From the Guidelines
The HACEK group is a collection of slow-growing, gram-negative bacteria that are known to cause infective endocarditis, and the most effective treatment is ceftriaxone (2g IV daily for 4 weeks) for native valve endocarditis, 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.
Clinical Significance
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 responsible for approximately 5-10% of all cases of community-acquired native valve endocarditis in patients who are not intravenous drug users, as stated in the guidelines by the American Heart Association 1.
Treatment
Treatment typically involves ceftriaxone, which is the preferred therapy due to its effectiveness against HACEK microorganisms, as shown in the guidelines 1. The duration of therapy for native valve endocarditis is 4 weeks, and for prosthetic valve endocarditis, the duration is 6 weeks.
Key Points
- The HACEK group is a collection of slow-growing, gram-negative bacteria that cause infective endocarditis.
- Ceftriaxone is the preferred treatment for HACEK endocarditis.
- Treatment duration is 4 weeks for native valve endocarditis and 6 weeks for prosthetic valve endocarditis.
- HACEK organisms are often difficult to culture, requiring extended incubation periods of up to 2-3 weeks for growth, as mentioned in the study 1.
From the Research
Definition of HACEK Group
- The HACEK group refers to a collection of Gram-negative bacteria, including Haemophilus spp., Aggregatibacter actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae 2, 3.
- These bacteria are part of the normal microbiota of the oral and upper respiratory tract in humans 3.
Characteristics of HACEK Organisms
- HACEK organisms are fastidious, meaning they are difficult to culture and require specific conditions to grow 3, 4.
- They are responsible for 1-3% of all infective endocarditis cases, with a favorable prognosis if properly identified and treated 2, 3.
- The most common presenting symptoms of HACEK endocarditis include fever, splenomegaly, new or changing murmur, and microvascular phenomena 5.
Diagnosis and Treatment of HACEK Endocarditis
- Diagnosis of HACEK endocarditis can be made using blood cultures, which may take several days to become positive 5.
- Treatment typically involves third-generation cephalosporins, such as ceftriaxone, or fluoroquinolones, with a favorable outcome in 80-90% of cases 2, 3.
- Surgical intervention may be necessary in some cases, particularly for patients with prosthetic valves or severe valve damage 2, 6.
Epidemiology and Prognosis of HACEK Endocarditis
- The incidence of HACEK endocarditis is estimated to be around 0.14 per 100,000 person-years 5.
- The overall survival rate for patients with HACEK endocarditis is around 87%, with a low mortality rate of 2% 5, 6.
- HACEK endocarditis is often associated with underlying heart disease or prosthetic valves, and can have a significant impact on patient outcomes if left untreated or misdiagnosed 2, 3.