o n s ? Published in 2019. Available from\: [LINK].
https\://app.geekymedics.com/notebook/2654/ 6/711/14/24, 10\:39 AM Tuberculosis (TB)

Reviewer

Dr Samantha Cockburn
Respiratory registrar

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Contents

Introduction
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