1: Pulmonary TB Flashcards
What is TB
Infection mycobacterium tuberculosis
In which gender is TB more common
Males
Which countries have a higher incidence of TB
India Indonesia China Nigeria Pakistan
What type of organism is mycobacterium TB
Gram positive acid-fast bacilli
what causes TB in 95%
Mycobacterium tuberculosis
what does mycobacterium bovis cause
GI TB
what causes mycobacterium bovis infection
Ingestion cow’s milk
what are 5 RF for mycobacterium TB
- Immunosuppressed
- Alcoholism
- DM
- Malnutrition
what are at-risk groups for TB
- Healthcare workers
- Prison workers
- Immigrants
- Alcoholics
- HIV
when is TB contagious
during active infection
what are constitutional of TB
- Weight Loss
- Night sweats
- Lymphadenopathy
- Malaise
- Fever
- Fatigue
what are pulmonary symptoms of TB
Dyspneoa
Haemoptysis
how does TB lymphadenitis present
painless enlarged cervical and supra-clavicular nodes
which region does GI TB usually affect
ileocaecal valve
how does GI TB present clinically and why
- colicky abdominal pain and vomiting. Inflammation leads to strictures which causes secondary BO
what is pott’s disease
Tuberculosis spondylitis
how does spinal TB present
Tenderness and pain over spine
Rare to have neurological symptoms
what is miliary TB
Dissemination multiple foci (2mm) around the lung - giving a millet seed appearance on CXR
what is CNS TB
infection brain and meninges
what are 3 risks for CNS TB
HIV
Immunocompromised
Under 3-years
what is GU TB
Infection GU tract presents with flank pain, dysuria and haematuria
what can GU TB cause in women
Infertility
what can GU TB cause in men
Prostatitis
what is cardiac TB
Pericarditis
what skin deformity does TB cause
lupus vulgaris: red-brown nodules on the face which then rupture and develop into ulcers
Explain primary tuberculosis infection
TB enters lungs (Inferior) where it is phagocytosed by macrophages. TB inhibits fusion of lysosome and phagosome enabling proliferation of bacteria = primary infection
What happens after primary infection
3W later: cell mediated response amounts which forms a granuloma surrounding TB. Cells in middle die making it a caseous necrosis
Explain Ghon Focus
Granuloma and caseous necrosis
What is a Ghon complex
TB in granuloma may spread directly to lymph nodes which is then termed a goon complex
What happens if individual becomes immunocompromised
TB may re-activate and spread to upper part of the lung
Why does TB spread to upper region of lung
More aerated
What happens once TB has spread
May spread haematogenously - causing miliary TB
what will be seen on CXR in TB
- Hilar lymphadenopathy
- Ghon complex (Lower/Middle lobe)
what does upper lobe cavitation on CXR indicate
re-activation of TB
what else can be seen on CXR in TB
miliary seed appearance
what investigations are ordered in TB
CXR Sputum Smear - and NAAT Sputum Culture HIV Test
how many specimens are required for sputum smear
3 specimens - one must be early morning sample
what is used to test for TB on sputum smear
Zeihl-Neelsen stain
how will TB present on ziehl nelson stain
Red
what medium is used to culture TB
Lowenstein-Jensen
what is gold-standard for TB diagnosis
Sputum culture
what is problem with sputum culture
Liquid: 1-3W
Solid culture: 4-8W
how will TB present in lowenstein-jensen agar
Rough, Buff and Tough
what test is used for rapid TB diagnosis
NAAT
explain nucleic acid amplification testing
- looks for DNA or RNA of M.tuberculosis in sputum.
- results take less than 8h
what test should be offered for all individuals with TB
HIV Test
what is offered to household contacts of someone with TB
Mantoux testing
what is tuberculin skin testing also called
Mantoux testing
what is the Mantoux test
Purified protein derivative of TB is injected into the skin. Left 48-72h and then size of induration is measured
what is the Mantoux test used for
Screen for latent TB
what diameter of induration is negative for TB
<6mm
what does 5mm diameter on Mantoux mean
- Has not been exposed to TB or is unvaccinated
how should those less than 6mm be managed
- Give BCG vaccine
what does induration 6-15mm mean
Hypersensitive to TB - either due to previous vaccination or exposure
what does induration more than 15mm mean
Hypersensitive to TB - due to previous infection
what is a test used when Mantoux test is equivocal
Interferon gamma release assay (IGRAS)
what does IGRAS do
Measures concentration of interferon released from T-cells
explain notification of TB
TB is a notifiable disease - inform CDC in 3-days
what are 5 causes of false negatives on Mantoux test
- Lymphoma
- Miliary TB
- Sarcoidosis
- Young Child
- HIV
explain drug management in TB
4 for 2 and 2 for 4:
Give rifampicin, isoniazid, pyrazinamide and ethambutol for two months.
Give rifampicin and isoniazid for 4-months
how is treatment success defined
completion therapy and negative sputum smear
how is CNS TB managed
RIPE - for 2 months
RI for 10 months
+ dexamethasone
why are steroids given in CNS TB
as TB cells rupture release antigens causing further immune response which can cause oedema and raise ICP
what are 2 side effects of rifampicin
- Orange secretions
- Hepatotoxicity
what are 2 side effects of isoniazid
- Hepatoxocitioy
- Peripheral polyneuropathy
what is given with isoniazid to prevent peripheral polyneuropathy
Pyroxidine (vitamin B6)
what. are 4 side effects of pyrazinamide
- High Uric Acid
- Hepatotoxicity
- Arthralgia
- Myopathy
what is a side effect of ethambutol
Optic neuritis
how is ethambutol monitored
Decease colour vision
what is multi drug-resistant TB
Resistant to rifampicin and isoniazid
what is extensively drug resistant TB
Resistant to rifampicin, isoniazid, one other injectable agent and fluoroquinolone
how is TB infection prevented
BCG vaccine
what infants are vaccinated against TB
Infants born in region where TB incidence is more than 40 in 100,000
if exposure to someone with TB how is person investigated
CXR
Tuberculin skin test
if positive following exposure what is done
treat for active TB
if negative following exposure what is done
treat for latent TB (vaccinate)
