Ocular Microbiology and Immunology Group
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2024 OMIG Abstract

Clinico - Molecular Analysis of Patients with Microbial Keratitis Showing
Unusual Oval or Spherical Structures in Direct Microscopic Examination
of Corneal Scraping

Savitri Sharma¹, Sikha Mishra², Nisha Rani², Sujata Das², Srikant K Sahu², Smrutirekha Priyadarshini², Himansu K Behera<sup>1

1</sup>Ocular Microbiology Service, ²Cornea & Anterior Segment Service, L. V. Prasad Eye Institute,
Bhubaneswar, Odisha

Purpose: To report a case series with atypical structures in direct microscopy of corneal scrapings that were subsequently identified as Candida and Citeromyces species with PCR assay and DNA sequencing.

Methods: This is a retrospective, non-comparative case series of 8 patients with infective keratitis, whose corneal scraping smear examination (potassium hydroxide+calcofluor white) showed fungal spore like structures closely but not convincingly resembling yeast. Routine cultures were negative. Conventional PCR assay using pan fungal primers was performed on the corneal scraping of these patients followed by sanger sequencing and the sequences were analyzed using NCBI-BLAST software for species identification. Medical treatment was done based on clinical suspicion and microbiology report. Therapeutic penetrating keratoplasty was done for patients not responding to medical antifungal therapy. Demographic and clinical data were collected from the electronic medical records of the patients.

Results: Amplification of fungal DNA was seen in PCR assay of all samples. Nucleotide sequences were found homologous (97-100%) to Candida albicans (n=7) and Citeromyces matriensis (n=1). Patients were treated with antifungal drugs such as topical natamycin or amphotericin B. The ulcer healed with scarring in 4 patients (50%), three patients required therapeutic penetrating keratoplasty (37.5%) and one patient (12.5%) was lost to follow up.

Conclusions: Adopting molecular analysis in the face of observation of atypical structures in direct examination of clinical samples helps identification of ambiguous organisms and specific management of patients.


Disclosure:

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