Conjuctival Discharge بسم الله الرحمن الرحيم Conjuctival Discharge 2014-2015 Diagnostic Medical Microbiology-Laboratory Manual

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.

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

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.

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.

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.

Specimen processing for conjunctiva

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.

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

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

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

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.

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