HACEK organism: Difference between revisions

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HACEK organisms is a group of fastidious, slow growing, pleomorphic [[Gram negative]] bacilli which form part of the oropharynx commensals and require enhanced carbon dioxide tension for recovery in culture. HACEK refers to the initials of organisms including:  
HACEK organisms is a group of fastidious, slow growing, pleomorphic [[Gram negative]] bacilli which form part of the oropharynx commensals and require enhanced carbon dioxide tension for recovery in culture. HACEK refers to the initials of organisms including:  


* ''[[Haemophilus parainfluenzae]]'', ''[[Aggregatibacter aphrophilus]]'' (formerly ''[[Haemophilus aphrophilus]]'' and ''[[Haemophilus paraphrophilus]]'')<ref name="pmid16957111">{{cite journal | author = Nørskov-Lauritsen N, Kilian M | title = 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 | journal = Int. J. Syst. Evol. Microbiol. | volume = 56 | issue = Pt 9 |pages = 2135–46 | year = 2006 | month = September | pmid = 16957111 | doi = 10.1099/ijs.0.64207-0 | url = | issn = }}</ref>
* ''[[Haemophilus influenzae]]'', ''[[Haemophilus parainfluenzae]]'', ''[[Aggregatibacter aphrophilus]]'' (formerly ''[[Haemophilus aphrophilus]]'' and ''[[Haemophilus paraphrophilus]]'')<ref name="pmid16957111">{{cite journal | author = Nørskov-Lauritsen N, Kilian M | title = 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 | journal = Int. J. Syst. Evol. Microbiol. | volume = 56 | issue = Pt 9 |pages = 2135–46 | year = 2006 | month = September | pmid = 16957111 | doi = 10.1099/ijs.0.64207-0 | url = | issn = }}</ref>


* ''[[Aggregatibacter actinomycetemcomitans]]'' (formerly ''[[Actinobacillus actinomycetemcomitans]]'')<ref name="pmid16957111">{{cite journal | author = Nørskov-Lauritsen N, Kilian M | title = 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 | journal = Int. J. Syst. Evol. Microbiol. | volume = 56 | issue = Pt 9 | pages = 2135–46 | year = 2006 | month = September | pmid = 16957111 | doi = 10.1099/ijs.0.64207-0 | url = | issn = }}</ref>
* ''[[Aggregatibacter actinomycetemcomitans]]'' (formerly ''[[Actinobacillus actinomycetemcomitans]]'')<ref name="pmid16957111">{{cite journal | author = Nørskov-Lauritsen N, Kilian M | title = 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 | journal = Int. J. Syst. Evol. Microbiol. | volume = 56 | issue = Pt 9 | pages = 2135–46 | year = 2006 | month = September | pmid = 16957111 | doi = 10.1099/ijs.0.64207-0 | url = | issn = }}</ref>

Revision as of 15:02, 1 May 2013

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Template:GCC

Overview

HACEK organisms is a group of fastidious, slow growing, pleomorphic Gram negative bacilli which form part of the oropharynx commensals and require enhanced carbon dioxide tension for recovery in culture. HACEK refers to the initials of organisms including:

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

HACEK organisms account for about 3% of cases of endocarditis,[2] with an insidious onset and subacute course. They are the most common Gram negative casue of endocarditis among people who do not use intravenous drugs. Most patients with HACEK endocarditis have preexisting cardiac defects or prior dental manipulations. The duration of symptoms prior to diagnosis is reported to be longer than 2 weeks but shorter than 6 months.[3]

Diagnosis

Laboratory Studies

Given the fastidious growth requirements, HACEK bacteria are a recognized cause of culture-negative endocarditis. The organisms can be identified after subculture on 5 to 8% sheep blood and chocolate agar at 35 to 37°C for 48 to 72 hours in an aerobic atmosphere containing 5 to 10% CO2.[4] Although the mean duration for incubation of blood cultures until detection of growth is 3 to 5 days, up to 30 days may be required. Biochemical properties are used to differentiate members of the HACEK group. However, biopatterns may be varied by inoculum volume and growth conditions, which prompts the utilization of molecular techniques such as 16S ribosomal RNA sequencing.[5][6][7]

Treatment

The treatment of endocarditis caused by HACEK organisms should be based on antimicrobial susceptibility tests, including tests for β-lactamase ctivity. Since many of these organisms are slow growing, such tests can be problematic. Currently, third-generation cephalosporins, including cefotaxime or ceftriaxone, are the drugs of choice for treating endocarditis caused by the HACEK organisms.[8] Native-valve endocarditis should be treated for 4 weeks of antiobiotics, whereas prosthetic-valve endocarditis requires 6 weeks of therapy. HACEK endocarditis is associated with a favorable prognosis, with a cure rate of 82 to 87% of patients with medical treatment alone or associated with surgery.[9]

References

  1. 1.0 1.1 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)
  2. 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)
  3. Das M, Badley AD, Cockerill FR, Steckelberg JM, Wilson WR (1997). "Infective endocarditis caused by HACEK microorganisms". Annu. Rev. Med. 48: 25–33. doi:10.1146/annurev.med.48.1.25. PMID 9046942.
  4. Brouqui P, Raoult D (2001). "Endocarditis due to rare and fastidious bacteria". Clin. Microbiol. Rev. 14 (1): 177–207. doi:10.1128/CMR.14.1.177-207.2001. PMC 88969. PMID 11148009. Unknown parameter |month= ignored (help)
  5. Das I, DeGiovanni JV, Gray J (1997). "Endocarditis caused by Haemophilus parainfluenzae identified by 16S ribosomal RNA sequencing". J. Clin. Pathol. 50 (1): 72–4. PMC 499719. PMID 9059363. Unknown parameter |month= ignored (help)
  6. Hamed KA, Dormitzer PR, Su CK, Relman DA (1994). "Haemophilus parainfluenzae endocarditis: application of a molecular approach for identification of pathogenic bacterial species". Clin. Infect. Dis. 19 (4): 677–83. PMID 7528552. Unknown parameter |month= ignored (help)
  7. Wormser GP, Bottone EJ, Tudy J, Hirschman SZ (1978). "Case report. Cardiobacterium hominis: review of prior infections and report of endocarditis on a fascia lata prosthetic heart valve". Am. J. Med. Sci. 276 (1): 117–26. PMID 727215.
  8. Loscalzo, Joseph; Longo, Dan L.; Fauci, Anthony S.; Dennis L. Kasper; Hauser, Stephen L (2011). Harrison's Principles of Internal Medicine, 18th Edition. McGraw-Hill Professional. ISBN 0-07-174889-X.
  9. Berbari EF, Cockerill FR, Steckelberg JM (1997). "Infective endocarditis due to unusual or fastidious microorganisms". Mayo Clin. Proc. 72 (6): 532–42. doi:10.1016/S0025-6196(11)63302-8. PMID 9179137. Unknown parameter |month= ignored (help)

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