Tuberculosis Flashcards
How many people are affected by TB worldwide?
2 billion
Why is TB becoming more of a problem in the UK?
Immigration from high risk countries
What bacteria is the cause of TB?
Mycobacteria
M.tuburculosis
M. Bovis
What sort of bacteria is mycobacteria? What stain is used?
Acid-Alcohol Fast Bacilli - AAFB
Doesn’t decolourise in acid, alcohol staining techniques so ZN stain used
Why can our bodies not fight off TB? Why does TB prefer apicies of lungs? Why is disease usually long and drawn out?
Resistant to macrophages and n.phils
Aerobic - so prefers apicies
Slow growing - long disease
How is M.Tuburculosis spread?
Coughing
Sneezing
Resp - droplets
How is M.Bovis TB spread?
Drinking infected cow’s milk - bacteria placed in cervical and intestinal lymph nodes
Pathology of TB, what happens in body as bacteria invades?
Invading mycobacteria triggers Th1 cells which activate macrophages, epitheliod cells and langhan’s giant cells that all accumulate around the infection and form granulomas
Causing central caseous necrosis
Why is the Th1 response a “two edged sword”?
As the response does get rid of infection - but the accumulation of stuff and subsequent necrosis causes problems
How would TB affect a malnourished/elderly patient?
Lots of tissue destruction
Organism proliferates and spreads
Ongoing disease
How would TB affect a healthy young patient?
May or may not have tissue destruction
Organism is contained
Disease is contained or can continue
When does primary disease occur? In who does it occur? Where is the infection focused?
Occurs in those with no immunity
Mainly children
Infection focused in alveoli
Where can the infection spread from alveoli to?
Lymphatics to other organs
Symptoms of primary TB are usually asymptomatic - what may appear?
Erythema nodosum
What are the effects of primary disease progression?
Cavitation
Hilar lymph nodes can enlarge and compress bronchi - causes lobar collapse and discharge of infection into bronchus. This causes TB bronchopneumonia - poor prognosis
What can occur 6-12 months after a primary infection?
Miliary TB
meningeal TB
TB pleural effusion
How does miliary TB show on a CxR?
Fine motting
Widespread small granuloma
How can meningeal TB be detected. Is it severe?
Very severe
CSF has high protein and lymphocyte readings
How can TB reinfection take place?
Reactivation of latent TB or re-infection from an outside source
In re-infection - is the host response similar?
It will be different - but if insufficient immunity the re-infection will cause tissue damage and progression
Risk factors of TB reinfection
Diabetes Immunosuppresed Previous TB Alcohol abuse IVDA Poor standards or living Immigration from high risk area
Symptoms of reinfected TB?
Cough with sputum and haemoptysis
Pleuritic chest pain
Malaise and weight loss
Fever and night sweats
What are the primary and secondary TB investigation steps?
Sputum samples
CxR
If sputum negative:
CT scan
Bronchoscopy with bronchoalveolar lavage (washing and collecting of washed sample) or biopsy
Pleural aspiration and biopsy if pleural effusion present
What is seen on a CxR?
Patchy shadowing on apices/upper zones OR apex of lower lobes
Often bilateral
Cavitation if advanced disease
Calcification in chronic/healed TB
Treatment - what NEVER to do?
Single drug treatment - creates a resistant organism
Treatment plan?
First 2 months: Rifampicin Isoniazid Ethambutol Pyrazinamide
For next 4 months (2-6 months):
Rifampicin
Isoniazid
When is TB declared non infectious in a patient?
2 weeks after treatment begins
Side effects of rifampicin?
Orange urine/tears
Makes oral contraceptive pill ineffective
Side effects of isoniazid?
Hepatitis
Peripheral neuropathy
Side effects of ethambutol?
Optic neuropathy
Side effects of pyrazinamide?
Gout
What are the 2 TB tests?
Test immunity to tuberculopritein
Mantoux
Heaf
How is mantoux measured?
Injected intradermally
Induration read at 48-72 hours - if over 10mm positive
How is heaf measured?
Multiple punctures
Read after 4-7 days
