Lab 6 Ears Flashcards
What type of media is used for specimens from the ears and incubation requirements?
BA - O2
CA - CO2
MAC - O2
all incubated at 35C.
Is a direct smear performed for ear specimens and if so what is read?
Yes, a direct smear. Read for bacteria, yeast and PMNs.
PMNs read at 10X
Bacteria & Yeast at 100X
Quantified as per table.
What are the major pathogens for Otitis externa?
S. aureus
S. pyogenes
P. aeruginosa
other GNB
If Chronic - ANO2s.
What are the major pathogens for Otitis media?
Strep. pneumoniae
H. influenzae
M. catarrhalis
S. pyogenes
If chronic - ANO2s
How are culture plates quantified for ear specimens?
Semi-quantitative, 1+ to 4+.
What can be contaminants in ear specimens?
Contaminants from skin:
Corynebacterium,
CoNS
Cutibacterium acnes
Also see list in lab learn notes.
How long are the plates incubated before calling no growth on the report?
up to 72 hrs
When can anaerobic cultures be performed from ear specimens?
When the specimen as been collected by aspirating, not on external swabs.
How are the culture plates read and worked up?
- Est. qty and describe morphology on each plate.
- Identify potential pathogens, usually 3-4+ growth, perform standard tests. Correlate with gram stained smear.
- Perform AST on applicable organisms.
What organism is the common cause of swimmer’s ear?
Pseudomonas aeruginosa and other GNB.
Swimmer’s ear - Diffuse otitis externa/ Acute otitis extrena
What can cause chronic otitis externa and typical bacterial causative agents?
Result of patients with otitis media with a perforated eardrum, & typically occurs 2 weeks after the acute infection.
Common agents: Pseudomonas aeruginosa and anaerobes.
What should the final report contain for a positive culture on an ear specimen?
- Report qty and morph of all organisms on gram smear, PMNs.
- Report qty and organisms ID for each morph type isolated on culture media with susceptibilities.
- Note possible contaminants as “XX amount” of indigenous flora present, possible contamination.
