Customised 96-ocular TaqMan (iCAM) microarray PCR card for rapid diagnosis of microbial keratitis

Area of Science:

• Ophthalmology
• Microbiology
• Molecular Diagnostics

Background:

• Microbial keratitis (MK) is a significant cause of vision impairment.
• Accurate and rapid diagnosis of the causative microbe is crucial for effective treatment.
• Current diagnostic methods, including cultures, can be time-consuming.

Purpose of the Study:

• To validate the diagnostic performance of a custom 96-micro-organism TaqMan PCR card (iCAM) for detecting microbes in corneal epithelial samples.
• To compare the iCAM test's performance against conventional microbiological methods.

Main Methods:

• A prospective cohort study involving patients with MK was conducted.
• Corneal epithelial samples were analyzed using both the iCAM PCR test and conventional culture methods.
• Microbial detection rates and positive predictive values (PPV) were evaluated.

Main Results:

• The iCAM test identified a causative microbe in 44% of samples, comparable to conventional methods (44%).
• iCAM test processing time ranged from 6 to 24 hours, significantly faster than conventional tests (up to 7 days).
• The overall microbial detection rate was 65%, with a 62% correlation between methods; sensitivity was 56% and PPV was 60%.

Conclusions:

• The iCAM test effectively detects a broad range of microbial pathogens (bacteria, fungi, viruses, protozoa) from a single corneal sample.
• Limitations include a small patient cohort and sample volume constraints when split for multiple tests.
• A multicenter trial is planned to further validate the clinical impact of iCAM on diagnostic accuracy and patient outcomes.