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.