Resp - Resp tract infections and immunity Flashcards
What happens as an infection travels further down the resp tract
Infection gets more and more severe
What are the signs of an upper tract infection
Cough Sneezing Runny nose Sore throat Headache
What are the signs of a lower tract infection
Productive cough Muscle ache Wheezing Breathlessness Fever Fatigue
What are the signs of pneumonia
Chest pain
Blue tinting of the lips
Severe fatigue
High fever
What is the global incidence of resp tract infection mortality
They caused around 5 million deaths in 2000 but then around 4 million in 2016 - this excludes TB which is much bigger than other infections
Describe the DALYs for acute respiratory infection
There are high DALYs for acute respiratory infection - this is because we often survive but many are left harmed or affected afterwards
Who is killed the most from respiratory tract infections
Adults over 70 (hot spots in Sub Saharan Africa)
Children under 5 in the developing world - e.g. Africa and India (not really in the developed world)
What is the leading cause of death in children under 1
Lower respiratory illness
What is the leading cause of death in children 1-5 globally
Malaria, followed by lower respiratory tract illness
What are the categories of risk factor for pneumonia
Demographic/ lifestyle Medication PMHx Social Specific risk factors for certain pathogens
Pneumonia RFs: demographic
65
Pneumonia RFs: medication
ICS
Immunosuppressants
PPIs
Pneumonia RFs: medical history
COPD Asthma Heart disease Lung disease Diabetes mellitus HIV Malignancy Hyposplenism Complement for IgG deficiencies Risk factor for aspiration Previous pneumonia
Pneumonia RFs: social
Contact with children under 15
Poverty
Overcrowding
Pneumonia RFs: specific for certain pathogens
Geographical location
Animal contact
Healthcare contacts
What are the common viral agents for respiratory infection
Influenza A/B RSV Human metapneumovirus Human rhinovirus Coronavirus
What are the common bacterial agents for respiratory infection
Streptococcus pneumoniae
Mycoplasma pneumoniae
Haemophilus influenzae
Mycobacterium tuberculosis
What was the deadliest pandemic
H1N1 Influenza A - Spanish Flu
How often do pandemics happen
Every 20 years approx - present significant challenge to healthcare services
What are the main types of bacterial pneumonia
Community
Healthcare
What are the typical agents for causing pneumonia
Strep pneumoniae
Haemophilus influenzae
Morexella catarrhalis
What are atypical causative agents of pneumonia (walking pneumonia)
Mycoplasma pneumoniae
Chlamydia pneumoniae
Legionella pneumophilia
What are the ventilator associated agents for pneumonia
Pseudomonas aeruginosa
Staph aureus
Enterobacter
Describe strep pneumoniae
Gram positive, extracellular, opportunistic pathogen
What are the main differences between typical and atypical pneumonia
Typical are common therefore easier to treat, they present more rapidly and have more aggressive symptoms. Atypical are more difficult to culture therefore we may need different ABx regimes, they typically take longer to develop and thus may have milder symptoms
What is pneumonia
Inflammation and swelling of the alveoli
What is bronchitis
Inflammation and swelling of the bronchi
What is bronchiolitis
Inflammation and swelling of the bronchioles
What is the mechanism of damage for pneumonia
Lung injury leads to arterial hypoxemia.
Bacteria leads to organ infection
Systemic inflammation causes swelling and fluid accumulation and damage therefore impairment of gas exchange
What are the consequences of pneumonia
ARDS
Sepsis
What do we use to grade pneumonia
CRB (primary care)
CURB-65 (secondary care
What is the criteria for CURB-65
1 point for each of the following:
Confusion Urea >7 mmol/L Resp rate >30/min Blood pressure: SBP <90, DBP ≤60 Over 65 years old
What does score 0 mean CURB-65
Low severity therefore can treat at howe with antibiotics
What does score 1-2 mean CURB-65
Moderate severity therefore consider hospital referral
What does 3-4 mean CURB-65
High severity therefore urgent hospital admission needed, and empirical ABx needed if life threatening
What supportive therapy do we have for pneumonia
Oxygen Fluids Analgesia Nebulised saline (expectoration) - gets rid of excess sputum Chest physio therapy to clear lungs
What ABx do we use for CAP CURB-65: 0
Amoxicillin (if allergic to penicillin - give doxycycline or clarithromycin)
What ABx do we use for CAP CURB-65: 1-2
Amoxicillin + calrithromycin (or doxycycline)
What ABx do we use for CAP CURB-65: 3-5
Benzylpenicillin IV + oral clarithro. (or calrithro + teicoplanin)
How long do we give ABx for CAP
5-7 days, but 7-14 days if atypical
What ABx do we use for HAP Curb-65: 0
Oral doxycycline
Give for 5-7 days
What ABx do we use for HAP Curb-65: 1-2
Oral doxycycline
Give for 5-7 days
What ABx do we use for HAP Curb-65: 3-5
Tazocin IV ± gentamicin IV
Give for 5-7 days
What does viral infection lead to
Cellular inflammation
Local immune memory
Mediator release
Damage to epithelium
What does damage to epithelium lead to
Loss of chemoreceptors
Poor barrier protection
Bacterial growth
Loss of cilia
What do almost all viruses cause disease but not all bacteria
Disease - this is because viruses are not pathobionts like many bacteria, which only some pathological in a state of dysbiosis
How does H1N1 cause severe disease
Highly pathogenic strain infects you.
Absence of prior immunity e.g. IFITM3 gene variant leads to immune deficiency
Predisposing illness/ conditions e.g. being frail, old or having COPD mean you are more likely to be subject to severe disease
Where do viruses usually bind
Tend to preferentially bind to the upper respiratory tract if they have existed in humans for a prolonged time, however viruses can infect cells throughout the respiratory tract.
Where does H1N1 bind
haemogluttinin binds to a2,6 sialic acids found in the nasal cavity
Where does H5N1 (avian flu) bind
Haemogluttinin binds to a2,3 sialic acids found in the bronchi
Where does SARS-CoV-2 bind and how is this affected by lifestyle
Spike protein binds to ACE2 which is found in the nasal epithelium and the type 2 pneumocytes - the numbers of ACE2 are increased by smoking
What defence mechanisms does the respiratory epithelium have
Tight junctions Mucus lining and cilia Interferon pathways Pathogen recognition receptors (intra+extra cellular) Antimicrobials
What are serotypes
Viruses which cannot be recognised by serum that recognises other viruses - this has implications on protective immunity
What is an antigen
Any molecule against which antibodies can be generated
What plasma cells are found in the nasal cavity
IgA - ECs express poly IgA receptors allowing for the export of IgA to the mucosal surface - Homodimer is stable in protease rich environment
What plasma cells are found in the alveoli
IgG - thin alveolar walls allow for the transfer of IgG into the alveolar space
Describe the immunity we have for influenza
We have no reinfection by the same strain
Describe the vaccine for influenza
Imperfect - the immunity form the vaccine rapidly wains, and provides us with mainly homotypic immunity therefore an annual jab is needed
Describe the immunity we have for RSV
Recurrent infection by similar strain - no vaccine
Describe the immunity we have for SARS-CoV-2
No prior immunity
Describe the vaccine we have for SARS-CoV-2
New - waning immunity, re-infection is possible but the regime for the vaccine is not clear
Describe RSV in children
RSV is the leading cause of infant hospitalisation in the developed world - affects 100% of children by the time they are 3 however 1% will develop severe bronchiolitis
What are the risk factors for severe bronchiolitis from RSV in children
Premature birth
Congenital heart and lung disease
What are the signs of severe bronchiolitis from RSV in children
Nasal flaring Chest wall retractions Hypoxemia Cough Cyanosis Tachypnoea Expiratory wheeze
Describe the age dependence of RSV in young children
Infantile bronchiolitis
Related with wheeze
Older siblings act as spreaders
Describe the age dependence of RSV in caring adults
Repeated colds
Transmitters
Rarely severe
Describe the age dependence of RSV in older people
Major cause of progressive lung disease and winter death
What supportive therapy do we have for RSV
Same as pneumonia - oxygen, fluids, analgesia, nebulised saline, chest physio
What prophylactic therapy do we have for RSV
Vaccines and antivirals
What therapeutic drugs do we have for RSV
Anti-virals (remdesivir)
Anti-inflammatory (dexamethasone, tocilizumab)
What are the most common causes of asthma and COPD exacerbations
Rhinoviruses
What are the CAP bacteria
Strep pneumoniae Mycoplasma pneumoniae Staph aureus Chlamydia pneumoniae Haemophilus influenzae
What are the HAP bacteria
Staph aureus Pseudomonas aeruginosa Enterobacter spp Kelbsiella E.Coli Acinetobacter spp
What the general difference between CAP and HAP
CAP tend to be more gram positive whereas HAP tend to be more gram negative
