Eikenella corrodens

Published 18.7.21

• Gram-negative fastidious facultative anaerobic bacillus; however, it is pleomorphic and could appear in coccobacillary form.

• It is non-motile, non-spore-forming and encapsulated.

• It is a member of the oral, gastrointestinal, and genitourinary flora.

• Adherence – lectin-like protein, pilli.

• Ability to aggregate RBC.

• Avoid phagocytosis – extracellular polysaccharide or slime layer.

• Cell wall lipopolysaccharide

Slow growing, small pin-point colony with a bleach-like smell.

It is a yellow-grey colour with a small greenish discolouration on the blood agar. 50% of colonies are pitting.

It can grow aerobically or anaerobically.

It usually requires hemin (X factor) and carbon dioxide for primary isolation.

Oxidase positive, catalase-negative (some weakly positive), urease negative, indole negative, reduce nitrate.

Identification - API20E , (API20NE with additional test), MALDI ToF

• Head and neck infection, sinusitis,

• Pulmonary infection, septic emboli

• Endocarditis

• Arthritis, skull infection, vertebral osteomyelitis

• Intraabdominal infection, pancreatic abscesses, liver abscess

• Chorioamnionitis

• Infection after human bite wounds (“clenched-fist injuries”) etc

• Skin infection in IVDUs (skin poppers)

It is a member of the HACEK group of organisms and can cause endocarditis (especially in IVDUs or prosthetic valve).
Most infections are polymicrobial.
The patient often has comorbidities like mental retardation with cerebral palsy, head and neck malignancies, Down’s syndrome, diabetes, leukaemia, or trauma history.
Surgical intervention is often required for a successful outcome.

• Penicillin, amoxicillin,
  First-generation cephalosporins – variable susceptibility, reported resistance to cephalexin
  Second and third-generation cephalosporins
  Betalactam-beta-lactamase combination – coamoxiclav and pip-tazobactam

• Tetracyclines

• Fluoroquinolones

• Cotrimoxazole

Non-susceptible to

• Clindamycin

• Macrolides – erythromycin, clarithromycin etc

• Aminoglycosides – gentamicin, amikacin etc

• Metronidazole.