New Pyrenochaeta Species Found in a Corneal Ulcer

Abstract

Purpose: : To report a new fungal species of Pyrenochaeta isolated on a patient with fungal keratitis

Methods: : A 77-year-old diabetic woman came to our centre with an infectious keratitis in her left eye. She had received many different treatments without any sign of improvement in the last three months. In the first visit, she presented conjunctival hyperaemia, peripheral corneal pannus, corneal oedema and an ulcer with white infiltrate. The patient was diagnosed with bullous kerathopathy and infectious keratitis. Corneal scrapings were taken to classical microbiology and PCR (amplification of the ITS-5.8S rRNA gene region).

Results: : In the corneal scraping we found Streptococcus viridans and in the direct examination filamentous suggesting fungal hyphae. Fungal PCR was positive, showing only 80 % homology with Leptosphaeria. The patient initiated treatment with topical amphotericin B, cefazolin and ofloxacin and oral fluconazole. After one week of treatment the patient condition deteriorated therefore a corneal biopsy was taken. Calcofluor white direct examination showed a great fungal invasion in the cornea. Again, the amplification and typing DNA showed 80 % homology with Leptosphaeria. After six days a filamentous fungus grew in Chocolate-agar showing its DNA sequence 100 % homology with the sequence obtained from the corneal samples. Due to the fact the sequence of its DNA showed low homology with the sequences of the databases, we suspected that it could be a new species. Therefore, the fungus was sent to the specialist centre to identify it. The fungus was identified as a new Pyrenochaeta species by the CBS with accession number CBS 121759. The study and description of this new species is currently in process.

Conclusions: : Application of PCR and molecular methods can help us to discover new pathogens involved in ocular infections.

Keywords: cornea: clinical science • inflammation • pathobiology