Respiratory tract infections & Immunity Flashcards by Dean Whaley

What are the signs and symptoms of Upper respiratory tract infections?

A cough
Sneezing
A runny or stuffy nose
A sore throat
headache

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What are the signs and symptoms of Lower respiratory tract infections?

A “productive” cough - phlegm
Muscle aches
Wheezing
Breathlessness
Fever
Fatigue

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What are the signs and symptoms of Pneumonia?

Chest pain
Blue tinting of the lips
Severe fatigue
High Fever

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What are some risk factors for pneumonia?

Age <2 years or >65 years
Cigarette smoking
Excess alcohol consumptionContact with children aged <15 years
Poverty
OvercrowdingInhaled corticosteroids
Immunosuppresants (e.g steroids)
Proton pump inhibitorsCOPD, Asthma
Heart disease
Liver disease
Diabetes mellitus
HIV, Malignancy, Hyposplenism
Complement or Ig deficiencies
Risk factors for aspiration
Previous pneumoniaGeographical variations
Animal contact
Healthcare contacts
YOU JUST NEED TO BE AWARE OF THESE

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What are sone common bacterial causes for respiratory infections?

Streptococcus pneumoniae
Myxoplasma pneumoniae
Haemophilus Influenzae

Mycobacterium tuberculosis

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What are sone common viral causes for respiratory infections?

Influenza A or B virus
Respiratory Syncytial Virus
Human metapneumovirus
Human rhinovirus
Coronaviruses

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What are some bacteria that are involved in community acquired pneumonia ?

Streptococcus pneumoniae (40-50%)
Myxoplasma pneumoniae
Staphylococcus aureus
Chlamydia pneumoniae
Haemophilus Influenzae

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What are the features of streptococcus pneumoniae?

Gram-positive, extracellular, opportunistic pathogen

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What are some bacteria that are involved in hospital acquired pneumonia?

Staphylococcus aureus
Psuedomonas aeruginosa
Klebsiella species
E. Coli
Acinetobacter spp.
Enterobacter spp.

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What are some bacteria involved in ventilator associated pneumonia?

Psuedomonas aeruginosa (25%)
Staphylococcus aureus(20%)
Enterobacter

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What are some typical pneumonias?

Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis

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What are some atypical pneumonias?

Mycoplasma pneumoniae, Chlamydia pneumoniae,

Legionella pneumophilia

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What is pneumonia?

Inflammation & swelling of the alveoli

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What is Bronchitis?

Inflammation & swelling of the bronchi

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What is bronchiolitis?

Inflammation and swelling of the bronchioles

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How do you grade potential bacterial pneumonia?

CRB/65
Confusion 
Respiratory rate – >30 breaths/min 
Blood pressure - < 90 systolic and/or 60 mmHg diastolic
65 -  65 years old or older

In hospital add
Urea - 7 mmol/L

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What are the criteria for CRB/65?

0 - low severity, home treatment
1-2 - moderate severity, consider hospital referral
3-4 - high severity, urgent hospital admission, empirical antibiotics if life threatening

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What is the supportive treatment for bacterial pneumonia?

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Oxygen (for hypoxia)
Fluids (for dehydration)
Analgesia (for pain)
Nebulised saline (may help expectoration)
Chest physiotherapy?

What are the Curative treatments for bacterial pneumonia?

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Penicillins e.g. amoxicillin – beta lactams that bind proteins in the bacterial cell wall to prevent transpeptidation

Macrolides e.g. clarithromycin – bind to the bacterial ribosome to prevent protein synthesis

What is the key to increasing the success of antibiotics?

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Time to administration - for every hour in septic shock survival is reduced by 7.9%.

Use of an effective antibiotic, typical CAP’s may respond to penicillins, Atypical CAP’s require Macrolides.

What is an opportunistic pathogen?

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A microbe that takes advantage of a change in conditions (often immuno-suppression).

What is a Pathobiont?

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A microbe that is normally commensal, but if found in the wrong environment (e.g. anatomical site) can cause pathology.

What is a Commensal Microbe?

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Microbes that live in a “symbiotic” relationship with their host. Providing vital nutrients to the host in the presence of a suitable ecological niche.

Why do viral infetcions result in disease?

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Mediator release
Cellular inflammation
Local Immune memory
Damage to epithelium

What damage do viruses inflict on the epithelium?

Loss of cilia Bacterial growth Poor barrier to antigen Loss of chemoreceptors

What causes severe disease in viral infections?

Highly pathogenic strains (zoonotic) Absence of prior immunity Predisposing illness/conditions

Which viruses bind to alpha-2 sialic acids?

2009 - H1N1 influenza A Haemogglutinin binds 𝛂2,6 sialic acids 2012 - H5N1 avian Flu Haemogglutinin binds 𝛂2,3 sialic acids

Where does SARS-CoV-2 bind?

Spike (S) protein binds Angiotensin converting enzyme 2 (ACE2) Increased ACE2 in smokers

Where do viruses tend to bind to?

Most respiratory viruses can infect cells throughout the respiratory tract, but tend to preferentially adapt to bind cells of the upper respiratory tract if they have existed in humans for a prolonged time

What is your first line of defence against viral infection?

Epithelial cells

What are some mechanisms used by epithelial cells to protect against viral infection?

Tight junctions – prevents systemic infection Mucous lining and cilial clearance – prevents attachment, clears particulates Antimicrobials – recognise, neutralize and/or degrade microbes and their products Pathogen recognition receptors – recognise pathogens either outside or inside a cell. Interferon pathways – activated by viral infection. Promotes upregulation of anti-viral proteins and apoptosis.

Define Serotypes:

pathogens which cannot be recognized by serum (really antibodies) that recognize another pathogen.

Where would you find IgA?

Upper respiratory tract, Able to withstand extracellular environment of the air space well, due to multiple disulphide bridges that prevent rapid degredation. Non-inflammatory, binds and neutralises threats.

Where would you find more IgG's?

Lower respiratory tract, circulation comes into closer proximation with air space due to thin walled alveolar space. You can have transfer of IgG to protect lower airways through a vaccine. Are inflammatory.

How is Antibody mediated immunity carried out?

Humoral immunity Adaptive, so dependent on prior exposure B cells activated to differentiate into antibody secreting plasma cells Different antibody classes provide different biochemical properties and functions

Describe Infleunza:

No re-infection by same strain Imperfect vaccines: Vaccine-induced immunity rapidly wanes Mainly homotypic immunity Annual vaccination required

Describe RSV:

Leading cause of infant hospitalization in the developed world 50% of children infected in year 1 of life, all children by year 3. 1% develop severe bronchiolitis. Can repeatedly infect children. Similar viruses at lower prevalence include hMPV and PIV. Risk factors; Premature birth Congenital heart and lung disease Recurrent re-infection with similar strains No vaccine; Poor immunogenicity Vaccine-enhanced disease Very active research field

Descrive SARS-CoV-2:

No prior immunity Newly licenced vaccine Waning immunity Potential for re-infection Unclear what vaccination regime will be required

What are the symptoms for RSV infected children?

``` Nasal flaring Croupy cough Hypoxemia & cyanosis Expiratory wheezing, prolonged expiration rales and ronchi tachypnea with apneic episodes ```

What are some treatment options for Viral infections?

Supportive Therapy ``` Oxygen (for hypoxia) Fluids (for dehydration) Analgesia (for pain) Nebulised saline (may help expectoration) Chest physiotherapy ```

What are some preventative treatment options for viral infections?

Vaccines Major surface antigen – spike protein Viral vector (e.g. adenovirus vaccine e.g. Oxford/AZ) mRNA vaccines (e.g. BioNtech/Pfizer)

What are some antivirals used to treat viral infections?

Remdesivir – broad spectrum antiviral – blocks RNA-dependent RNA polymerase activity Paxlovid – antiviral protease inhibitor Casirivimab and imdevimab - monoclonal neutralising antibodies for SARS-CoV-2

What are some anti inflammatory drugs used in severe viral infection?

Dexamethasone (steroids) | Tocilizumab (Anti-IL6R) or Sarilumab (anti-IL6)

What is the interplay between viral infections and Chronic lung diseases?

Viral bronchiolitis is associated with the development of asthma Rhinoviruses are the most common cause of asthma and COPD exacerbations High likelihood of secondary bacterial pneumonia after viral infection. 55% of rhinovirus-infected COPD patients also have bacterial infections

Respiratory tract infections & Immunity Flashcards

(44 cards)