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Eikenella - Catalase & Oxidase

Eikenella corrodens (E) belongs to the HACEK group of miscellaneous gram-negative bacilli which includes Haemophilus aphrophilus (H), Actinobacillus actinomycetemcometans (A), Cardiobacterium hominis (C) and Kingella kingae (K).
Cytochrome oxidase and catalase are two rapid tests that help separate the several members of this group.
  • E. corrodens shows cytochrome oxidase activity, but not catalase activity.
  • The positive oxidase reaction separates E. corrodens from H. aphrophilus and A. actinomycetemcomitans, which are both negative.
  • A. actinomycetemcomitans is also catalase positive, an additional characteristic separating it from E. corrodens, which is negative.
  • As Kingella kingae is also oxidase positive and catalase negative, other tests are needed for differentiation. K. kingae produces acid from glucose and maltose (E. corrodens is asaccharolytic).