EIKENELLA

SPECIES

Eikenella corrodens

MICROSCOPIC APPEARANCE

Gram Stains: Negative.
Morphology: Straight rods.
Size: 0.3-0.4 micrometers by 1.5-4.0 micrometers with rounded ends.
Motility: They are non-motile but may exhibit a "twitching motility" on some media. Short filaments are occasionally formed.
Capsules: None.
Spores: Non-sporeforming.
Other: Hemin is usually required for growth under aerobic conditions.

MACROSCOPIC APPEARANCE

Colonies are 0.2-0.5mm at 24 hours; 0.5-1.0mm at 48 hours. Colonies have moist, clear centers surrounded by flat, spreading growth. May appear to "corrode" the surface of the agar medium. A slight yellow pigmentation may be present in older cultures. Plate cultures have an odor described as "bleach like" or as resembling that of Haemophilus and Pasteurella species. Growth in liquid media is usually poor.

METABOLIC PROPERTIES

Facultatively anaerobic. No acids formed from glucose or other carbohydrates.

KEY BIOCHEMICAL REACTIONS

HABITAT

Eikenella corrodens is commonly found in the human mouth and intestine, and has also been isolated from the genitourinary tract.

PATHOGENICITY

Eikenella corrodens is an opportunistic pathogen, particularly likely to produce infection in compromised hosts. It has been implicated in osteomyelitis, arthritic, respiratory, and septicemic infections. Infection related to the mouth and upper and lower respiratory tract sinuses, lips and face is not uncommonly reported. Serious infections including brain abscesses have sometimes been encountered. Transfer from the mouth may cause infection of human bites. The ability of E. corrodens to survive in the intestine leads to its presence in abdominal infections, including wound infection, liver and other abscesses as well as peritonitis. Meningitis and fatal endocarditis have also been reported. (2)

RECOMMENDED MEDIA

For culture: Columbia Blood Agar, Blood Agar 5%.
For selective isolation: Todd Hewitt Agar with Clindamycin (5mcg/ml), Potassium Nitrate (2mg/ml) and Hemin (5mcg/ml). (1) (Not available commercially.)
For maintenance: Columbia Blood Agar, Blood Agar 5%. Horse serum is recommended for long-term storage at -70 degrees C.
Optimum pH: 7.3.

INCUBATION

Temperature: 35 degrees C. in 5-10% CO 2 .
Time: 24-48 hours.
Atmosphere: Aerobic; facultatively anaerobic.

REFERENCES

1. Holt, J.G., et al. 1994. Bergey's Manual of Determinative Bacteriology , 9th ed. Williams & Wilkins, Baltimore, MD.

2. Holt, J.G., et al. 1986. Bergey's Manual of Systemic Bacteriology , Vol. I & II. Williams & Wilkins, Baltimore, MD.

3. The Oxoid Vade-Mecum of Microbiology . 1993. Unipath Ltd., Basingstoke, UK.

4. Murray, P.R., et al. 1995. Manual of Clinical Microbiology , 6th ed. American Society for Microbiology, Washington, D.C.


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