IDENTIFICATION: GRAM POSITIVE

• Actinomyces

  • Colonies of most species are small, smooth, flat, convex, gray-white, translucent, with entire margins
  • Colonies of A. israelii may resemble a molar tooth and may be beta hemolytic
• NON-HEMOLYTIC/ALPHA HEMOLYTIC

  1. Bacteroides fragilis
  2. Bacteroides ovatus
  3. Bacteroides thetaiotaomicron
• Bacteroides urealyticus

  • Small, translucent, or transparent
  • May produce greening of agar on exposure to air
  • Colonies corrode and pit the agar or may be smooth and convex or spreading
• F. nucleatum subsp. nucleatum

  • Three colony types: breadcrumb-like, speckled, and smooth (gray to gray-white)
  • Greening of agar on exposure to air
  • Fluoresces chartreuse (yellow)
  • Usually nonhemolytic
• To identify P. acnes, perform Catalase and Indole test

  • Only gram +ve anaerobic bacilli that is catalase- and indole-positive
• A.israelli

  • VANCOMYCIN 5 ug (S)
  • KANAMYCIN 100 ug (S)
  • COLISTIN 10 ug R (S)
  • CATALASE (-)
  • INDOLE (-)
  • NITRATE REDUCTION (+)
  • AEROTOLERANCE (MA)
• P. acnes

  • VANCOMYCIN 5 ug (S)
  • KANAMYCIN 100 ug (S)
  • COLISTIN 10 ug R (R)
  • CATALASE (+)
  • INDOLE (+)
  • NITRATE REDUCTION (+)
  • AEROTOLERANCE (MA)
• Bifidobacterium

  • VANCOMYCIN 5 ug (S)
  • KANAMYCIN 100 ug (S)
  • COLISTIN 10 ug R (R)
  • CATALASE (-)
  • INDOLE (-)
  • NITRATE REDUCTION (-)
  • AEROTOLERANCE (OA)
• Eubacterium

  • VANCOMYCIN 5 ug (S)
  • KANAMYCIN 100 ug (S)
  • COLISTIN 10 ug (R)
  • CATALASE (+)
  • INDOLE (+)
  • NITRATE REDUCTION (+)
  • AEROTOLERANCE (OA)