Tuberculosis Flashcards
Is the disease burgen from TB globally falling or rising?
Falling
How are worldwide incidences of TB changing each year?
Falling by 2%
How have TB deaths changed since 2000?
Fallen 29%
What number of killer of communicable disease is TB?
Number 1
How does deaths caused by TB compare to HIV and malaria?
TB kills more than HIV and malaria combined
Where are 2/3 of TB cases?
Across 8 countries
India
China
Indonesia
Philippines
Pakistan
Nigeria
Bangladesh
South Africa
What 3 countries have the most TB deaths?
1) India
2) China
3) Indonesia
How many people are infected with TB worldwide?
2 billion
How does incidence of TB change within countries?
Different regions can have higher incidences, such as London having 39% of all UK cases
Who are vulnerable groups in the UK?
People from high prevalence countries
HIV positive, immunocompromised
Elderly, neonates, diabetes
Homeless, alcohol, mental health problems, prison
What percentage of UK TB cases are from non-UK born people?
70%
How many cases are from the homeless, alcohols, mental health problems and prisons?
1 in 10
What is TB caused by?
Mycobacterium
Where is mycobacterium found?
Soil and water
What species of mycobacterium are responsible for TB?
Tuberculosis
Africanum
Bovis
What species of mycobacterium cause disease other than TB?
Leprae (leprosy)
What is mycobacterium that causes disease other than TB called?
Atypical
How can the growth of mycobacterium be described?
Non-motile bacteria
Very slowly growing
What does non-motile bacteria means?
Lacks the ability to propel themselves through the environment
Is mycobacterium anaerobic or aerobic?
Aerobic
How would you describe the cell wall of mycobacterium?
Very thick fatty cell wall
What are the consequences of mycobacterium having a very thick, fatty cell wall?
Resistant to alcohol
Resistant to neutrophil and macrophage destruction
Acid and alcohol fast bacilli (AAFB)
What can be said about acid and alcohol fast bacilli (AAFB) and TB?
Not all AAFB cause TB
How is TB spread?
Airborne
What is the process of TB spreading airborne?
Someone with TB in their lungs coughs
Attaches to aerosol droplets and remain suspended in the air for many hours
Someone else breathes them in
What is an exception to mycobacterium being spread airborne?
Mycobacterium bovis
How is mycobacterium bovis spread?
Consumption of unpasteurized infected cow milk
What is the immunopathology of TB?
1) Activated macrophages
2) Epitheloid cells
3) Langhan’s giant cells
4) Accumulation of the above 3 leads to a granumla
What leads to a granuloma with TB?
Activated macrophages
Epitheloid cells
Langhan’s giant cells
What is the immune response of TB mediated by?
TH1
What does TH1 do in response to TB?
Eliminated invading mycobacterium but also causes tissue destruction due to activation of macrophages
What does the outcome of a TB infection depend on?
Infection
Susceptibility
What factors determine the infection ability of TB?
Virulence
Number
What factors determine the susceptibility of someone to TB?
Genetics
Nutrition
Age
Immunosuppresion
What is virulence?
Pathogens ability to infect host
What is a pathogens ability to infect the host called?
Virulence
What happens during a primary TB infection?
No preceding exposure or immunity
Mycobacterium spreads via lymphatics to draining hilar lymph nodes
Usually no symptoms, can be fever, malaise
How does mycobacterium spread in a primary TB infection?
Lymphatics to draining hilar lymph nodes
What are some possible symptoms of primary TB?
Fever
Malaise
What is malaise?
General feeling of discomfort, illness or unease whose exact cause is difficult to identify
What is the general feeling of discomfort, illness or unease whose exact cause is difficult to identify called?
Malaise
What are the possible outcomes of primary infection?
Progressive disease
Contained latent
Cleared (cured)
In what percentage of people does the infection progress to tuberculosis bronchopneumonia?
1%
What does tuberculous pneumonia cause?
Primary focus continues to enlarge, leading to cavitation
Enlarged hilar lymph compress bronchi, lobar collapse
Enlarged lymph nodes discharges into bronchus
What is the prognosis of tuberculous pneumonia like?
Poor
What is cavitation?
Formation of an empty space within a solid object or body
What is formation of an empty space within a solid object or body called?
Cavitation
In what percentage of people does the primary infection lead to military TB?
1-3%
What are examples of diseases that primary tuberculosis can progress to?
Tuberculous pneumonia
Military TB
How does military TB develop?
Haematogenous spred of bacteria to multiple organs
What does haematogenous mean?
Originating or carried by the blood
Why are post primary diseases only present in humans?
Animals usually succumb to the primary disease
What are the 2 possible post primary diseases?
TB bacteria entering dormant stage with low or no replication over a prolonged period of time
Balanced state of replication and destruction by immune mechanisms
What are the clinical presentations of TB?
Cough
Fever
Sweats (mainly at night)
Weight loss
What is important to remember about the typical clinical presentations of TB?
They are not present in all cases:
Fever absent in 37%
Sweats absent in 39%
Weight loss absent in 38%
All 3 absent in 25%
What does diagnosing primary TB use?
Chest X-ray
What is typically seen in the chest X-ray of primary TB?
Mediastinal lymphadenopathy (mainly unilateral, 15% bilateral)
Pleural effusion
What is typically seen in the chest X-ray of post primary TB?
Apices, soft fluffy/nodular upper zone
Cavitation in 10-30%
Normal chest X-ray in 13%
Lymphadenopathy is rare
When should you consider getting a CT?
Normal chest X-ray but clinical suspicion
Military TB
Cavitation
Lymphadenopathy
What is lymphadenopathy?
Abnormal size or number of lymph nodes
What is abnormal size of number of lymph nodes called?
Lymphadenopathy
What does a proper diagnosis require?
Sample of the bug
How is a sample of the bug obtained?
Sputum
Bronchoscopy with BAL
Endobronchial ultrasound (EBUS) with biopsy
Lumbar puncture in CNS TB
Urine in urogenital TB
Aspirate/biopsy from tissue
What does EBUS stand up for?
Endobronchial ultrasound
What was the first TB drug?
Streptomycin
When was streptomycin discovered?
1944
What other TB drugs have been discovered since streptomycin?
Isoniazid (H)
Pyrazinamide (Z)
Rifampicin (R)
Ethambutol (E)
What is the evolution of TB treatment?
Monotherapy (streptomycin)
2 drugs in 1950s, duration 18-24 months
3 drugs in 1960s, duration 12-18 months
3 drugs late 1960s, duration 9 months
4 drugs 19702, duration 6 months
What are the rules for the treatment of TB?
Multiple drug therapy is essential
Single agent treatment leads to increased drug resistance within 14 days
Therapy must continue for at least 6 months
TB is a job for commited specialists only
Legal requirment to notify all cases of TB
Test for HIV, hep B and hep C
What is a legal requirment in terms of TB?
Notify of all cases
When someone has TB, what should you also check for?
HIV
Hep B
Hep C
How long must therapy for TB continue for?
At least 6 months
Why is multiple drug therapy essential?
Single agent treatment leads to drug resistance within 14 days
What is the standard treatment for TB?
2 R/H/Z/E + 4R/H per day
6 month duration at least
Pyridoxine (vitamin B6) with isoniazid to reduce risk of neuropathy
Steroids
Vitamin D substitution
What is given with TB treatment to reduce the risk of neuropathy?
Pyridoxine (vitamine B6) with isoniazid
When does treatment last for longer than 6 months?
7-9 months if monoresistant
12 months for CNS TB
9-12 months, or 18-20 months if multidrug resistant
What percentage of MTB is dead within 2 days when treatment uses isoniazid?
90%
What percentage of MTB is dead within 14 days when treatment uses isoniazid and rifampicin?
99%
What is the annotation for the number of drugs and months?
What are some side effects of rifampicin?
Orange urine/tears
Induces liver enzymes
All hormonal contraceptives ineffective
Hepatitis
What are side effects of isoniazid?
Hepatitis
Peipheral neuropathy
What are side effects of pyrazinamide?
Hepatitis
Gout
What is gout?
A form of arthiritis caused by excess uric acid
What is a form of arthiritis caused by excess uric acid?
Gout
What are side effects of ethambutol?
Optic neuropathy
What vaccine is used to fight TB?
BCG
Who is the BCG given to?
Neonates
Unvaccinated children under 5 whose parents/grandparents were born in a country with an annual incidence of TB of 40/100,000 or greater
Unimmunised contacts of cases
Unimmunised high risk employees
What must the incidence of TB be to get the BCG?
40/100,000
When is screening for TB done?
Contacts of people with active pulmonary or laryngeal TB who are aged less than 65 (hepatoxicity increases with age)
New entrants from high endemic areas
Pre biologics
Outbreaks
What is the treatment for latent TB?
