Tuberculosis Flashcards
What is the epid of TB?
- 9.6million cases per year
- Co infection with HIV in 12% cases
- Leading cause of death worldwide
- 5million deaths/yr
What are RF for TB?
- HIV
- Immunosuppressive medication i..e. RA, IBD
- Overcrowding more likely relatives>strangers + homeless people
- Travel: sub Saharan Africa Indica/bangledesh
What is the cause of TB?
infection by mycobacterium tuberculosis affecting multiple organs
What lobes are usually affected in TB?
upper lobes as ventilated better as bacteria need oxygen
When does active TB infection happen?
- active infection happens when containment by immune system (T cells. macrophages) is inadequate
- Can arise by primary infection or reactivation of previous latent disease
How common is latent disease changing?
Latent disease and lifetime risk of reactivation is 5-10% - if immunosuppressed or aging
What are the 3 things possible after initial infection?
- Successful clearance
- Active TB
- Latent TB
What are key points of active TB?
transmissible and pt requires treatment
What are key points of latent TB?
> 90%, not transmissible and TB contained in “caseating granulomas”
What are the systemic features of TB?
- Low grade fever
- Anorexia
Weight loss - Malaise
- Night sweats
- Clubbing
- Erythema nodusm
What are pulmonary features of TB?
- Cough: dry then productive
- Pleurisy
- Haemoptysis (late)
- Dyspnoea/SOB
- Pleural effusion
What is TB lymphadenitis and how is it investigated?
- Usually painless enlargement of cervical or supraclavicular lymph nodes
- Firm to touch and not acutely inflammaed
- Investigate with FNA and AFB staining and culture
How does GI TB manifest?
- Ileocaecal
- Colicky abdominal pain and vomiting
- Peritonitis
- Ascites
- BO can occur from bowel wall thickening
How can you diagnose GI TB?
- Biopsy for diagnosis
2. Caseation necrosis and absence of transmural cracks/fissures distinguish from Crohns
How does Spinal TB manifest?
- Local pain and bony tenderness for weeks-months
- Slow insidious progressive
- Pott’s disease – TB spinal effect
- Spinal cord compression
- Osteomyelitis
What is Miliary TB?
- Haematogenous dissemination leads to formation of discrete foci (around 2cm) of granulomatous tissue throughout lung
- Sputum may be negative for AFB
- Untreated moratlity 100%
How does CNS TB manifest?
- Haematogenous spread lead to foci of infection in brain and spinal cord
- Foci can enlarge to form tuberculomas
- Foci rupture lead to meningitis
- Headache, meningism, seizure, confusion, focal neurological deficient
- meningitis
What do you look for in LP and examination of CSF for CNS TB?
- leucocytosis
- Raised protein
- CSF plasma glucose <50%, AFP stain,
- PCR and culture
What are symptoms and result of genitourinary TB?
- Dysuria
- Frequency
- Loin pain
- Haematuria
- Can cause infertility
- Renal failure
- Sterile pyuria
- Epidiymo-orchtiis
What does cardiac TB result in?
- Pericarditis
- Pericardial effusion
- Constrictive pericarditis
- Normocytic anemia
What are the skin manifestations in TB?
- Lupus vulgaris
- Addison’s disease
- Scrofuloderma
- Erythema nodosum
- Clubbing
What is Lupus vulgaris?
persistent progressive cutaneous TBL red brown apple jelly nodules
What basic obs are done in active TB/symptomatic?
HR, RR, BP, O2 Sats, Temp
What bedside tests are done for active TB/symptomatic?
sputum MCS (x3 samples, one in early morning)
What Microscopy and culture is done for TB?
- Microscopy: AFB stain – Ziehl-Neelsen (cultured in Lowenstein jensen medium)
- Culture takes 6-8 weeks (most sensitive/sepcific)
What bloods are done for active TB/symptomatic?
- FBC: high WCC, anaemia
- CRP: high CRP
- ABG: dyspnoea
- HIV
What other tests are done for TB active?
- CXR
2. Lymph node biopsy
What would CXR for TB show?
- Consolidation: patchy/heterogenous
- Bi-hilar lymphadenopathy
- Upper lobe scarring
- Cavitating lesions
- Pleural effusions
What would lymph node biopsy for TB show?
caseating granuloma
What tests are done for latent TB?
- Tuberculin skin test (Mantoux test) >15 mm – affected by BCG vaccine
- Interferon Gamma release Assay (>99% specific)
What is good/bad about latent TB tests?
- if either is +ve (exposed to TB) get chest CXR
- also used to screen close contacts
- can’t tell if TB is active or latent
What does miliary TB show on CXR?
- nodular shadowing
2. lymphohematogenous dissemination of TB throughout the body – BAD SIGN
What antibiotics are used to treat TB?
- Rifampicin
- Isoniazid
- Pyrazinamide
- Ethambutol
What are SE of rifampicin?
Red/orange secretions
What are SE of isoniazid?
peripheral neuropathy + Vit B6 deficiency so give pyridozine
What are SE of pyrazinamide?
Hyperuricaemia (gout)
What are SE of ethambutol?
eye – optic neuritis (reversible red-green colour blindness)
What acronym is used for treatment of TB?
RIPE
