Seminar 1 - Pneumonia Flashcards
Describe the pathogenesis of HSV1 encephalitis
Virus enters brain – via trigeminal nerve or reactivation in brain itself
Virus PAMPs recognised by TOL receptors of innate immune cells
Inflammatory response triggered leading to necrosis and apoptosis of viral cells and brain cells
Leads to swelling, oedema and raised ICP
Describe the structure of a foreign body granuloma
Foreign materials found in the center of the granuloma
Sometimes found within giant cells
There will be epithelioid cells & giant cells on the surface of the foreign body
Describe the pathogenesis of a cerebral abscess
Bacteria enter the brain
Recognized by TOL receptors on astrocytes and microglia
Initiate the inflammatory response compromising the BBB and bringing peripheral inflammatory cells to the site causing massive inflammation and abscess formation
Fibroblasts from the vessel walls in the granulation tissue then contribute to the capsule formation
Describe the difference between gram positive and gram negative
Gram positive organisms have a thick peptoglycan layer and single phospholipid bilayer in cell wall
Gram negatives have 2 phospholipid bilayers and a thin peptoglycan layer in their cell wall
Gram positive will stain purple (as thick layer can retain dye) whereas gram negative stains pink (dye is washed out)
How do viruses infect a cell
They bind to receptors on host cells and enters them where they use the cell to replicate their own DNA
Products can trigger cell death
Name the 4 main types of acute inflammation
Serous inflammation
Fibrinous inflammation
Purulent inflammation and abscesses
Ulcers
What is primary TB
When disease occurs in previously unexposed individual
What are club cells
Cells found in cuboidal epithelium in the respiratory system that have roles in immune modulation, surfactant production, and detoxification
They are secretory and non-ciliated
What are the signs of constrictive pericarditis
Muffled heart sounds,
Raised JVP
Oedema (incl. hepato and splenomegaly)
What is the purpose of granuloma formation
It is a cellular attempt to contain an offending agent that is difficult for the body to get rid of
Which type of inflammation is more likely to lead to scarring - acute or chronic
Chronic
How do you diagnose pericarditis
Blood tests (FBC, U&E cardiac enzymes)
Appropriate test for underlying cause
Echo (effusion) or CXR (cardiomegaly)
How does tissue necrosis cause inflammation
Dying cells release molecules which stimulate the inflammatory response
This includes uric acid from DNA breakdown and ATP from the mitochondria
Picked up by receptors on other cells - signal of cell damage
Inflammation will occur regardless of the cause of cell death (trauma, ischaemia etc.)
What structures are considered part of the upper respiratory tract
all of the structures above the vocal folds: nasal cavity, paranasal sinuses and the pharynx (split into naso- oro- and laryngo-)
Sometimes includes the larynx
What cell types are found in the alveoli
Type 1 alveolar cells cover 95% of the surface and are simple squamous epithelium, providing a permeable barrier for gases
Type 2 alveolar cells produce surfactant and are involved in alveolar repair since they can proliferate and give rise to type I alveolar cells
Also find resident alveolar macrophages which digest particles which have been missed by the mucous lining of the airway.
What is the definition of transmissibility
How easily pathogens are spread i.e. the proportion of persons exposed to a pathogen who are infected by it
What are the 2 main types of granuloma
Foreign body granulomas
Immune granuloma
What is the definition of a pathogen
A microorganism (or virus) that causes disease
How do you diagnose streptococcal toxic shock syndrome
No specific test
Diagnosis is made if organ failure and low blood pressure is found in a patient with a group A strep infection
What causes a cerebral abscess
Usually bacterial infection
Common organisms: strep and staph
Describe the epidemiology of cerebral abscesses
More common in developing countries Men Vs Women almost 3:1 Most at risk groups: Men< 30 Children aged 4-7 Neonates PWIDs Immunocompromised
How do infections spread locally
By releasing toxins or enzymes they can move through tissues by causing damage
What are the microscopic features of an empyema
A a high neutrophil count and large numbers of other leukocytes.
What is meningitis
Inflammation/ infection of all 3 layers of the meninges surrounding the brain
How can we distinguish between strep throat (bacterial) and viral causes of URTI
The following symptoms suggest a virus is the cause of the illness instead of strep throat: cough, runny nose, hoarseness and conjunctivitis
What is the definition of infection
The invasion and multiplication of pathogens in the body causing damage to tissues/ triggering an immune response
What are the macroscopic features of meningitis
Dense exudate covering the surface of the brain - worse in some areas
Prominent engorged blood vessels protruding from surface
What cancers affect the larynx
Most commonly squamous cell carcinoma
Less commonly adenocarcinoma
Affects the supraglottis most commonly
How much fluid is normally found in the pleural space
Normally there is less than 15ml in the space to lubricate the surfaces
Describe the appearance of lobar pneumonia
Confluent consolidation involving entire lung lobe.
When is complete resolution most likely to occur
When the injury is limited or short lived
When the damaged cells are able to regenerate due to limited tissue destruction
Also depends on that particular tissues capacity for regeneration
e.g. Liver can, heart and brain cannot
What are the symptoms of adherence mediastinopericarditis
Systolic indrawing of diaphragm Pulsus paradoxus (systolic drops by at least 10mmHg on inspiration)
What is chronic inflammation
A response of prolonged duration (weeks or months) in which inflammation, tissue injury, and attempts at repair coexist in varying combinations
In response to persistent stimuli or those that are hard to destroy
What are the two main subtypes of chronic pericarditos
Adherence mediastinopericarditis and constrictive pericarditis
What is the definition of a virus
A core of nucleic acid surrounded by a protein shell that can only reproduce in a living cell
Not classed as a microorganism
What causes fibrinous/serofibrinous pericarditis
Acute MI, trauma, cardiac surgery, uraemia and cancer.
What causes serous pericarditis
Mainly caused by non-infectious inflammatory disease (rheum fever, SLE, scleroderma)
Infections in nearby tissue (if they cause enough irritation)
Viral infections in other areas of the body (URTI, lung) can sometimes lead onto it
Tumours if they invade the pericardium or nearby lymph nodes
How do you diagnose an empyema
Signs of effusion on CXR
Yellow and turbid fluid on aspiration
Presents as exudate on analysis with high neutrophil count
How does a cerebral abscess cause death
Raises ICP which affects perfusion or causes herniation
This damages the respiratory and cardiac centers in the brainstem
Describe adherence mediastinopericarditis
Fibrotic adhesions attach the heart to surrounding structures in the mediastinum.
The heart works harder as each contraction is pulling against new resistance - can lead to cardiac hypertrophy and dilation
Describe the histology of the pleura
The pleura are a serous membrane formed of simple squamous cells also called the mesothelium
This layer faces into the pleural space
Underneath is a supporting layer of connective and elastic tissues
How long does it take a cerebral abscess to form
Takes about 2 weeks from point of infection
Symptoms may start to arise at any point during abscess formation
Define drug resistant TB
Classed as resistance to rifampicin and isoniazid with or without any other resistance.
Requires a regime of at least 6 anti-TB drugs to which the mycobacterium is likely to be sensitive.
Describe the structure and histology of the bronchioles
<1mm diameter
No cartilage or glands but some goblet cells
Epithelium decreases in height from columnar to cuboidal as it descends the respiratory tree to the smallest bronchiole
What are the symptoms of an empyema
Usually begins as a pneumonia or another infection (and their symptoms)
Then develops a recurring fever
What is the definition of a commensal
An organism that lives in or on, and benefits from, another organism
The host receives no benefit but is not harmed.
May be part of body’s normal flora
What are the common pathogens that enter via the skin
Epidermal injury – Staph aureus, Strep pyogenes
Needles – HIV, Hep C
Bites – malaria, rabies, Lyme’s disease
Superficial infections – dermatophytes (fungi)
Which cell types are involved in an immune granuloma
Activated Th1 cells produce cytokines like interferon gamma which activated macrophages
Some parasitic infections can trigger a Th2 response and eosinophils
How do leukocytes reach the site of injury
They enter the tissues through the gaps in endothelial cells
Mediated by adhesion molecules and chemokines
Margination - move to the outside of lumen due to stasis
They roll along the endothelium and then bind to integrins
Move across the wall and then follow the chemical signals to the site of damage where they become active
They are key to eliminating the inflammatory trigger
What is the definition of a bacteria
A unicellular microorganism that has an organised nucleus and usually a cell wall but lacks organelles
Some have the ability to cause disease
What are the risk factors for streptococcal toxic shock syndrome
Age 65+
These with chronic illness (diabetes, alcohol use)
Breaks in the skin (recent surgery etc.)
What is vertical transmission
From mother to foetus or newborn
Mother infected in pregnancy can pass it on to growing foetus which may cause defects
Babies can pick up infections when passing through the birth canal such as chlamydia
Some pathogens can be passed through breast milk (HIV, Hep B)
What are the terminal bronchioles
The final and smallest bronchioles not involved in gas exchange (end of conducting zone)
Beyond this are the respiratory bronchioles
Describe fibrinous inflammation
Occurs when there is greater vascular permeability (as fibrinogen is a large molecule) or when there is a pro-coagulant stimuli (e.g. cancer)
Commonly seen in inflammation of the linings of body cavities (e.g. pericardium)
Fibrin is formed and deposited in extracellular space and can form mesh-like structures
Then either dissolved by fibrinolysis and cleared by macrophages or it develops into scarring
What causes haemorrhagic pericarditis
The most common cause is metastases to the pericardial space.
Other causes include cardiac surgery, infection, underlying bleeding disorders or TB.
How is the innate immune system activated in sepsis
Infection causes release of pro-inflammatory cytokines and other inflammatory mediators
Activation of the complement system to signpost the infection site and upregulates the immune response
What are the main types of meningitis
Bacterial - most common
Viral
Chronic
Non-infectious
Describe the histology of the oropharynx
Non-keratinized stratified squamous epithelium
It is different from the rest of the URT as it has to transmit both air and swallowed food
Which individuals are at higher risk of HAP
Those with severe underlying disease, immunosuppression, prolonged antibiotic therapy, or invasive access devices, e.g. intravascular catheters.
Mechanical ventilation is particualrly high risk
What is the definition of virulence
The pathogenic ability of a microbe ( their ability to cause disease)
Used a measure of severity
Describe the pathogenesis of TB
M. tuberculosis uses host receptors to enter host macrophages via phagocytosis
The bacteria replicates within alveolar macrophages and prevents itself being killed
Its proliferation within macrophages and air spaces results in a bacteremia and multiple seeding sites Most still asymptomatic at this stage
Around 3 weeks post-infection, a TH1-mediated response is initiated and leads to granulomatous inflammation
What are the 3 main outcomes of inflammation
Complete resolution
Healing by connective tissue replacement/ scarring
Progression to chronic inflammation
What infections usually affect the larynx
Laryngitis is the main disease and can be an isolated infection but is more commonly a feature of generalized URTI
H.influenza can lead to laryngoepiglottitis
Croup - laryngotracheobronchitis
Define a transudate
Fluid is low in protein (pleural:serum ratio < 0.5)
Pleural LDH: serum LDH <0.6
Low specific gravity
No cells present
List the 5 R’s of inflammation
Recognition of the offending agent/stimulus by receptors on inflammatory cells
Recruitment of leukocytes and plasma proteins into the tissues
Removal of the stimulus by phagocytosis
Regulation of the response
Repair (regeneration and/or scarring)
What are zoonotic illnesses
Those which spread from animals to humans via bites or consumption of animal products
How would a CSF sample appear in viral meningitis
Not purulent
Lymphocytes present
Moderate protein elevation
Normal glucose content
What are the risk factors for cerebral abscesses
Immunocompromise
Bacterial endocarditis
Bronchiectasis
What are the microscopic features of meningitis
Subarachnoid space filled with neutrophilic exudate
Also has enlarged blood vessels
Describe caseous pericarditis
This subtype is commonly seen in TB patients.
There will be focal regions of caseation in the pericardium.
Presents very similarly to purulent/suppurative
What are the symptoms and signs of a pleural effusion
May be asymptomatic
Shortness or breath and pleuritic pain
Stony/dull percussion, reduced chest expansion, vocal resonance and air entry on affected side
Trachea may deviate away from affected side if severe
Mycoplasma pneumoniae causes pneumonia in which population groups
Children and young adults
Often get local epidemics (schools etc)
What organisms are common cause of lung abscesses
Staphylococci, streptococci, numerous gram-neg species, and anaerobes are implicated.
Mixed infections are common due to aspiration being a common cause
What are the main causative organisms in aspiration pneumonia
A mixed picture of anaerobic oral flora and aerobic bacteria
Oral: bacteroides, prevotella, fusobacterium, pepto-streptococcus.
Aerobes: Strep. Pneumonia, staph. Aureus, h. influenzae, pseudomonas aeruginosa.
What are the 4 main routes of infection into the CNS
Haematogenous - most common
Direct implantation - usually after trauma or surgery, may be due to malformations that allow access
Local extension - sinuses, teeth, skull or vertebrae are the most commo
Along peripheral nerves (for viruses like zoster)
Describe the pathological appearance of a secondary TB infection
Usually affects the lung apices
Florid cavitation occurs - tissue damage more extensive
Initial lesion in secondary infection tends to be small, well-circumscribed, firm, grey-white to yellow in colour and with variable degrees of caseation and fibrosis
Describe an ulcer
A local defect/excavation of the surface of an organ or tissue that is produced by the sloughing (shedding) of inflamed necrotic tissue
Occur only when tissue necrosis & resultant inflammation exist on/near a surface
What are the common symptoms and signs of pericarditis
Sharp, central pleuritic pain, may be better on leaning forward, worse on inspiration or lying flat
Fever
Pericardial rub
Saddle shaped ST elevation on ECG
May have congestive symptoms if there’s an effusion (SOB etc.)
What is the definition of incubation period
The time between exposure to a pathogen and the development of symptoms
How does fibrinous/serofibrinous pericarditis present
Classic pericarditis symptoms
If there is a significant volume of fluid the rub may be diminished
Microscopically the fluid is made up of serous fluid and fibrinous exudate
What are the 2 main complications of chronic inflammation
Abscess
Granuloma
What are the symptoms of peritonsillar or retropharyngeal abscesses
Severe pain
Difficulty swallowing
Breathing difficulty - if it obstructs the airway
What is granulomatous inflammation
A form of chronic inflammation characterized by collections of activated macrophages, often with T lymphocytes (sometimes associated with necrosis)
Describe the epidemiology of TB
Leading cause of death worldwide from a single infectious agent (above HIV/AIDS)
Highest incidence in South-East Asia
What is the benefit of granulomatous inflammation in TB
In most, this response will halt the infection response to avoid significant tissue destruction
More likely to progress to caseous necrosis in the elderly and immunosuppressed (particularly HIV+)
What are the pathological features of TB
Granulomatous inflammation – accumulation & aggregation of activated macrophages (“epithelioid” cells), some may fuse to form giant cells
Caseating granulomas are characteristic - central necrosis is surrounded by lymphocytes and activated macrophages
The combination of granulomatous lesions in the lung parenchyma + lymph nodes = Ghon complex
Define hospital acquired pneumonia
Defined as pulmonary infections acquired >48hrs after hospital admission
Which pathogens are the most common cause of bacterial meningitis
Strep pneumonia, Neisseria meningitides E.coli Group B strep Listeria monocytogenes
What is the role of macrophages in chronic inflammation
They are the dominant cell type
They secrete cytokines and growth factors to activate other cells such as lymphocytes - stimulate inflammatory response
hey also ingest harmful pathogens and cellular debris and also initiate repair
How does streptococcal toxic shock syndrome present
Begins with fever and chills, muscle aches, nausea and vomiting
24-48 hours later the blood pressure drops and symptoms develop: tachycardia, tachypnea and other signs of organ failure e.g. bleeding/ bruising, jaundice
What are some of the complications of treating a cerebral abscess
Mainly complications of the craniotomy Blood clot needing further surgery Brain swelling CSF leak Movement of the skull cap Infection Seizure Stroke Nerve damage Loss of mental function
What is complete resolution
When the site is returned to normal once the inflammatory reaction is complete
Why are women more susceptible to infections of the urinary tract
They have a much shorter urethra so pathogens don’t have to travel as far
How does post-streptococcal glomerulonephritis occur
Strep products can lead to formation of immune complexes that get deposited in the kidneys
Not a strep infection in the kidneys! It is the immune response and complexes which cause it
Produces a local inflammatory reaction in the kidney which leads to injury
What organisms commonly cause meningitis in the immunocomprimised
Listeria, TB, Klebsiella, cryptococcus neoformans, anerobics
How do neutrophils and macrophages aid the inflammatory response
They can ingest and destroy the pathogens
Macrophages also produce growth factors to aid repair
What is a cerebral abscess
A thin walled, discrete collection of suppurative material within the brain parenchyma often with inflammation surrounding it.
In young people pericarditis often occurs alongside which other condition
Myocarditis
Describe the histology of the nasal cavity
Vestibule (initial part) = keratinised stratified squamous epithelium
As you move deeper into cavity, the keratin is lost and eventually becomes respiratory epithelium
There is specialized olfactory epithelium found in the roof of the nose to allow smell
What are the 3 main types of nasopharyngeal cancer
Keratinising squamous cell carcinoma (worst prognosis)
Non-keratinising carcinoma (undifferentiated) and non-keratinising carcinoma (differentiated)
Basaloid squamous cell carcinoma
What are the systemic features of a secondary TB infection
Low grade fever
Night sweats
Weight loss
Pleuritic pain if it extends into pleura
How do you treat a pleural effusion
Slow and controlled drainage- through appropriate pleural space
Pleurodesis with talc if recurrent - sticks layers together to obliterate space, prevents fluid accumulating
Surgery if there is recurrent collections and thickening of the pleura
Describe constrictive pericarditis
A dense fibrotic scar surrounds the heart.
This restricts the heart’s movement and therefore function
Hypertrophy is not possible as the heart is encased
Cardiac output may be reduced but also cant increase in response to normal systemic needs
What organisms commonly cause meningitis in the elderly
Strep pneumo > listeria
Describe how vasodilation occurs in the inflammatory process
Mediators of inflammation such as histamine act on the smooth muscle to induce dilation
How do Miliary TB and TB meningitis occur
Haematogenous spread of a primary TB infection
Rare occurrence
What are the potential outcomes of an empyema
Can resolve but more commonly organisation occurs and it leaves a dense fibrous adhesion
This will affect lung expansion
What is the purpose of inflammation
It is a protective mechanism
It rids the body of the initial cause of cell injury (microbes, toxins etc.)
It also rids the host of the consequences of such injury like necrotic cells and tissues
What are the common pathogens that infect the upper respiratory tract
Rhinovirus
Adenoviruses
Influenza viruses
How do you determine whether fluid is a exudate or transudate
Aspiration and analysis of the sample
Further cytology and cellular counts can indicate underlying cause - e.g. Find malignant cells
What are the major complication of a strep throat infection
Peritonsillar or retropharyngeal abscesses
Rheumatic fever
Glomerulonephritis
Toxic shock syndrome.
How does meningitis cause death
Viral tends not to be fatal
Bacterial can cause raised ICP and herniation
Can also cause sepsis and subsequent septic shock
What happens when group A strep infects the URT
It causes acute pharyngitis and tonsillitis otherwise known as “strep throat”
Infections can range from minor, self-limiting illnesses to severely debilitating, deadly diseases
What happens when the endothelium becomes activated due to sepsis
Loosened endothelial junctions mean that proteins can pass through
Vessels become ‘leaky’ leading to widespread interstitial oedema
What are the clinical features of HSV1 encephalitis
Fever Malaise Headache Nausea Altered mental state- confusion, memory problems Seizures Focal neurological deficits Personality changes Reduced consciousness, coma and stupor
Which part of the brain is most commonly affected by HSV1 encephalitis
Temporal lobe
What are the 4 main causes of inflammation
Infections
Tissue necrosis
Foreign bodies
Immune reactions
How does breaching the epithelial surface allow infection
Breaks in the physical epithelial barrier can allow pathogens to enter the body
Any form of injury (needles, bites, cuts) can allow pathogens in
What are the most common sites for ulcer formation
Mucosa of mouth, stomach, intestines or genitourinary tract
Skin & subcutaneous tissue of the lower extremities in those with vascular insufficiency (diabetes)
When does streptococcal toxic shock syndrome occur
Occur when the strep get into the bloodstream (across mucus membranes)
Name the recesses formed by the pleura
Costodiaphragmatic and costomediastinal recesses
These are clinically relevant as this is where fluid will collect
What is the definition of colonization
The presence of bacteria on a body surface which is not causing disease in the host
How do foreign bodies cause inflammation
Presence alone may cause inflammation - identified as non-self antigens
The trauma caused by them entering the body can be the cause or this can introduce microbes
Some substances produced by the body itself can lead to inflammation if the are deposited in large amounts in tissue (e.g. Urate crystals in gout)
What is the definition of a saprophyte
An organism that grows and feeds on dead or decaying organic material.
A lot of fungi come under this group too
Describe the pathological appearance of a lung abscess
May be single or multiple and vary in size
Will have a suppurative central destruction of lung tissue within the central area of cavitation
Central cavity may be filled with pus or air
If chronic they will be surrounded by a reactive fibrotic wall
How do infections cause inflammation
Different pathogens will elicit the immune response through different means such as toxins, host response etc
Reaction can be mild to severe
How does purulent/suppurative pericarditis present
Classic symptoms + symptoms of systemic infection
Macroscopic findings include: reddened and granular serous surfaces with exudate covering it and the exudate which ranges from cloudy serosal fluid to frank pus.
Define an exudate
Fluid is high in protein content (pleural:serum ratio > 0.5)
Contains cells from the blood
Pleural LDH: serum LDH >0.6 or more than 2/3 of normal upper limit for serum
When does healing by connective tissue replacement/ scarring occur
After substantial tissue destruction
When the tissues involved in the injury are incapable of regeneration
When there is abundant fibrin exudation that cannot be adequately cleared
Common in the body cavities (pleura etc.)
What is the most common cause of purulent inflammation
Infection with a pyogenic bacteria
This is a bacteria that causes liquefactive tissue necrosis
One example is staphylococci
What is chronic pericarditis
This when there is organisation of the inflammation (scar formation)
This leads to fibrous thickening of the serosal membrane or even thin adhesions.
This doesn’t always impact heart function but can effectively destroy the pericardial space or restrict heart movement
What is the definition of a fungi
A large and varied group of eukaryotes that are either parasitic or saprophytic
Some can act as pathogens in humans.
They produce spores and feed on organic matter
Includes molds and yeast
What is the common symptom of pleuritis
Pleuritic pain is common as that tissues are inflamed
What are the usual defenses of the respiratory system
Large microorganisms are trapped in the mucocilliary system and sent to GI tract
Smaller ones are phagocytosed by macrophages in the alveoli
What are the risk factors for nasopharyngeal cancer
Being of south Chinese or north African descent
A diet very high in salt-cured meats and fish
Exposure to EBV
Regular exposure to hardwood dust
Family history
Exposure to HPV virus
About 3 times as many men as women are affected
What are the main causes of URTI
Almost always viruses (rhinovirus, coronavirus, adenovirus, influenza)
Bacteria is rare - around 15% of acute pharyngitis only (strep throat)
Chlamydia psittaci causes pneumonia in which population groups
Bird owners (typically parrots)
How do viruses reach the meninges
Infected with the virus and then it enters the blood, travels across the BBB to infect the brain
What are the risk factors for laryngeal carcinomas
Smoking - biggest
Regular drinking large amounts of alcohol
Family history of head/neck cancer
Unhealthy diet
Exposure to certain chemicals and substances, such as asbestos and coal dust
How do you treat a peritonsillar or retropharyngeal abscesses
May need to be drained by an ENT specialist
Can improve on their own
What causes a foreign body granuloma
Inert foreign bodies that are too large or complex to be broken down (e.g. fibers, talc, sutures)
They induce inflammation in the absence of T cell-mediated immune response
How do you treat nasopharyngeal cancer
External beam radiotherapy, sometimes supplemented with chemotherapy
Surgery doesn’t have a major role unless for biopsy, radiation resistant tumours or local recurrence
What is the main feature of purulent inflammation
Production of pus - an exudate consisting of high number of neutrophils, debris from dead cells and oedema fluid
What are the features of an acutely inflamed ulcer
Polymorphonuclear infiltration
Vascular dilation in margins of defect
Strep pneumonia causes pneumonia in which population groups
Commonest cause of CAP so affects all ages
Especially in elderly, immunocompromised, alcoholics and those with HF or existing lung disease
What are the symptoms of rheumatic fever
Migratory polyarthritis
Fever
Symptoms of heart failure (chest pain, SOB, tachycardia)
Chorea
What organisms commonly cause meningitis in infants
E coli
Group B strep
Listeria
How does healing by connective tissue replacement/ scarring occur
As it says on the tin
Connective tissue grows in the area of inflammation (organisation)
Granulation tissue fills the site of injury
It is progressively replaced by collagen which is called fibrosis - scar
What is secondary TB
When disease occurs in previously exposed host
The infection can reactivate and cause TB if host immunity declines (risk is around 5-10%)
How do infections spread through the lymphatic system
Can either access directly or carried in immune cells (macrophages or lymphocytes)
From lymph nodes, pathogens can access the bloodstream
What is the definition of infectious period
The time in which a host can spread the disease and infect others
Describe the histology of the bronchus
Lined by respiratory epithelium Has ring of smooth muscle under lamina propria Has adipose tissue & submucosal glands in submucosa. Irregular cartilage plates are found
How do you treat an empyema
Drainage and treat the underlying cause
What is an empyema
Purulent pleural exudate
They form when bacteria spreads into the pleural space
Forms localised areas of yellow/green pus that usually becomes walled off by fibrosis
How do bacteria reach the meninges
Skull fracture, head surgery, cribiform plate fracture
Spread from a local infection ie sinusitis
Haematogenous spread from another infection site
Haematogenous spread from nasopharyngeal colonisation
What are the macroscopic features of laryngeal carcinomas
In most cases they are obvious following inspection of the larynx with a laryngoscope
Surface is usually smooth, white or reddened with focal thickenings
May have keratosis or ulcerated regions
How does sexual transmission lead to infection
Prolonged and unprotected mucosal contact
Microtrauma allows entry to bloodstream
Passed via bodily fluids
Can be systemic or affect reproductive tract
Describe the appearance of bronchopneumonia
Patchy exudative consolidative with focal areas of acute suppurative inflammation
Can be confined to one lobe but tend to be bilateral and basal due to the tendency of secretions to gravitate to the lower lobes
How long do symptoms of an URTI typically last
7-10 days (can persist up to 3 weeks)
How do you treat constrictive pericarditis
Surgical resection of the constricting tissue (pericardiotomy)
What are the macroscopic features of encephalitis
Temporal/frontal necrosis
Haemorrhage
Staph aureus causes pneumonia in which population groups
Often complicates viral illness.
Young, elderly, PWID, underlying disease (e.g. leukaemia, lymphoma, CF).
Which patients are at risk of aspiration pneumonia
Reduced consciousness – alcoholism, drug overdose, general anaesthesia, seizure.
Oesophageal conditions – dysphagia, GORD
Neurologic disorders – MS, dementia
Mechanical conditions – NG tube, endotracheal intubation, GI endoscopy, other feeding tubes.
Protracted vomiting
General debilitation
Poor dental hygiene.
What proportion of primary TB infection are progressive
Only 5%
Will resemble a bacterial pneumonia (lobar consolidation and pleural effusions)
Caseous necrosis occurs - usually around a granuloma and reginal lymph node
This area becomes known as a ghon focus
What are some of the long term complications of a cerebral abscess
Seizures
Loss of mental acuity
Focal neurological deficits
Describe how a fibrinous exudate can form a scar
Fibrin is deposited
If not removed it will stimulate the ingrowth of fibroblasts and blood vessels
This forms the scar
What causes purulent/suppurative pericarditis
An active infection that invades the pericardium.
Can be direct invasion, lymphatic, haematogenous or seeded during surgery
How does an empyema form
Via bacterial seeding into the pleural space
This most commonly occurs through direct spread from the lungs but can be lymphatic or haematogenous
Describe the mechanisms of increased vascular permeability in inflammation
Gaps in between endothelial cells can open (cells retract)
This is caused by histamine
Endothelial injury - can lead to necrosis and detachment
This can be due to either physical damage or the action of microbes or inflammatory cells
What are the physiological defenses of the nasopharynx
Nasal hairs, ciliated epithelia and IgA
What is the most common complication of aspiration pneumonia
Lung abscess is often seen in surviving patients
What conditions are more likely to lead to bronchopneumonia
COPD, cardiac failure (elderly), complication of viral infection, aspiration of gastric contents
How does serous pericarditis present
Microscopic features: large number of lymphocytes and may have neoplastic cells if cancer is the cause.
Mild inflammatory infiltration of the epicardial fat
Presents with classic symptoms
What are the 4 main signs of inflammation
Redness - caused by vasodilation Heat - caused by vasodilation Pain - pressure or surrounding nerves Oedema - caused by accumulation of exudate Loss of function
Minor symptoms that occur with almost every
What are the microscopic features of encephalitis
Cowdry A intranuclear viral inclusions
Perivascular inflammatory cells
What are the risk factors for TB reactivation
New infection (<2y) Organ transplantation Immunosuppression, Silicosis Illicit drug use Malnutrition High-risk setting (homeless shelter, prison) Low socio-economic status Haemodialysis
What are the clinical features of a lung abscess
Swinging fever Cough, haemoptysis Purulent, foul-smelling sputum Pleuritic chest pain Malaise, weight loss Check for finger/toe clubbing, anaemia, crepitations Empyema develops in 20-30%
How do you diagnose meningitis
Bloods (culture, FBC, U&E, creatinine, electrolytes, LFTs, clotting, procalcitonin, meningococcal and pneumococcal PCR, serology, glucose )
Throat swab for bacterial culture
CSF sample for microscopy and PCR
How does fluid move through the pleura
It moves through this layer due to pressure gradients
It is drained primarily by the lymph system
Describe the anatomy of the pleura
- The pleura are the continuous membranes that surround each lung
They are divided into visceral pleura (in direct contact with lung tissue) and parietal pleura (in contact with the body wall)
The parietal pleura are further divided into 4 sections based on the area they are in contact with.
These are: cervical, costal, diaphragmatic and mediastinal
What are the main causes of chronic inflammation
It may occur on its own or follow acute inflammation
Persistent infection - some bacteria are more likely to cause chronic
Hypersensitivity or autoimmune diseases
Prolonged exposure to toxic agents
H. influenza causes pneumonia in which population groups
Common cause in adults, especially with COPD
In children it causes life-threatening LRTI and meningitis
Moraxella catarrhalis causes pneumonia in which population groups
Elderly
What are the risk factors for URTI
Smoking
Conditions such as asthma or allergic rhinitis,
Close contact with children
Poor hygiene
Immunocompromised state
Anatomical abnormalities - polyps, removed tonsils
When does acute inflammation progress to chronic
When the acute inflammation cannot be resolved
May be due to persistence of stimuli or interference with normal process of healing (remaining infection, diabetes, poor perfusion etc.)
What cell types are found in a granuloma
Strong activation of T lymphocytes leading to macrophage activation
Macrophages can develop abundant cytoplasm and begin to resemble epithelial cells and are called epithelioid cells
Some fuse and become multinucleated giant cells
Describe the appearance of Miliary TB
Widespread seeding of TB
Foci are 2mm in diameter on average, yellow/white in colour, well-circumscribed and firm.
What is encephalitis
Infection of the brain that’s within the brain parenchyma itself
May have an associated meningitis
Define the term exudation
Used to describe the movement of fluid and cells from the vascular system to the body cavity or tissue
How does a transudate form
- It is basically plasma that is forced into the tissues due to an imbalance in the hydrostatic or osmotic pressure in the vessels
If hydro is too high (e.g. heart failure and excess fluid) or is osmo is too low e.g. (decreased protein as seen in liver or kidney diseases)
Describe the microscopic appearance of a cerebral abscess
Purulent exudate full of neutrophils
How do you treat rheumatic fever
Antibiotics (to treat group A strep)
Painkillers and steroids if pain is severe
What are the symptoms of strep throat
A sore throat that can start very quickly
Pain while swallowing
Fever
Inflamed tonsils (sometimes with white patches or streaks of pus, petechiae on the soft or hard palate)
Enlarged lymph nodes in front of the neck
Children can sometimes experience nausea and vomiting, headaches and stomach pain
May also develop a rash known asscarlet fever
How can inhalation allow infection
A huge number of microorganisms are inhaled each day
If they can bypass the usual defenses they can infect the respiratory tract
Pathogens are spread via respiratory droplets (larger and travel shorter distances) or as airborne particles (suspended in air)
Most respiratory infections are droplets
Is pus an exudate or transudate
Exudate
Because it it contains many cell types - neutrophils and debris
What type of inflammation can lead to abscess formation
Purulent -
Abscesses are localised collections of pus, produced by seeding by pyogenic bacteria into a tissue
Can indicate chronic inflammation
How do you treat streptococcal toxic shock syndrome occur
Treated as a medical emergency - urgent hospital treatment
IV antibiotics
Describe acute inflammation
Quick and self-limiting reaction
Usually in response to pathogens that the body can eliminate quickly such as bacteria
Will have exudation of fluid and proteins (oedema) and leukocytes will move into the area (mainly neutrophils)
Damage is usually repaired once the reaction is complete
What causes encephalitis
Mainly viral - most commonly HSV1
Also CMV, rabies
Can be fungal in immunocompromised patients - e.g. acanthomeba
Which conditions predispose you to CAP
Extremes of age
Chronic disease (e.g. COPD)
Immune deficiencies
Hyposplenism.
How do you treat post-streptococcal glomerulonephritis
Diuretics to increase urine flow
Limit salt/water to treat oedema
Manage hypertension
What are the 3 main components of acute inflammation
Vasodilation
Increased permeability of vessels
Emigration of leukocytes
How can physical contact allow infection
○ Through skin shedding (sharing towels)
Describe the pathogenies of constrictive pericarditis
May develop after acute pericarditis
However, can occur without a history of acute pericarditis
What conditions are more likely to lead to lobar pneumonia
Usually community-acquired and in otherwise healthy young adults.
What infections most commonly affect the nose
Main organisms are adenoviruses, echoviruses and rhinoviruses Inflammatory conditions such as the common cold (infective rhinitis) are the most common disease
What are the common symptoms of URTI
Cough, sore throat, runny nose, nasal congestion, headache, low grade fever, facial pressure, sneezing, malaise, myalgia
What are the clinical features of meningitis
Signs of background infection plus signs of meningeal irritation
Headache, photophobia, neck stiffness, aches, fever, vomiting confusion and irritability
Classic non-blanching rash seen in meningococcal infection
What organisms commonly cause meningitis in adults
Strep pneumo > Neisseria meningitides
Describe how rheumatic fever develops
Usually develops 1-5 weeks after strep throat
Thought to be caused by an immune response which leads to a generalized, multisystem inflammatory response
What are the common causative organisms for HAP
Most commonly gram negative rods (enterobacteriaceae & pseudomonas sp.) or gram positive cocci (mainly staph. Aureus).
Also: pseudomonas, Klebsiella, Bacteroides, and clostridia
Accumulation of serous fluid in the body cavities is given what name
Effusion
e.g. pleural effusion
What are some of the potential complications of rheumatic fever
Risk of reactivation
Murmurs and arrhythmias
What is respiratory epithelium
Pseudostratified ciliated columnar epithelium with goblet cells
It covers the majority of respiratory tract, except the initial part of the nasal cavity and the true vocal cords
Describe the structure of an abscess
They have a central liquified region made of necrotic leukocytes and tissue cells
Usually a zone of preserved neutrophils around this necrotic focus
On the outside there may be vascular dilation and parenchymal and fibroblastic proliferation
May become walled off and ultimately replaced by connective tissue.
How do you treat pericarditis
NSAIDs (gastric protection)
Add colchicine 500mcg OD or BD for 3 months to prevent recurrence
Treat underlying cause
Give an example of a condition that leads to fibrinous inflammation
Following pericarditis
Fibrinous exudate develops within pericardial sac
This can be converted to scar tissue which leads to fibrous thickening of the pericardium
If extensive it can destroy the pericardial space
What are the most common causes of pleuritis
Majority of cases arise due to inflammation of the associated lung tissue such as TB, pneumonia, abscesses or infarctions
Other causes include immunological disorders (such as RA or SLE), systemic infection , metastatic cancer affecting the pleura and radiotherapy to the lung or mediastinum
Give an example of a condition leading to serous inflammation
Skin blister following a burn or viral infection
Serous fluid accumulates within the damaged epidermis
The epidermis and dermis are separated by the effusion
Can a tissue still function if a scar forms after inflammation
Although pathological the tissue is usually still able to function
The scar provides structural stability
However, certain disease are the results of excess fibrosis (IPF or cirrhosis)
What are the main symptoms of nasopharyngeal cancer
Alumpin the neck Unilateral hearing loss Tinnitus Blocked nose Nose bleeds Often not present until the cancer is advanced
Describe the aetiology of lung abscesses
Can be due to aspiration of infective material (common in right lung)
Occur secondary to bacterial infection - higher risk if immunosuppressed
Obstructive tumours can lead to abscess
Infection can spread from adjacent organs or haematogenous spread of pyogenic organisms
How long does it usually take symptoms of a URTI to begin
Onset of symptoms: 1-3 days post exposure
What are the common pathogens that infect the GI tract
Norovirus and rotavirus
Virbrio cholerae, giardia, shigella, salmonella, H pylori
C diff in antibiotic use
Klebsiella pneumoniae causes pneumonia in which population groups
Debilitated and malnourished individuals
Elderly, diabetics, esp. chronic alcoholics
What is the purpose of increased permeability in inflammation
It allows plasma proteins & leukocytes to leave the circulation and reach the site of damage
Describe the epidemiology of pneumonia
It is the leading cause of death of children worldwide (highest rates in Sub-Saharan Africa and South East Asia)
Undernutrition, air pollution, second-hand smoke and HIV+ all contribute to pneumonia deaths
Why does the inflammatory response need to be regulated
If the reaction continues once the pathogen is eliminated the body can be overwhelmed by the inflammatory response
It will end up causing more damage to tissues
What organisms commonly cause meningitis in adolescents
Neisseria meningitides
Pneumocystis jirovecii causes pneumonia in which population groups
Immunosuppressed
Specifically in HIV+ patients
(CD4 count of around <200)
What infections usually affect the nasopharynx
○ Pharyngitis and Tonsillitis
Often accompany URTI
Rhino, adeno and echo are most common causes but influenzas and RSV can also cause
What are the clinical features of bacterial pneumonia
High fever, rigors, productive cough occasionally with haemoptysis.
Pleural involvement – friction rub + pleuritic chest pain.
Correct antibiotic administration significantly improves condition.
What is the definition of inflammation
A response of vascularized tissues that delivers leukocytes and molecules of host defense from the circulation to the sites of infection and cell damage in order to eliminate the offending agents
How do you diagnose constrictive pericarditis
CXR - small heart and calcification
CT if need to make sure not restrictive cardiomyopathy
What is pleuritis/pleurisy
Pleuritis is the inflammatory form of a pleural effusion
Can be serous, serofibrinous or fibrinous but all are inflammatory in origin
What are the complications of a lung abscess
Extension into pleural cavity Haemorrhage Septic embolization Development of brain abscess or meningitis Rarely - secondary amyloidosis
Describe the pathogenesis of meningitis
When the pathogen reaches the meninges it triggers the inflammatory response
Tissue damage, swelling and oedema
How do you treat laryngeal carcinoma
Early-stage (T1 and T2) - Surgery or radiation therapy
Moderately advanced (T3): Radiation therapy and sometimes chemotherapy
Advanced (T4): Surgery (often followed by radiation therapy +/- chemotherapy) or sometimes chemotherapy + radiation therapy
What are the main morphological features of chronic inflammation
Infiltration with mononuclear cells
Tissue destruction and fibrosis
Attempts at healing by connective tissue replacement
Describe the pathogenesis of pneumonia
Microorganisms, pollution and debris are inhaled but evade the usual host defences
Pathogens can disrupt these systems by attaching & proliferating locally (e.g. influenza), paralysing cilia via toxins (e.g. h. influenzae), or evading death by phagocytosis (mycobacterium tuberculosis)
Once a pathogen reaches the lungs there is immune activation and a build up of fluid and cells in the alveoli
This leads to impaired gas exchange
How does sepsis promote coagulation
Many immune factors favor coagulation
Stasis in small vessels leads to formation of thrombi
List the stages of cerebral abscess formation
Early cerebritis (day 1-4)
Late cerebritis (day 4-10)
Early capsule formation (day 11-14)
Late capsule formation (> 14 days)
What is the most effective way for infection to spread
Via the bloodstream
From here, the pathogen can spread to all organs and produce a systemic response
How do you treat HSV1 encephalitis
Acyclovir 10mg/kg every 8hrs for 14-21 days
Which cells are recruited to the sites of inflammation
Leukocytes, antibodies and complement proteins
Some will have been circulating in the blood and are brought to the area via the circulation and become active (triggered by cellular signals)
Others are found in the tissues at all time and pick up invaders/changes
What are the potential outcomes of pleuritis/ pleural effusion
With treatment, most cases will resolve and the fluid is absorbed.
Sometimes there is minimal fibrosis if the effusion had a fibrinous component which is reorganised
If the effusion is substantial, it can prevent the lungs from expanding fully and may even cause collapse
- This would lead to respiratory distress
Which pathogens are the most common cause of viral meningitis
Enteroviruses
Influenza
Herpes simplex
Mumps
What is pericarditis
Inflammation of the pericardium
Can be acute (majority) or chronic
How do infections spread through the CNS
Some viruses can proliferate in peripheral nerves and then travel up the axons to access the CNS - Varicella zoster
Bacteria can reach the CNS in the bloodstream where they can proliferate in the CSF as well as tissues - Neisseria meningitidis
What happens if the inflammatory response goes uncontrolled and becomes systemic
It can lead to SIRS and sepsis
Systemic features include: fever, production of acute-phase proteins, increased production of WBC, increased pulse and BP, rigors, anorexia and malaise (may be due to effect of cytokines on the brain)
How does TB cause haemoptysis
Apical lesions can expand into the adjacent lung, bronchi and vessels
What is the definition of contagious
Able to be transmitted from one human to another
How does a lung abscess present on CXR
Walled cavity
Often with an air/fluid level
How does complete resolution occur
Macrophages will remove the cellular debris and microbes
Lymphatic system will reabsorb the oedema fluid
The damaged tissue is then regenerated by surviving cells or tissue stem cells (normal cells are restored)
What are some of the main complications of pneumonia
Lung abscess (if inadequately treated)
Respiratory failure
Hypotension (due to dehydration and vasodilation in sepsis)
AF (common in elderly) – resolves with treatment of infection.
Pleural effusion
Empyema
Systemic dissemination - endocarditis, meningitis, suppurative arthritis, metastatic abscesses
What are the symptoms of laryngeal cancer
Hoarse voice Pain or difficulty when swallowing Lump or swelling in the neck Persistent cough or sore throat Ear ache Difficulty breathing
What causes pericarditis
There are a wide range of causes including infectious agents, disorders of the immune system, MI and cardiac surgery
Can leukocytes themselves cause tissue damage
Yes
This can prolong inflammation
List some common pathogens of the urogenital tract
E coli (UTI) candida albicans (disruption of vaginal flora) STIs
Describe the macroscopic appearance of a cerebral abscess
Discrete lesion with central liquefactive necrosis
Surrounding fibrous capsule
How can immune reactions such as hypersensitivity cause inflammation
Sometimes the immune system can attack the individuals own tissue in response to harmless stimuli
Can be directed against self-antigens (autoimmune disease), environmental stimuli (allergies)
This leads to persistent/ hard to cure inflammation as stimuli cannot be eliminated
How does an exudate form
There is increased blood flow to an area and the vessels become more permeable
This allows cells and plasma proteins to move out into the area
Common and normal occurrence in inflammation
How can primary TB become latent
Initial infection is controlled by the T cell response
The Ghon complexes progressively fibrose and leave a fibrocalcific nodule
Some viable organism s can remains dormant in the granulomas
What is the purpose of vasodilation in inflammation
This increases blood flow to the area to aid delivery of cells/fluid
What are the risk factors for TB drug resistance
Previous TB treatment
Contact with drug-resistant disease
Birth or residence in country where resistance is high
What are the macroscopic features of nasopharyngeal cancer
Most arise on the lateral wall of the nasopharynx
Most grow outwards
Usually a smooth, discrete raised nodule below the mucosa
Around 10% will be ulcerated
Cervical node mets are common
What are the physiological defenses of the oropharynx
Saliva, sloughing and coughing
How does HSV1 encephalitis cause death
Increased ICP leads to herniation
Can also affect cerebral perfusion
What are some of the long term complications of HSV1 encephalitis
Behavioural issues, antegrade amnesia, seizures, difficulty with new tasks
Define the oropharynx
Extends from soft palate to epiglottis
What are the features of septic shock
DIC (clotting leads to tissue hypoxia)
Hypotensive shock (systemic hypotension)
Metabolic imbalances
Multiorgan failure
What are the complications of streptococcal toxic shock syndrome occur
Limbs removed through surgery
Serious scarring from having infected tissues removed
Between 3 and 7 in 10 people with STSS die
What are the clinical features of a cerebral abscess
Headache
Site dependent focal neurological signs
Seizures
Signs of raised ICP - N&V, double vision, confusion and drowsiness
What are the main causes of a pleural effusion
Occur due to primary pleural diseases such as infection or mesothelioma
Or it can be from secondary inflammation or infection
Other causes include: decrease in osmotic pressure (nephrotic), decreased lymph drainage (cancer) and increased intrapleural pressure (collapse)
How do animal vectors spread disease
Through their bites (e.g. Malaria and mosquitos)
Can spread bacteria, viruses or protozoa
What is the most common subtype of pericarditis
fibrinous/serofibrinous
Give an example of a condition that causes purulent inflammation
Acute appendicitis
How do you treat strep throat
Usually self limiting - rest etc.
Resistant to most common antibiotics but if one is given its phenoxymethylpenicillin
What are the common causative organisms of CAP
Typical: Strep. Pneumonia, H. influenzae, Moraxella catarrhalis
Atypical: Mycoplasma pneumoniae, staph. Aureus, Legionella sp., and chlamydia
Viruses only account for 15% of cases
Which diseases can present with granulomas
TB - granuloma is called a tubercle
Crohn’s and sarcoidosis
What factors increase your risk of respiratory infection
Smoking, being on a ventilator or CF all lead to damage of the mucocilliary system - more vulnerable
Immunocompromised hosts also a risk - PJ in AIDS
Describe the epidemiology of HSV1 encephalitis
Most common type
Children and the elderly are the most commonly infected and most severely affected
Male:female affected equally
Its sporadic across the globe and has no seasonal preference
Describe the inflammatory process of lobar pneumonia
You get the initial congestion from the classic acute inflammatory response (appears heavy and boggy)
Massive neutrophilic exudation with haemorrhage leads to red hepatisation
RBC disintegrates whilst fibro-purulent exudates remain leading to grey hepatisation
Finally you get resolution - enzymes digest the consolidated exudates
What is the definition of contamination
The accidental introduction of microorganisms
When does post-streptococcal glomerulonephritis occur
Occurs about 10 days after strep symptoms
Legionella causes pneumonia in which population groups
Colonises water tanks kept <60 degrees C (air-conditioning & hot water systems).
Immunocompromised patients
What is a pleural effusion
An accumulation of excess fluid in the pleural space
Can be inflammatory or non-inflammatory in nature
How can ingestion lead to infection
Most common is through food or drink contaminated by faecal matter which leads to diarrheal diseases (faecal-oral route)
If a pathogen is acid resistant they can survive the usual protective mechanism
Or they can produce toxins or adhere to areas of damage
Affect the GI tract
How do you treat a cerebral abscess
Mainly antibiotics and surgery
Ceftriaxone for strep and vancomycin for staph
Surgery is either aspiration or craniotomy
Describe the aetiology of pneumonia
Caused by bacterial, viral or fungal organisms
In certain conditions there is impairment in the local (CF) or systemic (AIDS) immune system which puts people more at risk
Intubation inhibits complete clearance of microbes via mucociliary escalator which also increases risk
What are the symptoms of post-streptococcal glomerulonephritis
Red/brown urine Oedema Less urine Fatigue (caused by a mild anemia) Proteinuria Hypertension
Describe the natural history of HSV1 encephalitis
Infected when young – cold sore virus Remains latent for several years Reactivates and presents acutely or sub acutely Antiviral treatment for 14-21 days Can have long term complications
Explain the relationship between pericarditis and URTIs, pneumonia and pleuritis
URTI and lung infections such as pneumonia can precede pericarditis
Areas of pneumonia or empyema can directly invade the pericardium and lead to purulent pericarditis
In this case the URTI etc. would be considered the primary infection site
How do you diagnose rheumatic fever
Throat swab for a group A strep infection
Blood test for group A strep antibodies
ECG & echocardiogram
What is the definition of community acquired pneumonia
Lung infection in a healthy individual that is picked up in the normal environment
They have had no recent healthcare exposure
Pseudomonas aeruginosa causes pneumonia in which population groups
Common in cystic fibrosis & neutropenic patients.
Common cause of HAP, esp. in ITU or post-surgery
Which bacteria is in Group A strep
Streptococcus pyogenes
Pyogenic so can produce pus
What are the pathologic features of pericarditis
Exudate is made up of blood and fibrinous/suppurative effusion.
If cancer is the underlying cause, then neoplastic cells may be found on cytology of the exudate.
How do you diagnose a pleural effusion
Chest X-ray - blunting of costophrenic angles and fluid level seen
US - useful for guidance
Diagnostic aspiration
Biopsy if aspiration is inconclusive
Describe the natural history of meningitis
Starts with exposure to the virus or bacteria
Takes between 3-7 days from infection for the inflammatory processes to take place and to see symptoms
Seek medical attention
Treatment – 1-2 weeks for bacterial or supportive management for 7-10 days for viral
Potential for long term complications
How do you diagnose laryngeal carcinoma
Laryngoscopy
Operative endoscopy
Biopsy + imaging tests for staging
How do you diagnose strep throat
Examination and swab
Can be diagnosed by rapid streptococcal antigen tests in pharyngitis and culture in other cases
Use the FeverPAIN score to differentiate from a viral infection
What causes aspiration pneumonia
Inhalation of gastric or oropharyngeal contents into the lower airways
Pneumonia occurs due to presence of foreign material in the lungs
What are the normal defenses of the respiratory system
Mucociliary clearance
The cough reflex
Resident alveolar macrophages & neutrophils
What causes an immune granuloma
Caused by a variety of agents that can induce a persistent T cell-mediated immune response
Occurs when the microbe is particularly hard to get rid off
What commonly leads to adherence mediastinopericarditis
Infection, surgery or radiation
Which pathogens are the most common cause of chronic meningitis
TB
Cryptococcus
Describe the histology of the trachea
Lined by respiratory epithelium
Layer of basal lamina then lamina propria of CT
It has between 15-20 cartilage ‘C’ shapes
The open side has fibroelastic tissue and smooth muscle (trachealis muscle)
Also has many submucosal glands which secrete mucus onto the surface
What is the definition of a parasite
An organism that lives in or on, and benefits from, another organism whilst causing harm to its host. Includes protozoa (unicellular)
Describe the role of T and B lymphocytes in chronic inflammation
They prolong the inflammation
They can secrete cytokines which promotes inflammation
Memory function may be key to prolonged inflammatory reactions
How do you treat meningitis empirically
Ceftriaxone IV 2g bd plus dexamethasone IV 10Mg qds
If over 65 or immunocompromised add in amoxicillin IV 2g 4hrly (listeria cover)
How do you diagnose HSV1 encephalitis
Lumbar puncture
EEG
MRI
PCR on CSF for HSV1
Describe serous inflammation
Exudation of cell-poor fluid into spaces created by tissue damage or into body cavities (pleural or pericardial)
No microbes present in fluid and little to no leukocytes
Fluid in cavities either comes from the plasma or secretions from the mesothelial cells due to local irritation
Purulent pericarditis often leads to chronic pericarditis - true or false
True - particularly constrictive
the severe inflammation usually leads to scarring
Describe the pathogenesis of URTI
Organism is acquired by inhalation of infected droplets
It then successfully invades the mucosa of the upper airway, bypassing the bodies defenses
Once invaded the inflammatory response initiated
What are the common pathogens that infect the lower respiratory tract
Staph. aureus, Haemophilus influenzae, Mycobacterium tuberculosis
Mycoplasma pneumonia
What are the features of an chronically inflamed ulcer
Fibroblastic proliferation & scarring of margin & base of ulcer
Accumulation of lymphocytes, macrophages & plasma cells
How would a CSF sample appear in bacterial meningitis
Cloudy or purulent, High pressure High neutrophils Increased protein Markedly reduced glucose
What is the main protective mechanism of the UG tract
Frequent bladder emptying
