Multiplex Polymerase Chain Reaction Assay for Screening of Mycotoxin Genes From Ocular Isolates of Fusarium species

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Abstract

Purpose:

To identify mycotoxin genes among clinical ocular isolates of Fusarium species and to correlate these with clinical outcomes of Fusarium keratitis.

Methods:

Fifty-four clinical isolates of Fusarium were retrieved from the Bascom Palmer Eye Institute Ocular Microbiology Laboratory data bank. Multiplex polymerase chain reactions were run to confirm the identification of Fusarium species [internal transcribed spacer sequence, translation elongation factor 1-α (TEF) and β-tubulin] and to detect the presence of genes encoding production of fumonisin B mycotoxins (FUM1 and FUM8) and trichothecene mycotoxins (deoxynivalenol and nivalenol). The presence or absence of mycotoxins was compared with patient outcomes.

Results:

Forty-three (79%) of the 54 isolates were confirmed as Fusarium species, by an internal transcribed spacer sequence in 3 (5.6%) and by TEF in 43 (79.6%) of the 54 isolates. Fumonisin biosynthetic gene 1 (FUM1) was detected in 57.4% (n = 31/54) of the Fusarium isolates. No FUM8, deoxynivalenol genes, and nivalenol genes were detected among these in the clinical isolates group. Initial best-corrected visual acuity ranged from 20/25 to 20/80 in the FUM1 gene-negative group and from 20/20 to light perception in the FUM1 gene-positive group. There was no difference in the time to cure between both groups. The presence of FUM1 genes in 5 fungal isolates seemed to be associated with progression to penetrating keratoplasty in the 5 patients from whom the fungi were isolated. Fusarium solani was recovered from all patients requiring penetrating keratoplasty.

Conclusions:

Fumonisin B biosynthetic gene 1 may be common among clinical Fusarium isolates and contribute to worse initial visual acuity and high-risk progression to penetrating keratoplasty.

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