A DNA dot hybridization model for molecular diagnosis of parasitic keratitis.

PURPOSE

Developing a DNA dot hybridization model for diagnosing parasitic keratitis.

METHODS

Newly designed oligonucleotide probes for detecting and microsporidia were tested with target reference strains of (n = 20) and microsporidia (n = 3), and non-target microorganisms, including bacteria (n = 20) and fungi (n = 20). These probes, which had passed the preliminary tests, were then assembled as a parasite dot hybridization (PDH) model for assessing 33 clinical samples from patients with clinically suspected and microsporidia keratitis, including eight positives for , 13 positives for microsporidia, and 12 negatives for both pathogens.

RESULTS

Two probes for detecting and two for detecting microsporidia passed the tests using target and non-target strains and then were assembled in the PDH model. For clinical samples, one -positive sample (proved with pathology) was falsely negative according to the PDH assay. The sensitivity and specificity of the PDH assay for diagnosing keratitis were 87.5% and 100%, respectively, while the sensitivity and specificity for diagnosing microsporidia keratitis were 100%. The infectious agent of all clinical samples of microsporidia keratitis was identified as with DNA sequencing, while those of keratitis were caused by four species of , with found in four samples (50%, 4/8).

CONCLUSIONS

The PDH model has the potential to be a molecular assay for diagnosing and microsporidia keratitis. However, a prospective clinical study might be needed before the model is adopted in routine clinical practice.