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)
Define Acute Otitis Media (AOM)
Infection of the middle ear space leading to inflammation & fluid accumulation
What are the typical clinical presentations of AOM?
1) Otalgia
2) Otorrhea
3) Ear fullness & popping
4) hearing impairment
5) Dizziness
6) fever
7) Non-specific in young infants: ear rubbing, excessive crying, change in sleep & behavioral pattern
AOM is more common in _________ patients due to ______________
pediatric (esp < 5yrs)
;having a shorter & straighter eustachian tube allowing easier backflow of mucus & bacteria from the nasopharynx after viral URTI
What are the microbes that can cause AOM?
Viral (40~45%):
- Respiratory Syncytial Virus (RSV)
- adenovirus
- rhinovirus
- parainfluenza
Bacterial (55~60%):
- Strep pneumo
- H. influenzae
- Moraxella catarrhalis
Describe the pathogenesis of AOM
Viral URTI (e.g. common cold) causes nose sniffing/ inflammation & secretions ⇒ eustachian tube becomes obstructed & has negative pressure ⇒ allow reflux of secretions into middle ear ⇒ medium for bacteria accumulation & growth
What are the risk factors for AOM?
1) siblings
2) attending daycare
3) supine position while feeding
4) exposure to tobacco smoke
5) pacifier use
6) winter season
How can AOM be prevented?
1) decrease exposure to tobacco smoke
2) exclusive breastfeeding for the first 6 months
3) minimize pacifier use
4) vaccinations (influenza, pneumococcal, H. influenza type B Vaccine)
How is AOM diagnosed? What are the diagnosis criteria in children?
Using a pneumatic otoscope
Diagnosis criteria in children:
- Acute onset < 48hrs
- Otalgia (non-verbal child may tug/ rub ear)
- erythema of tympanic membrane
- bulging tympanic membrane
What are the challenges in managing AOM?
Viral & bacterial AOM are indistinguishable; however early Abx initiation in bacterial AOM can help ↓ symptom duration by ~1 day
** ~80% cases of bacterial AOM may resolve spontaneously w/in 3-4 days
** Overprescribing Abx may cause resistance
What is the basis of allowing an observation period when managing bacterial AOM?
Some patients may X req Abx to recover
(~80% cases of bacterial AOM may resolve spontaneously w/in 3-4 days)
Supportive care for 48-72 hrs; if symptoms worsen/ don’t improve, initiate ABx therapy
Under what conditions may an observation period be considered when managing bacterial AOM?
When all of the following criteria are fulfilled:
1) ≥ 6 months old
2) Non-severe illness
3) No otorrhea (suggests tympanic membrane perforation otherwise)
4) possible for a close follow up
5) Caregiver/ parents approve of the decision
Define severe AOM (which warrants immediate Abx initiation)
Any one:
- moderate to severe otalgia
- otalgia ≥ 48 hrs
- fever ≥ 39°C in last 48 hrs
Suggest appropriate first-line antibiotic options for bacterial AOM & under what conditions they should be used
1) High dose amoxicillin if all 3 criteria are met: - X amoxicillin in last 30 days - X concurrent purulent conjunctivitis (✓ S. AUreus; X covered by amox alone) - X penicillin allergy
2) Augmentin if any is applicable: - amoxicillin in the last 30 days - concurrent purulent conjunctivitis - ✓ history of AOM non-responsive to amoxicillin (recurrent AOM; resistant organisms)
What are some alternative antibiotic options for bacterial AOM?
1) IM Cefuroxime/ Ceftriaxone (possible in mild pen allergy)
2) Clindamycin (for severe penicillin allergy; only covers S. pneumo)
When should improvement of AOM symptoms be expected?
48-72hrs
Suggest an appropriate duration of antibiotic treatment for Bacterial AOM
< 2 y/o: 10 days
Severe symptoms: 10 days
≥ 2-5 y/o & non-severe symptoms: 7 days
≥ 6 y/o & non-severe symptoms: 5-7 days
What are the typical clinical presentations of influenza?
Fever Fatigue & weakness Chills Chest discomfort & cough Bodyache Headache Sore throat
How do clinical presentations differ between influenza & COVID?
Loss of taste & smell + NVD are less likely to occur in influenza
What are the possible complications associated with influenza?
1) viral pneumonia
2) Post influenza bacterial pneumonia (may involve S. AUreus; > 30% mortality)
3) Respiratory failure
4) exacerbate underlying cardiac/ pulmonary comorbidities
5) febrile seizures
6) myocarditis/ pericarditis
Which groups of individuals are more at risk of influenza-associated complications?
1) extremes of age: <5 y/o , ≥65 y/o
2) Pregnant women or w/in 2 weeks postpartum
3) Residents of nursing homes/ long term care facilities
4) Obese; BMI ≥ 40 kg/m2
5) individuals w/ chronic medical conditions (e.g. asthma, CVD)
How can influenzal infection be prevented?
1) good personal hygiene
2) healthy lifestyle (diet, exercise, sleep, X smoking)
3) vaccination (yearly IM tri/quadrivalent vaccine)
How is influenza diagnosed?
Outpatient: empiric therapy
Inpatient: Reverse transcriptase PCR (RT-PCR)
When is antiviral therapy considered in patients suspected of influenza?
Initiate asap w/in 48 hrs of symptom onset if:
hospitalised/ ↑ risk of complications/ severe or complicated or progressive illness
What is the antiviral used to treat influenza?
Oseltamivir
What is the mechanism of action of Oseltamivir?
neuraminidase inhibitor ⇒ interferes w/ protein cleavage & inhibits the release of new flu virion
What is a suitable dosing regimen for Oseltamivir?
PO 75mg bd x 5 days
~10 days if immunocompromised/ critically ill
What are the side effects of Oseltamivir?
generally well-tolerated
headache; mild NVD
Dose adjustment for Oseltamivir is required in ___________
renal impairment
Oseltamivir is used to treat influenza _________
A&B
