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Nocardia sienata: a new causative species of infectious keratitis
  1. Arman Mosenia1,
  2. Anh H Nguyen2,
  3. Mark R Mandel3 and
  4. Gerami D Seitzman4
  1. 1School of Medicine, UC San Francisco, San Francisco, California, USA
  2. 2University of California San Francisco, San Francisco, California, USA
  3. 3California Pacific Medical Center, San Francisco, California, USA
  4. 4Ophthalmology, University of California San Francisco, San Francisco, California, USA
  1. Correspondence to Dr Gerami D Seitzman; gerami.seitzman{at}


A 25-year-old man presented with a 2-month history of progressively worsening left eye pain and an atypical corneal ring infiltrate. His condition deteriorated despite topical antibiotic therapy. Cultures for bacteria, fungus and acanthamoeba, repeated twice, all demonstrated no growth. On third corneal scraping, culture on Middlebrook agar grew colonies after 3 weeks of incubation. Sixteen-second deep sequencing identified Nocardia sienata as the pathogen. This species of Nocardia has not previously been described as a causative pathogen for infectious keratitis. Sloughing and loose epithelium with recurrent filament formation are unusual in infectious keratitis and could be associated with this species. In culture-negative cases, clinicians should consider Nocardia as a cause of keratitis despite its rarity outside of south Asia and use steroids cautiously. Next generation sequencing technology may facilitate identification of the causate of keratitis and can be especially useful in culture-negative cases and with unexpected pathogens.

  • ophthalmology
  • anterior chamber
  • infectious diseases

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  • Contributors GDS conceived of the report and was the primary doctor caring for the patient described. AM wrote the manuscript and was supervised by GDS. AN and MM participated in the care of the patient described and edited the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.