Aim of the test
An etiological diagnosis of bacterial conjunctivitis by aerobic cultivation with identification and susceptibility test of the isolated bacteria.
Types of specimen
Discharge from the eye(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
Common pathogen
- Streptococcus pyogenes
- Pseudomonas aeruginosa
- Chlamydia trachomatis
- Staphylococcus aureus
- Neisseria gonorrheae
- Haemophilus influenza
- Haemophilus aegyptius
- Streptococcus pneumonia
- Acremonium curvularia
Commensals Bacteria
- Occasion pseudomonas aeruginosa
- Various streptococcus spp
- Various Enterobacteriaceae
- Staphylococcus aureus
- Propionibacterium spp
- Lactobacillus spp
- Staphylococcus epidermidis
Specimen collection
1. Pull down the lower eyelid so that the lower conjunctival fornix is exposed.
2. Swab the fornix without touching the rim of the eyelid with the sterile cotton swab.
3. Place the swab immediately in a bacterial transport medium or, if the specimen is brought to the laboratory immediately, in a sterile test tube with 0.5 mL of buffered saline (pH 7).
Quantity of specimen
Sufficient amount on swab
Time relapse before processing the sample
Eye specimen should be processed immediately because tears contains lysosomes which may kill the organism
Storage
Refrigerated (2-8 °C).
Media
- Blood Agar
- Chocolate Agar
- MacConkey Agar
- Fluid Thioglycollate
Result reporting:
Report Gram stain finding as an initial report. Report the isolated pathogen and its sensitivity pattern as a final report.
Turnaround time:
Gram stain results should be available 1 hour after specimen receipt. Isolation of a possible pathogen can be expected after 2-3 days. Negative culture will be reported out 1-2 days after the receipt of the specimen.
Additional information
All bacteria isolated in fair amounts and not resembling contaminants will be identified and tested for antibiotic susceptibility, including susceptibility to chloramphenicol.
- If trachoma is suspected, conjunctival scraping should be smeared onto a microscopic slide, air-dried and fixed in absolute methanol. Chlamydia antigen detection systems are available for this purpose.
