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Respiratory block > Tuberculosis > Flashcards

Tuberculosis Flashcards

1
Q

What is the epidemiology of TB ?

A

The disease burden is falling incidence rate is falling about 2% a year
TB deaths have fallen by 29% since 2000
Number 1 killer of communicable diseases
TB kills more than HIV and malaria together
2 billion infected worldwide

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2
Q

How many of the 2 billion infected people with tuberculosis have HIV ?

A

1.1 million

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3
Q

What groups are vulnerable to TB ?

A

Those from high prevalence countries
70% are non-UK born, most ages between 15 and 44
HIV positive, immunocompromised
Elderly, neonates, diabetics
Homeless, alcohol dependency, IVDUs, those with mental health problems and those in prisons- approx. 1/10 of all cases

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4
Q

What is the microorganism responsible for TB ?

A

Mycobacteria

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5
Q

What are the specific names for the organisms responsible for TB ?

A

Mycobacterium tuberculosis
M. bovis (“bovine TB”)
M. Africanum

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6
Q

Are all AAFB TB ?

A

No

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7
Q

Describe the type of bacterium that Mycobacterium TB is ?

A

Non-motile bacillus
Very slowly growing
Aerobic - predilection for apices of lungs (ventilated but not perfused)
Very thick cell wall lipids, peptidoglycans, arabinomannans
Resistant to acids, alkalis and detergents
Resistant to neutrophil and macrophage destruction
Aniline based dyes such as carbon fuchsin complex with cell wall
Unable to remove dye from cell wall
Acid - and alcohol - fast bacilli (AAFB) (Ziehl Neilson stain)

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8
Q

How is TB transmitted ?

A

Airborne
Coughs, sneezes, yells, sings
Aerosol droplets which can remain suspended in air for many hours
Prolonged close contact

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9
Q

How can M. Bovis be transmitted ?

A

Consumption of unpasteurised cows milk (UK)

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10
Q

What removes mycobacteria outdoors ?

A

UV radiation

Dilution

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11
Q

Who is normally affected by the primary infection ?

A

Usually children, 80% Infected focus in alveolus, (lymph nodes, gut)

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12
Q

Where do mycobacteria spread to once they are in the alveoli ?

A

Spread via lymphatics to draining hilar lymph nodes

Then there is haematogenous seeding of mycobacteria to all organs of the body (lung, bone, genitourinary system)

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13
Q

What are the symptoms of TB ?

A

Usually no symptoms, can be fever, malaise, erythema nodosum, rarely chest signs

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14
Q

What are the three outcomes of a primary infection ?

A

Progressive disease - ineffective immune response from the patient
Contained latent - activates when the patient becomes immunosuppressed (old)
Cleared and cured

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15
Q

How common is a primary infection of TB ?

A

Small percentage (1%)

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16
Q

How does a primary infection of TB progress ?

A

Primary focus continues to enlarge - cavitation

Hilar lymph nodes become enlarged to the point they compress bronchi causing lobar collapse

Lymph node discharges into bronchus (tuberculosis bronchopneumonia)

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17
Q

Describe the incidence and findings in miliary TB ?

A

Small percentage (1%)

6-12 months after infection

Fine mottling on the X-ray, widespread small granulomata - looks like millet seed in the lung - very serious

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18
Q

How can TB affect the CSF and the pleura ?

A

Can cause meningeal TB (severe, CSF high protein, lymphocytes)
AND
Tuberculosis pleural effusion

19
Q

What is meant by post primary disease ?

A

Reactivation of mycobacterium from latent primary infection disseminated by the blood stream around the body

New re-infection from outside source

20
Q

What are the sites of post primary disease from TB ?

A

Pulmonary disease

Lymph nodes, usually cervical

Bone and joint; spine, hip, etc

Genito-urinary; kidney, ureter, bladder

Males; infertility - vas deferens

Females; infertility - uterus, Fallopian tubes

Pericardium; constrictive pericarditis

Abdomen; ascites, ileal TB obstruction

Adrenal Addison’s disease

Skin; lupus vulgaris

Just about any other tissue!

21
Q

What are the features of TB usually after 6-12 months ?

A

Miliary , meningeal, pleural TB

22
Q

What are the features of TB after 1-5 years ?

A

Post primary disease - pulmonary and skeletal

23
Q

What are the features of TB after 10 years ?

A

Genitourinary, Cutaneous TB

24
Q

How would you describe the progression of Post-primary TB ?

A

Slow, may be no symptoms for many months

25
Q

What are the symptoms for Post primary TB ?

A

Respiratory; cough, sputum, haemoptysis, pleuritic pain or breathlessness
Systemically unwell
Malaise, fever, weight loss (“night sweats”) - very characteristic of TB

26
Q

What is characteristic PMH for Post-primary Pulmonary Tuberculosis ?

A

Diabetes, Immunosuppressive diseases, Previous TB

27
Q

How is post-primary TB diagnosed ?

A

Classical: apices, soft ‘fluffy’/nodular upper zone, cavitation in 10-30%
Lymphadenopathy rare
Normal CXR in 13% of definitive plum, TB (22% in HIV)

28
Q

When should a CT be considered ?

A 
Normal CXR but clinical suspicion 
     Miliary TB
     Caviation and other differentials 
     Lymphadenopathy, alternative diagnosis 
     Targets for BAL
29
Q

What are the means of diagnosing TB ?

A

Sputum analysis
Chest radiograph
CT scan of thorax
Bronchoscopy with alveolar lavage, transbronchial biopsy
Pleural aspiration and biopsy if pleural effusion

30
Q

How do we analyse sputum samples for TB ?

A

ZN stain - immediate answer if AAFB

Culture

Sputum PCR

31
Q

What features of a chest radiograph confirms presence of TB ?

A

Patch shadowing, often in apices/upper zones, or apex or lower lobes
Cavitation
Calcification if chronic or healed TB

32
Q

What happens after the fluid is collected from the pleural aspiration ?

A

Fluid cytology (lymphocytes)

Fluid for AAFB and culture

Biopsy histology

1 biopsy sent in Saline for culture

33
Q

What is treatment of tuberculosis ?

A

Vitamin D causes macrophages to release Cathelecidin which is a very potent antibiotic.

Surgery - Collapse of the cavity by: Phrenic crush (crushing the phrenic nerve causes the diaphragm on that side to become paralysed and rise up, closing the cavity), artificial pneumothorax (collapses the lung and therefore the cavity), pneumoperitoneum, thoracoplasty (Six to eight ribs were broken and pushed into the thoracic cavity to collapse the lung beneath), lung resection (removal of a segment of lung).

34
Q

How are drugs used against TB ?

A

Multiple used to prevent resistant organisms forming,

Therapy at least 6 months, slowly growing organism

ONLY SPECIALISTS TREAT

35
Q

What are the legal requirements behind treating TB ?

A

Legal requirement to notify all cases

low threshold for HIV testing, AIDS defining condition

36
Q

What are the drugs used for TB management ?

A 
Streptomycin 
Isoniazid
Pyrazinamide
Rifampicin
Ethambutol
37
Q

What are the side effects of Rifampicin ?

A

Orange urine, tears, induces liver enzymes, prednisolone, anticonvulsants, oral contraceptive pill is ineffective
Hepatitis

38
Q

What are the side effects of Isoniazid ?

A 
Hepatitis 
Peripheral neuropathy (pyridoxine B6)
39
Q

What are the side effects of Pyrazinamide ?

A

Hepatitis

Gout

40
Q

What are the side effects of Ethambutol ?

A

Optic neuropathy

41
Q

What can all 4 drugs also cause ?

A

Rash

42
Q

What is the point of TB contact tracing ?

A

Find out where the patient has caught it and who they might have spread it to

43
Q

Likelihood of infection with TB depends on ?

A

Duration of contact

Intensity of infection

44
Q

What is the treatment for latent TB ?

A

Rifampicin & Isoniazid for three months, or
Isoniazid only for six months, or
Rifampicin only for six months, or
Rifapentine & Isoniazid once weekly for 12 weeks (underserved population)

Respiratory block (38 decks)

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