upper respiratory tract infections Flashcards
what is the upper respiratory tract?
nasal cavity, pharynx and larynx
name common URTIs
common cold
pharyngitis
what are other names for the common cold?
rhinopharyngitis/nasopharyngitis
what causes the common cold?
Caused by rhinoviruses, coronaviruses, adenoviruses, myxoviruses
what causes pharyngitis?
adenoviruses, myxoviruses etc.
o Pharyngitis – adenovirus, herpes simple virus, coxsackleviruses
what is the most common cause of URTIs?
viruses
what is the most common viral cause of nasopharyngitis?
rhinovirus
what is the major cause of transmission of the rhinovirus?
inhaling droplet in the air from sick people sneezing, coughing or blowing their nose then touching a surface contaminated with the virus and then touching your eyes, nose or mouth
how long can the rhinovirus survive outside of the nose?
3 hours
what is the incubation time of rhinovirus?
1-5 days
what is the incubation time or RSV?
7 days
what is the pathophysiology of nasopharyngitis?
- Virus binds to the host cell in the URT – epithelial lining
- Recognised by surface receptors, releases genetic material into host cell
- Replication of genetic material and use of host transcriptional processes to code for proteins
- Coat proteins and genetic material are made and assembled into viruses
- Viruses are replicated and released from the cell and ready to infect more host cells
what are the symptoms of a common cold?
Rhinorrhea) & nasal obstruction
• Runny nose, sore throat, cough, sneezing, loss of appetite, low-grade fever, watery eyes, headaches, earaches and nausea sensation
define rhinorrhea
excess mucus filling in the nasal cavity
what causes nasal obstruction in a common cold?
swollen cells and swollen blood vessels lead to feeling of congestion in the airways
what is the pathophysiology of human rhinovirus?
• HRV infects airway epithelial cells
•Recognition of the virus by TLR and retinoic acid-inducible gene-I-like (RIG) receptors
• When these PRRs bind to the viral epitope, it then leads to signalling mechanisms in a cell – leads to secretion and release of inflammatory mediators e.g. TNF-a, IFN and CXCL8 (chemokines)
In HRV: leads to recruitment + activation of inflammatory and immune-effector cells (e.g. neutrophils)
• Cellular and molecular inflammation swelling, redness, fever, pain
what is the pathophysiology of RSV?
• HRV infects airway epithelial cells
• Recognition of the virus by TLR and retinoic acid-inducible gene-I-like (RIG) receptors
• When these PRRs bind to the viral epitope, it then leads to signalling mechanisms in a cell – leads to secretion and release of inflammatory mediators e.g. TNF-a, IFN and CXCL8 (chemokines)
• In RSV: mediators trigger and activate innate and adaptive responses
o Dendritic cells present to T cells which activate B cells
o B cells make RSV-specific antibodies
how does RSV impede immune recognition?
• High glycosylation and structural variability of surface G protein impedes immune recognition
• Soluble G-protein is released during viral replication and binds RSV-specific antibodies – reduces concentrations available for RSV neutralisation
o Can also inhibit TLR-induced IFN induction, amplifying the suppressive effect of RSV nucleoproteins
what % of asthma exacerbations does rhinovirus account for?
50-80%
why are asthmatics more susceptible to HRV?
T-helper Th2-type immune response with increased synthesis and release of cytokines e.g. IL-4, IL-5, IL-10 and IL-13 –> increase expression of intercellular adhesion molecules (major HRV receptor on surface of bronchial epithelial cells) –> more susceptible to HRV infection
BECs in asthmatics also produce reduced levels of IL-12, IFN-a, IFN-gamma – cytokines for limiting viral replication increases HRV severity
what viral pathogens cause COPD to get worse?
Viral pathogens = RV, RSV and influenza virus
how do frequent acute exacerbations caused by viruses have an effect on COPD?
- FAE worsening of respiratory symptoms change in medication
- FAE increased airway inflammation, worsening hyperinflation, lung function decline
- FAE increased disease progression, increased hospitalisation death
how can you prevent infection?
- Avoid contact with viral particles
- Wash hands frequently
- Avoid touching your eyes with contaminated hands
- Use disposable tissues
- Use instant hand sanitisers to stop the spread of germs
- Avoid touching your nose
name common cold remedies
rest, increased fluid intake, warm salt water gargling for sore throat, warm steam for congestion
name treatments for common cold and what symptoms they alleviate
o Nasal and/or systemic steroids – clear pollutants, thin mucus – stop swelling and stagnation and infection
o Antibiotics – fight infection
o Decongestants – fight stagnation and infection
o Mucolytics – clear mucus and fight stagnation and infection
o Nasal and/or systemic steroids – reduce swelling
how long should a cold last for and how long is it symptomatic for?
- Duration; up to 14 days
* Symptomatic; 7-11 days
which cold symptoms resolve early and which last longest?
- Fever, sneezing and sore throat – resolve early
* Cough, nasal discharge – last longest
what is the site of action of decongestants?
blood vessels and surrounding nasal sinuses
what is the mechanism of action of decongestants?
alpha-1 adrenoreceptor agonists – cause vasoconstriction of nasal blood vessels broad nasal pathway decongestion
what is the pharmacological effect of decongestants?
vasoconstriction
what is pharyngitis?
sore throat
what are the 2 methods of sore throat assessment?
FeverPAIN score
Centor score
explain the criteria of the FeverPAIN score
1 point for each – higher score = more severe symptoms
o Fever (during previous 24 hours)
o Purulence (pus on tonsils)
o Attend rapidly (within 3 days after onset of symptoms)
o Severely Inflamed tonsils
o No cough or coryza (inflammation of mucus membranes in the nose)
explain the criteria and assessment of the Centor score
1 point for each o Tonsillar exudate o Tender anterior cervical lymphadenopathy or lymphadenitis o History of fever (over 38°C) o Absence of cough
for each range of FeverPAIN/Centor scores what antibiotic advice should you give?
- FeverPAIN score 0-1/Centor score: 0-2: do not offer an antibiotic
- FeverPAIN score 2-3: consider no antibiotic or a back-up antibiotic prescription
- FeverPAIN score 4 or 5/Centor score 3 or 4: consider an immediate antibiotic or a back-up antibiotic prescription
when should someone be offered immediate antibiotic prescription?
• If the person is;
o Systemically very unwell
o Has symptoms/signs of a more serious illness/condition
o Has high risk of complications
when should you refer someone to hospital?
Refer to hospital if severe systemic infection or severe complications
what is the first choice antibiotic for an adult with pharyngitis?
phenoxymethylpenicillin
what are alternative first choices for penicillin allergy/intolerance?
clarithomycin
erythromycin
