35. ACEK | Notion

What they are

The HACEK group (H= Haemophilus and covered here)

URT commensals
Potential to invade à sterile site infections, endocarditis (3% all IE)
Cause of Cx-neg IE

Genus	Aggregatibacter	Cardiobacterium
ID (spp) – main	actinomycetemcomitans aprophilus
segnis
kilianii	Hominis
valvarum	corrodens
New since 2019:
exigua
halliae
longinqua	kingae
dentrificans
potus
oralis
negevensis
Site	URT
Mouth	URT	URT
Mouth
?UGI tract	URT
Clinical syndromes	IE
Dental disease	IE	IE
Bite infection	IE
Kid: BJI

| Risk Factors | Patient

Poor dental health (50% IE cases assc with recent dental work / poor dentition)
Structurally abnormal heart valve (prosthetic or damaged native) | | --- | --- |

Lab ID

Genus	Growth in air or CO2	Micro	Colony	Size
Aggregatibacter actinomycetemcomitans	Air
May require CO2	Nonbranching Coccobacilli	Star-shaped
Nonhaemolytic
Rough surface
Can be pitting	1mm @24h	+	+	-
Aggregatibacter
Aphrophilus	Air and CO2		Yellow
Nonhaemolytic	1.5mm @24h	-	-	-
Cardiobacterium
hominis & valvarum	May require CO2	Pleomorphic GNB	Smooth, convex, opaque
Slight α-haem	1-2mm @48h	-	+	-
Eikenella
Corrodens	5-10% CO2	Small GNB	Small, moist, clear centres
50% ‘corroding’	0.5-1mm @48h	-	+	-
Kingella
kingae	CO2 not needed	Gm V
Coccobacillus
Short, tapered ends	Spreading corroding or smooth convex
Can be mucoid with small zone β-haemolysis		-	+	-

Confirm: MALDI,16S RNA PCR, Reflab report if available

Treatment

Endocarditis Rx Recommendations: (NVE: 4 weeks, PVE: 6 weeks)

Guideline	ABx
BSAC 2012	3G-Ceph (or Amox if known S)
+Gent for 1st 14d

Cipro can also be used | | ESC 2015 | Ceftriaxone 2g od If S: Amox 12g/d + Gent 3mg/kg/d (in 2-3 doses) Cipro 750mg bd (or 400mg tid) | | AHA 2015 | 3-4G Ceph If S: Amox 12g/d Recommend against Gentamicin Quinolones if can’t tolerate Cephs (e.g. Cipro 500mg bd) |