The HACEK Group of Gram-Negative Bacilli

Christina F. Burger, PharmD; Marcus W. Brown, PharmD; Jeffrey A. Kyle, PharmD, BCPS


US Pharmacist 

In This Article

Abstract and Introduction


ACEK is an acronym for a group of organisms that are small, fastidious gram-negative bacilli.[1] The HACEK organisms include Haemophilus species, Aggregatibacter actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae.[2,3] These organisms commonly colonize the human oropharynx as normal, indigenous flora that could cause mouth infections.[4] HACEK organisms are most often associated with infective endocarditis, accounting for up to 10% of cases.[1,5–7] Rarely, HACEK organisms may cause severe systemic infections.[4] This article will briefly review the HACEK pathogens, resulting infections, and common treatment approaches.