Otitis Media/Externa

Question 1

what are some suppurative complications of AOM

Answer 1

○ Acute mastoiditis
○ Meningitis
○ Brain abscesses

Question 2

what are the common otopathogens

Answer 2

• streptococcus pneumoniae
• Haemophilus influenzae
• Moraxella catarrhalis
• pseudomonas aeruginosa

Question 3

what are the virulence factors of moraxella catarrhalis

Answer 3

• antibiotic resistance
• outer membrane proteins
• iron-regulated proteins
• lipid A chains/lipooligosaccharides

Question 4

what are the virulence factors of streptococcus pneumoniae

Answer 4

• polysaccharide capsule
• fimbriae
• surface proteins that inhibit activation of complement

Question 5

what is Pseudomonas aeruginosa

Answer 5

an opportunistic pathogen that becomes an infectious agent following the burning away of skin; can also cause otitis externa

Question 6

what are the virulence factors of pseudomonas aeruginosa

Answer 6

• Fimbriae and adhesins to improve attachment
• Formation of biofilms
• Produce enzymes like elastase, which breaks down elastic fibres, degrades complement -system, cleaves IgG and IgA antibodies
• Pyocyanin with triggers free radical accumulation (this is what causes tissue damage)

Question 7

what are the virulence factors of streptococcus aureus

Answer 7

1. enzymes
   - Coagulase, hyaluronidase, staphylokinase
   - Lipase, beta-lactamase
2. structural defenses
   - Capsule/slime layer glycocalyx
   - Binding IgG antibody stem regions
3. toxins
   - Cytolytic toxins to disrupt membranes of a large number of cell types
   - Leukocydin – kills leukocytes (another means of avoiding phagocytosis)
   - Epidermal Cell Differentiation Inhibitors – produces large holes in the lining of blood vessels
   - Exfoliative toxins (Toxic Shock Syndrome Toxin)