Prunuske -- Otitis Media

Question 1

Otitis externa

Answer 1

external otic canal infection

Question 2

Otitis media

Answer 2

middle ear canal infection

Question 3

Labrinthitis

Answer 3

inner ear infection

Question 4

Mastoiditis

Answer 4

mastoid bone infection

Question 5

Otitis media with effusion

Answer 5

build up of fluid in Eustachian tube

Question 6

Acute otitis media

Answer 6

bacterial or viral

pain, red ear drum, pus, and fever

~70% of children experience at least 1 episode of otitis media during childhood probably b/c tubes are more narrow and horizontal and 1/3 have had 3 or more episodes

More common in males and Native American/Alaskan Natives

Question 7

Common etiologic agents of acute otitis media

Answer 7

Streptococcus pneumoniae: 25-50%
Haemophilus influenzae (mostly non-typable): 15-30%
Moraxella catarrhalis: 3-20%
Viral (especially RSV, rhinovirus): 5-22%
No pathogen identified: 16-25%

Question 8

Streptococcus pneumoniae

Answer 8

Gram positive, diplococcus

Resistance due to changes in the penicillin binding protein

Capsule- blocks phagocytosis by interfering with the
deposition of complement on surface of organism

Choline-binding proteins- bind carbohydrates present
on surface of epithelial cells

Neuraminidases- cleave sialic acid in host mucins

_Autolysin A (LytA)_- degrades peptidoglycan and causes
 α-hemolysis during growth

Pneumolysin- pore forming toxin is released disrupts cilia

• Transmitted by contact with secretions
• Asymptomatic colonization of naso oropharynx
• Can be a carrier for weeks to months especially in winter
• If spreads to middle ear or terminal airways leads to rapid inflammation

Question 9

These illnesses are common, often occur together, and caused by similar agents…

Answer 9

Bacterial conjunctivitis, otitis media, and sinusitis

Question 10

Recurrent otitis media is associated with…

Answer 10

conductive hearing loss as well as meningitis and mastoiditis

Question 11

Acute otitis media is treated with ________ but patients need to be monitored for treatment failure as there is an increasing number of drug resistant strains and physicians need to minimize selection for these strains by practicing appropriate writing of prescriptions.

Answer 11

amoxicillin

beta-lactam; binds PBP to block transpeptidation step

Question 12

Match the bacteria/virus with the description…

Red eye, mild cold, clear drainage

Answer 12

Adenovirus

Question 13

Match the bacteria/virus with the description…

Visual field deficit most common in
HIV infected individuals

Answer 13

Cytomegalovirus

Question 14

Match the bacteria/virus with the description…

Releases pneumolysin pore forming toxin

Answer 14

Streptococcus pneumoniae

Question 15

Match the bacteria/virus with the description…

Green-yellow discharge from the eyes

Answer 15

Neisseria gonorrhea

Question 16

Haemophilus influenzae

Answer 16

Small, pleomorphic, gram-negative, coccobacillus, nonmotile, biofilms, facultative anaerobe

• Humans are only known host
• Fastidious require additional blood factors for growth hematin (X) and NAD (V) both present in chocolate agar
• Nontypeable- nonencapsulated (NTHi) colonize nasopharynx in 80% of people and if spreads to the eustachian tubes causes otitis media. (vaccine available)
• Many express β-lactamases
• Other mucosal sites of infection include
  genital tract and conjunctivitis

Question 17

Moraxella catarrhalis

Answer 17

Gram-negative, aerobic, diplococcus, oxidase-positive, nonmotile, fastidious-chocolate agar, pili

• Colonization of upper respiratory track in infants
• 95% of M. catarrhalis produce β-lactamases
• Hockey puck test- easily slide across agar and be stacked

Question 18

Recommended treatment for Acute Otitis Media

Answer 18

• 6-24 months start empiric treatment: Amoxicillin provides coverage against Streptococcus pneumoniae, Haemophilus influenzae with limited side effects (?).
• If no improvement within 48 hours switch to _Amoxicillin- Clavulanate _

Question 19

For which organisms would you expect clavulanate to potentially expand coverage?

Answer 19

clavulanate is a beta-lactamase inhibitor

clavulanate is commonly used with beta-lactam drugs such as amoxicillin

In this case it would improve coverage for organisms that have resistance through beta-lactamases… such as

Moraxella catarrhalis
Haemophilus influenzae

Question 20

Otitis externa- common etiologies

Acute localized ?

Acute diffuse ?

Malignant ?

Fungal ?

Answer 20

• Acute localized- most often Staphylococcus; pustule or furuncle associated with hair follicles
• Acute diffuse- Pseudomonas aeroginosa itches, red canal, and painful
• Malignant- Pseudomonas aeroginosa, invasion of adjacent bone and cartilage which can progress to cranial nerve palsy and death. More common in elderly, poorly controlled diabetes, and immunocompromised.
• Fungal- Aspergillus and Candida

Question 21

Staphylococcus aureus

general info and virulance factors

Answer 21

clustered, Gram positive cocci

Virulence factors

• Capsule and Protein A binds Fc portion of IgG to interfere with phagocytosis
• Coagulase binds prothrombin initiating the polymerization of fibrin and clotting- retard migration of phagocytes to site of infection
• Membrane damaging toxins hemolysin and leukotoxin