Eikenella corrodens

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Scientific classification
Eikenella corrodens on chocolate agar after 36 hours. Notice how colonies pit the agar; A distinct characteristic of this species. Eikenella corrodens.jpg
Eikenella corrodens on chocolate agar after 36 hours. Notice how colonies pit the agar; A distinct characteristic of this species.

Eikenella corrodens is a fastidious Gram-negative facultative anaerobic bacillus. It was first identified by M. Eiken in 1958, who called it Bacteroides corrodens. [1]

Growth medium liquid or gel used for the growth of microorganisms or cells

A growth medium or culture medium is a solid, liquid or semi-solid designed to support the growth of microorganisms or cells, or small plants like the moss Physcomitrella patens. Different types of media are used for growing different types of cells.



Eikenella corrodens is a pleomorphic bacillus that sometimes appears coccobacillary and typically creates a depression (or "pit") in the agar on which it is growing. Only half produce the pitting of the agar considered characteristic.[ citation needed ]


A coccobacillus is a type of bacterium with a shape intermediate between cocci and bacilli. Coccobacilli, then, are very short rods which may be mistaken for cocci.

It grows in aerobic and anaerobic conditions, but requires an atmosphere enhanced by 310% carbon dioxide.[ citation needed ]

Carbon dioxide chemical compound

Carbon dioxide is a colorless gas with a density about 60% higher than that of dry air. Carbon dioxide consists of a carbon atom covalently double bonded to two oxygen atoms. It occurs naturally in Earth's atmosphere as a trace gas. The current concentration is about 0.04% (410 ppm) by volume, having risen from pre-industrial levels of 280 ppm. Natural sources include volcanoes, hot springs and geysers, and it is freed from carbonate rocks by dissolution in water and acids. Because carbon dioxide is soluble in water, it occurs naturally in groundwater, rivers and lakes, ice caps, glaciers and seawater. It is present in deposits of petroleum and natural gas. Carbon dioxide is odorless at normally encountered concentrations. However, at high concentrations, it has a sharp and acidic odor.

The colonies are small and greyish, they produce a greenish discoloration of the underlying agar, and smell faintly of bleach (hypochlorite).[ citation needed ]

Hypochlorite anion

In chemistry, hypochlorite is an ion with the chemical formula ClO. It combines with a number of cations to form hypochlorites, which may also be regarded as the salts of hypochlorous acid. Common examples include sodium hypochlorite and calcium hypochlorite.

They are oxidase-positive, catalase-negative, urease-negative, and indole-negative, and reduce nitrate to nitrite.[ citation needed ]

An oxidase is an enzyme that catalyzes an oxidation-reduction reaction, especially one involving dioxygen (O2) as the electron acceptor. In reactions involving donation of a hydrogen atom, oxygen is reduced to water (H2O) or hydrogen peroxide (H2O2). Some oxidation reactions, such as those involving monoamine oxidase or xanthine oxidase, typically do not involve free molecular oxygen.

Catalase protein-coding gene in the species Homo sapiens

Catalase is a common enzyme found in nearly all living organisms exposed to oxygen. It catalyzes the decomposition of hydrogen peroxide to water and oxygen. It is a very important enzyme in protecting the cell from oxidative damage by reactive oxygen species (ROS). Likewise, catalase has one of the highest turnover numbers of all enzymes; one catalase molecule can convert millions of hydrogen peroxide molecules to water and oxygen each second.

Urease enzyme

Ureases, functionally, belong to the superfamily of amidohydrolases and phosphotriesterases. Ureases are found in numerous bacteria, fungi, algae, plants, and some invertebrates, as well as in soils, as a soil enzyme. They are nickel-containing metalloenzymes of high molecular weight.

In 2006, Azakami et al reported that the periodontal pathogen E. corrodens have ortholog of luxS, the gene required for quorum sensing (QS) signal molecule AI-2 synthesis and E. corrodens can produce AI-2 signal for cell-to-cell communication and AI-2 has a role on biofilm formation by E. corrodens. [2] Karim et al reported that this bacteria can produce AI-2 inactivation enzyme during its stationary phase. [3] Karim et al also reported that LuxS-mediated QS may facilitate the maturation and detachment of biofilm formation in E.corrodens, which can leads to progression of periodontal disease. [4]

Medical importance

Eikenella corrodens is a commensal of the human mouth and upper respiratory tract. It is an unusual cause of infection and when it is cultured, it is most usually found mixed with other organisms. Infections most commonly occur in patients with cancers of the head and neck, [5] but it is also common in human bite infections, especially "reverse bite", "fight bite", or "clenched fist injuries". [6] It also causes infections in insulin-dependent diabetics and intravenous drug users who lick their needles ("needle-licker's osteomyelitis"). [7] It is one of the HACEK group of infections which are a cause of culture-negative endocarditis. In general, the HACEK organisms are responsible for approximately 3% of all cases of infective endocarditis (IE). IE due to E. corrodens is usually a result of poor oral hygiene and or periodontal infection. Manipulation of the gingival or oral mucosa for dental procedures also can predispose patients to infection since E. corrodens is a common constituent of the human oral flora. [8]

Eikenella corrodens infections are typically indolent (the infection does not become clinically evident until a week or more after the injury). They also mimic anaerobic infection in being extremely foul-smelling.[ citation needed ]

Eikenella corrodens was mentioned in an episode of Forensic Files, in which a hotel employee punched a woman in the mouth, knocking out two of her teeth. The tooth bacteria caused a major infection in the man's hand.


Eikenella corrodens can be treated with penicillins, cephalosporins, or tetracyclines. It is innately resistant to macrolides (e.g., erythromycin), clindamycin, and metronidazole. It is susceptible to fluoroquinolones (e.g., ciprofloxacin) in vitro, but no clinical evidence is available to advocate their use in these infections. [9]

Related Research Articles

Periodontal disease human disease of the tissues surrounding the teeth

Periodontal disease, also known as gum disease, is a set of inflammatory conditions affecting the tissues surrounding the teeth. In its early stage, called gingivitis, the gums become swollen, red, and may bleed. In its more serious form, called periodontitis, the gums can pull away from the tooth, bone can be lost, and the teeth may loosen or fall out. Bad breath may also occur.

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. HACEK is an abbreviation of the initials of the genera of this group of bacteria: Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella. The HACEK organisms are a normal part of the human microbiota, living in the oral-pharyngeal region.

Infective endocarditis endocarditis that is characterized by inflammation of the endocardium caused by infectious agents.

Infective endocarditis is an infection of the inner surface of the heart, usually the valves. Symptoms may include fever, small areas of bleeding into the skin, heart murmur, feeling tired, and low red blood cell count. Complications may include valvular insufficiency, heart failure, stroke, and kidney failure.

Blood culture To find organisms in blood

Blood culture is a microbiological culture of blood. It is employed to detect infections that are spreading through the bloodstream. This is possible because the bloodstream is usually a sterile environment.

<i>Staphylococcus haemolyticus</i> species of bacterium

Staphylococcus haemolyticus is a member of the coagulase-negative staphylococci (CoNS). It is part of the skin flora of humans, and its largest populations are usually found at the axillae, perineum, and inguinal areas. S. haemolyticus also colonizes primates and domestic animals. It is a well-known opportunistic pathogen, and is the second-most frequently isolated CoNS. Infections can be localized or systemic, and are often associated with the insertion of medical devices. The highly antibiotic-resistant phenotype and ability to form biofilms make S. haemolyticus a difficult pathogen to treat.

Dental plaque is a biofilm or mass of bacteria that grows on surfaces within the mouth. It is a sticky colorless deposit at first, but when it forms tartar, it is often brown or pale yellow. It is commonly found between the teeth, on the front of teeth, behind teeth, on chewing surfaces, along the gumline, or below the gumline cervical margins. Dental plaque is also known as microbial plaque, oral biofilm, dental biofilm, dental plaque biofilm or bacterial plaque biofilm. Bacterial plaque is one of the major causes for dental decay and gum disease.

<i>Pseudomonas aeruginosa</i> common bacterium

Pseudomonas aeruginosa is a common encapsulated, Gram-negative, rod-shaped bacterium that can cause disease in plants and animals, including humans. A species of considerable medical importance, P. aeruginosa is a multidrug resistant pathogen recognized for its ubiquity, its intrinsically advanced antibiotic resistance mechanisms, and its association with serious illnesses – hospital-acquired infections such as ventilator-associated pneumonia and various sepsis syndromes.

<i>Staphylococcus epidermidis</i> species of bacterium

Staphylococcus epidermidis is a Gram-positive bacterium, and one of over 40 species belonging to the genus Staphylococcus. It is part of the normal human flora, typically the skin flora, and less commonly the mucosal flora. It is a facultative anaerobic bacteria. Although S. epidermidis is not usually pathogenic, patients with compromised immune systems are at risk of developing infection. These infections are generally hospital-acquired. S. epidermidis is a particular concern for people with catheters or other surgical implants because it is known to form biofilms that grow on these devices. Being part of the normal skin flora, S. epidermidis is a frequent contaminant of specimens sent to the diagnostic laboratory.

<i>Stenotrophomonas maltophilia</i> species of bacterium

Stenotrophomonas maltophilia is an aerobic, nonfermentative, Gram-negative bacterium. It is an uncommon bacterium and human infection is difficult to treat. Initially classified as Bacterium bookeri, then renamed Pseudomonas maltophilia, S. maltophilia was also grouped in the genus Xanthomonas before eventually becoming the type species of the genus Stenotrophomonas in 1993.

<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 Pasteurellaceae family. The bacteria are facultatively aerobic or anaerobic, capable of fermenting carbohydrates, and of reducing nitrates. The genomic DNA contains between 40 and 47 mol % guanine plus cytosine.

Kingella kingae is a species of Gram-negative aerobic 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>Cardiobacterium hominis</i> species of Gammaproteobacteria

Cardiobacterium hominis is a Gram-negative bacillus (rod-shaped) bacterium commonly grouped with other bacteria into the HACEK group. It is one of several bacteria that is normally present in the mouth and upper part of the respiratory tract such as nose and throat. However, it may also rarely cause endocarditis, an infection of the heart valves.

<i>Staphylococcus capitis</i> species of bacterium

Staphylococcus capitis is a coagulase-negative species (CoNS) of Staphylococcus. It is part of the normal flora of the skin of the human scalp, face, neck, and ears and has been associated with prosthetic valve endocarditis, but is rarely associated with native valve infection.

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

Anaerobic infections are caused by anaerobic bacteria. Obligately anaerobic bacteria do not grow on solid media in room air ; facultatively anaerobic bacteria can grow in the presence or absence of air. Microaerophilic bacteria do not grow at all aerobically or grow poorly, but grow better under 10% carbon dioxide or anaerobically. Anaerobic bacteria can be divided into strict anaerobes that can not grow in the presence of more than 0.5% oxygen and moderate anaerobic bacteria that are able of growing between 2 and 8% oxygen. Anaerobic bacteria usually do not possess catalase, but some can generate superoxide dismutase which protects them from oxygen.

Campylobacter concisus is a Gram-negative, highly fastidious, mesophilic bacterium that grows under both anaerobic and microaerobic conditions with the presence of hydrogen significantly aiding growth. Motile, with either unipolar or bipolar flagella, the organisms have a characteristic spiral/corkscrew appearance and are oxidase-positive. Although the human oral cavity is the natural colonization site of the bacterium, C. concisus may also colonize the intestinal tract of some individuals. In particular, several studies have reported higher intestinal prevalence of C. concisus in patients with IBD compared to healthy controls, which has led to current speculation of the bacterium's implication in the induction of Crohn's disease.

Neisseria bacilliformis is a bacterium commonly found living as a commensal in the mucous membranes of mammals. However, depending on host immunocompetence, there have been documented cases of N. bacilliformis infections of the respiratory tract and oral cavity thus making it an opportunistic pathogen. It was originally isolated from patients being treated in a cancer center. Rarely, a more serious infection such as endocarditis can occur often as a result of a predisposing condition.

Dialister pneumosintes is a nonfermentative, anaerobic, gram-negative rod that grows with small, circular, transparent, shiny, smooth colonies on blood agar. D. pneumosintes has been recovered from deep periodontal pockets, but little is known about the relationship between the organism and destructive periodontal disease.

Actinomyces viscosus is a human and animal pathogen/pathobiont which colonises the mouths of 70% of adult humans. A. viscosus has a low level of virulence and is often mistaken with other actinomycetes.


  1. Eiken, M (1958). "Studies on an anaerobic, rodshaped, gram-negative microorganism: Bacteroides corrodens n. sp". Acta Pathologica et Microbiologica Scandinavica. 43 (4): 404–16. doi:10.1111/j.1699-0463.1958.tb04677.x. PMID   13594456.
  2. Azakami, Hiroyuki; Teramura, Izumi; Matsunaga, Tetsuro; Akimichi, Hiromi; Noiri, Yuichiro; Ebisu, Shigeyuki; Kato, Akio (2006). "Characterization of autoinducer 2 signal in Eikenella corrodens and its role in biofilm formation". Journal of Bioscience and Bioengineering. 102 (2): 110–7. doi:10.1263/jbb.102.110. PMID   17027872.
  3. Karim, Mohammad Minnatul; Nagao, Ayako; Mansur, Fariha Jasin; Matsunaga, Tetsuro; Akakabe, Yoshihiko; Noiri, Yuichiro; Ebisu, Shigeyuki; Kato, Akio; Azakami, Hiroyuki (2013). "The Periodontopathogenic BacteriumEikenella corrodensProduces an Autoinducer-2-Inactivating Enzyme". Bioscience, Biotechnology, and Biochemistry. 77 (5): 1080–5. doi:10.1271/bbb.130047. PMID   23649272.
  4. Karim, Mohammad Minnatul; Hisamoto, Tatsunori; Matsunaga, Tetsuro; Asahi, Yoko; Noiri, Yuichiro; Ebisu, Shigeyuki; Kato, Akio; Azakami, Hiroyuki (2013). "LuxS affects biofilm maturation and detachment of the periodontopathogenic bacterium Eikenella corrodens". Journal of Bioscience and Bioengineering. 116 (3): 313–8. doi:10.1016/j.jbiosc.2013.03.013. PMID   23639420.
  5. Sheng, W.-S.; Hsueh, P.-R.; Hung, C.-C.; Teng, L.-J.; Chen, Y.-C.; Luh, K.-T. (2001). "Clinical Features of Patients with Invasive Eikenella corrodens Infections and Microbiological Characteristics of the Causative Isolates". European Journal of Clinical Microbiology and Infectious Diseases. 20 (4): 231–6. doi:10.1007/s100960100477. PMID   11399011.
  6. Goldstein, E. J. C. (1992). "Bite Wounds and Infection". Clinical Infectious Diseases. 14 (3): 633–8. doi:10.1093/clinids/14.3.633. PMID   1562653.
  7. Swisher, Loice A.; Roberts, James R.; Glynn, Martin J. (1994). "Needle licker's osteomyelitis". The American Journal of Emergency Medicine. 12 (3): 343–6. doi:10.1016/0735-6757(94)90156-2. PMID   8179747.
  8. "Infective endocarditis caused by HACEK microorganisms". www.educus.com. Retrieved 2016-05-17.
  9. Sheng, W.-S.; Hsueh, P.-R.; Hung, C.-C.; Teng, L.-J.; Chen, Y.-C.; Luh, K.-T. (2001). "Clinical Features of Patients with Invasive Eikenella corrodens Infections and Microbiological Characteristics of the Causative Isolates". European Journal of Clinical Microbiology and Infectious Diseases. 20 (4): 231–6. doi : 10.1007/s100960100477. PMID   11399011