Eikenella species

MICROBIOLOGY

• Facultatively anaerobic, fastidious, Gram-negative coccobacillary organism [Fig 1].
  • Pits agar on culture plates [Fig 2, note: only ~50% of such colonies produce this pitting].
  • Grows best if enhanced by 3-10% CO₂.
• Eikenella corrodens is the primary human pathogen.
  • Other species members described as rarely causing human illness are E. halliae sp. nov., and E. exigua sp. nov.
• Often found as a component of mixed infections.
• Member of the HACEK group of endocarditis-associated bacteria (Haemophilus spp., Actinobacillus, Cardiobacterium, Eikenella, Kingella).