Respiratory Infections Flashcards
Conducting and respiratory zones diagram
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In high income countries, acute respiratory infections are the —- cause of morbidity and mortality.
6th
What % decrease in global respiratory infections death since 1990? What can this decrease be attributed to?
- 23% decrease since 1990
- immunisation
- access to antibiotics
- reduced poverty
Highest risk of acute respiratory infection:
- immune system (poor nutrition, young children, elderly)
- poverty and poor access to basic amenities
- smoke pollution
- overcrowding
- immunocompromised HIV
An opportunistic infection is one which:
1 = affects the immunocompromised
2 = cannot be treated
3 = causes a pneumonia
4 = invades healthy lung tissue
5 = overcomes the lung’s defences
1
Which of these is the commonest cause of community acquired pneumonia?
1 = Haemophilus influenza
2 = Legionella pneumophila
3 = Mycoplasma pneumoniae
4 = Staphylococcus aureus
5 = Streptococcus pneumoniae
5
Which of these organisms lives in asymptomatic, healthy individuals?
1 = Aspergillus fumigatus
2 = Escherichia coli
3 = Haemophilus influenza
4 = Legionella pneumophila
5 = Mycobacterium tuberculosis
3
Pathogenesis of respiratory infections:
- lungs are constantly exposed to particulate material and microbes from the upper airway
- lower airways are usually devoid of conventional pathogens
Lower airways are usually devoid of conventional pathogens: Innate Immunity:
- cilia - mucociliary escalator (MCE) removes debris and pathogens
- alveolar macrophages:
- secrete antimicrobials
- engulf and kill other pathogens
- recruit other immune cells
- process and present antigens to T cells
Lower airways are usually devoid of conventional pathogens: Acquired immunity:
- B cell/ T cell: responses essential for intracellular pathogens, such as mycobacteria, viruses and fungi
- IgA secreted by plasma cells interferes with adherence and viral assembly
Response to infection (4):
- inflammation = bodys response to insult
- macroscopic = redness, swelling, heat, pain and loss of function
- microscopic = vasodilation, increased vascular permeability and inflammatory cell infiltration
- acute or chronic
Commensals in respiratory tract: mouth:
- staphylococcus aureus
- streptococcus pneumoniae
- anaerobes
- bacteriodes
Commensals in respiratory tract: sinus/nasal passage:
Sinus/nasal passage:
strep pneumoniae
haemophilus influenzae
staph aureus (MRSA)
rhinovirus
Commensals in respiratory tract: throat:
candida (thrush)
strep pyogenes
MRSA
Viral infections of the respiratory tract:
- adenovirus
- cytomegalovirus
- INFLUENZA
- RHINOVIRUS
- coronavirus
- parainfluenza
– RESPIRATORY SYNCYTIAL VIRUS (RSV)
Cold:
- name
- affects
- causes
- rhinovirus
- upper respiratory tract
- causes nasal discharge
Tonsillitis:
- name
- affects
- causes
- streptococcus Grp A
- upper respiratory tract
- inflamed tonsils
2 pathogens that can cause bronchitis are:
- streptococcus pneumoniae
- haemophilus influenzae
Bronchiolits occurs in
infants
A pathogen that causes bronchiolitis
Respiratory Syncytial Virus (RSV)
4 pathogens that cause pneumonia:
- streptococcus pneumoniae
- haemophilus influenzae
- legionella pneumophila
- mycoplasma pneumoniae
How often does the common cold occur a year in preschool children?
5-7x a year
How often does the common cold occur a year in adulthood?
2-3 a year
Most common pathogen causing cold? What % of common colds caused?
- rhinovirus
- 30-50%
Human coronaviruses cause what % of common colds?
10-15%
Transmission of the common cold:
- hand contact: virus remains viable for upto 2 hours on the skin or several hours on surfaces
- droplet transmission from sneezing/ coughing/ breathing
The common cold:
- incubation period
- symptoms last
- 2-3 days
- 3-10 days
- upto 2 weeks in 25% patients
What causes the symptoms of the common cold:
- sore throat and nasal congestion
- sneezing
- nasal discharge
- cough
- systemic symptoms = fever
- bradykinin accumulation in throat: causes a sore throat, nasal congestion due to vasodilation
- sneezing is mediated by the stimulation of the trigeminal sensory nerves = histamine mediated
- nasal discharge due to myeloperoxidase
- cough is mediated by the vagus nerve, inflammation has to extend to the larynx to trigger this; hyper reactive response in URTI
- cytokines responsible for systemic symptoms such as fever
bradykinin is
a peptide that produces inflammation by increase conc of prastocyclin, NO and other factors
Myeloperoxidase
a peroxidase enzyme in neutrophils used to attack pathogens
Nasal discharge changes colour (common cold) due to
increasing number of neutrophils (myeloperoxidase)
white to yellow to green
The common cold vs influenza:
- appearance
- affect
- symptoms
- fever
- work
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Influenza:
- pathogens causing?
- occurs in
- usually at
- influenza A or B
- occurs in outbreaks and epidemics worldwide
- usually during winter season so swaps hemispheres over the course of the year
Spanish flu occured when?
Caused by?
- 1918 pandemic
- influenza
Uncomplicated influenza generally lasts between
1-4 days
Influenza symptoms:
- abrupt onset of fever (38-41 degrees C)
- cough
- headache
- myalgia
- malaise
- sore throat
- nasal discharge
- can be acutely debilitating
Influenza: Risk groups for complications (5):
- immunosuppression
- chronic medical conditions (diabetes, COPD, asthma)
- pregnancy or 2 weeks post partum
- age: <2 or >65 yrs
- BMI >40
Influenza Complications (4):
- primary viral pneumonia
- secondary bacterial pneumonia: bacteria that would normally not cause disease cause disease
- Central Nervous System disease
- death (estimated mortality among people infected in the US is 0.13%)
Coryzal symptoms
- symptoms of a cold
chellenges for the virus
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How does the influenza virus invade the cells?
- influenza virus has a haemagglutinin surface protein (H) which binds to sialic acid receptors on the host cell in the respiratory tract, allowing the virus to enter the cell
- reproduction using host cell mechanisms
- the neuraminidase (N) (enzymes) on the surface of the virus allows the virus to escape by cleaving the sialic acid bonds - otherwise all the escaping virions clump together
- the influenza virus has a segmented genome (8 parts) so can reassort if 2 different viruses infect the same cell
Why influenza classified via the HN classification?
- influenza virus haemagglutinin (H) surface protein allows entry into cell
- neuraminidase (N) on the surface of the virus allows the virus to escape the cell after reproduction
neuraminidase is an
enzyme
Exact nature of H & N remain the same despite new strains of influenza.
True or False?
False
Influenza shift and drift
Antigenic drift in influenza
- neutralising antibodies against haemagglutinin (H) blocks binding of the virus to the host cells
- virus mutates
- mutations alter the haemagglutinin (H) epitopes (sequences of active site) so that the neutralising antibody no longer binds
- hence multiple reassortment events occur
Prevention of influenza
- hand hygiene and droplet precautions (mask)
- active immunisation - against haemagglutinin (H) and neuraminidase (N) components (annual vaccine against H1N1)
Treatment of influenza:
- Tamiflu = oseltamivir = neuraminidase inhibitor
- neuraminidase inhibitor will block the enzyme neuraminidase so will prevent the replication of the virus
Pneumonia
infection of the lung parenchyma
alveoli full of inflammation (infected fluid and pus) = reduces oxygen transfer
Bacterial pneumonia:
- inflammation of , which reduces
- symptoms
- signs
- in elderly:
- alveoli full of inflammation (infected fluid and pus) - reduces oxygen transfer
- fever, breathlessness, cough, sputum production, pleuritic chest pain
- tachpnoea (increased respiratory rate), reduced chest expansion and breath sounds, consilidation (dullness on percussion & increased TVR + VR) + bronchial breathing
- hypoxia
- in elderly: absence of typical symptoms, present with confusion, generally unwell, not eating, dehydrated
Classification of penumonia
- CAP = community acquired pneumonia
- HAP = hospital acquired pneumonia
- Healthcare Associate pneumonia if in hospital for 48 hours and then develop symptoms
- ventilator associated pneumonia (VAP)
- aspiritin pneumonia
Both pneumonia and pleural effusion can result in dullness when percussing. What in the respiratory exam can differentiate?
- pneumonia = increased tactile vocal resonance and vocal resonance because fluid in the lungs, transmits better
- pleural effusion = decreased tactile vocal resonance and vocal resonance as fluid outside the lungs
CAP:
- annual incidence
- prevalence
- mortality rate
- hospital admissions in those who first go to GP with lower respiratory tract infection
- more than half the pneumonia related deaths occur in those older than
- community acquired pneumonia
- common acute lung infection that affects those
- incidence = 5-11/1000 adult population
- prevalence: 0.5-1% of adults in the UK
- 5-14% mortality rate
- 22-42% of those who go to GP admitted to hospital
- more than half the pneumonia related deaths occur in those older than 84 years
Symptoms of CAP:
- productive cough, green/rusty brown sputum
- fevor
- rigors
- pleuritic chest pain
- dyspnoea
- haemoptysis, night sweats, headache, myalgia, nause, vomiting, diarrhoea, lethargy
- elderly or immunocmprimised: above can be present or absent, new confusion
Clinical signs of CAP:
- coughing
- temp (86%)
- tachypnoae ( RR>20)
- tachycardia (pulse>100bpm)
- consolidation:
- decreased air entry
- dullness on percussion
- increased vocal resonance
- coarse crackles
- bronchial breathing
elderly: absence of fever, confusion
Radiological diagnosis of pneumonia
- plain Chest X ray
- consolidation - alveoli and bronchioles completley fillwed with inflammatory debris/pus/pathogens
- heart borders or diaphragm obscured due to loss of solid gas interface
- air bronchograms - air in larger bronchi outlined by surrounding consolidation
- lobar pneumonia
- bronchopneumonia
Chest x ray
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chest x ray
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5 bacteria in CAP and do they live in us?
- Streptococcus pneumoniae (lives in us)
- Haemophilus influenzae (lives in us)
- Mycoplasma pneumoniae (need to think about sources and outbreaks)
- Legionella pneumophila (need to think about sources and outbreaks)
- Staphylococcus aureus ( can become resistant to antibiotics)
Bacteria in CAP: respiratory viruses are probably responsible for
1/3 CAP
pneumocytis jiroveci (PCP) in cell-mediated immunodeficiency
- occurs in severely immunocompromised pts: in people with HIV
Fungal pneumonia pathogen example
aspergillus fumigatus
Streptococcus pneumoniae:
- how common
- gram positive or negative
- risk factors (6):
- entry?
- asymptomatic carriage
- quick test
- prevention
- treatment
- most common organism causing CAP
- gram positive cocci
- risk factors:
- alcoholics, respiratory disease,
smokers, hyposplenism (absent or reduced spleen function), chronic heart
disease
- HIV - acquired in nasopharynx
- asymptomatic carriage in 40-50%: smokers>non-smokers
- pneumococcal antigen in urine
- prevention = vaccine every few years
- treatment = amoxicillin, clarithromycin or co-amoxiclav if severe CAP
HIV increases risk to invasive pneumococcal disease in HIV+
50 to 100 fold
PCP must take a
bronchoscopy
look under microscope
Haemophilus Influenzae Pneumonia:
- gram positive or gram negative
- asymptomatic carriage
- type of pneumonia
- affects
- complications are common or rare?
- example of complication?
- mortality in adults?
- treatment?
- gram negative bacteria
- asymptomatic carriage in healthy individuals
- bronchopneumonia
- affects those with co-morbidities
- complications common (empyema)
- mortality in adults 12-29%
- Treatment: Tetracycline eg: doxycycline
Mycoplasma Pneumonia:
- most common cause of
- generally in what age group
- symptoms
- labs
- diagnosis
- treatment
- most common cause of ambulatory “atypical pneumonia”
- classically presents in a young patient, vague constitutional upset, several weeks
- extrapulmonary symptoms are very common
- lacks a cell wall so:
- resistant to penicillin
- can not grow on normal lab plates - diagnosis: PCR of throat swab
- treatment: macrolides or tetracyclines (erythromycin or doxycycline)
Should penicillin be prescribed for mycoplasma pneumonia?
No
resistant to penicillin due to lack of cell wall
Legionella Penumophila:
- occurs as a
- how common?
- causes
- risk factors
- diagnosis
- treatment
- can occur as a sporadic infection or in outbreaks associated with a contaminated water source
- uncommon - 350 cases a year
- causes severe, life-threatening infection
- RFs = smoking and chronic lung disease
- diagnosis:
- don’t grow on routine culture; needs
special conditions and longer
- urinary legionella antigen - treatment: macrolides or quinolones ( erythromycin or ciprofloxacin)
Clinical assessment and management of CAP:
- CURB-65 score
- C= confusion R= respiratory rate B = blood pressure U = urea
Management:
- oxygen for type 1 respiratory failure
- antibiotics
- mortality 2-40%
Hospital Acquired Pneumonia:
pneumonia that develops more than 48 hours after admission to hospital in someone who did not have pneumonia on admission
Risk factors for hospital acquired pneumonia:
- elderly
- co-morbidities
- immunocompromised
HAP associated with more virulent organisms (4):
- pseudomonas aeruginosa
- klebsiella pneumoniae
- escherichia coli
- MRSA
HAP accounts for what percentage of all infections acquired in hospital?
1.5%
HAP accounts for —– infection-associated deaths in hospital
most
HAP has a higher morbidity and mortality than CAP.
True or False?
True
HAP morbidity and mortality between
30-70%
Multi-drug resistance is common in hospital acquired pneumonia.
True or False?
True
Hospital acquired pneumoniae patients often develop type 2 respiratory failure.
True or False?
False
Type 1
Ventilator associated pneumonia develops in what % of patients who are intubated and ventilated through either micro-aspiration or through contamination of the ventilator equipment
50%
VAP multi-drug resistance is common?
Yes
Risk factors for VAP:
- hospitalisation for more than 48 hours
- antibiotic therapy in the last 6 months
- underlying lung disease
- immunosuppression
- significant other co-morbidities (diabetes, cardiovascular, renal)
Empyema:
- is
- complication
- complication
- incidence
- mortality
- infection (pus) in the pleural space
- complication of pneumoniae
- complication of pleural intervention eg pleural aspiration
- 80,00 cases a year in the UK
- mortality is 20%
Risk factors for empyema (4):
- elderly
- immunocompromised
- alcoholics
- diabetes mellitus
Diagnosis of empyema:
- chest x ray, thoracic ultrasound, CT thorax
- pleural aspiration: pus, low pH, exudate, bacteria
Management of empyema:
- long course of antibiotics (at least 6 weeks)
- intrapleural fibronolytic drugs (streptokinase)
- pleural drainage
- surgery (VATS= video assisted thorascopy)
Opportunistic infections risk factors (5):
- HIV (most)
- immunosuppression (chemotherapy, steroids)
- haematological malignancies (leukaemia)
- solid organ transplantation
- primary immunodeficiencies
Opportunistic infections: Organisms (4):
- Pneumocystis jiroveci (PCP)
- Atypical mycobacteria
- Fungal: aspergillus, candida,
histoplasmosis, cryptococcus - Viral pneumonia eg CMV
PNEUMOCYSTIS JIROVECI:
- type of pathogen
- in environment
- route of infection
- lung colonisation
- results from
- P jiroveci (formerly P carinii)
- Atypical fungus (previously a protozoan)
- Ubiquitous in the environment
- Airborne route of infection, person to
person spread - Asymptomatic lung colonization in
immunocompetent
PCP may result from reactivation or new
exposure
PCP can affect patients with HIV and a CD4 count of
< 200/mm^3
PCP Symptoms (4):
- cough
- severe breathlessness
- hypoxia
- chest x ray will show bilateral, interstitial ground glass shadowing in a bats wing appearance
PCP treatment:
Co-trimoxazole
CD4 count is
T cells which are reduced in HIv
covid 19 gains access to host cells via
spike protein and ACE receptor protein
ACE protein found in pneumocytes and lymphocytes
Incubation period of Covid-19
6.4 days
supportive management of covid-19 pneumoniae
- O2therapy (high flow O2, CPAP, intubation and ventilation)
Recovery trail: Covid-19 Pneumoniae:
- dexamethasone
- remdesivir
- tocilizumab
