ACANTHAMOEBA, CULTURE, EYE/CORNEAL SCRAPINGS (SBH AND WL ONLY)

Test Code: ACAN

Test Indications:
To aid in the diagnosis of Acanthamoeba-associated keratitis.
Acanthamoeba are free-living soil and freshwater amoeba.  Infectious keratitis due to Acanthamoeba is nonfatal but vision-threatening; early diagnosis and treatment is essential.  The most common predisposing factor is use of contact lenses: improper use or contamination of contact lens systems, overnight or extended use of contact lenses, or exposure to contaminated water while wearing contact lenses.  The great majority of contact lens infections are bacterial, predominantly due to Gram-negative organisms, e.g., Pseudomonas, followed by Gram-positive bacteria (Staphylococcus and Streptococcus).  Fungi and Acanthamoeba are an uncommon cause but may lead to more severe clinical outcomes.
Acanthamoeba culture and identification are performed using an agar plate technique.  Corneal scrapings are inoculated on special media, preferably at the bedside, and transported immediately to the laboratory for culture. Contact lens and sediment of contact lens solution may be submitted for Acanthamoeba culture but are considered suboptimal.

Recommendations:
Collection of samples for Acanthamoeba Culture requires prior consultation (24 hours’ notice) with the laboratory.
For best results, obtain appropriate media from the microbiology laboratory to enable direct inoculum of the sample at point-of-care.
For other causes of eye infections, including keratitis, refer to thecorresponding LIM entries in the See Also section below.
For information on other microbiology tests not performed by Shared Health Clinical Microbiology Laboratories (e.g., virus detection), please refer to the relevant laboratory that performs the testing.
Samples and requisitions must be labeled/completed in accordance with the Shared Health Specimen Acceptance Policy.
Accurate patient identification must be made prior to sample collection. Patient identification should be done in accordance with the site policy.

Patient Preparation Instructions:
Corneal samples should be obtained aseptically.
Corneal scraping:
1.  Instill 2 drops of local anesthetic into the conjunctival sac and/or onto the corneal epithelium.
2.  Using a sterile spatula, scrape ulcers or lesions and inoculate a pre-prepared non-nutrient agar plate coated with a bacterial overlay of E. coli.
3.  If no pre-prepared media is available, place scraping in a small amount of Page’s saline (1-2 mL) and transport immediately to the laboratory.

Preferred:  Non-nutrient agar coated with a bacterial overlay of E. coli - provided by SBH or WL micro labs
Alternate: Sterile specimen container with a small amount of Page's saline (1-2 mL) - provided by SBH or WL micro labs
The laboratory requires 24 hours notice to ensure that the seeded plate can be prepared.

_SH Microbiology - Provincial Requisition (R250-10-06)

No Acanthamoeba isolated.
Plates are examined daily. Positive cultures for Acanthamoeba are reported immediately.
A final negative report is issued after 10 days.

Daily

FUNGI, CULTURE, ALL SPECIMEN TYPES EXCLUDING BLOOD (E.G., CORNEAL SCRAPINGS/FLUID/TISSUE/BONE MARROW/GASTRIC WASHINGS)

FLUID (PERICARDIAL FLUID/PERITONEAL FLUID (INCLUDING CAPD FLUID)/PLEURAL FLUID/SYNOVIAL FLUID/VITREOUS FLUID), CULTURE, AEROBIC/ANAEROBIC BACTERIA - (Fl)

EYE (CONJUNCTIVA/CORNEAL SCRAPINGS/ORBITAL IMPLANTS/STYE/HORDEOLUM), CULTURE, AEROBIC BACTERIA

Specimen Handling:
Local:  ≤15 minutes at room temperature (Page’s saline).
Courier/local storage:  ≤4 hrs at room temperature (inoculated plate). 
Ensure samples that are being sent to a referral laboratory are packaged in accordance with Transport of Dangerous Goods recommendations for diagnostic samples.