Tuberculosis

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Tuberculosis

(TB)

  • disease caused by Mycobacterium tuberculae

  • often spread by droplets and affects lungs

  • bovine disease spread by milk in 3rd world

  • Incidence 11/100,00 (UK) , 100-200/100,000

Pathology

  • transmission by aerosol droplets

  • produces caseating (cheese-like) necrosis

  • Langerhans giant cells

History

  • Fever

  • Cough

    • greater than 3 weeks

  • Lethargy

  • anorexia

  • weight loss

  • failure to gain weight (children)

  • haemoptysis

  • dyspnoea

  • pleurisy

  • glandular enlargement

Associations

  • Immunosuppression

    • HIV

  • Proximity

    • poor housing

    • overcrowding

    • doctor / nurse / dentist

  • Diabetes

  • Alcoholism

  • Isolated communities

  • Malnutrition

  • General debilitation

  • Steroids

Examination

  • General

  • Pulmonary TB - signs variable and due to fiibrosis and scarring

    • consolidation

    • cavitation

    • effusion

  • Meningitis

    • fever

    • headache

    • neck stiffness

    • vomiting

    • cranial nerve palsies

  • Brain abscess

    • hemiparesis

    • other localising signs

  • Eye

    • choroidal tubercles

  • Bone / Joint

    • local pain / stiffness

    • joint effusion

    • paraspinal abscess +/- paraparesis (anterior discitis)

    • psoas abscess

  • Genitourinary

    • polyuria

    • sterility

    • endometrial disease

    • orchitis

  • Gastrointestinal

    • abdominal pain (mesenteric nodes)

    • hepatomegaly

    • diarrhoea (ileitis)

    • ascites

  • Haematological

    • normocytic anaemia

    • pancytopenia

Old TB

  • Observation

    • elderly patient

    • Asian / Irish origin

    • abnormal chest shape

  • Hands

  • Face

  • Neck

    • Trachea to side of collapse

  • Chest

    • Inspection

      • old thoracotomy scar

      • rib missing

    • Palpation

    • Percussion

      • dull

    • Auscultation

      • bronchial breathing

      • crackles

      • vocal resonance decreased

Investigations

  • FBC

  • ESR extermely high

  • LFTs

  • Blood cultures (results may not be back for 6 weeks)

  • Sputum

    • Early morning (x3)

    • Ziehl-Neelsen staining

    • Culture

  • Bronchial washings, Lymph node biopsy, bone marrow aspiration, liver biopsy, pleural biopsy

  • Tuberculin testing

  • CXR

  • Early morning urine (x3)

  • CT

    • brain

    • spine

    • abdomen

Primary Tuberculosis

  • Usually asymptomatic

  • Heals with fibrosis and calcification

  • single Ghon focus ~ 10mm

  • spreads to hilar lymph nodes

Investigations

  • CXR

    • Ghon focus

      • primary lesion

      • small

      • periphery of lung

    • Primary complex

      • Ghon focus + large draining lymph nodes

  • Tuberculin test positive

Complications

  • Cavitation

  • Pleural Effusion

  • Lymph node spread

    • bronchpneumonia

    • miliary TB

    • pericarditis

  • compression of bronchus

    • collapsed segment

    • middle lobe bronchiectasis

  • Fungal Mycetoma

  • Malignant change in old scar tissue

Post-Primary Infection

  • Reactivation of previous infection

  • apical foci

  • ~30mm

Miliary TB

  • dissemination of tuberculosis through body

  • in immunocopmromised

    • leaves small 'millet-seed' like lesions

    • sites

      • adrenals

      • bone

      • meninges

      • brain

      • fallopian tubes

      • epididymis

      • kidney

      • joints

Symptoms

Early

  • insidious onset

  • sweats

  • malaise

  • pyrexia

  • weight loss

Late

  • dry cough

  • meningitis

Signs

  • Crackles

  • Choroidal tubercles on retina

  • pleural effusion

  • frequently absent

Investigations

  • CXR

    • mottled

    • scattered

    • fine

Treatment

  • 2 month 4 drugs

    • Isoniazid

      • risk of peripheral neuropathy

      • so with pyridoxine 10mg

    • Rifampicin

      • most effective anti-TB drug

      • expensive

      • stains body secretions pink / orange

      • induces liver enzymes

        • reduces effectiveness of OCP

    • Pyrazinamide

      • risk of hepatic toxicity

    • Ethambutol

      • can lead to colour blindness

  • 6 months 2 drugs

    • Rifampicin (UK)

    • Isoniazid

  • Streptomycin

    • if drug resistance suspected

    • if meningitis

    • if patient very ill

    • can cause vestibular nerve damage

  • Others

    • thiacetozone, ethionamide, prothionamide, cycloserine, capreomycin, amikacin, kanamycin, paraminosalicylic acid, ciprofloxacin, clofazimine

Prophylaxis

  • Bacille Calmette-Guerrie (BCG)
    • intradermal
    • tuberculin test goes positive 6-8 weeks
    • papule raised 10-14 days
    • 80% protection over 10 years
  • Chemoprophylaxis
    • 6 months isoniazid
    • 2 months rifampicin + pyrazinamide

Multi-drug resistant TB

  • resistance to rifampicin and isoniazid
  • 0.8% incidence in UK
  • Risk factors
    • previous treatment
    • HIV infection
    • homelessness
    • IV drug use
    • contact with MDR TB
    • travel from area of high prevalence

Management

  • 5 or more drugs
    • as many as possible that patient has not had before
  • regular sputum culture
  • 2 years of treatment after last positive sputum culture
  • ? surgery
 

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