Tuberculosis Flashcards
What is the effect of Tuberculosis worldwide
Second leading cause of death from infection
What is the responsible organism that causes TB
Mycobacterium TB
Slow growing with a thick cell wall composed of lipids, peptidoglycans, arabinomannans (polysaccharide)and found in the soil
Where is TB usually located in the lungs
located upper zones or apex of lower lobes
as mycobacterium like living in aerobic conditions
How is mycobacterium detected
Acid - and alcohol - fast bacilli (AAFB)
Ziehl Neilson stain
How is mycobacterium TB transmitted
as an airborne droplet
Inhaled and deposited into alveoli
What environment is TB more likely to be transmitted in and why
More likely to be transmitted inside, as outdoors mycobacteria eliminated by UV radiation and infinite dilution
What are two types of mycobacterium
Mycobacterium TB
Mycobacterium bovis
What is the transmission and pathology of Mycobacterium bovis
Consumption of Infected cows’ milk, deposited in cervical, intestinal lymph nodes
What is the pathology of the TB infection result in a Th1 cell mediated response
TB infection in the alveoli, Macrophages digest TB, Macrophage go to the lymph node Presents itself to Th1 cells, TH1 cells move toward infection proliferating and activate macrophages
How does granulomas form from a TB infection
TB is resistant to macrophage breakdown,
Accumulation of macrophages results in epithelioid and; Langhan’s cells formation
This creates a GRANULOMA
How does Central caseating necrosis occur in TB
Tissue damage - caused by the activated macrophages
What is a redeeming factor in the Th1 cells mediated response in fighting TB infection
Eliminates / Reduces number of invading mycobacteria
What factors effect the outcome of the infections
Virulence
Susceptibility
Duration of contact
Intensity of infection
What is immune pathology of primary TB infection if the host is susceptible and primary infection results in a progressive disease
- Tissue destruction
- Organism proliferates (cavitation)
- progressive disease
Spread via lymphatics entering first and enlarging the hilar lymph nodes
What is the possible outcome of enlarged hilar lymph nodes as a result of progressive TB
compress bronchi,
lobar collapse
Discharges into bronchus and cause TB bronchopneumonia
When would TB be considered primary infection
If you previously haven’t been exposed or immunised against TB
What is the majorty of outcome with primary TB infection
Initial leison
spreads to local lymph nodes
Heals with or without scar
develop an immunity to tuberculoprotein
What is the potentially outcome if the TB primary infection lies dormant for 6-12months in order of severity
Military TB
Meningeal TB
Tuberculous pleural effusion
What is present in military TB
widespread small granulomas
Where does Meningeal TB affect and what is increased
Increases protein content in the cerebral final fluid of the meninges = meningitis
When would TB be classed as a post primary disease
Reactivation of mycobacterium from latent primary infection
OR
A new re-infection from outside source
Why does TB infections causing post primary diseases typically take 1-5 years to appear
Is a slow and progressive process
What is the symptoms of post primary disease TB
malaise, fever, weight loss cough, sputum, haemoptysis, pleuritic pain Dysnopea Erythema nodosum,
Whos is clinically at a high risk of developing the post primary disease from TB exposure
Diabetics elderly / adolescence Immunosuppressed patients - HIV Patients - Steroid patients Malignancy Immigrants high incidence area alcoholics IVDA poor social circumstances malnourished
There is usually no signs but what are the possible signs of an advanced TB
may be crackles,
bronchial breathing.
Finger clubbing is rare unless very chronic infection
What are the investigations carried out in the diagnosis of TB
Sputum microbiology (Culture, PCR, Smear) Chest Xray Bronchoscopy Pleural aspiration + biopsy CT scan of thorax
What does the chest x ray look like for a patient with TB
Patchy located upper zones or apex of lower lobes
Cavitation present if advanced
Calcification seen in healed or chronic TB
What is the modern day treatment for TB
Multiple drug therapy for at least 6 months
Two Months: Rifampicin Isoniazid Ethambutol Pyrazinamide
Four Months:
Rifampicin
Isoniazid
What is the most important factors in the management and treatment of TB
legal requirement to notify all cases
HIV testing necessary
When are rendered no infectious from TB
two weeks after treatment
What is the possible side effects of rifampicin
Orange ‘Irn Bru’ urine, tears
Induces liver enzymes to increase the metabolism of prednisolone, anticonvulsants
Oral contraceptive pill ineffective
Hepatitis
What is the possible side effects of Isoniazid
Hepatitis
Peripheral neuropathy
What is the possible side effects of Ethambutol
Optic neuropathy
What is the possible side effects of Pyrazinamide
Gout
What is the purpose of TB contact tracing
Identify source
Identify transmission
Having a BCG gives you what
immunity to tuberculoprotein
By injecting weakened mycobacterium bovis
What tests is used to screen if you have been exposed to TB
Heaf
Mantoux
Inject TB antigen PPD, red bump appears within two days if had previous exposure
What is the 3 different pathologies from primary TB infection
- Heal and develop immunity
- Progressive disease
- Lies dormant 6-12months (Meningeal/ Military/Pleural effusion TB)
