HACEK organism: Difference between revisions
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==Overview== | ==Overview== | ||
HACEK organisms is a group of fastidious, pleomorphic [[Gram negative]] bacilli which form part of the oropharynx commensals and account for about 3% of cases of [[endocarditis]] | HACEK organisms is a group of fastidious, pleomorphic [[Gram negative]] bacilli which form part of the oropharynx commensals and are slow growing and require enhanced carbon dioxide tension for recovery in culture. HACEK organisms account for about 3% of cases of [[endocarditis]], typically with an insidious onset and subacute course.<ref name="pmid2346159">{{cite journal | author = Steckelberg JM, Melton LJ, Ilstrup DM, Rouse MS, Wilson WR | title = Influence of referral bias on the apparent clinical spectrum of infective endocarditis | journal = Am. J. Med. | volume = 88 | issue = 6 | pages = 582–8 | year = 1990 | month = June | pmid = 2346159 |doi = | url = | issn = }}</ref> HACEK refers to the initials of organisms including: | ||
* ''[[Haemophilus parainfluenzae]]'', ''[[Aggregatibacter aphrophilus]]'' (formerly ''[[Haemophilus aphrophilus]]'' and ''[[Haemophilus paraphrophilus]]'') | * ''[[Haemophilus parainfluenzae]]'', ''[[Aggregatibacter aphrophilus]]'' (formerly ''[[Haemophilus aphrophilus]]'' and ''[[Haemophilus paraphrophilus]]'') | ||
Revision as of 10:22, 1 May 2013
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Template:GCC
Overview
HACEK organisms is a group of fastidious, pleomorphic Gram negative bacilli which form part of the oropharynx commensals and are slow growing and require enhanced carbon dioxide tension for recovery in culture. HACEK organisms account for about 3% of cases of endocarditis, typically with an insidious onset and subacute course.[1] HACEK refers to the initials of organisms including:
- Haemophilus parainfluenzae, Aggregatibacter aphrophilus (formerly Haemophilus aphrophilus and Haemophilus paraphrophilus)
Pathophysiology
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.
In addition to valvular infections in the heart, these organisms can also produce other infections such as bacteremia, abscesses, peritonitis, otitis media, conjunctivitis, pneumonia, peritonitis, arthritis and osteomyelitis, and periodontal infections.
Epidemiology and Demographics
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.
Diagnosis
Laboratory Studies
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).
Treatment
The treatment of choice for HACEK organisms in endocarditis is ceftriaxone, a cephalosporin antibiotic. The dose is 2 g I.V. daily as a single dose for 4 weeks.
References
- ↑ Steckelberg JM, Melton LJ, Ilstrup DM, Rouse MS, Wilson WR (1990). "Influence of referral bias on the apparent clinical spectrum of infective endocarditis". Am. J. Med. 88 (6): 582–8. PMID 2346159. Unknown parameter
|month=ignored (help) - ↑ Nørskov-Lauritsen N, Kilian M (2006). "Reclassification of Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus, Haemophilus paraphrophilus and Haemophilus segnis as Aggregatibacter actinomycetemcomitans gen. nov., comb. nov., Aggregatibacter aphrophilus comb. nov. and Aggregatibacter segnis comb. nov., and emended description of Aggregatibacter aphrophilus to include V factor-dependent and V factor-independent isolates". Int. J. Syst. Evol. Microbiol. 56 (Pt 9): 2135–46. doi:10.1099/ijs.0.64207-0. PMID 16957111. Unknown parameter
|month=ignored (help)