Capnocytophaga spp.


  • C. canimorsus (previously known as DF-2, dysgonic fermenter) and C. cynodegmi (previously known as DF-2-like organism) are fastidious, facultatively anaerobic Gram-negative rods, part of normal oral flora of dogs and cats.
    • On Gram stain may be fusiform; older cultures may render pleomorphism.
    • Slow-growing organisms are often incorrectly identified in clinical microbiology laboratories.
    • C. cynodegmi is considered less virulent than C. canimorsus.
    • Other Capnocytophaga species may be part of animal oral flora, or normal human oral flora/dental plaques, e.g., C. sputigena, C. canis, C. endodontalis sp. nov. and C. gingivalis.
  • Organisms have a long, fusiform appearance on Gram stain, making it distinctive enough to consider morphologic identification pending cx results.
  • Organisms are considered fastidious by the micro lab.
  • Most strains are resistant to polymyxin, fusidic acid, fosfomycin and trimethoprim.

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Last updated: January 19, 2023