Microbiology: Tuberculosis and other mycobacteria Flashcards
Cough with haemoptysis, fever, with night sweats, weight loss, malaise. Most likely diagnosis?
Mycobacterium tuberculosis
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Describe mycobacterium
gram +ve, aerobic, acid alcohol fast, thick waxy cell wall.
What are the two ways in which TB can present?
- Post-primary (Young adults)
- Reactivation
- Primary (Children, elderly, HIV)
Outline presentation of Post-primary TB
- Upper lobes affected
- May progress rapidly to cavitation
- Classic lesion: Caseating granuloma
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- Miliary spread is rare
- Healing by fibrosis + Calcification
Outline presentation of Primary TB
- Usually occurs in Children, elderly or HIV patients
- Can be asymptomatic
- Generalised lymphohaematogenous spread
- Mulitplies at pleural surface (Ghon Focus)
- Taken by Mo to LN (Primary complex).
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- Granuloma is characteristic lesion (Langhan’s giant cells)
- Tuberculoma
- Miliary TB
Cough with fevers and night sweats. Caseating granuloma. Most likely diagnosis?
Post-primary TB
Cough, fevers, weight loss in elderly man. Diffuse miliary infiltrate on chest xray. Most likely diagnosis?
Primary TB
Outline management for TB
- 1st line
- Rifampicin (6 months)
- Isoniazid (6 months)
- Pyrazinamide (2 months)
- Ethambutol (2 months)
- 2nd Line
- Injectables (Eg capreomycin)
- Quinolones (Eg Moxifloxacin)
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“RIPE”
Outline management for TB meningitis
- 1st line
- Rifampicin (8-10 months)
- Isoniazid (8-10 months)
- Pyrazinamide (2 months)
- Ethambutol (2 months)
- 2nd Line
- Injectables (Eg capreomycin)
- Quinolones (Eg Moxifloxacin)
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“RIPE”
So you’ve got a patient with TB currently recieving appropriate treatment. They have raised transaminases. What is the most likely cause of this?
Rifampicin
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It also induces cyt P450
+causes orange secretions
A 45 year old man with TB is currently recieving appropriate treatment. He complains that his urine has turned a reddish orange colour.
What is the most likely cause of this?
Rifampicin
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It also induces cyt P450
+causes raised transaminases
A 45 year old man is seen for follow up in a TB clinic and is recieving the appropraite treatment. He complains of loss of sensation in his toes.
What is the most likely cause of this?
Isoniazid causing peripheral neuropathy
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Give B6/Pyrodoxine
A 45 year old man is seen for follow up in a TB clinic and is recieving the appropraite treatment. A recent blood test shows raised serum uric acid.
What is the most likely cause of this?
Hyperuricaemia due to Pyrazinamide
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Also causes hepatotoxicity
A 45 year old man is seen for follow up in a TB clinic and is recieving the appropraite treatment. He complains of visual disturbances.
What is the most likely cause of this?
Optic neuritis caused by ethambutol
Sputum microscopy:
Ziehl–Neelsen stain: show acid fast bacilli.
gram +ve rods.
Most likely diagnosis?
Mycobacterium tuberculosis
Outline the investigations for TB
- CXR
- Sputum cultures (x3) with ZN staining
- Tuberculin skin tests (TSTs), aka mantoux test
- IGRA (Interferon gamma release assays)
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ZN stain = Ziehl–Neelsen stain
Extrapulmonary TB: Common sites?
- Lymphadenitis
- Pericarditis
- Peritonitis (Abdominal)
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+ Others. I guess any extra symptom could be extrapulmonary TB
Fever, night sweats, weight loss, back pain.
CT reveals Iliopsoas abscess.
Most likely diagnosis?
Spinal TB
Head aches, neck stiffness, fevers, previous night sweats. Impaired consciousness. Most likely diagnosis?
TB Meningitis
Depigmented skin, macules, plaques, nodules, trophic ulcers. Sensory neuropathy. examination of eyes show kerititis. Skin biopsy shows acid fast bacilli. Most likley diagnosis?
Leprosy, Hansen’s disease
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M. Leprae + M. Lepromatosis
BCG vaccine is contraindicated in which condition?
HIV
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Can lead to IRIS (Immune reconstitution inflammatory syndrome).
45 south Asian man, new diagnosis of HIV, starts recieving HIV treatment. Develops fevers and night sweats. Most likely diagnosis?
Immune reconstituion inflammatory syndrome (IRIS) due to underlying TB
A 35 year old man from South Asia has a cough, high fever or chills, night sweats, abdominal pain, diarrhoea. History of HIV. Pharyngitis is also noted. Bronchoscopic lung biopsy showed a poorly defined granuloma consisting of pale blue, striated histiocytes filled with mycobacteria
Most likely diagnosis?
Mycobacterium Avium complex
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striated histiocytes
A 35 year old man who presents to his GP with Clusters of plaque/papules. He has a history of Crohn’s disease for which he takes azathioprine. He owns a swimming pool. Most likely diagnosis?
M. Marinarum (Fish tank granuloma)
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Associated with impaired immunity
A 35 year old man has recently come bacl from travelling around Austrailia. he developed a painless nodule and has presented to the GP after it has causes ulceration and scarring. Skin biopsy reveals acid fast bacilli. Most likely diagnosis?
M. Ulcerans (Buruli Ulcer)
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