A HACEK organism is one of a set of slow-growing Gram negative bacteria that form a normal part of the human flora. They are a frequent cause of endocarditis in children. Gram-negative bacteria are those that do not retain crystal violet dye in the Gram staining protocol. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... The human body contains a large number of bacteria, most of them performing tasks that are useful or even essential to human survival. ... Endocarditis is an inflammation of the inner layer of the heart, the endocardium. ... Clinical Examination Pediatrics (also spelled paediatrics) is the branch of medicine that deals with the medical care of infants, children, and adolescents (from newborn to age 16-21, depending on the country). ...

The name is formed from their initials:

• Haemophilus aphrophilus, Haemophilus parainfluenzae and Haemophilus paraphrophilus
• Actinobacillus actinomycetemcomitans
• Cardiobacterium hominis
• Eikenella corrodens
• Kingella kingae

Template:Bacterial diseases Eikenella corrodens is a fastidious Gram-negative facultative anaerobic bacillus. ...

All of these organisms are part of the normal oropharyngeal flora which grow slowly, prefer a carbon dioxide–enriched atmosphere and share an enhanced capacity to produce endocardial infections, especially in young children. Collectivelly, they account for 5-10% of cases of infective endocarditis involving native valves and are the most common gram-negative cause of endocarditis among people who do not use IV drugs. Because of their fastidious growth requirements, they have been a frequent cause of culture-negative endocarditis. Culture negative refers to its inability to produce a colony on regular agar plates, this is because they are fastidious (require a specific nutrient).

In addition to valvular infections in the heart, they can also produce other infections such as bacteremia, abscess, peritonitis, otitis media, conjunctivitis, pneumonia, peritonitis, arthritis and osteomyelitis, and periodontal infections.

The treatment of choice for HACEK organisms in endocarditis is ceftriaxome, a cephalosporin antibiotic.