GEP (Life Protection) Week 5 Flashcards
What are the 4 types of chronic inflammation?
- Non-specific
- Autoimmune
- Chronic suppurative
- Chronic granulomatous
Define chronic inflammation?
This is where inflammation persists for weeks, months or longer. It may occur from acute inflammation or from the outset. It is more likely to cause tissue destruction and heal with irreversible scarring rather than regeneration.
3 process occurs simultaneously
-Persistent tissue injury and destruction
-Ongoing inflammatory response to limit the damage
-Attempts to organise and heal by fibrosis (scarring)
Describe the different response of the innate and adaptive immune response to inflammation?
What is a granuloma?
This is an aggregate of activated (epithelioid) macrophages, which have formed when a causeative agent cannot be removed. This granuloma is formed by a ring of macrophage, TH1 cell and others walling the site of inflammation to stop the spread.
Composition of granuloma:
-Macrophages
-Lymphocytes: mainly T-cells & some B-cells
-Fibroblasts, connective tissue (collagen)
-Necrotic tissue
How many types of hypersensitivity is there?
There are 5 types of hypersensitivity
Describe the different types of hypersensitivity (1,2,3,4)
Describe the different types of hypersensitivity (1,2,3,4) continued.
Describe type 5 hypersensitivity?
Type 5 hypersensitivity is technically classified as type 2 but given different calssification because of their antigen-mediated stimulatory/inhibitory effect.
Except 2 exceptions:
graves and myasthenia gravis are type 2 hypersensitivity.
What is the definition and aetiology of Tuberculosis?
-TB is the infection of mycobacterium tuberculosis.
-It is spread by inhalation of infectious droplets released when coughing
-There needs to be a prolonged contact for transmission.
-Aerobic rod-shaped bacilli, with a high oxygen demand, so usually infect the upper lobes of the lung
-‘Acid fast’ when using the Ziehl-Neelsen stain.
Mycobacteria are called acid-fast bacilli because they are rod-shaped bacteria (bacilli) that can be seen under the microscope following a staining procedure in which the bacteria retain the color of the stain after an acid wash (acid-fast).
Brief Epidemiology of TB
-1 of the Top 10 causes of death worldwide
-1.7-2 billion people have latent TB worldwide.
-Significant mortality from co-infection with HIV
-40% of UK cases occur in London.
Describe the pathophysiology of TB?
What is a ghon focus
It is a small focus of granulomatous inflammation, which may become visible on a chest X-ray if it grows large enough or if it calcifies. A Ghon focus usually heals without further trouble, but in some patients tuberculosis spreads from it via the lymphatics, the air spaces, or the bloodstream.
What is a ghon complex
A ghon complex= ghon focus + ipsilateral mediastinal lymph nodes
Describe the natural history of TB infection
What are the clinical signs and differential for TB
Differentials
-Lung cancer
-COVID
-Pneumonia
-Sarcoidosis
-Lymphoma
-Other!
What are the extrapulmonary manifestations?
-CNS - TB meningitis (headache, neck stiffness, vomiting), reduced consciousness, focal neurological signs)
-Lymph node TB - enlarged, firm, non-tender cervical lymph nodes
-Genitourinary TB
-Pericardial TB - pericardial effusion, constrictive pericarditis
-Bone - Pott’s disease, spinal pain, often localised
-GI - mostly affects ileocecal region, causes abdo pain, bloating and obstruction
what are the risk factors for TB?
Risk factors
-Close contact with TB patient, increased risk with duration of exposure
-Ethnic minority groups
-Being born in high prevalence areas - India, Pakistan, Romania, Bangladesh, Somalia
-HIV positive
-Other causes of immunocompromise
-Extremes of age
-Homelessness
-Prisoners
-IVDU
What are the steps of diagnosing TB?
How do you diagnose latent TB?
Latent TB - screening of at risk patients
1) Do a Mantoux test
-Positive - TB specialist to assess for active TB
-Active TB positive - treat
-Active TB negative - consider IGRA, if more evidence of latent infection is needed to decide on treatment
2) Underserved groups (prisoners, substance misusers) offered a single IGRA
- Interferon Gamma Release Assay (IGRA)
Assays detect the interferon gamma response to TB antigens
Unaffected by prev BCG
What is the management of active TB?
-Use the Mnemonic- RIPE
(4 for 2 months then 2 (RI) for 4 months)
-Also infrom public health.
What is the management of latent TB?
Latent TB
-6 months of isoniazid with pyridoxine
Usually chosen if concerned about rifampicin interactions
-3 months of isoniazid (with pyridoxine) and rifampicin
Preferred if the patient is younger than 35 if hepatotoxicity is a concern.
What is the management of multidrug resistant TB?
This is a Growing problem
Do NAAT (nucleic acid amplification test) for rifampicin resistance if suspicious
Treatment may last 18- 24m with at least 6 drugs
How would you treat TB meningitis?
RIPE 2 months followed by RI for a further 10 months
+ Steroids
What is the BCG vaccination?
TB vaccination are live attenuated strain of Mycobacterium Bovis (relative of M. TB that does not cause harm in humans)
Effectiveness:
-Prevents severe and complicated disease but less effective at preventing pulmonary TB
-More effective in children than adults
Which Demographic are most at risk?
Neonates/children
-High risk area in the UK for catching TB (London)
-Parent/grandparent born in country with higher risk of catching TB
-Lived for >3 months/going to country with higher risk of catching TB
-Living with/regular close contact with someone who has/had TB
Adults
-High risk through work: healthcare worker, lab operative, vets & abattoir, work with people at high risk of getting TB (homeless, asylum seekers & refugees, prisoners, drug users)
-Staying >3 months in high-risk country
-Arriving to UK from high-risk country
What is the Mantoux test?
Screening test that detects exposure to previous TB: active, latent, BCG vaccine -> Therefore does not diagnosis TB
How it works:
Inject patient intradermally with Tuberculoprotein Purified Protein Derivative (PPD)
PPD presented to memory T-cells -> cell-mediated response
Recruitment of B-cells & inflammation -> erythema & induration -> Type 4 Hypersensitivity reaction
Positive: induration>5mm after 72hrs
Indications
Tested prior to BCG vaccination for:
>6 years
History of residence/prolonged stay in high risk country
Close contact with a person with TB
FMHx TB within last 5 years
Note: HIV infected/ low CD4+ count patients may have negative Mantoux test despite active TB
How to interpret an X-ray
ABCDEFGH is the best Mnemonic:
A: Adequacy
PIER
Airway
B: Breathing
Zone symmetry
Bone & soft tissue
C: Circulation & Cardiomediastinal contour
D: Diaphragm
E: Effusions & Everything else
F: Fields, fissures & foreign bodies
G: Gastric bubble
H: Hila
E to H is mostly covered in ABCD
CxR anatomy
Describe A in the X-ray Mnemonic
Adequacy
PIER
P: Patient details & position - PA (posterior anterior) vs AP (Anterior posterior)
PA the preferred modality
AP if patient is bed-bound & unable to stand (portable X-ray machine)
I: Inspiration: 8-10 posterior ribs visible
E: Exposure: Heart, blood vessels, spinal processes & thoracic vertebrae visible
R: Rotation: symmetrical & equidistant (from spinous processes) clavicles
PA
Scapula in periphery of thorax
Clavicles project over lung fields
Posterior ribs more distinct
Low diaphragm
Normal cardiac silhouette
Narrow superior mediastinum
AP
Scapula over lung fields
Clavicles above apex of lungs
More magnified
Anterior ribs more distinct
Magnification of heart
Widening of mediastinum
Describe A in the X-ray Mnemonic (continued)
-Check for tracheal deviation (it may sit slighly to the right due to the aortic arch/ascending aorta
-If you see a push trachea: this could be a large pleural effusion or tension pneumothorax.
-Pulling of the trachea: Consolidation+ lobular collapse.
Describe B in the X-ray Mnemonic
Breathing
Check for symmetry
Look for areas of abnormal lucency
Masses & nodules
Examine lung fields in sequence
Fluid/tumours appear bright
Consolidation:
Material filling the alveoli:
Pus: pneumonia
Water: Pulmonary oedema
Blood: Trauma
Cells: tumour
There are 3 zones, upper, middle and lower
(Note: Described as zones not lobes because lobes are superimposed on each other, thus cannot be sure which lobe structure is in).
Describe B in the X-ray Mnemonic (continued)
Bone & soft tissue
Fractures
Mineralisation/osteopenia
Lucent bone: decreased density (dark)
Sclerotic bone: increased density (white)
Lesions (metastases)
Describe C in the x-ray Mnemonic
**Circulation & Cardiomediastinal contour (&hila) **
Cardiac edges - sharp & pronounced
Opacities
Silhouette sign
Size of heart: less than half of chest width
Describe D in the x-ray Mnemonic
Diaphragm
-Shape
Right & left hemidiaphragms: Right usually higher than left due to liver
-Sharp costophrenic angles
-Gastric bubble
Air on right: pneumoperitoneum
Describe E in the x-ray Mnemonic
Effusion and Everything else
Build-up of fluid
Everything else:
Tubes: NGTs
Lines: Central lines, ECGs
Pacemakers/ICDs
Artificial heart valves
Describe F in the X-ray Mnemonic
Fields, Fissures and Foriegn Bodies
-Observing the fissures are in the correct location and there are no visible foriegn bodies
Describe G in the X-ray Mnemonic
Gastric bubble
Normally seen in the left side of an x-ray and is dark, indicating gas
Describe H in the x-ray Mnemonic
Hila
Lie at same level (left may sometimes lie higher than right)
Similar size & density
Another way of remembering how to interpret an X-ray
What is koch’s postulates
Designed to show causative relationship between microbe & disease - Germ Theory
-Demonstrate that the organism is in the lesions in all cases of that disease
-Be able to isolate the organism and cultivate it in pure culture outside the host
-Produce the same disease if the pure culture is injected into a healthy subject
-Recover microbe from experimentally infected host
However we now know:
-Not all organisms can be cultured
-Can detect their DNA/RNA by PCR
-Not universally applicable to all diseases e.g., cancers associated with viruses (HepB; EBV)
