otitis media/ externa (wk 5)

Question 1

stages of acute otitis media

Answer 1

stage of hyperemia
stage of exudation
stage of suppuration
stage of coalescence
stage of complication

Question 2

suppurative complications of acute otitis media

Answer 2

acute mastroidits
meningitis
brain abscesses

Question 3

otitis media with effusion

Question 4

chronic suppurative otitis media

Question 5

causes of otitis media

Answer 5

socioeconomic status, education, smoking, no breastfeed, hyrgeine, virual URTI, males, family history etc

Question 6

Eustachian tube in infant vs adult

Answer 6

more otitis media in infant because tube is shorter and more horizontal

Question 7

common otopathogens for otitis media

Answer 7

streptococcus pneumoniae
haemophilus infleunzae
mortadella catarrhalis
psuedomonas aeruginosa

Question 8

H inflenza factors?

Answer 8

chocolate agar

X factor (hemin)
v factor (NAD+)

Question 9

h influenza virulence factors

Answer 9

Adhesins
Polysaccharide capsule
Lipid A chains/lipooligosaccharides Fimbriae
IgA protease
Biofilms

Question 10

moraxella catarrhalis

Answer 10

Gram –ve, diplococcus, aerobic bacteria

Common for URT, middle ear, eye infections

Commonly resistant to beta lactam drugs

Part of normal microbiota of ~3% of people. (children more)

Question 11

moraxella catarrhalis

Answer 11

Antiobiotic resistance (b-lactamase resistance)

Outer Membrane Proteins
- uspA1-A2, Pili

Iron-Regulated Proteins
- Transferrin-Binding proteins
- Lactoferrin-binding proteins

Lipid A chains/lipooligosaccharides

Question 12

streptococcus pneumonia virulence factors

Answer 12

Polysaccharide capsule

Fimbriae

Surface proteins that inhibit activation of complement

Question 13

what causes otitis externa

Answer 13

pseudomonas aeruginosa and staphylococcus aureus

Question 14

pseudomonas aeruginosa

Answer 14

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

Question 15

pseudomonas aeruginosa virulence factors

Answer 15

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 16

pseudomonas aeruginosa where is it found?

Answer 16

soil

P. aeruginosa is found mostly in soil; not a component of regular microbiota

Cannot penetrate epidermal layer independently – good news!

Common nosocomial infection agent (10% of hospital infections)

Question 17

staphylococcus aureus

Answer 17

Salt tolerant, facultative anaerobe, resistant to dessication, UV radiation and heat

Along with Staphylococcus epidermidis, make up ~90% of microbiota of skin.

Common cause of otitis externa

Question 18

what are the enzymes in staphylococcus aureus that are virulence factors

Answer 18

coagulase, hylauronidase, staphylokinase, lipase, beta lactamase

Question 19

what does the virulence factor hylauronidase and collagenase in staphylococcus aureus do>

Answer 19

breaks down junctions and enters into epithelial cells

Question 20

what does the virulence factor coagulase and kinase in staphylococcus aureus do>

Answer 20

coagulase forms clots and staphylokinase then dissolve the clot and releases bacteria

clot forms to avoid detection from immune system then spread systemically

Question 21

what does the virulence factor beta lactamase in staphylococcus aureus do>

Answer 21

breaks down beta lactamase i.e. penicillin

Question 22

what are the structural defesnes in staphylococcus aureus that are virulence factors

Answer 22

capsule/ slime layer glycocalx

binding IgG antibody stem regions

Question 23

what does the virulence factor of binding IgG antibody stem regions in staphylococcus aureus do>

Answer 23

inhibits antibody binding to FC receptor of phagocytes

prevent opsonization

Question 24

what does the virulence factor of capsule/ slime layer glycocalx in staphylococcus aureus do>

Answer 24

blocks phagocytosis

Question 25

what are the toxins that are virulence factors in staphylococcus aureus?

Answer 25

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)

Question 26

what are other diseases outside of otitis externa that are causes by staphylococcus aureus

Answer 26

skin disease: folliculitis, sty, furuncle, carbuncle, staphylococcal scalded skin syndrome, impetigo

reproductive: stpahylococcal toxic shock syndrome

cardivovascualr/ systemic: endocarditis, bacteremia

respiratory: penumonia

GI: food poison