A Brief Synopsis of

1
A Brief Synopsis of HACEK organisms

• Michael Addidle

2
HACEK ORGANISMS

• H-H. parainfluenzae
• A-Aggregatibacter actinomycetecomitans
• - Aggregatibacter aphrophilus and paraphrophilus.
• C-Cardiobacterium hominus
• E-Eikenella corrodens
• K-Kingella species

3
What do HACEK organisms have in common?

• Gram negative
• Commensals in oropharyngeal area
• Relatively fastidious
• Prefer CO2 enriched atmosphere
• All have a propensity to cause endocarditis,
  usually secondary to rotten teeth or recent
  dental treatment or combination of both.
• Endocarditis- long interval between first
  symptoms and dx.
• Frequent embolisation
• May be large vegetations on left sided valves.
• Can all cause non-endocardial infections also.

4
Haemophilus parainfluenzae

• H. aphrophilus and H. paraphrophilus have moved
• Cause endocarditis more commonly than H.
  influenzae but all endocarditis caused by
  Haemophilus is rare.

5
A-Aggregatibacter actinomycetecomitans

• Common cause of periodontitis
• Most endocarditis caused by this bacteria have
  underlying heart disease.
• Star-shaped colonies

6
Cardiobacterium hominis

• In contrast to other members of the group, almost
  exclusively associated with endocarditis
• May also be commensal of GI tract
• Characteristic Gram stain bulbous ends and
  irregular staining. May have a rosette pattern.
• .

7
Eikenella corrodens

• Oral commensal. May implicated in bite
  infections.
• May cause infections at several different sites
  within the body.
• Slightly yellow colonies after a few days
• Bleach like odour
• Pit into agar.
• Beta-lactamase strains are not infrequent.

8
Eikenella corrodens
9
Kingella species

• K. kingae, K dentrificans, K.oralis, K. potus
• Square ends, uneven decolorisation on Gram stain.
• May be mildly haemolytic on blood agar
• Colonise pharynx of many children 6 months to 4
  years.
• Common cause of septic arthritis in this age
  group.
• Infections in adults usually in
  immunocompromised.
• Injection of aspirate into BC media improves
  detection rates.

10
Kingella species
11
Kingella species
12
Molecular detection

• In modern blood culture systems, HACEK organsims
  grow within 5 days.
• 16s PCR
• Most useful for heart valves
• May also be useful for negative blood cultures
  where high index of suspicion.