A Brief Synopsis of A Brief Synopsis of “HACEK” organisms“HACEK” organisms

Michael AddidleMichael Addidle

HACEK ORGANISMSHACEK ORGANISMS

H-H-H. parainfluenzaeH. parainfluenzae A-Aggregatibacter A-Aggregatibacter

actinomycetecomitansactinomycetecomitans - Aggregatibacter aphrophilus and - Aggregatibacter aphrophilus and

paraphrophilus.paraphrophilus. C-Cardiobacterium hominusC-Cardiobacterium hominus E-Eikenella corrodensE-Eikenella corrodens K-Kingella speciesK-Kingella species

What do HACEK organisms have in What do HACEK organisms have in common?common?

Gram negativeGram negative Commensals in oropharyngeal areaCommensals in oropharyngeal area Relatively fastidiousRelatively fastidious Prefer CO2 enriched atmospherePrefer CO2 enriched atmosphere All have a propensity to cause endocarditis, usually All have a propensity to cause endocarditis, usually

secondary to rotten teeth or recent dental treatment or secondary to rotten teeth or recent dental treatment or combination of both.combination of both.• Endocarditis- long interval between first symptoms and Endocarditis- long interval between first symptoms and

dx.dx.• Frequent embolisationFrequent embolisation• May be large vegetations on left sided valves.May be large vegetations on left sided valves.

Can all cause non-endocardial infections also.Can all cause non-endocardial infections also.

Haemophilus parainfluenzaeHaemophilus parainfluenzae

H. aphrophilus and H. H. aphrophilus and H. paraphrophilus have movedparaphrophilus have moved

Cause endocarditis more commonly Cause endocarditis more commonly than H. influenzae but all than H. influenzae but all endocarditis caused by Haemophilus endocarditis caused by Haemophilus is rare.is rare.

A-Aggregatibacter A-Aggregatibacter actinomycetecomitansactinomycetecomitans

Common cause of periodontitisCommon cause of periodontitis Most endocarditis caused by this Most endocarditis caused by this

bacteria have underlying heart bacteria have underlying heart disease.disease.

Star-shaped coloniesStar-shaped colonies

Cardiobacterium hominisCardiobacterium hominis

In contrast to other members of the In contrast to other members of the group, almost exclusively associated group, almost exclusively associated with endocarditiswith endocarditis

May also be commensal of GI tractMay also be commensal of GI tract Characteristic Gram stain: bulbous Characteristic Gram stain: bulbous

ends and irregular staining. May ends and irregular staining. May have a rosette pattern.have a rosette pattern.

..

Eikenella corrodensEikenella corrodens

Oral commensal. May implicated in bite Oral commensal. May implicated in bite infections.infections.

May cause infections at several different May cause infections at several different sites within the body.sites within the body.

Slightly yellow colonies after a few daysSlightly yellow colonies after a few days Bleach like odourBleach like odour Pit into agar.Pit into agar. Beta-lactamase strains are not infrequent.Beta-lactamase strains are not infrequent.

Eikenella corrodensEikenella corrodens

Kingella speciesKingella species K. kingae, K dentrificans, K.oralis, K. potusK. kingae, K dentrificans, K.oralis, K. potus Square ends, uneven decolorisation on Gram Square ends, uneven decolorisation on Gram

stain.stain. May be mildly haemolytic on blood agarMay be mildly haemolytic on blood agar Colonise pharynx of many children 6 months to Colonise pharynx of many children 6 months to

4 years.4 years. Common cause of septic arthritis in this age Common cause of septic arthritis in this age

group.group. Infections in adults usually in Infections in adults usually in

immunocompromised. immunocompromised. Injection of aspirate into BC media improves Injection of aspirate into BC media improves

detection rates.detection rates.

Kingella speciesKingella species

Kingella speciesKingella species

Molecular detectionMolecular detection

In modern blood culture systems, In modern blood culture systems, HACEK organsims grow within 5 HACEK organsims grow within 5 days.days.

16s PCR16s PCR Most useful for heart valvesMost useful for heart valves May also be useful for negative blood May also be useful for negative blood

cultures where high index of cultures where high index of suspicion.suspicion.