title: Necrotizing keratitis caused by acyclovir-resistant herpes simplex virus.
abstract: BACKGROUND
  We report a case of necrotizing keratitis caused by acyclovir (ACV)-resistant herpes simplex virus (HSV) with a clinical appearance similar to a previous fungal keratitis infection.
  
  
  METHODS
  Observational case report.
  
  
  RESULTS
  Penetrating keratoplasty was performed in the left eye with a history of herpetic keratitis that resolved with periodic treatment with ACV ointment and a topical steroid. The left eye was painful and red with an abscess and corneal erosion in the peripheral donor cornea. Examination of the scraped corneal epithelium by light microscopy and culturing identified Candida albicans; polymerase chain reaction (PCR) was negative for human herpes viruses. After antifungal treatment, the ocular pain gradually decreased and the lesions slowly improved but recurred with a similar clinical appearance. A second light microscopy examination and cultures were negative for pathogens including C. albicans. PCR was positive for HSV-1 DNA; treatment with 3% topical ACV ointment was unsuccessful. A third examination showed only HSV-1 DNA. Despite antiviral ACV ointment, no clinical improvement occurred based on the HSV DNA copy numbers, which were the same before and after treatment, indicating a possible ACV-resistant strain. When topical trifluorothymidine was substituted for ACV, clinical improvement occurred and the HSV DNA copy numbers decreased.
  
  
  CONCLUSIONS
  Necrotizing keratitis induced by ACV-resistant HSV occurred independently after fungal keratitis, with a similar clinical appearance in this case, making diagnosis and treatment difficult. Monitoring the HSV DNA load by real-time PCR could be useful for refractory cases even with atypical clinical appearances.
authors.affiliation: Department of Ophthalmology, Ehime University School of Medicine, Toon, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Toriyama
authors.affiliation: Department of Ophthalmology, Ehime University School of Medicine, Toon, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Inoue
authors.affiliation: Department of Ophthalmology, Ehime University School of Medicine, Toon, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Department of Ophthalmology, Ehime University School of Medicine, Toon, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: Department of Ophthalmology, Ehime University School of Medicine, Toon, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ohashi
keywords: Acyclovir-resistant herpes simplex virus; Fungal infection; Herpes simplex virus; Necrotizing keratitis; Real-time polymerase chain reaction