5. Pathophysiology
• A URTI usually involves direct invasion of the
upper airway mucosa by the organism.
• The organism is usually acquired by inhalation
of infected droplets.
7. Protective mechanisms
Barriers that prevent the organism from attaching to
the mucosa include
• The hair lining that traps pathogens.
• The mucus which also traps organisms.
• The angle between the pharynx and nose which
prevents particles from falling into the airways.
• Ciliated cells in the lower airways that transport
the pathogens back to the pharynx.
• The adenoids and tonsils also contain
immunological cells that attack the pathogens.
12. Sinusitis
Symptoms: Headache/facial pain, nasal mucus,
Plugged nose
• Agents of acute sinusitis:
• Viruses (most common cause): Rhinoviruses,
Influenza viruses, Parainfluenza viruses
• Bacterial agents: Streptococcus pneumoniae,
Haemophilus influenzae, Moraxella catarrhalis,
Pseudomonas and other gram- negative bacilli
(nosocomial sinusitis)
• Agents of chronic sinusitis: Obligate anaerobes,
Staphylococcus aureus, Fungi
13. Pharyngitis and Tonsillitis
Symptoms:
• Pharynx and/or tonsils become inflamed, red,
swollen, show exudates and sometimes a
membrane is formed.
• Viruses: (most common cause) Influenza virus,
Parainfluenza virus, Coxsackievirus A,
Rhinovirus, Coronavirus, Epstein-Barr virus,
Adenoviruses.
14. • Bacteria: Streptococcus pyogenes (most common
bacterial cause), Streptococcus groups C and G,
Arcanobacterium species, Corynebacterium
diphtheriae and C. ulcerans, Mycoplasma
pneumoniae
• Vincent’s angina - Treponema vincentii &
Leptotrichia buccalis
• Fungal: Candida albicans
15. Laryngitis
• Symptoms: Hoarseness of voice, Lowering and
deepening of voice
• Mostly viral agents: Influenza virus,
Parainfluenza virus, Rhinovirus, Adenovirus,
Coronavirus, Human metapneumovirus
• If membrane or exudate present: Streptococcus
pyogenes, C. diphtheriae, Epstein-Barr virus
17. Epiglottitis
• Edema and inflammation of epiglottis and soft
tissue above vocal cords
• Age: children 2–6 years
• Symptoms: Fever, Difficulty in swallowing,
inspiratory stridor
• Most common agent: Haemophilus influenzae
type b
• Must be treated with antibiotic – Ampicillin.
18. Laboratory Diagnosis
Specimen
Throat swab: Two swabs should be collected, one
for direct examination, other one for culture
A part of the membrane, if present
Nasopharyngeal aspirate for viral diagnosis or for
B.pertussis
Serum for Streptococcal pharyngitis or
infectious mononucleosis
19. Microscopy
• Gram staining
• Albert staining - metachromatic granules in the
ends of the bacilli of C. diphtheriae
20. Culture
• For bacteriological culture: Blood agar, chocolate
agar and MacConkey agar.
• For isolation of C. diphtheriae: Loeffler’s serum
slope and potassium tellurite agar.
• For fungal pathogen isolation: Sabouraud
dextrose agar.
• Viral - Appropriate cell lines.
21. Approach to diagnosis of upper respiratory tract infections
For suspected
bacterial URTIs
Throat swab and
membrane
Serum
ASO (S.pyogenes)
Microscopy
Gram stain
Albert stain
Culture
Blood agar
Loeffler’s serum
slope (diphtheria)
Antibiotic
sensitivity
Upper respiratory
tract infections
NP swabs and aspirates
Throat swabs
Serum
For suspected
fungal URTIs
Culture
Throat swab on
SDA for Candida
Paul–Bunnell test
(IM)
Anti-EBV IgM
Cell culture
(Adenoviruses,
EBV, HSV, Influenza
For suspected
viral URTIs
22. Treatment
• Symptomatic therapy: Antipyretic, Antihistamine,
Steam inhalation, Salt water gargling, Nebulization.
• Antibiotics if indicated
