URTIs & Influenza Flashcards
What are the typical clinical presentations of pharyngitis?
1) Acute onset of sore throat
2) Pain upon swallowing
3) Fever
4) Redness & inflammation of pharynx & tonsils (with/out patchy exudates)
5) Tender, swollen lymph nodes
What are the microbes that can cause pharyngitis?
Viral (80%): rhinovirus, coronavirus, influenza, parainfluenza, Epstein-Barr
Bacterial (20%): Streptococcus Pyogenes (grp A β-hemolytic streptococcus)
Describe the pathogenesis of pharyngitis.
Direct contact w/ droplets of infected saliva/ nasal secretions (coughing/ sneezing)
Short incubation period of 24~48 hrs
What are some complications that may arise in pharyngitis?
Viral: Self-limiting
Bacterial: Self-limiting/ may have complications which usually occur 1~3 wks later
1) Acute rheumatic fever (can be prevented w/ early & effective antibiotics)
2) Acute glomerulonephritis (X prevented with antibiotics)
What are the challenges in managing pharyngitis?
DIfficult to differentiate viral & bacterial pharyngitis as they have similar presentations; however initiation of antibiotics is only useful in bacterial pharyngitis
How does antibiotic use help in bacterial pharyngitis?
- Prevents rheumatic fever (complication)
- ↓ duration of symptoms by 1~2 days
- decreases transmission (with 24h of antibiotic use, pt becomes non-infectious)
How is pharyngitis clinically diagnosed?
Modified Centor Criteria
1 pt: fever > 38°C, swollen lymph nodes, tonsillar exudates, absence of cough, aged 3~14 yo
0 pt: age 15~44
-1 pt: age >44yo
**<3 yrs presumed to be viral (S. pyogenes less likely a cause)
Suggest appropriate response to pharyngitis if points = 0-1, 2-3, 4-5
0-1: No additional testing; presumed to be viral
2-3: Test for S. pyogenes pharyngitis & treat if +ve OR start empiric antibiotics for S. pyogenes
4-5: Start empiric antibiotics (high risk of bacterial pharyngitis)
Suggest appropriate antibiotic therapy and duration of therapy for S. pyogenes pharyngitis.
Fist line: Penicillin VK
Alternatives: Amoxicillin, Cefalexin, Clindamycin, Clarithromycin
for 10 days
How long does it typically take for the patient to respond to treatment against bacterial pharyngitis?
24-48 hours
Why is Augmentin not used to treat bacterial pharyngitis?
Too broad-spectrum; Main causative organism is S. pyogenes only
May cause C diff & emergence of more resistant strains
Define sinusitis.
Acute inflammation & infection of nasal & paranasal mucosa (w/in 4 wks)
What are the typical clinical presentations of sinusitis?
Major symptoms:
1) Purulent anterior nasal discharge
2) Purulent/discoloured posterior nasal discharge
3) Nasal congestion/ obstruction
4) Facial fullness/ congestion
5) face pain/ pressure
6) Hyposmia/ anosmia (↓/X smell)
7) fever >38°C
Minor symptoms:
1) headache
2) ear pain, pressure, fullness
3) halitosis (bad breath)
4) dental pain
5) cough
6) fatigue
What are the requirements to confirm that a patient has sinusitis?
≥ 2 major symptoms
OR
1 major + ≥2 minor symptoms
What are the microbes that can cause sinusitis?
Viral (90%): rhinovirus, adenovirus, influenza, parainfluenza
Bacterial (10%): Strep pneumo & H. influenzae (most common), Moraxella catarrhalis, S. pyogenes
Describe the pathogenesis of sinusitis
Direct contact w/ infected droplets of saliva/ nasal secretions
Bacterial sinusitis usually preceded by viral URTIs (e.g. pharyngitis, common cold)
Inflammation → sinus obstruction; nasal mucosal secretions trapped; bacteria trapped & multiply
What are some challenges in diagnosing sinusitis?
- viral & bacterial sinusitis have similar symptoms
- diagnostic tests have limited use:
- imaging studies: non-specific
- Sinus aspirate: invasive, painful & time-consuming
How is bacterial sinusitis diagnosed clinically?
Presence of sinusitis (≥ 2 major symptoms OR 1 major + ≥ 2 minor symptoms)
+
Presence of any bacterial sinusitis criteria:
1) Persistent symptoms > 10days & not improving
2) Severe symptoms @ onset (purulent nasal discharge for 3-4 days or Fever >39°C)
3) “Double sickening” (symptoms worsen after 5-6 days of initial improvement; bacterial sinusitis often follows viral URTI)
Suggest appropriate antibiotic therapy for bacterial sinusitis.
First line: Amoxicillin OR Augmentin
Alternatives:
- Respiratory FQs (Moxi/ Levofloxacin)
- Cotrimoxazole (trimethoprim + sulfamethoxazole)
- Cefuroxime (2nd gen ceph)
Suggest an appropriate duration of treatment for Bacterial sinusitis.
Adults: 5- 10 days
Pediatrics: 10-14 days
What is the mechanism of resistance of Strep Pneumoniae?
Multistep mutation of bacterial transpeptidase/ PBP → penicillin unable to bind & inhibit bacterial cell wall synthesis (cross-linking)
** MIC of penicillin ↑; req higher dose to be effective
What are some considerations for the treatment regimen if resistant S. pneumonia is suspected?
1) Choose amoxicillin > penicillin
* * amoxicillin has better absorption ⇒ ↑ systemic exposure; require lower dosing to reach MIC
2) Use “high dose” amoxicillin (2 times of std dosing)
What is the mechanism of resistance of H. influenzae?
Production of β-lactamase which cleave β-lactam rings
⇒ require β-lactamase inhibitor (e.g. clavulanic acid)
When should Augmentin be initiated in treatment of bacterial sinusitis?
Use Augmentin (amox/clav) if any one:
- recent course of antibiotics (~30days)
- recent hospitalization (likely to have more resistant strains)
- Failure to improve after 72 hrs of amoxicillin
- presence of organism X covered for
- organism shows resistance (Production of β-lactamase)
