Kingella species

MICROBIOLOGY

• Fastidious, Gram-negative facultative anaerobic coccobacillus of the Neisseriaceae family.
  • Labs may misidentify due to the organism’s tendency for crystal violet dye retention, therefore appearing Gram-positive.
  • β-hemolytic, catalase-negative; will not grow on MacConkey agar.
  • Polysaccharide capsule aids in virulence and invasive abilities.
    • Described factors: including type IV pili and the Knh trimeric autotransporter (adherence to the host), a potent RTX-family toxin (epithelial barrier breach), and multiple surface polysaccharides (complement and neutrophil resistance).
• Part of normal oral/respiratory and GU flora, especially in children.
  • Colonization rates:
    • 0-6 mos: 1%
    • 12 mos- 4 yrs: 10-28% (toward higher-end, especially in the daycare population)
    • Adults: 1%
• Kingella kingae most frequent human pathogen.
  • Other occasional species include K. dentrificans and K. oralis.
• Generally susceptible to many antibiotic classes.
  • Intrinsically resistant to vancomycin and other glycopeptides; variable to clindamycin.