MICROBIOLOGY

• 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.
  
  • Variably active: beta-lactams, erythromycin, quinolones, metronidazole, vancomycin, and aminoglycosides.
  • Usually active: beta-lactam/beta-lactamase inhibitors and carbapenems.