1. Conjuctival Discharge
بسم الله الرحمن الرحيم
Conjuctival Discharge
Diagnostic Medical Microbiology-Laboratory Manual

2. Conjunctival Discharge
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
Two swabs from 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.

3. Common pathogens Commensals flora
Streptococcus pyogenes
Staphylococcus epidermidis
Pseudomonas aeruginosa
Lactobacillus spp
Chlamydia trachomatis
Propionibacterium spp
Streptococcus pneumoniae
Staphylococcus aureus
Haemophilus influenzae
Various Enterobacteriaceae
Haemophilus aegypticus
Various streptococcus spp
Occasion pseudomonas aeruginosa
Neisseria gonorrheae

4. Pre specimen processing
Who is authorized to order the test
Physician.
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
Maintain specimen swab at room temperature .Don’t refrigerate.

5. Pre specimen processing
Conjunctival discharge Specimen collection:-
Pull down the lower eyelid so that the lower conjunctival fornix is exposed.
Swab the fornix without touching the rim of the eyelid with the sterile cotton swab.
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 phosphate buffered saline.

6. Conjunctival discharge Specimen collection
Palpebral or tarsal conjunctiva lines the eyelids
Bulbar or ocular conjunctiva covers the eyeball, over the sclera. This region of the conjunctiva is tightly bound to the underlying sclera by Tenon's capsule and moves with the eyeball movements.
Fornix conjunctiva Forms the junction between the bulbar and palpebral conjunctivas. It is loose and flexible, allowing the free movement of the lids and eyeball.

7. Specimen processing for conjunctiva

8. Specimen processing for conjunctiva
Direct Visual Examination
All material submitted for culture should always be smeared and examined directly by gram stain or other appropriate techniques.
Specimen in which chlamydia is suspected can be stained immediately with monoclonal antibody conjugated to fluorescein for detection of elementary bodies or inclusions.
Culture
Because the constant washing action of the tears the number of organisms recovered from cultures of certain eye infection may be relatively low, so Conjunctival scrapings place directly onto media yield the best results.

9. Specimen processing for conjunctiva
One should use blood, MacConkey and chocolate agar plates, because potential pathogen may present in an eye without causing infection it maybe very helpful when any one eye is infected to culture both eyes, If a potential pathogen grows in cultures of both infected and un infected eye the organisms may not be causing the infection, now ever if the organism only grows in culture from the infected eye, it is most likely the causative.
Non Culture Methods
ELISA and DIFA staining are now available for detection of Chlamydia trachomatis

10. Direct Immuno-fluorescence (DIF) Antibody labeling for
Chlamydia trachomatis

11. Chlamydia trachomatis
With Giema stain
With Iodine stain
Giemsa stain of Chlamydia inclusion bodies (purple "caps" on epithelial cell).

12. 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 2-3 days.
Negative culture will be reported out 1-2 days after the receipt of the specimen.

13. END LECTURE
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