HACEK organisms

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The HACEK organisms are a group of fastidious Gram-negative bacteria that are an unusual cause of infective endocarditis, which is an inflammation of the heart due to bacterial infection. [1] HACEK is an abbreviation of the initials of the genera of this group of bacteria: Haemophilus , Aggregatibacter (previously Actinobacillus ), Cardiobacterium , Eikenella , Kingella . [1] The HACEK organisms are a normal part of the human microbiota, living in the oral-pharyngeal region. [2]

Contents

The bacteria were originally grouped because they were thought to be a significant cause of infective endocarditis, but recent research has shown that they are rare and only responsible for 1.4–3.0% of all cases of this disease. [1]

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. [1] Some reviews of medical literature on HACEK organisms use the older classification, [3] but recent papers are using the new classification. [4] [5] [6]

A list of HACEK organisms:

Presentation

All of these organisms are part of the normal oropharyngeal flora, which grow slowly (up to 14 days), prefer a carbon dioxide–enriched atmosphere, and share an enhanced capacity to produce endocardial infections, especially in young children. Collectively, 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 drugs intravenously. They have been a frequent cause of culture-negative endocarditis. Culture-negative refers to an inability to produce a colony on regular agar plates because these bacteria 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, arthritis, osteomyelitis, and periodontal infections.

Treatment

The treatment of choice for HACEK organisms in endocarditis is the third-generation cephalosporin and β-Lactam antibiotic ceftriaxone. Ampicillin (a penicillin), combined with low-dose gentamicin (an aminoglycoside) is another therapeutic option. [7]

Related Research Articles

<span class="mw-page-title-main">Septic arthritis</span> Inflammation of a joint due to infection

Acute septic arthritis, infectious arthritis, suppurative arthritis, pyogenic arthritis, osteomyelitis, or joint infection is the invasion of a joint by an infectious agent resulting in joint inflammation. Generally speaking, symptoms typically include redness, heat and pain in a single joint associated with a decreased ability to move the joint. Onset is usually rapid. Other symptoms may include fever, weakness and headache. Occasionally, more than one joint may be involved, especially in neonates, younger children and immunocompromised individuals. In neonates, infants during the first year of life, and toddlers, the signs and symptoms of septic arthritis can be deceptive and mimic other infectious and non-infectious disorders.

<i>Haemophilus influenzae</i> Species of bacterium

Haemophilus influenzae is a Gram-negative, non-motile, coccobacillary, facultatively anaerobic, capnophilic pathogenic bacterium of the family Pasteurellaceae. The bacteria are mesophilic and grow best at temperatures between 35 and 37 °C.

<i>Actinomyces</i> Genus of bacteria

Actinomyces is a genus of the Actinomycetia class of bacteria. They all are Gram-positive and facultatively anaerobic, growing best under anaerobic conditions. Actinomyces species may form endospores, and while individual bacteria are rod-shaped, Actinomyces colonies form fungus-like branched networks of hyphae. The aspect of these colonies initially led to the incorrect assumption that the organism was a fungus and to the name Actinomyces, "ray fungus".

<span class="mw-page-title-main">Pasteurellaceae</span> Family of bacteria

The Pasteurellaceae comprise a large family of Gram-negative bacteria. Most members live as commensals on mucosal surfaces of birds and mammals, especially in the upper respiratory tract. Pasteurellaceae are typically rod-shaped, and are a notable group of facultative anaerobes. Their biochemical characteristics can be distinguished from the related Enterobacteriaceae by the presence of oxidase, and from most other similar bacteria by the absence of flagella.

<i>Eikenella corrodens</i> Species of bacterium

Eikenella corrodens is a Gram-negative facultative anaerobic bacillus that can cause severe invasive disease in humans. It was first identified by M. Eiken in 1958, who called it Bacteroides corrodens. E. corrodens is a rare pericarditis associated pathogen. It is a fastidious, slow growing, human commensal bacillus, capable of acting as an opportunistic pathogen and causing abscesses in several anatomical sites, including the liver, lung, spleen, and submandibular region. E. corrodens could independently cause serious infection in both immunocompetent and immunocompromised hosts.

Aggregatibacter actinomycetemcomitans is a Gram-negative, facultative anaerobe, nonmotile bacterium that is often found in association with localized aggressive periodontitis, a severe infection of the periodontium. It is also suspected to be involved in chronic periodontitis. Less frequently, A. actinomycetemcomitans is associated with nonoral infections such as endocarditis. Its role in aggressive periodontitis was first discovered by Danish-born periodontist Jørgen Slots, a professor of dentistry and microbiology at the University of Southern California School of Dentistry.

<i>Actinobacillus</i> Genus of bacteria

Actinobacillus is a genus of Gram-negative, nonmotile and non-spore-forming, oval to rod-shaped bacteria occurring as parasites or pathogens in mammals, birds, and reptiles. It is a member of the family Pasteurellaceae. The bacteria are facultatively anaerobic or aerobic, capable of fermenting carbohydrates, and of reducing nitrates. The genomic DNA contains between 40 and 47 mol % guanine plus cytosine.

<i>Kingella kingae</i> Species of bacterium

Kingella kingae is a species of Gram-negative facultative anaerobic β-hemolytic coccobacilli. First isolated in 1960 by Elizabeth O. King, it was not recognized as a significant cause of infection in young children until the 1990s, when culture techniques had improved enough for it to be recognized. It is best known as a cause of septic arthritis, osteomyelitis, spondylodiscitis, bacteraemia, and endocarditis, and less frequently lower respiratory tract infections and meningitis.

<i>Kingella</i> Genus of bacteria

Kingella is a genus of bacteria of the family Neisseriaceae. It belongs to the HACEK group of fastidious Gram-negative bacteria that tend to cause endocarditis. Kingella kingae is its type species.

Cardiobacterium hominis /ˌkɑːrdiəʊbækˈtɪəriəm ˈhɒmɪnɪs/ is a microaerophilic, pleomorphic, fastidious, Gram-negative bacterium part of the Cardiobacteriaceae family and the HACEK group. It is most commonly found in the human microbiota, specifically the oropharyngeal region including the mouth and upper part of the respiratory tract. It is one of the causes of endocarditis, a life-threatening inflammation close to the heart's inner lining and valves. While infections caused by Cardiobacterium hominis are uncommon, various clinical manifestations are linked to the bacterium, including meningitis, septicemia, and bone infections.

<span class="mw-page-title-main">Pharynx</span> Part of the throat that is behind the mouth and nasal cavity

The pharynx is the part of the throat behind the mouth and nasal cavity, and above the esophagus and trachea. It is found in vertebrates and invertebrates, though its structure varies across species. The pharynx carries food to the esophagus and air to the larynx. The flap of cartilage called the epiglottis stops food from entering the larynx.

Aggregatibacter is a genus in the phylum Pseudomonadota (Bacteria), which contains three species, namely:

Haemophilus parainfluenzae is a species of Haemophilus.

Aggregatibacter aphrophilus is a species of bacteria. It is one of the HACEK organisms.

Periodontal pathogens are bacteria that have been shown to significantly contribute to periodontitis.

Suttonella indologenes, formerly Kingella indologenes, is a Gram-negative rod-shaped bacterium of the family Cardiobacteriaceae. Like other members of its family, it is a bacterium that is assumed to be normally present in the respiratory tract. It has been found to rarely cause endocarditis, an infection of the heart valves. It also been found in the eye. It may cause eye infections. Little is known about it as a bacterium other than its structure and biochemical composition. Like other members in its family, it has a characteristic 16S ribosomal RNA which consists of 1474 base pairs.

Cardiobacterium valvarum is a Gram-negative species of bacteria belonging to the Cardiobacterium genus. It belongs to the HACEK group of fastidious bacteria that are present in normal oropharyngeal flora and can develop into infective endocarditis.

N-glycosyltransferase is an enzyme in prokaryotes which transfers individual hexoses onto asparagine sidechains in substrate proteins, using a nucleotide-bound intermediary, within the cytoplasm. They are distinct from regular N-glycosylating enzymes, which are oligosaccharyltransferases that transfer pre-assembled oligosaccharides. Both enzyme families however target a shared amino acid sequence asparagine—-any amino acid except proline—serine or threonine (N–x–S/T), with some variations.

Actinobacillus equuli is a gram-negative, non-motile rod bacteria from the family Pasteurellaceae.

Aggregatibacter segnis is a species of bacteria. A. segnis can be cultured on chocolate agar.

References

  1. 1 2 3 4 5 Nørskov-Lauritsen, N (Apr 2014). "Classification, identification, and clinical significance of haemophilus and aggregatibacter species with host specificity for humans". Clinical Microbiology Reviews. 27 (2): 214–40. doi:10.1128/CMR.00103-13. PMC   3993099 . PMID   24696434.
  2. ↑ Feder HM, Jr; Roberts, JC; Salazar, J; Leopold, HB; Toro-Salazar, O (Jun 2003). "HACEK endocarditis in infants and children: two cases and a literature review". The Pediatric Infectious Disease Journal. 22 (6): 557–62. doi:10.1097/01.inf.0000069795.12338.cf. PMID   12799515. S2CID   3238233.
  3. ↑ Raza, SS; Sultan, OW; Sohail, MR (Aug 2010). "Gram-negative bacterial endocarditis in adults: state-of-the-heart". Expert Review of Anti-infective Therapy. 8 (8): 879–85. doi:10.1586/eri.10.76. PMID   20695743. S2CID   48457.
  4. ↑ Chambers, ST; Murdoch, D; Morris, A; Holland, D; Pappas, P; Almela, M; Fernández-Hidalgo, N; Almirante, B; Bouza, E; Forno, D; del Rio, A; Hannan, MM; Harkness, J; Kanafani, ZA; Lalani, T; Lang, S; Raymond, N; Read, K; Vinogradova, T; Woods, CW; Wray, D; Corey, GR; Chu, VH; International Collaboration on Endocarditis Prospective Cohort Study, Investigators (2013). "HACEK infective endocarditis: characteristics and outcomes from a large, multi-national cohort". PLOS ONE. 8 (5): e63181. Bibcode:2013PLoSO...863181C. doi: 10.1371/journal.pone.0063181 . PMC   3656887 . PMID   23690995.
  5. 1 2 3 4 Sen Yew, H; Chambers, ST; Roberts, SA; Holland, DJ; Julian, KA; Raymond, NJ; Beardsley, J; Read, KM; Murdoch, DR (Jun 2014). "Association between HACEK bacteraemia and endocarditis". Journal of Medical Microbiology. 63 (Pt 6): 892–5. doi: 10.1099/jmm.0.070060-0 . PMID   24681996. S2CID   206195338.
  6. 1 2 3 Wassef, N; Rizkalla, E; Shaukat, N; Sluka, M (May 15, 2013). "HACEK-induced endocarditis". BMJ Case Reports. 2013: bcr2012007359. doi:10.1136/bcr-2012-007359. PMC   3670033 . PMID   23682079.
  7. ↑ , eMedicine, HACEK organism infection. June 2005.
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