Eye / conjunctival / lid swabs are collected for the diagnosis of conjunctivitis.
It is preferable that both eyes be swabbed, even if the infection is unilateral. Swabs should be collected prior to the instillation of topical anaesthetics or antibiotics, and sent in transport medium.
Viral isolation requires special universal transport media (UTM).
Occasionally, specimens collected by an ophthalmologist will be inoculated directly onto culture plates at the bedside. The ophthalmologist will inoculate the plates in a short spiral line. If lid swabs are also collected, these will be inoculated onto the same culture plates next to the conjunctival inoculation. Lid swabs will be inoculated in the shape of an “L” or “R” indicating left or right, respectively. These plates should be kept in the incubator (35°C) until processed.
|Blood Agar (BA)||CO2, 35°C x 48 hours|
|Chocolate Agar (CHOC)||CO2, 35°C x 48 hours|
If Neisseria gonorrhoea requested, add:
|Vancomycin-Colistin-Nystatin Agar (VCN)||CO2, 35°C x 72 hours|
Any growth of S. aureus, H. influenzae, M. catarrhalis, N. gonorrheae, Gp.A Strep, S. pneumoniae, Moraxella spp., and P. aeruginosa is significant. Susceptibility tests are not performed except if S. aureus is identified and only to screen for MRSA.
“Normal flora” or “No growth”. If GC culture was set up, report “No N. gonorrhoeae isolated”
Quantitate all significant isolates. If normal flora is also present, report with quantitation.
If S. aureus was isolated screen for MRSA only and report as either “MRSA isolated” or “S. aureus isolated”. Do not report susceptibility on any isolate. Add comment “Susceptibility testing of topical antibiotics is not standardized and not routinely performed on superficial eye specimens.”
H.D. Isenberg, 2004. Wound Cultures – Wound and Soft Tissue Cultures, p. 184.108.40.206 – 220.127.116.11. In Clinical Microbiology Procedures Handbook, 2nd Edition, Vol 1 ASM Press, Washington, D.C.
H.D. Isenberg. 2004. Ocular Cultures p. 3.10.1. – 3.10.8. In Clinical Microbiology Procedures Handbook, 2nd Edition, Vol 1 ASM Press, Washington, D.C.