HACEK organisms

HACEK organisms are a group of Gram-negative bacteria that are an uncommon cause of infection in humans. The acronym HACEK stands for the genera of bacteria that make up this group: Haemophilus, Aggregatibacter (previously Actinobacillus), Cardiobacterium, Eikenella, and Kingella.

Characteristics

HACEK organisms are part of the normal microflora of the human mouth and throat. They are aerobic, oxidase-positive, non-motile bacteria. These organisms are slow-growing and can be difficult to identify in the laboratory due to their slow growth and the need for special culture media.

Clinical significance

HACEK organisms are most commonly associated with endocarditis, an infection of the heart valves. They are responsible for approximately 3% of all cases of endocarditis. Other infections caused by HACEK organisms include pneumonia, meningitis, arthritis, and cellulitis.

Diagnosis

Diagnosis of HACEK infection is made by blood culture, but can be difficult due to the slow growth of these organisms. Identification may require special culture media and extended incubation times.

Treatment

Treatment of HACEK infections typically involves antibiotics. The choice of antibiotic depends on the specific organism and the site of infection.

See also

• Gram-negative bacteria
• Endocarditis
• Blood culture