Acute Respiratory Infecitons And Pneumonia Flashcards
What are the anatomical defences in the respiratory tract?
Nose hairs which filter particles
Nasal conchae which rapidly humidify and warm air
Epithelial linings
Cilia
What are the mechanical defences in the respiratory tract?
Coughing and sneezing reflex
Mucociliary escalator
What is the mucociliary escalator?
Pseudostratified columnar epithelia has a lining of cilia, with a mucous layer overlying on top. The cilia co-ordinate the beating to clear mucus upwards before reaching the lungs. It is present in the nose, bronchi.
-> This can become damaged by inflammation, particularly worse in smoking.
What are the immune mediated defences in the respiratory tract?
Innate immune defences, including
Antimicrobial peptides, macrophages, and inflammatory cells.
Adaptive immune defences including,
Lymphocytes specific to the pathogen.
What are the nasal turbinates?
Also known as the nasal conchae, they are shelves of bone in the lateral walls of the nasal cavity which can trap large particles. It serves to direct the flow of air, warming and humidifying it as air passes through.
The superior and middle are projections of ethmoid bone. The inferior concha is a separate bone.
What is the histology of the nasal cavity?
Lamina propia
Goblet cells
Pseudostratified columnar epithelia
Basal cells
Bowman’s gland
Which structure produces nasal secretions?
Goblet cells produce the mucus nasal secretions containing antimcirobial enzymes such as anti-proteases, alpha-1 trypsin and lysozymes. Immune cells such as IgA are present here.
What is the histology of the respiratory tract?
Pseudostratified columnar epithelia which contains tight junctions that prevent pathogen entry and goblet cells to produce mucus. It is lined with cilia which moves mucous in the sol phase for the mucocilary escalator movement
Which conditions impair the functioning of the mucociliary escalator?
Cystic Fibrosis
Primary ciliary dyskinesia.
What is cystic fibrosis?
Genetic condition caused by deficiency in the CFTR gene encoding for the CFTR Cl- ion channels for Cl- secretion that affects water transport for mucus fluidity. This causes mucus to harden over the epithelia of the tract and cause damage, commonly resulting in Bronchieactasis where the airways widen due to damage.
What is primary ciliary dyskinesia?
Cilia has absence of dynein arm which connects microtubules together and contains ATPase for energy breakdown. This means cilia is unable to move and beat for the mucociliary escalator, resulting in recurrent upper respiratory tract infections, sinusitis and Bronchieactasis. It can result in dextrocardia, where the heart is on the right side.
Cilia are present in the sperm and ovum and this can result in infertility.
What is the role of alpha-1 trypsin?
Protease inhibitor which protects the nasal cavity and lungs from proteolytic damage due to the inflammatory microbicidals like elastase released by neutrophils and macrophages during infection.
What is emphysema?
“Pink puffers”
Damage to the alveoli which limits elastic recoil and gas exchange in the lungs. This occurs due to chronic inflammation, which may occur when there is a deficiency of alpha-1 anti trypsin that mediates lung damage from immune cell action. They generally have pursed lips.
What is PRRS?
Pathogen recognition receptors: Germ-line encoded receptors which we inherit and express on immune cells and epithelia to recognise both PAMP (pathogen associated molecular patterns) and DAMP (damage associated molecular patterns) for innate immunity.
Induces chemokine and cytokine production.
What is a PAMP?
Pathogen associated molecular pattern, highly conserved sequence part of the structure that a pathogen requires in order to survive.
What are toll-like receptors?
Pathogen recognition receptor type that can differentiate between microbial classes and initiate the innate immune response.
What is humoural immunity?
Immune defences due to antibodies produced by B lymphocytes. In the upper airways, this is mainly via IgA present in mucus.
IgG and IgM travel via the bloodstream.
IgG is present in the alveoli.
Where is IgA found?
Mucus
Where is IgE found?
Tissues
Where is IgM found?b
Bloodstream.
Where is IgG found?
Bloodstream.
Where is IgD found?
Surface of B lymphocytes, as an antigen receptor.
What is cell mediated immunity?
Type of adaptive immunity generated by macrophages and T lymphocytes against Intracellular pathogens, which includes cytotoxic T cells.
What is commensalism?
Relationship where one organism benefits and the other is unaffected.
What are the opportunistic pathogens of the upper respiratory tract?
Streptococcus pneumonia
Staphylococcus aureus
Haemophilius influenza
Maraxella catarrhalis
-> These are part of the normal flora of the URT and when the immune system defences are lowered, they can colonise and cause infection.
Which part of the respiratory tract is more prone to infection?
Upper respiratory tract
-> Lower respiratory tract contains macrophages which provide an effective defence via phagocytosis.
What is the leading cause of death in infectious diseases?
Lower respiratory tract diseases.
What does marexella catarrhaxis cause?
Gram negative diplococcus bacteria which is part of the normal flora of the URT and typically causes otitis media in children and sinusitis in adults. It is treated with amoxicillin.
What is the typical presentation of upper respiratory tract infections?
Tend to be benign and self-limiting
Sneezing, facial pain, nasal congestion, sore throat, fever, runny nose and cough.
What is the typical presentation of lower respiratory tract infections?
More severe
Dyspnoea, chest pain, fever, wheezing, chest tightness.
Which fungi causes respiratory infection?
Aspergillus mould
Pneumocystis jirovecci
Coccidocomycosis
Which viruses cause respiratory infection?
Adenovirus
SARS-COV2
Rhinovirus
Influenza A and B
What is acute bronchitis?
Inflammation of the bronchi with a peak incidence in winter that occurs due to an infection.
Common symptoms are productive coughing that is hacking, and the colour depends on the causative agent. There tends to be shortness of breath, cough and wheezing due to partially obstructed airways but tends to be self-limiting.
For elderly or immunocompromised, antibiotics are given. Shows no consolidation on X-ray.
What is the cause for acute bronchitis?
Commonly caused by viruses such as:
Adenovirus, Influenza A/B, Rhinovirus and coronavirus.
Bacterial agents are the opportunistic bacteria and mycoplasma pneumoniae.
What is chronic bronchitis?
“Blue bloaters”
Type of Chronic obstructive pulmonary disease characterised by a productive cough lasting longer than 3 months. It is caused by hyperplasia and hypertrophy of the mucous gland, and smoking is the biggest risk factor for smoking and there is reduced function of the cilia so there is buildup of mucus.
Presents with dyspnoea, cyanosis, obesity, tachycardia and wheezing and a major risk factor is smoking. There is hypoxaemia and hypercapnia, therefore there is vasoconstriction to areas of the lung, which increases right sided heart failure.
What is exacerbation of COPD?
Sudden worsening of COPD symptoms with shortness of breath, increased mucus quantity and colour lasting several days. This occurs typically due to an acute infection of the lower respiratory tract, such as acute bronchitis. There will be no consolidation on a chest X-ray.
What is pneumonia?
Inflammation of the lung tissue typically affecting the alvoeli caused by infection or gastric contents. It is characterised by a loss of silhouette signs on chest X rays that affects the lower lobes.
What is the pathophysiology of community acquired pneumonia?
Pathogen overwhelms the host immune response or the defence’s are weakened from an existing morbidity which enables propogation in the lung parenchyma. Alveolar macrophages are the primary defences in the lungs and release inflammatory cytokines such as TNF and IL-8 to promote neutrophil chemotaxis however leads to constitutional symptoms of fever and dyspnoea, however in excess can lead to multi organ dysfunction and sepsis.
What are the types of pneumonia?
Pneumonia is colonisation by a pathogen of the lower respiratory tract which is split into:
Lobar pneumonia
Bronchopneumonia
Interstitial pneumonia
What is presentation of pneumonia?
-> Exertional Dyspnoea
->Pleuritic chest pain
->Productive cough but may be dry
->Fever and fatigue
->Pleuritic chest pain
->Confusion, nausea and altered mental state in the elderly or very young
What are the findings on respiratory examination with pneumonia?
Crackles and dullness to percussion with increased tactile vocal fremitus due to fluid accumulation
Bronchial breathing
What is bronchial breathing?
Harsh breath sounds over the trachea louder in inspiration on auscultation which is harsh and unjoined up, inducing lung infection with pneumonia and bronchitis.
What are vesicular breath sounds?
Normal soft and low pitched breath sounds
What is lobar pneumonia?
Exudative inflammation affecting an entire lung lobe which has 4 stages of progression;
Congestion
Red hepatisation
Grey hepatisation
Consolidation
It is caused by the bacterial agent streptococcus pneumoniae
What is congestion?
Occurs in the first 24 hrs where blood vessels and alveoli in the affected region of the lung lobe fill with excess fluid.
What is red hepatisation?
Occurs after 2-3 days: The exudative material containing RBC, WBCs and fibrin fill the airspaces and begin to solidify.
What is grey hepatisation?
The RBCs in the exudative material begins to break down and it will take on a grey colour.
What is resolution?
Occurs on day 8:Exudative material is digested/ingested or coughed up at the end of pneumonia.
What is bronchopneumonia?
Inflammation of the bronchioles which is in patchy areas throughout the lungs to the alveoli due to an infection arising from the bronchi or bronchioles. This creates multiple foci of consolidation caused by neutrophil collection in the alveoli and bronchi.
Infants and elderly are at greater risk due to weaker immune defences.
What is cavitation pneumonia?
Death of lung tissue results in central liquefactive necrosis. This occurs in immunocomprosimed patients due to staphylococcus aureus and pseudomonas aerugonosia and mycobacteria tuberculosis.
What is interstitial pneumonia?
AKA atypical pneumonia, occurs due to interstitial lung tissue, typically caused by SARS-COV2 and pneumocystis jirovecci.
It is concentrated mainly in the perihilar region, the area closest to the sternum.
What is community acquired pneumonia?
Pneumonia acquired outside healthcare settings with a greater incidence in males, and during winter.Typically presents with cough, fever and chest pain
What is the treatment of community acquired pneumoniae?
Amoxicillin and clarithromycin
What are the typical bacterial causes of Community acquired pneumonia?
Majority are due to:
streptococcus pneumoniae and haemophilius influenzae, and staphylococcus aureus
Kleibsella pneumonia
Moraxella catarrhaxis
What are the atypical bacterial causes of community acquired pneumonia?
Chlamydia pneumoniae: typically contracted from birds
Mycoplasma pneumoniae
Legionella pneumoniae
—> they lack a cell wall
What are the viral causes of community acquired pneumoniae?
RSV
Adenovirus
SARS-COV2
Influenza
What is the most common fungal causes of community acquired pneumoniae?
Cocciodides
Pneumocystis jirovecci
Histoplasmosis
What are the complications with pneumonia?
Pleural Effusion
Emphysema
Lung abscess
Septicaemia
What is the treatment for community acquired pneumonia?
Macrolide antibiotics like clarithrocymin and Azithromycin
What is the treatment for hospital pneumonia?
Fluroquinolones such as ciprofloxacin
OR
Combination of beta-lac tam antibiotics with a macrolide antibiotic
What is legionella pneumoniae?
Gram negative bacilli transmitted from air conditioning, water tubs, like jacuzzi or swimming pool and results in fever with diarrhoea, abdominal pain and patchy consolidation in a lung lobe.
It causes hyponatremia and Pontiac fever.
What is the most common cause of atypical pneumoniae?
Mycoplasma pneumoniae is the most common causative agent for atypical pneumonia, and is a mild presentation, with the disease typically resolving in 10-14 days.
What are the typical causes of Hospital acquired pneumonia?
MRSA
Staphylococcus aureus
Kliebsella pneumonia
Pseudomonas aeurogionosa
What are the risk factors for pneumonia?
Smoking
Alcohol
Immunosuppressive
Sepsis
Drugs like proton inhibitors
What are the microbiological investigations for pneumonia?
FBC for inflammatory markers like ESR and C-reactive protein
Blood cultures
Urine culture
Blood serology
Throat swab
Respiratory specimen
CXR showing load pneumonia and pleural effusion
How is pneumonia severity assessed?
CURB-65 score to assess mortality risk from pneumonia
C: consciousness
U: urine for uraemia greater than 20mg/l
R: respiratory rate greater than 30
B: blood pressure low at systole and diastole
65 years old or over
What is hospital acquired pneumoniae?
Pneumonia occurring 48 hours after admission and is the leading cause of death. Typically caused by gram negative aerobes and staphylococcus alerells
What is a common cause of hospital acquired pneumonia?
Streptococcus pneumonia- MOST COMMON
Staphylococcus aureus
MRSA
Pseudomonas aeuroginosa
What is Pseudomonas aeuroginosa?
Gram negative bacilli associated with hot tub use, and causes meningitis and pneumonia in those who are immunocompromised.
What is aspirational pneumoniae?
Caused by aspiration of gut contents such as bile into the lungs, typically caused by kleibsella, a gram negative bacilli.
What is a consequence of emphysema?
The lack of elastic recoil in the lungs reduces the structural support for breathing, especially during expiration. This increases the tendency of the smaller bronchioles to collapse.
How can we determine pneumonic from a respiratory examination?
Dullness to percussion and loud vocal fremitus because sound travels better in fluid filled lungs than air.
