From the Guidelines
The HACEK group is a collection of fastidious gram-negative bacteria that are known causes of infective endocarditis, and the most effective treatment is ceftriaxone (2g IV daily for 4 weeks) as recommended by the American Heart Association 1.
Definition of HACEK Group
The HACEK group is an acronym that stands for Haemophilus species (H. parainfluenzae, H. aphrophilus, H. paraphrophilus), Aggregatibacter species (formerly Actinobacillus actinomycetemcomitans), Cardiobacterium hominis, Eikenella corrodens, and Kingella species.
Characteristics of HACEK Organisms
These organisms are part of the normal oral flora and can enter the bloodstream during dental procedures or with poor oral hygiene. HACEK organisms are slow-growing bacteria that require specialized culture techniques and extended incubation periods (up to 21 days) for detection.
Treatment of HACEK Endocarditis
When treating HACEK endocarditis, ceftriaxone (2g IV daily for 4 weeks) is typically the recommended antibiotic regimen 1, though fluoroquinolones may be used in patients with beta-lactam allergies. The American Heart Association recommends ceftriaxone as the first-line treatment for HACEK endocarditis, with a duration of therapy of 4 weeks for native valve endocarditis and 6 weeks for prosthetic valve endocarditis 1.
Epidemiology of HACEK Endocarditis
HACEK endocarditis accounts for approximately 5-10% of all cases of infective endocarditis in patients who are not intravenous drug users 1. The prognosis of HACEK endocarditis is generally better compared to endocarditis caused by more virulent organisms like Staphylococcus aureus.
Key Points
- The HACEK group is a collection of fastidious gram-negative bacteria that are known causes of infective endocarditis.
- The most effective treatment is ceftriaxone (2g IV daily for 4 weeks) as recommended by the American Heart Association 1.
- HACEK organisms are slow-growing bacteria that require specialized culture techniques and extended incubation periods (up to 21 days) for detection.
- HACEK endocarditis accounts for approximately 5-10% of all cases of infective endocarditis in patients who are not intravenous drug users 1.
From the Research
Definition of HACEK Group
- The HACEK group refers to a collection of bacteria that includes Haemophilus spp., Aggregatibacter actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae 2, 3, 4, 5, 6.
- These bacteria are fastidious gram-negative organisms that are part of the normal microbiota of the oral and upper respiratory tract in humans 3.
Characteristics of HACEK Endocarditis
- HACEK endocarditis is a rare cause of infective endocarditis, responsible for approximately 1-3% of cases 2, 3, 4, 5, 6.
- It mostly affects patients with underlying heart disease or prosthetic valves, and is characterized by an insidious course, with a mean diagnosis delay of 1-3 months 3.
- The clinical manifestations of HACEK endocarditis include fever, splenomegaly, new or changing murmur, and microvascular phenomena 4.
Diagnosis and Treatment of HACEK Endocarditis
- The diagnosis of HACEK endocarditis relies on positive blood cultures for any of the HACEK organisms in the setting of no definite focus of infection 2.
- Treatment with ceftriaxone or a fluoroquinolone is recommended, even without obtaining antibiotic susceptibilities 2.
- The decision to proceed with surgical intervention should be individualized, and the overall outcome of HACEK endocarditis is excellent with a low in-hospital mortality rate 2, 6.
Epidemiology and Outcomes of HACEK Endocarditis
- The incidence of HACEK endocarditis is estimated to be 0.14 per 100,000 person-years 4.
- The overall survival rate for patients with HACEK endocarditis is high, ranging from 87% to 96% 4, 6.
- HACEK endocarditis is associated with a younger age, a higher prevalence of immunologic/vascular manifestations and stroke, but a lower prevalence of congestive heart failure and death 6.