Aggregatibacter actinomycetemcomitans
A) "rough" colony morphology of a clinical isolateB) "smooth" colony morphology of a spontaneous variant

Dr David Figurski

Bone loss from aggressive periodontitis that led to an exposed furcation on an upper molar.

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Farmer at the dentist

Johann Liss 1616

Aggregatibacter actinomycetemcomitans

  • General information

    • the following information is not yet verified
      Family: Pasteurellaceae, previously: Actinobacillus

      Natural habitat
      Part of the normal flora of the mouth and pharynx

      Clinical significance
      It is one of the bacteria that might be implicated indestructive periodontal disease.

      It is an oral commensal often found in association with localized aggressive periodontitis, a severe infection of the periodontium.

      It is also associated with non-oral infections, such as abscesses (abdominal, brain, facial, hand, mediastinal and thyroid) and from cases of actinomycosis, endocarditis, meningitis, pneumonia, septicemia and vertebral osteomyelitis.

  • Gram stain

    • the following information is not yet verified
      Gram negative coccobacillary rods,

      0.3-0.5 x 0.6-1.4 µm,

      (in agar cultures), may occur singly, in pairs or in small (big) clumps and show the tendency to bipolar staining.

      This gives an appearance of a "Morse code" of dots and dashes.

      Cells have a microcapsule.

  • Culture characteristics

    • the following information is not yet verified

      Facultative anaerobic

      5% CO2 improves the growth

      Colonies are small, 0.5-3 mm, no hemolysis, they adhere to the agar and are described as starlike or “crossed cigars”.

      Colonies may sometimes have a rough surface and they become mucoid and non-adherent after repeated subculture.

      When grown in broth bacteria form granules at the bottom and up the sides of the tube (“tiny colonies”), while subsequent cultures become less adherent and exhibit uniform turbidity.

      McConkey no growth

      BBAØ growth

  • Characteristics

  • References

    • James Versalovic et al.(2011) Manual of Clinical Microbiology 10th Edition

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