بسم الله الرحمن الرحيم Diagnostic Medical MicrobiologyLaboratory Manual Ear Culture Aim of the test Etiological diagnosis of otitis externa or otitis media by aerobic and anaerobic culture with identification and susceptibility test of the isolated organisms ID: 562422
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Slide1
Ear Culture
بسم الله الرحمن الرحيم
Diagnostic Medical Microbiology-Laboratory ManualSlide2
Ear CultureAim of the test
Etiological diagnosis of otitis externa or otitis media by aerobic and anaerobic culture with identification and susceptibility test of the isolated organism(s).
Types of specimenTwo swabs from the external or aspiration from middle ear(s).
Criteria of specimen rejection
Inappropriate specimen transport device; mislabeled specimen; unlabeled specimen; specimen received after prolonged delay (usually more than
two hour
); specimen received in expired transport media.Slide3
Common Pathogens
Commensals flora
are present in the external ear canal
Staphylococcus
aureus
Staphylococcus
epidermidis
Streptococcus
pyogenes
Lactobacillus spp.
Pseudomonas
aeruginosa
Propionibacterium
spp.
Other Gram negative bacilli
Staphylococcus
aureus
Streptococcus
pneumoniae
Various
Enterobacteriaceae
Haemophilus
influenzae
Various streptococcus
spp
Anaerobic bacteria
Candida spp. other than
albicans
Proteus spp.
Occasion Pseudomonas
aeruginosaSlide4
Pre specimen processingWho will collect the specimen
Medical technologist, Microbiologist for swab from external ear.
Otolaryngologist for aspiration from middle ear.
Who is authorized to order the testPhysician.
Time relapse before processing the sample
Not more than
2 hours
.
Storage
Maintain specimen swab at room temperature.Slide5
Pre specimen processingExternal Ear Specimen collection
Collect a specimen of the discharge on a thin, sterile cotton wool or Dacron swab.
Place the swab in a container with the transport medium, breaking off the swab stick to allow the stopper to be replaced tightly.
Label the specimen and send it to the laboratory.Slide6
External Ear Specimen collectionSlide7
Specimen processing for Otitis externaSlide8
Specimen processing for Otitis mediaSlide9
Specimen processing
Ear specimen submitted for culture should be inoculated to blood agar, MacConkey, and chocolate agar plates, anaerobic culture also should be setup on those specimens obtained by
tympanocenthesis
or those obtained from patients with chronic otitis media, or mastoiditis.
Direct visual examination for material aspirated from the middle ear or mastoid is also examined directly for bacteria or fungi.
Cultures from mastoid are generally taken on swabs during surgery and should be transported anaerobically.Slide10
Additional information
For external ear infections only Staphylococcus
aureus, Streptococcus pyogenes, Pseudomonas
aeruginosa, Vibrio spp. and Aspergillus will be looked for and reported.
For middle ear infections only pneumococcus,
Streptococcus
pyogenes
,
Haemophilus
influenzae and Staphylococcus aureus will be reported with a susceptibility test.
For the chronic discharging ear,
Bacteroides
species and fungi will also be reported in addition to the organisms reported for middle ear infections.Slide11
Post specimen processing
Interfering factors:
Patient
on antibiotic
therapy.
Improper
sample collection.
Result reporting:
Report Gram stain finding as an initial report.
Report the isolated pathogen and its sensitivity pattern as a final report.
Turn around time:
Gram stain result should be available half hour after specimen receipt.
Isolation of a possible pathogen can be expected after 2-4 days.
Negative culture will be reported out 1-2 days after the receipt of the specimen.Slide12
End of Lecture