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The HACEK organisms are a group of fastidious Gram-negative bacteria that are an unusual cause of infective endocarditis (IE), which is an inflammation of the heart due to bacterial infection. HACEK is an abbreviation of the initials of the genera of this group of bacteria: ''Haemophilus'', ''Aggregatibacter'' (previously ''Actinobacillus''), ''Cardiobacterium'', ''Eikenella corrodens'', ''Kingella''.〔 The HACEK organisms are a normal part of the human flora, living in the oral-pharyngeal region. The bacteria were originally grouped because they were thought to be a significant cause of infective endocarditis, but recent literature has shown that they are rare and only responsible for 1.4–3% of all cases of this disease.〔 ==Organisms== HACEK originally referred to ''Haemophilus parainfluenzae'', ''Haemophilus aphrophilus'', ''Actinobacillus actinomycetemcomitans'', ''Cardiobacterium hominis'', ''Eikenella corrodens'', and ''Kingella kingae''. However, taxonomic rearrangements have changed the A to ''Aggregatibacter'' species and the H to ''Haemophilus'' species to reflect the recategorization and novel identification of many of the species in these genera.〔 Some reviews of medical literature on HACEK organisms use the older classification, but recent papers are using the new classification.〔〔 A list of HACEK organisms: *''Haemophilus'' species * *''Haemophilus parainfluenzae''〔 * *''Haemophilus influenzae''. The incidence of endocarditis due to ''H. influenzae'' declined after the introduction of the Hib vaccine.〔 * *''Haemophilus haemolyticus'' * *''Haemophilus parahaemolyticus''〔 *''Aggregatibacter'' * *''Aggregatibacter actinomycetemcomitans'' (previously ''Actinobacillus actinomycetemcomitans'') * *''Aggregatibacter segnis'' * *''Aggregatibacter aphrophilus'' (previously ''Haemophilus aphrophilus'') * *''Aggregatibacter paraphrophilus'' (previously ''Haemophilus aphrophilus'') *''Cardiobacterium'' * *''Cardiobacterium hominis''. Most common species in the ''Cardiobacterium'' genus. * *''Cardiobacterium valvarum'' *''Eikenella'' * *''Eikenella corrodens'' *''Kingella'' * *''Kingella kingae''. Most common species in the ''Kingella'' genus. * *''Kingella denitrificans''〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「HACEK endocarditis」の詳細全文を読む スポンサード リンク
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