Respiratory: TB Flashcards
Mycobacteria are:
- gram-negative cocci shaped bacteria
- gram-postive cocci shaped bacteria
- gram-negative rod shaped bacteria
- gram-postive cocci shaped bacteria
- gram-negative spiral shaped bacteria
Mycobacteria are:
- gram-negative cocci shaped bacteria
- gram-postive cocci shaped bacteria
gram-negative rod shaped bacteria
- gram-postive rod shaped bacteria
- gram-negative spiral shaped bacteria
What are the red flag pathologies (on BMJ BP) for haemoptysis? [8]
- Pulmonary TB
- Primary lung cancer
- Lung metastasis
- Anticoagulants
- Toxic inhalation
- Mitral valve stenosis
- PE
- LVF
- Coagulopathy
- Thrombocytopenia
- Aspergilloma
- Aspiration of foreign body
Pathogenesis of TB?
- Inhaled bacteria in droplets carried into lungs:
typically settle in subpleural area mid or lower lung zones - Engulfed by alveolar macrophages form Ghon Focus
- TB laden macrophages travel to local lymph nodes
- Form Primary complex (aka Ghon Complex) = primary TB lung infection in non-immune host (Ghon Focus, TB granuloma), plus draining lymph nodes.
- 5% Ptx have primary pulmonary TB
- 5% will control TB temporarily, but it will be reactivated later (latent): post primary TB
- 90 % have no more disease progression
What is a ghon focus? [1]
What is a ghon complex? [1]
A small lung lesion known as a Ghon focus develops. The Ghon focus is composed of tubercle-laden macrophages.
The combination of a Ghon focus and hilar lymph nodes is known as a Ghon complex
Investigating for TB:
Which stain do you use for Tb? [2]
What colour do they appear when using this stain? [2]
Ziehl–Neelsen stain: bright- red colored rods when a is used.
Auramine: flourescent coloured
Investigating TB:
How do you diagnose if you’ve got latent TB or not? [2]
Tuberculin sensitivity Test – aka PPD (Purified Protein Derivative) (Manteux) test:
- Tuberculin is injected between layers of the dermis, tuberculin is a component of the bacteria, and if a person has previously been exposed to TB, the immune system reacts to the tuberculin and produces a small, localized reaction within 48 to 72 hours; if the reaction creates a large enough area of induration (rather than just redness), it’s considered to be a positive test.
DOESNT DISTINGUISH BETWEEN LATENT AND ACTIVE TB
IFN-γ assay
- If patient has had TB infection, T lymphocytes produce interferon gamma in response – measured and compared with control sample.
If a patient has suspected primary TB, which investigations would you order? [2]
Primary investigations for active pulmonary infection include:
- chest x-ray
- three sputum samples obtained for microscopy, culture, and nucleic acid amplification testing (NAAT).
Describe the three different sputum analyses used for TB investigations [3]
Sputum microscopy
- three samples are required.
- Ziehl-Neelsen stain
Culture Gold standard
- can take up to 6 weeks in solid media
- can take 1-3 weeks in liquid media
NAAT:
- amplifies a specific nucleic acid sequence that can be detected via a nucleic acid probe
- some NAATs can detect genes encoding drug resistance
Describe the two NAAT tests / assays used for TB [2]
Xpert MTB/RIF assay:
- detects M tuberculosis
- detects rifampin-resistance mutations.
Amplified Mycobacterium tuberculosis direct test:
- detects TB but NOT drug resistance.
Which form of investigating for latent TB is preferred for patients with a history of BCG vaccincation? [1]
An IGRA is preferred in individuals with a history of BCG vaccination.
The NICE guidelines on tuberculosis (2016) describe “deep cough” sputum samples. If they are not producing enough sputum, the options are what? [2]
Sputum induction with nebulised hypertonic saline
Bronchoscopy and bronchoalveolar lavage (saline is used to wash the airways and collect a sample)
Describe the clinical presentation of latent TB [1]
Latent infection of TB is asymptomatic and non-contagious
Name this sign of TB [1]
Erythema nodosum
Describe the clinical presentation of primary or reactivaed TB
Pulmonary TB:
* Dyspnoea, cough (+/- haemoptysis) , chest pain.
* Cough: over 2 to 3 weeks; initially dry, later productive.
* Chest examination: crackles, bronchial breath sounds, or maybe normal.
* Fever: usually gradual onset and low-grade.
* Night sweats: maybe drenching.
* Weight loss, anorexia, and malaise are also common.
* Erythema nodosum(tender, red nodules on the shins caused by inflammation of the subcutaneous fat)
Where is the most common extra-pulmonary site for TB? [1]
Describe how they change [3]
Lymph nodes:
* Enlarged
* Firm
* Non-tender
NB: most commonly affects cervical and supraclavicular nodes.
Describe the clinical findings on respiratory an examination for TB [4]
- 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 effusions
State 4 differential diagnoses for pulmonary TB [4]
- Bacterial pneumonia or viral respiratory tract infection
- Interstitial lung disease
- Malignancy including lymphoma
- Sarcoidosis
Describe the cough in primary TB [1]
Cough: over 2 to 3 weeks; initially dry, later productive.
Patients with TB can present with an abscess. Describe the nature of this abcsess [3]
A cold abscess:
- a firm, painless abscess
- usually in the neck.
- They do NOT have the inflammation, redness and pain you expect from an acutely infected abscess.
Describe 3 groups for risk factors for TB reactivation?
Immunocompromised states:
- infection with HIV
- Diabetes mellitus
- Silicosis
- Malnutririon
- Ageing
- Prolonged therapy with corticosteroids
- Other immunosuppressive therapy
- Organ transplant
Substance abuse
- IV
- Alchoholics
Others:
* Tumor necrosis factor- alpha [TNF-α] antagonists (used in RA)
* Haematological malignancy
* Severe kidney disease /haemodialysis
Treatment of which drug type is a risk factor for TB re-activation?
Prolonged therapy of corticosteroids
Explain the pathology of primary TB
Primary TB:
- After exposure macrophages ingest the bacteria, they produce a protein that inhibits fusion of macrophage and lysosome, which allows the mycobacterium to survive
- Proliferates, and creates a localized infection.
- About 3 weeks after initial infection, cell-mediated immunity kicks in, and immune cells surround the site of TB infection, creating a granuloma, essentially an attempt to wall off the bacteria and prevent it from spreading.
- The tissue inside the middle dies as a result, a process referred to as caseous necrosis, which means “cheese-like” necrosis, since the dead tissue is soft, white, and looks a bit like cheese. This area is known as a “Ghon focus.
Why would post-primary TB / reactivation of latent TB occur? [1]
Where is post primary TB most likely to be found ? [1]
Reactivation of latent TB causes: Post primary TB
- If the host becomes immunocompromised the initial infection may become reactivated. Reactivation generally occurs in the apex of the lungs and may spread locally or to more distant sites.
- In lungs characterized by cavitary lesions, typically in oxygen rich upper lobes. Relates to hosts previous exposure to MTB and immune response.
Would would CXR of Ptx with TB present like? [3]
Apex of the lung often involved (more aerobic!)
Ill defined patchy consolidation
Cavitation usually develops within consolidation
Healing results in fibrosis
Hilar lymphadenopathy
What is biggest risk factor for mTB reactivating? [1]
All suspected and confirmed cases of TB must have an WHAT test? [1]
HIV / AIDs (due to both infections impacting T helper cells)
All suspected and confirmed cases of TB must have an HIV test
What would CXR look like in:
- Primary TB
- Reactivated TB
- Millary TB
Primary TB may show patchy consolidation, pleural effusions and hilar lymphadenopathy
Reactivated TB may show patchy or nodular consolidation with cavitation (gas filled spaces in the lungs) typically in the upper zones
Disseminated Miliary TB give a picture of “millet seeds” uniformly distributed throughout the lung fields
Which type of TB is depicted? [1]
Miliary TB
Which type of TB is depicted? [1]
Tuberculosis, post-primary. There are large cavities in both apices and smaller cavities scattered throughout the lungs. The lungs are over-aerated and there is already scarring present. Dilated bronchi (tuberculous bronchiectasis) is present throughout the lungs.
What vaccination do you give for TB? [1]
Which population do you give it to? [1]
BCG: Bacille Calmette-Guerin vaccine
Given to children: little evidence protecting adults
Describe the first line treatment active TB? [4]
The recommended regimen for drug-susceptible individuals is:
Intensive phase:
Intensive phase: two months of
- isoniazid
- rifampicin
- pyrazinamide
- ethambutol.
Continuation phase: four months of:
- isoniazid
- rifampin.
Second line Treatment medications for TB?
Quinolones (Moxifloxacin)
Injectables
Capreomycin, kanamycin, amikacin
Ethionamide/Prothionamide
Cycloserine
PAS (Para-aminosalicylic acid)
Linezolid
Clofazamine
How should you monitor treatment treatment of TB? [1]
Sputum samples (microscopy and culture) should be obtained for acid-fast bacilli smear and culture at monthly intervals until two consecutive cultures are negative.
Which treatments do you provide for certain lenght of time for in TB? [1]
6 months total treatment duration
First two months: Rifampicin, Isoniazid (with pyridoxine), Pyrazinamide, Ethambutol
Next 4 months – if MTB drug susceptibility conforms- isoniazid (with pyridoxine) and rifampicin
What is miliary TB?
When does it occur? [1]
Name 5 other areas is can effect
Miliary TB:
- systemic spread of bacilli through blood stream
- during: primary infection or reactivation
- lungs are always involved
- Often multiple organs involved:
i) Headaches suggest meningeal involvement
ii) Pericardialpleural effusions
iii) Ascites(involvement of peritoneum)
iv) Retinal involvement (choroid tubercles in the eye)
v) Adrenal glands – may causes adrenal insufficiency
Name 5 places that extra-pulmonary TB likely spread to [3]
Lymphadenitis
Cervical LNs most commonly
Abscesses & sinuses
Gastrointestinal
Swallowing of tubercles in mucous coughed up – any part gut
Peritoneal
Ascitic or adhesive
Genitourinary
Slow progression to renal disease
Subsequent spreading to lower urinary tract
Bone & joint Haematogenous spread
Spinal TB most common- called Pott’s disease
Tuberculous meningitis
Chronic headache, fevers
CSF – markedly raised proteins, lymphocytosis
Q2: Please list the four first line medications used to treat TB, and for each medication one described side effect
Rifampicin: Raised transaminases & induces cytochrome P450; Orange secretions / urine
Isoniazid: Peripheral neuropathy (prevent with pyridoxine 10mg od); Hepatotoxicity
Pyrazinamide:Hepatotoxicity
Ethambutol: Visual disturbance
How do you manage interruption of treatment? [2]
-
Extending the duration of treatment
or - Restarting the treatment from the beginning.
What would classify TB as being mutli-drug resistant? [1]
TB resistant to at least both isoniazid and rifampin.
What would classify TB as being extensively drug-resistant? [1]
Resistant to at least isoniazid, rifampin, and fluoroquinolones (ciprofloxacin, delafloxacin, levofloxacin, moxifloxacin) as well as either aminoglycoside (amikacin, kanamycin) or capreomycin or both.
Describe the treatment regime for extensively drug resistant TB [5]
The regimen consists of at least five drugs: comprised of susceptible first-line drugs if any. These are:
- fluoroquinolone,
- bedaquiline
- linezolid
- additional oral agents (clofazimine, cycloserine, or terizidone).
How do you treat TB with CNS involvement? [2]
Isoniazid, rifampicin, pyrazinamide and ethambutol for two months
AND
Isoniazid and rifampicin for a further TEN months
Describe how you treat latent TB [2]
-
three months of isoniazid and rifampicin
OR - Six months of isoniazid only
What do you give when treating TB to avoid peripheral neuropathy? [1]
To avoid peripheral neuropathy, pyridoxine (vitamin B6) is always given with isoniazid
How long is the duration of drug resistant? [1]
Different regimens of combination of second-line drugs are used for a duration of 9 to 18 months.
Which of the following reduces the effect of the combined pill?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
Which of the following reduces the effect of the combined pill?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
Which of the following requires vitamin B6 to be prescribed alongside it?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
Which of the following requires vitamin B6 to be prescribed alongside it?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
Which of the following causes a risk of gout?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
Which of the following causes a risk of gout?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
Which of the following causes a risk of kidney stones?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
Which of the following causes a risk of kidney stones?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
Which of the following causes a risk of peripheral neuropathy?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
Which of the following causes a risk of peripheral neuropathy?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
I’m-so-numb-azid
Which of the following causes a risk of colour blindness and reduced visual acuity?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
Which of the following causes a risk of colour blindness and reduced visual acuity?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
“eye-thambutol”
Which of the following is not associated with a risk of hepatoxicity?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
Which of the following is not associated with a risk of hepatoxicity?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
Which of the following may cause orange/red tears?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
Which of the following may cause orange/red tears?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
rifampicin (“red-I’m-pissin’”)
A 26-year-old male presents to the General Practitioner with anorexia, loss of appetite, hot flushes, especially at night and weight loss for the past six months. He has had a cough with expectoration and intermittent fever for the past month. Chest X-ray shows a large (4.5 cm) left upper-lobe cavity.
Which of the following investigations leads to a definitive diagnosis?
Blood cultures
Computed tomography (CT) scanning of the chest
Mantoux test
Serum inflammatory markers
Sputum sample
Sputum sample
A patient presenting with a history of taking which drugs might indicate investigating for TB? [1]
anti-TNF medication
Most tuberculosis cases have been seen with infliximab. The British Thoracic Society recommends clinical examination, chest X-ray and tuberculin test before starting treatment with anti-TNF antibody medications.
Which of the following is associated with a risk of joint pain?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
Which of the following is associated with a risk of joint pain?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
