IC15 URTI Flashcards
Describe the pathophysiology of URTI (how it is transmitted)
- airborne transmission (droplets/aerosols containing the virus expelled when a infected person talks/cough/sneeze)
- formites (touch contaminated surface –> touch face)
- sharing food with an infected person without a sharing spoon
pathogens are inhaled into respiratory tract via the 3 mechanisms above –> invade upper airway mucosa
Describe our innate immunity that protects us against URTI
- nostril hair
- mucus
- angle between pharynx and nose
- mucociliary clearance
- adenoids and tonsils that contain immunological cells that attack pathogens
What are the risk factors for URTI?
- close contact with children (day cares, schools)
- lack of personal/hand hygiene
- smoking
- chronic respiratory diseases (asthma, COPD)
- immunocompromised
- anatomical anomalies
How can we prevent URTIs?
- practice personal and hand hygiene
- wear mask
- stay away from sick contact and crowds
- keep up to date w vaccinations
- manage known risk factors eg. smoking cessation, control asthma/COPD
What vaccinations should we keep up to date with to prevent URTI?
- influenza
- pneumococcal
- Haemophilus influenzae
Describe the management of URTI (What to do, when to initiate abx, how to prevent recurrence)
- symptomatic relief
- use antibiotics only if it is a bacterial infection (ie. cannot use for common cold & influenza & viral infections)
- prevent future recurrence by managing/reducing risk factors
What are some options for symptomatic relief of URTI for
- pain
- nasal congestion
- rhinorrhea
- sore throat
- cough
pain: paracetamol, NSAIDS
nasal congestion: nasal decongestant, saline nasal irrigation
rhinorrhea: antihistamines (first gen H1)
sore throat: lozenges, warm water/tea, honey
cough: mucolytics & expectorant (productive), cough suppressants (non-productive)
What are the common URTIs?
- common cold
- flu
- covid-19
- pharyngitis
- sinusitis
Describe the clinical presentation of a common cold (subjective factors)
- low grade fever (>37 deg C)
- runny nose
- blocked nose
- sneezing
- sore throat
- productive cough
- some headache
- body ache
Describe the objective factors that support the diagnosis of a common cold
- lack of high fever >38 deg C
- normal HR
- lungs clear to auscultation bilaterally
Is the common cold viral or bacterial?
viral
What are the possible pathogens that cause the common cold?
- rhinovirus
- coronavirus
Describe the selection of antibiotics for the common cold
viral in nature = DON’T treat with abx
Describe the monitoring of response for common cold
- will start to feel better within 3-4 days, most ppl recover in 7-10 days, but symptoms may linger for a few wks eg. cough may last 2-3 weeks
- normal for nasal discharge to change color (even if purulent, doesn’t necessarily mean its bacterial; just indicates presence of inflammation as our body is fighting off the pathogen)
- if symptoms do not improve after 10 days/worsens, see a Dr
Describe the clinical presentation of the flu
- fever >38 deg C
- chills
- headache
- malaise
- myalgia
- anorexia
- dry/non-productive cough
- sore throat
- nasal discharge
- confusion in elderly
What are the possible complications of the flu?
- primary viral pneumonia
- secondary bacterial pneumonia (Staph aureus, Strep pneumoniae, H Influenzae)
- exacerbation of chronic respiratory disease
- myocarditis
Who are at a high risk of complications from influenza?
- children <5
- elderly ≥65
- pregnant women / 2 week post partum
- residents of nursing homes/long term care facilities
- obese (BMI ≥40)
- chronic medical conditions/comorbidities
Are the following symptoms more associated with the common cold or flu?
1. abrupt symptom onset
2. fever
3. sneezing
4. runny nose
5. sore throat
6. headache
- flu
- flu
- cold
- cold
- cold
- flu
What is the difference between flu and COVID-19?
COVID-19 is more severe as
- more contagious (contagious even if asymptomatic)
- causes more severe disease in vulnerable pop
What are the likely pathogens associated with the flu?
Human influenza A and B
Which of the influenza types is more likely to cause pandemics?
Influenza A
What is the nomenclature for influenza A subtypes?
H and N
[H] Hemagglutinin
[N] Neuraminidase
What are their functions?
[H] viral entry
[N] release of viral progenitor cells
What is the classification of influenza B viruses?
B/Yamagata
B/Victoria
What are the peak influenza periods in SG?
- middle of the year
- end & beginning of the year
In what situations would antivirals be required for influenza?
for high risk patients that meet any one of the criteria:
- hospitalized
- high risk for complications
- severe, complicated, progressive illness
When can we initiate antivirals for influenza?
ASAP
- best within 2 days (for outpatient)
- within 5 days for high risk patients
What is the antiviral used for influenza?
Tamiflu - Oseltamivir
Describe the MOA + dosing regimen + S/E of Oseltamivir
- MOA: Neuraminidase inhibitor - interferes with protein cleavage and thus inhibits release of new virus
- dose: 75mg (1 cap) BD x 5 days
- S/E: generally well-tolerated, might cause some headaches & mild GI discomfort (N/V)
When is dosage adjustment required for the influenza medication?
renal impairment, CrCl < 60 mL/min (stage G3-5 CKD)
Describe the monitoring of response to influenza treatment
- symptoms may last up to a week
- see a Dr if
symptoms does not improve after 10 days
symptoms improved then worsened (developed new fevers, worsening dyspnea/SOB or cough)
What kind of vaccine is the influenza vaccine?
Inactivated trivalent/quadrivalent vaccine
When should the influenza vaccine be taken in different regions of the world?
northern hemisphere: Nov - Feb
southern hemisphere: May - July
Who is recommended to take the influenza vaccine?
everyone ≥ 6 months old
How long does the influenza vaccine take to confer immunity?
2 weeks
What is the efficacy of the influenza vaccine?
75%
What is the general clinical presentation of pharyngitis?
- sore throat (worse w swallowing, ie. dysphagia)
- fever
- erythema & inflammation of pharynx & tonsils (w or w/o patchy exudates)
- tender, swollen lymph nodes
What is the clinical presentation for VIRAL pharyngitis?
- low grade fever
- malaise
- fatigue
- runny nose
- cough
- hoarseness
- oropharyngeal lesions (ulcers, vesicles)
- conjunctivitis
(viral infection more likely to spread and affect other parts of the URT, causing other ENT symptoms - conjunctivitis, rhinorrhea, cough & hoarseness)
What is the clinical presentation for BACTERIAL pharyngitis?
- fever
- sore throat w patchy exudates
- cervical lymphadenopathy
Which pathogen is more associated with pharyngitis?
VIRUS > bacteria
What are the viruses that can cause pharyngitis?
- rhinovirus
- coronavirus
- influenza
- parainfluenza
- Epstein-Barr
What are the bacteria that can cause pharyngitis?
Grp A strep (Strep pyogenes)
What is the criteria used to determine if a patient has Grp A Strep pharyngitis?
Modified Centor Criteria
Describe the Centor Criteria
- fever >38 deg [1]
- cervical lymphadenopathy [1]
- tonsillar exudate [1]
- no cough [1]
- age
- 3-14 y/o: [1]
- 15-44: [0]
- ≥45: [-1]
What do the results of the criteria tell us?
0-1 points
* unlikely to be Strep pyogenes pharyngitis
* likely to be viral
* no abx req
2, 3 points
* test for Strep pyogenes
* treat w abx if +ve
4, 5 points
* likely to be Strep pyogenes pharyngitis
* initiate empiric abx therapy
How do we test for Strep pyogenes pharyngitis? How long does it take to get the results of the test?
- throat culture (gold standard) - 1-2 days
- rapid antigen detection test (RADT) - minutes
*not performed in SG, more common in UK
What is the goal of treatment of pharyngitis?
- reduce symptom severity and duration
- prevent ACUTE complications (otitis media, peritonsillar abscesses)
- prevent DELAYED complications (acute rheumatic fever, acute glomerulonephritis)
- reduce transmission (no longer infectious aft 24h of abx)
Are the complications a/w viral or bacterial pharyngitis?
bacterial
When do the complications of bacterial pharyngitis usually develop? How can they be prevented?
1-5 weeks later, usually 2-3 weeks
acute rheumatic fever - prevented w early initiation of effective abx
acute glomerulonephritis - not prevented w abx
What are the choice of antivirals for viral pharyngitis?
none; self-limiting
What is the first line antibiotics for bacterial pharyngitis?
Likely pathogen: Strep pyogenes
PO Penicillins
1. Pen V 250mg q6h
2. Amoxicillin 500mg q12h
What are the alternative antibiotics for bacterial pharyngitis in the case of NON-severe allergy to PENICILLIN?
Likely pathogen: Strep pyogenes
non-severe allergy to penicillin: PO cephalexin 500mg q12h
What happens if the patient has non-severe allergy to AMOXICILLIN?
ampi, amox, cephalexin have similar R1 side chains
non-severe allergy to amoxicillin: PO cefuroxime 250mg q12h
What are the alternative antibiotics for bacterial pharyngitis in the case of SEVERE penicillin allergy?
severe penicillin allergy (ie. avoid beta lactams)
1. PO macrolides
- Clarithromycin 250mg q12h
- Azithromycin 500mg OD
*However, increasing resistance to macrolides :(
2. PO Clindamycin 300mg q8h
Explain the choice of antibiotics for bacterial pharyngitis in the case of penicillin allergy
if allergic to penicillins but not severe life threatening rxn, avoid penicillin class and use cephalosporin class instead –> therefore, cephalexin is used
amoxicillin, ampicillin and cephalexin have similar R1 side chains
- therefore, if allergic to amox, patient is likely to be allergic to cephalexin –> hence, have to replace with cefuroxime (does not share a similar R1 side chain to any abx that we learnt)
What is the duration of treatment for bacterial pharyngitis?
10 days
5 days for azithro (due to long half life)
Describe the monitoring of response of pharyngitis
- viral - sore throat typically lasts for less than a week
- bacterial - fever and symptoms typically resolve within 1-3 days of abx
- if symptoms does not improve/worsens, see a Dr
What is the mode of transmission of pathogens causing sinusitis?
airborne transmission
What is a common reason people develop bacterial sinusitis?
typically preceded by viral URTI
- viral URTI –> inflammation –> mucus secretion –> nasal congestion –> bacterial overgrowth
What are the common symptoms of sinusitis?
- purulent nasal discharge
- facial pain/pressure
- fever
- blocked nose
- reduced sense of taste (hyposmia) / smell (anosmia)
- headache
- cough
- ear fullness/pressure
- bad breath
- dental pain
What is the pathogen that is more associated with sinusitis? And why?
virus
bacterial sinusitis is likely a secondary infection due to preceding viral URTI
What are the bacteria that can cause sinusitis?
most common:
* Strep pneumoniae
* Haemophilus influenzae
others:
* Strep pyogenes
* Moraxella catarrhalis
* anaerobic bacteria
When do we initiate treatment for bacterial sinusitis?
if patient meets at least one of the following criteria:
1. symptoms are SEVERE
- high fever >39 deg C, or
- purulent nasal discharge, or
- facial pain for >3 consecutive days
2. symptoms PERSIST for >10 days
3. symptoms improve –> worsen for >3 days (5-6 days)
- new onset fever, or
- headache, or
- increased nasal discharge
What are the first line antibiotics for bacterial sinusitis?
Likely pathogen: Strep pneumoniae, H influenzae
PO Penicillins
1. PO Amoxicillin 500mg q8h
2. PO Amox-clav 625mg q8h
Out of the first line antibiotics for bacterial sinusitis, which is usually preferred and why?
amox > amox-clav
bacterial sinusitis is more commonly caused by strep pneumoniae, and amoxicillin is specific for strep pneumoniae
amox-clav is a first line option in the event that it is caused by H influenzae (as there is increasing resistance of H influenzae to amox)
What are the alternative antibiotics for bacterial sinusitis in the case of penicillin allergy?
non-severe:
1. PO cefuroxime 500mg q12h
severe:
2. Respi fluoroquinolones
- PO levo 500mg OD
- PO moxi 400mg OD
What are the abx that can be used for bacterial sinusitis according to SOA table? How were the final few abx chosen?
Likely pathogens: Strep pneumoniae, H influenzae
SOA table:
* Amox
* Amox-clav
* Pip-tazo
* All cephalosporins except first gen & ceftazidime
* Carbapenems
* Macrolides
* Tetracyclines
* Respi fluoroquinolones
* Co-trimoxazole
why the other abx were not chosen:
* pip-tazo, carbapenem: too broad spectrum
* macrolides, tetracyclines, co-trimoxazole: increasing resistance of strep pneumoniae
What is the duration of treatment for bacterial sinusitis?
5-7 days
What are the possible complications of bacterial sinusitis?
bacteria may spread to orbits and brain/CNS, which requires immediate referral to ED
What are the symptoms of bacterial sinusitis complications?
- limited ocular movement
- acute vision loss
- confusion
- unilateral weakness
Describe the monitoring of response of sinusitis
- viral / non-severe bacterial: will recover in 7-10 days
- severe bacterial: symptoms should improve within 7-10 days
- if symptoms are severe/persistent/worsen, see a Dr
