Conjunctival scrapings for chlamydia trachomatis

Objectives: Aetiological diagnosis of inclusion conjunctivitis and trachoma by demonstrating the agent Chlamydia trachomatis by light microscopy or by immunological methods. Light microscopy lacks sensitivity, and the immunological methods are recommended for a definitive diagnosis.

Test material: Conjunctival discharge.

Collection time: Early in the infection when the number of organisms is high.

Equipment: Request form, cotton wool sponge, anaesthetic eye drops, spatula or sterile cotton or dacron tipped swabs, microscope slides or heat resistant glass vial, methanol or acetone.

Procedure: Giemsa- or iodine-stained preparation

1. Anaesthetize the conjunctiva with anaesthetic eye drops.

2. Carefully remove excess exudate from the surface of the eye before sampling.

3. Using a spatula with a thin, blunt end, scrape the whole of the conjunctiva.

4. Spread the specimen evenly on to the central area of a microscope slide.

5. Air dry the specimen, fix it with methanol for 2-3 minutes.

Immunofluorescent staining technique

1. Anaesthetize the conjunctiva with anaesthetic eye drops.

2. Carefully remove excess exudate from the surface of the eye before sampling.

3. Using a spatula with a thin, blunt end, scrape the whole of the conjunctiva.

4. Spread the specimen evenly on to the central area of a microscope slide.

5. Air dry the specimen, fix it with acetone for 2-3 minutes.

Enzyme immunoassay technique

1. Anaesthetize the conjunctiva with anaesthetic eye drops.

2. Carefully remove excess exudate from the surface of the eye before sampling.

3. Vigorously apply an appropriate swab to the lower lid conjunctiva of the affected eye.

4. Place the swab in 1 mL diluted transport medium in a heat resistant glass vial and send this immediately to the laboratory.

Storage: Send the sampling immediately to the laboratory.

Transportation: Preferably in a cooling box (2-8 °C), if transportation time is more than one hour.

Reporting: Specimens from newborns are examined immediately by microscopy and the result is conveyed to the treating physician. Specimens from older children and adults are considered "non-urgent" specimens.

Comments: Neonatal inclusion conjunctivitis is distinguished clinically from the more serious gonococcal ophthalmia neonatorum by the latter's shorter incubation period (3 days).