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Unit 13 (Tommy) > 13.3. TB alert 1 > Flashcards

13.3. TB alert 1 Flashcards

1
Q

Explain what mycobacterium tuberculosis is

A
  • Aerobic
    • Predilection for lung
  • High lipid content and high mycolic acid content in cell wall
    • Likely reason for virulence and resistance
    • “Acid-fast bacillus”
    • Unable to Gram stain
    • Ziehl-Neelsen staining
  • Slow growing and long-living
  • Group of genetically related mycobacteria

Mycobacterium TB complex

  • MTB complex e.g.
    • M. TB
    • M. africanum
    • M. bovis
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2
Q

How can Mtb be spread?

A
  • Airborne droplet nuclei e.g. coughing, singing, communual smoking
  • Can remail suspended in the air for hours
  • Overcrowded living e.g. prisons
  • Oropharyngeal/intestinal deposition
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3
Q

What are the consequences of being exposed to Mtb?

A
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4
Q

What is a granuloma?

A
  • It is a ccollecction of lymphocytes, macrophages, epithelial cells (if has central necrosis = caseating granuloma)
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5
Q

What symptoms does Mtb commonly present with?

A
  • Pulmonary
    • Cough
    • Purulent sputum / haemoptysis
    • Breathlessness
  • Extrapulmonary
    • CNS / ocular
    • Bone / joint
    • GI
    • Lymph nodes
    • Pericardial
  • Constitutional symptoms
    • Fever
    • Cachexia (extreme ‘weight loss’ and muscle loss)
    • Night sweats
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6
Q

How long to symptoms occur for?

A
  • Weeks-months
  • Symptoms are progressive
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7
Q

What are the at risk groups of Mtb?

A
  • Immunosuppressed
  • Previous close TB contact (esp if in past 2 years)
  • Recent travel from high prevalence TB countries
  • Prisoners
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8
Q

What are common X-ray abnormalities found in Mtb patients?

A
  • Consolidation (air that normally fills small airways in lung are replaced by fluid, pus, blood etc.)
  • Effusion (pleural)
  • Decreased volume/collapsed lung
  • Mediastinal lymphadenopathy (abnormal size or consistency of lymph nodes) e.g. enlarged hilar nodes
  • Miliary shadowing
  • In picture = bilateral consolidation
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9
Q

What are radiological features of post primary TB (reactivation TB)?

A
  • On CXR (chest C-ray) with past TB contact may have:
    • Granuloma
    • Apical scarring
  • Nodular in upper zones of the lungs
  • Consolidation
  • Cavitation (Dead, or necrotic, tissue tends to tear and break down e.g. in the lungs)
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10
Q

What is this an example of?

A

Cavitation in the lungs (Dead, or necrotic, tissue tends to tear and break down)

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11
Q

What is this an example of?

A

Calcified granulomas

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12
Q

What is this an example of?

A

Biapical scarring & granulomas

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13
Q

What is this an example of?

A

Consolidation of the left & right apex

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14
Q

Describe miliary TB

A
  • TB spread via blood (haematogenous spread)
  • Often suggests immunodeficiency
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15
Q

What are the symptoms of TB and radiological features?

A
  • In lung
    • Widespread fine nodules
    • Uniform distribution on CXR
  • Elsewhere
    • Liver / spleen in 80-90%
    • Kidney 60%
    • Bone marrow 25-75%
    • CNS disease in 20%
  • Patient usually very unwell
  • Often have multisystem symptoms
  • On CXR has multiple fine nodules throughout the lungs
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16
Q

What are the main sites of extrapulmonary TB?

A
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17
Q

Explain TB lymphadenitis and diagnosis and treatment

A
  • Cervical LN: scrofula
  • Commonest extrapulmonary site
    • Cervical chain in 45-70%
  • Presentation
    • Slowly progressive LN swelling
    • Usually over 1-2 months
    • Fever in 20-50%
    • Widespread lymphadenitis if HIV / immunosuppression
  • Diagnosis
    • Fine needle aspiration or biopsy
  • Treatment
    • Standard drug therapy
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18
Q

Explain CNS TB and diagnosis and treatment

A
  • Presentation depends on site
  • TB meningitis
    • Meningeal symptoms preceded by 2-8 weeks of non-specific symptoms
    • Cranial nerve palsies in 40-50%, visual loss, hydrocephalus
  • Diagnose through CSF examination
    • High protein, high lymphocytes
    • TB bacilli difficult to culture
    • Molecular testing: PCR, WGS (see later)
  • 12 months of TB treatment needed
    • Oral steroids often used
  • Significant mortality (if focal neurology or reduced consciousness)
  • Other presentations: Tuberculoma, intracranial abscess, spinal cord meningitis
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19
Q

Explain spinal TB and diagnosis and treatment

A
  • More common in thoracic and lumbar vertebra
  • 1/3 have evidence of TB elsewhere. 25% have abnormal CXR
  • 1/3 have associated psoas abscess
  • Presentation
    • Non-specific
    • Back pain and systemic symptoms
  • Diagnosis
    • Biopsy site and send for AFB
  • Treatment
    • May need surgery to stabilise area
    • 9-12 months TB drugs (n.b. guidelines say 6 months)
20
Q

Explain urogenital TB and diagnosis and treatment

A
  • TB spreads via blood to urogenital tract
  • Males > females
  • Gradual onset
    • Average time between pulmonary TB and urogenital TB is 2 decades
  • Presentation
    • Dysuria (pain during urination), haematuria, pain
    • Fever rare
    • Scrotal mass
  • Diagnosis
    • Recurrent sterile pyuria
    • Urine culture
    • Biopsy
  • Treatment
    • Standard TB drug treatment
21
Q

How to diagnose someone with TB using microscopy/culture?

A
  • Sputum
    • Send 3 samples
    • Ziehl-Neelsen staining can show Acid Fast Bacilli*
    • “Smear positive” = infectious
    • Rapid liquid culture (< 2 weeks)
    • Solid-medium culture (6-8 weeks)
  • Bronchoscopy
    • Not needed if coughing sputum
    • May be needed if other differential diagnoses (cancer)
  • Other tissue samples
    • Early morning urine (renal TB)
    • Pleural biopsy (pleural TB)
    • Lymph node biopsy

•Etc

22
Q

What are the molecular techniques used to diagnose TB?

A
  • PCR
    • Rapid confirmation of presence of MTB complex
    • Can identify rifampicin resistance
    • Near patient kits can provide result in <2 hours
  • Whole genome sequencing (WGS)
    • Identifies species, drug resistance, and can identify transmission cluster
    • Important in controlling epidemics
    • Compared with traditional contact tracing
    • Increasingly quick and affordable
    • All positive samples on AFB stain or culture in UK sent for WGS
23
Q

How can we prevent resistence in TB?

A

By using multiple drugs to prevent resistance e.g. rifampicin, isoniazid, pyrazinamide

24
Q

What are the side effects of rifampicin?

A
  • Orange urine, tears
  • Rashes and abnormal liver function
  • Thrombocytopenia (low levels of platelets)
  • Renal failure
  • Shock
  • Visual disturbance
  • Nausea & abdominal pain
25
Q

Briefly describe rifampicin

A
  • Bactericidal
  • Kills active & semi-dormant bacteria
  • Has excellent absorption
  • Less effective on CNS
26
Q

What are the side effects of isoniazid?

A
  • Hepatotoxicity
  • Nausea and vomiting
  • Histaminee foods reactions e.g. fish
  • Aplastic anaemia (not enough RBC made)
  • Cutaneous hypersensitivity
  • Neurotoxicity
27
Q

Briefly describe isoniazid

A
  • Only active against Mtb
  • Kills actively dividing cells
  • Good oral absorption
    • ​Metabolised by acetylation
  • Therapeutic levels in CSF
  • Excreted in urine
28
Q

What are the side effects of pyrazinamide?

A
  • Hepatotoxic
  • Rash
  • GI disturbances
  • Gout
29
Q

Briefly describe pyrazinamide

A
  • Kills dormant bacteria
  • Inhibits fatty accid synthesis
  • Well absorbed
    • Also good absorption to CSF
  • In hepatic metabolism inhibits renal excretion of uric acid
30
Q

Briefly describe ethambutol

A
  • Bacteriostatic (capable of inhibiting the growth/replication of bacteria)
  • Inhibits arabinosyl transferase
  • Absorption can be inhibited by ALCOHOL
  • Poor CSF penetration (unless active meningitis)
31
Q

What are the principles of treatment of tuberculosis?

A
  1. Begin treatment with ALL 4 drugs
    • DO NOT reduce until 2 months of treatment AND drug sensitivities available
  2. If FULLY sensitive AND better –> change to isoniazid and rifampicin for 4 months
  3. If ABSCENT drug sensitivity –> use 3rd agent drug
  4. Different treatment of CNS affected (usually drugs for 12 months - 2 initial all 4 then 10 months isoniazid and rifampicin)
  • Early detection and treatment (completion) is key
32
Q

Who is more at risk of drug induced liver injury during treatment of Mtb?

A
  • Caucasians
  • Older patients
33
Q

What is IRIS (immune reconstitution inflammatory syndrome)?

A
34
Q

Explain infection control in hospitals related to TB

A
  • If able, do not admit to hospital
  • Smear positive/suspected pulmonary TB
    • nurse in side room vented to outside air, facemask.
  • Barrier nursing not necessary for smear negative non MDR TB.
  • MDR TB barrier nurse negative pressure side room.
  • If HIV negative non MDR TB, usually non infectious after 2/52 treatment.
  • If patient found to have TB, risk of infection is low, only those in same room as coughing smear positive case for >8hrs at increased risk.
35
Q

Explain contact tracing in TB

A
  • Vital in preventing spread of TB
  • “Close contact”
    • People who have had prolonged, frequent or intense contact with a person who has had infectious (Smear +ve) TB
  • If symptomatic close contact
    • Assess for active TB: CXR, sputum AFB
  • If asymptomatic close contact and <65 years old
    • Test for latent TB: Interferon Gamma Release Assay (IGRA) – “Quantiferon gold”
    • Consider treatment of latent TB if positive
    • Reduces risk of developing active TB by 2/3.
36
Q

Explain diagnosis of latent TB

A
  • Evidence of positive immune response to TB with normal CXR and no symptoms.
    • Immune response assessed by:
      • Interferon Gamma Release Assay (IGRA)
      • Skin test (Mantoux)

Unable to differentiate from those who have cleared bacteria (but immune response remains) and those who have persistent viable bacteria

  • Latent TB associated with risk of developing active TB
    • Preventative treatment reduces this risk
37
Q

What are the risks of developing active TB from latent TB?

A
  • Risk of developing active disease increased in:
    • Recent (<2 years) contact with infectious (smear positive) individual
    • HIV coinfection / immunosuppressed
    • Chronic alcohol excess
    • Diabetes
    • Anti-TNF drug therapy / immunusppressive therapy
    • Partial gastrectomy (removal of part of the stomach)
  • Balance risk of developing TB with risk of treatment
    • Care if frailty, high risk of hepatotoxicity etc
38
Q

What is chemoprophylaxis?

A

The use of drugs to prevent disease.

39
Q

Who are the vulnerable groups of TB patients?

A
  • Children
  • New immigrants/refrugees
  • Older people
  • Homeless, mental health patients
  • HIV, Hep B and C patients
  • Known TB contacts
  • Asian/african groups
  • People with co-morbidities e.g. diabetes or immunosuppresed
40
Q

What is the role of a TB nurse?

A

To reduce the incidence of TB within the local population

  • Case managing TB patients
  • Contact screening / incident screening
  • New entrant screening
  • Working with other professionals
  • Involvement with Regional TB networks/ TB regional Board
  • Raising awareness and education
41
Q

How does a TB nurse help patients to be compliant with TB treatment?

A
  • Monitoring the patient at home
  • Ensuring patient is taking medication as prescribed
  • Maintaining adequate medication
  • Monitoring side effects of antibiotics
  • DOT / VOT / tablet counts
  • Supporting patient attendance with hospital appointments
42
Q

What are the risk factors of TB?

A
  1. Poor housing
  2. Low incomoe
  3. Nutrition
  4. Lack of resources and information
  5. Immunosuppression, secondary diseases (e.g. HIV)
  6. Language/cultural barriers
  7. Overcrowding
  8. Vitamin D deficiency
  9. Homelessness
  10. Smoking
43
Q

What are the advantages of home visits that TB nurses do?

A
  • Patients talk more about worries and concerns of treatment
  • Can identify contacts that patient hasn’t divulged
  • Quick access to consultant with issues
  • Provide advice and support with treatment and social needs
44
Q

What are the main symptoms of TB?

A
  • Cough lasting longer than 3 weeks
  • Unexplained weight loss
  • Fatigue / Feeling unwell / loss of appetite
  • Night sweats / Pyrexia (raised body temperature)
  • Haemoptysis (coughing up blood)
  • Swollen lymph glands
45
Q

Explain the BCG vaccine

A
  • BCG vaccine helps to protect children mainly against TB Meningitis
  • Children may have few symptoms of TB though they can become very ill quickly
  • BCG vaccine is 70-80% effective against TB, doesn’t last a lifetime
  • Can only be given once, doesn’t always leave scar
46
Q
A

Unit 13 (Tommy) (15 decks)

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