M6 Ear Infections

Question 1

What is the pathogenesis, the manner of development, of external ear infections?

Answer 1

There are two common pathogenesis:
1. Trauma including excessive moisture, damage to canal surface and ear wax.
2. Infection from middle ear can drain into external ear canal.

Question 2

What damage of the internal ear is a pathogenesis to ear infections?

Answer 2

Deformed or defective eustachian (auditory) tube

Question 3

What other body area infections can lead to inner ear infections (pathogenesis)?

Answer 3

Upper respiratory infections can lead to secondary infections in the ear.

Question 4

What clinical manifestations of acute otitis externa can spread easily to the pinna?

Answer 4

inflammation of external auditory canal which can spread
to the pinna

Question 5

What organisms could cause acute otitis externa of the pinna in the form of furuncle formation?

Answer 5

Localized infection of the pinna include furuncle formation
(like a superficial wound)= same pathogens:
Staphylococcus aureus/ Streptococcus pyogenes

Question 6

What organism is likely to cause a diffuse infection related to softening of tissue due to swimming or hot/humid environment?

Answer 6

Diffuse infection is related to softening of tissue due to
swimming or hot/humid environment: Pseudomonas
aeruginosa or other GNB could play a role.

Question 7

What can cause a chronic ear infection?

Answer 7

Chronic infections can occur from the irritation of drainage from the middle ear.

Question 8

What area of the ear is affected in Otitis media?

Answer 8

Inflammation of area behind the eardrum (tympanic membrane)

Question 9

What are the 3 conditions for inflammation behind the eardrum (or Otitis media) to occur?

Answer 9

3 conditions must be met
* adherence to nasopharynx
* entry to eustachian tube
* multiply at site

Question 10

Who is Otitis media (or infections behind the eardrum) common in?

Answer 10

Most common in children.

Question 11

What organisms are involved in Otitis externa and Otitis media chronic infections?

Answer 11

Externa: P. aeruginosa; anaerobes

Media: anaerobes

Question 12

What organisms are involved in Otitis media disease?

Answer 12

Streptococcus pneumoniae,
Haemophilus influenzae
Moraxella catarrhalis
S. pyogenes
Respiratory syncytial virus
Influenza virus

Question 13

What organisms are known to cause Acute Sinusitis in Young adults?

Answer 13

Young adults:
Haemophilus influenzae
Streptococcus pneumoniae
Streptococcus pyogenes
Moraxella catarrhalis

Question 14

What organisms are known to cause Acute Sinusitis in children?

Answer 14

Children
S. pneumoniae
H. influenzae,
M. catarrhalis
Rhinovirus

Question 15

What other body part is the Indigenous normal flora of the ear similar to?

Answer 15

Sparse & similar to conjunctiva

Question 16

What organisms are more commonly found in the external ear canal?

Answer 16

Organisms more commonly found in external ear canal:
1. Strep. pneumoniae
2. Cutibacterium acnes
3. S. aureus
4. Enterobacterales
5. Candida spp.
6. Occasionally P. aeruginosa

Question 17

Are middle ear infections typically diagnosed in the lab?

Answer 17

Usually, middle ear infections not diagnosed in Lab.

Question 18

How are specimens for external otitis collected for the lab from the patient? What is the ideal method?

Answer 18

1. External otitis: disinfect area and collect fluid after, specially
   after spontaneous perforation of eardrum.
2. Ideal: needle aspiration (tympanocenthesis) of middle ear

Question 19

What media are used to culture organisms suspected of causing ear infections?

Answer 19

External and Internal
* Choc (CA), BA, Mac (some labs add more selective media: PEA)
* direct smear

Question 20

If an aspirate specimen from the ear is done, what additional type of culture can be done?

Answer 20

• If aspirated, anaerobic culture can be done (not on external swabs)

Question 21

What are unacceptable specimens from the ear?

Answer 21

Unacceptable:
leaking,
improper transport media or time (less than 24 hours,
>2 hours refrigerate), clerical errors, etc

Question 22

From the culture plates for external ear infection how do you determine significance of growth?

Answer 22

Determine significance of growth by:
* organism isolated
* amount of growth
* purity of culture
* All these factors combined will lead to lab protocol (varies)

Correlate growth with direct smear.

Question 23

From the culture plates for internal ear infection how do you determine significance of growth?

Answer 23

Determine significance of growth by:
* organism isolated
* amount of pure growth if normal skin flora

Correlate growth with direct smear.

Question 24

What and when do you report if there is no growth on the plates for external swabs? internal swabs?

Answer 24

External: 48 hours incubation before calling “no growth”

Internal: 72 hours incubation before calling “no growth”

Question 25

When is an AST performed for an ear infection specimen for external and internal swabs?

Answer 25

AST to do if applicable to the organism