Colonies on blood-agar at 24 hr were 0.5 mm; at 48 hr, 0.5-1.0 mm in diameter.
Corroding strains appear as if in a shallow pit in the agar, and the colony appears
rough to the naked eye. The edge is circular or irregular. Noncorroding strains may
occur. Nonhemolytic; a slight greening of blood media around colonies may occur.
The odor of cultures resembles that of organisms in the genera Pasteurella and
Facultatively anaerobic. Optimal growth temperature is 35-37 ºC. At 25 ºC, minute
colonies are visible in 5-7 days. Growth is good at 40 ºC, but poor at 42 ºC. No growth
occurs at 44 ºC. The optimal pH for growth is 7.3. Growth is favored by 5-10% CO2.
Typically requires hemin for aerobic growth. Best growth is obtained with hemin
concentrations of 5 to 25 μg / ml of medium.
Phylum Proteobacteria, Class Betaproteobacteria, Order Neisseriales, Family Neisseriaceae, Genus Eikenella, Eikenella corrodens
(Eiken 1958) Jackson and Goodman 1972 - type species of the genus.
Old synonyms: Bacteroides corrodens Eiken 1958, Ristella corrodens (Eiken 1958) Prevot 1966.
Gram-negative straight rods, 0.3-0.4 x 1.5-4.0 μm, unbranched, with rounded ends and a regular morphology. Short filaments are
occasionally formed. Nonmotile, not flagellated, but “twitching motility” may occur on agar media. Nonsporeforming.
Isolated from human clinical samples (sputum, brain abscess, liver abscess, osteomyelitis, and infected wounds).
Susceptible to penicillin G, ampicillin, efoxitin, chloramphenicol, tetracycline, rifampicin, and colistin.
Resistant to penicillinase-resistant penicillins, lincomycin, clindamycin and metronidazole. Moderately susceptible or resistant to
cephalothin, cephapirin, and cephaloridine. Resistance to aminoglycosides is variable.
Probably is a normal inhabitant of the mouth and upper respiratory tract of man. May be an opportunistic pathogen and sometimes
occurs together with streptococci. Has been associated with infections, including brain abscesses, endocarditis, pneumonia,
osteomyelitis, and septic arthritis.
Frequently found in subgingival plaque in patients with advanced periodonitis. Wounds infections due to transfer from the mouth
through human bites were reported.
The ability to survive in the intestine leads to its presence in abdominal infections, including wound infection, abscesses, and
peritonitis of the liver and other viscera.
Experimental endocarditis, rarely fatal and seldom bacteremic, has been produced in catheterized rabbits.
- Tone Tonjum, 2005. Order IV. Neisseriales ord. nov. In: Bergey’s Manual of Systematic Bacteriology, Second edition, Vol two, part C
The Alpha-, Beta-, Delta-, and Epsilonproteobacteria, George M. Garrity (Editor-in-Chief), pp 774-863.
- Jackson (F.L.) and Goodman (Y.E.): Transfer of the facultatively anaerobic organism Bacteroides corrodens Eiken to a new genus
Eikenella. International Journal of Systematic Bacteriology, 1972, 22, 73-77.
- Euzeby J.P., List of Prokaryotic names with Standing in Nomenclature, Genus Eikenella, http://www.bacterio.net/eikenella.html,
Positive results for H2S production (traces), nitrate reduction to nitrite, oxidase &
Negative results for arginine dihydrolase, catalase, gelatin hydrolysis, indole production, gamma-glutamyltransferase, acid
production from adonitol, arabinose, dulcitol, galactose, glucose, inositol, lactose, maltose, mannose, mannitol, raffinose, salicin,
sorbitol, sucrose & trehalose.
Variable results for lysine decarboxylase & ornithine decarboxylase.
(c) Costin Stoica