Mycobacterium chelonei masquerading as Corynebacterium in a case of infectious keratitis: a diagnostic dilemma

Cornea. 1998 Mar;17(2):230-2. doi: 10.1097/00003226-199803000-00021.


Purpose: The diagnosis of Mycobacterium keratitis can often be missed both clinically and microbiologically and this report highlights one such case.

Methods: Review of medical and microbiological records.

Results: We report a case of Mycobacterium keratitis in a 25-year-old man that was misdiagnosed as Corynebacterium keratitis at initial presentation. Presence of partially stained and beaded bacilli in a Gram-stained smear of repeat corneal scrapings raised the suspicion of an unusual organism. Ziehl-Neelsen staining of the decolorized Gram-stained smear and subculture on Löwenstein-Jensen medium helped us to establish the diagnosis.

Conclusions: A high degree of suspicion needs to be maintained, especially in cases in which (a) there is a history of corneal trauma involving a foreign body, (b) the Gram-stained smear of corneal scrapings shows a paucity of organisms and the presence of partially stained and beaded bacilli in the presence of confluent growth of colonies resembling those of Corynebacterium, and (c) a typical corneal feature like "cracked windshield" stromal lesion is seen, to avoid such a misdiagnosis. Inclusion of a Löwenstein-Jensen culture at the initial presentation, especially when the clinical presentation is atypical, as seen in this case, will lead to an early diagnosis.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Amikacin / administration & dosage
  • Amikacin / therapeutic use
  • Anti-Bacterial Agents / administration & dosage
  • Anti-Bacterial Agents / therapeutic use
  • Cornea / microbiology
  • Corynebacterium / isolation & purification*
  • Corynebacterium Infections / diagnosis*
  • Corynebacterium Infections / microbiology
  • Diagnosis, Differential
  • Eye Infections, Bacterial / diagnosis*
  • Eye Infections, Bacterial / drug therapy
  • Eye Infections, Bacterial / microbiology
  • Humans
  • Keratitis / diagnosis*
  • Keratitis / drug therapy
  • Keratitis / microbiology
  • Male
  • Mycobacterium Infections, Nontuberculous / diagnosis*
  • Mycobacterium Infections, Nontuberculous / drug therapy
  • Mycobacterium Infections, Nontuberculous / microbiology
  • Mycobacterium chelonae / isolation & purification*
  • Ophthalmic Solutions


  • Anti-Bacterial Agents
  • Ophthalmic Solutions
  • Amikacin