Eikinella corrodens wound infection in a diabetic foot: a brief report

Abstract

Eikinella corrodens normally forms part of the flora of the oral cavity and mucous membranes of the respiratory tract. It is usually associated with dental, head and neck infections (Cohen, Powderly, 2004, Infectious Diseases) and is considered to be an unusual cause of orthopaedic infections. We recently treated a diabetic patient with E. corrodens osteomyelitis of the fifth metatarsophalangeal joint, a phenomenon which has been reported in only three cases previously (Konugres et al., 1987, E. corrodens as a cause of osteomyelitis in the feet of the diabetic patients. Report of three cases). We recommend including E. corrodens in the spectrum of causative pathogens in diabetic foot infections.

Introduction

Eikinella corrodens has been known to cause orthopaedic infections for more than 20 years. This fastidious facultative gram‐ negative organism is part of the endogenous flora of the mouth and nasopharynx. The usual mechanism is bite injuries to the hand or metacarpophalangeal joint inflicted in the course of a fight. Apart from direct inoculation (application of saliva in some form to the area of the wound), oral organisms can also enter the bloodstream via transient bacteremia caused by chewing and tooth brushing. Eikinella is frequently recovered from the site of infection in conjunction with other bacterial species. Clinical syndromes include head and neck infections (56%); pulmonary infections (23%); intra‐abdominal infections (14%); cutaneous infections (5%); skeletal infections (2%); endocarditis (2%) and pelvic abscesses (2%). More than half of the patients (56%) have associated factors predisposing them to invasive E. corrodens infection (1).

Case description

A 61‐year‐old Israeli male security guard with a 20‐year history of diabetes mellitus type 2 was hospitalised in our diabetic foot unit due to an infected wound on the left fifth metatarsophalangeal (MTP) joint. The lesion had developed 2 weeks previously from a callus, which he had attempted to remove by way of an over‐the‐counter product composed of an adhesive‐impregnated plaster. On questioning, the patient denied any trauma to the involved foot, any contact with animals, any use of sharp instruments on the limb (including toothpicks) or any memory of transfer of saliva to the infected wound. He presented with no fever and no notable pathological signs apart from the left foot which was swollen and inflamed. X‐ray revealed signs of destruction of the head of the fifth MTP joint, indicative of osteomyelitis. Laboratory tests were normal, including a white blood cell count of 9700/l. Orthopaedic surgical consultation recommended resection arthroplasty of the fifth MTP joint. Surgery was performed, and in the course of the operation, pus was drained from the wound and sent for culturing. Empirical intravenous therapy with amoxicillin and clavulonic acid (Augmentin, GlaxoSmithKline) was initiated. Two days later, results from a preoperative swab culture of the wound revealed growth of E. corrodens. The intraoperative specimen, including pus and fragments of bone, produced growth of E. corrodens and Bacteroides fragilis, a common anaerobic pathogen in diabetic foot. Blood cultures taken prior to the initiation of the antibiotic therapy were sterile. The antibiotic therapy was continued after receiving the antibiogram, which revealed sensitivity to the aforementioned drug (Table 1).

Table 1.

Wound swab results that were taken before and during the resection arthroplasty of the fifth metatarsophalangeal joint

Wound swab antibiogram (Eikenella corrodens 100 cfu/ml)
Ampicillin	SIR
Trimethoprim/sulfa	SIR
Gentamicin	SIR
Cefazolin	SIR
Ciprofloxacin	SIR
Amoxicillin/clavulonic acid	SIR
Ceftriaxone	SIR
Amikacin	SIR
Piperacillin	SIR
Ceftazidime	SIR
Aztreonam	SIR
Colistin	SIR
Piperacillin/tazobactam	SIR
Cefepime	SIR
Meropenem	SIR
Ertapenem	SIR

CFU/ml = colony‐forming units; SIR, sensitive intermediate resistant.

The patient was released 4 days postoperatively with a clean wound, and no complications and instructions to continue a further 10 days of antibiotic therapy.

Discussion

An examination of the literature revealed numerous reports of E. corrodens in orthopaedic infections such as osteomyelitis, discitis and septic arthritis. Most of these cases involve some form of trauma with the introduction of saliva to the area (intravenous drug use, bites and infections of the oropharyngeal cavity with subsequent spread) 2, 3, 4, 5, 6, 7, 8, 9). There are very few reports of infections caused by this pathogen in diabetic patients. Newfield et al. (10) describes two paediatric cases of particular interest: A diabetic girl who, through chronic finger biting, caused infection, eventually leading to amputation of the finger, and one who developed an acute thigh abscess at the site of insulin injection. Diabetic foot infections with this pathogen are very rare, as our experience in the field has taught us, and only three individual reports of this could be found (11).

Conclusion

Diabetic patients are exposed to infections of the skin due to daily microtraumas induced by the injection of insulin and the measurement of blood sugar levels. Infections due to E. corrodens can occur if patients lick or suck their wounds, a common practice in the general population but potentially dangerous for this group. For this reason, most of the cases of infection with this pathogen in diabetics are in the fingers or hands. However, although Eikinella infections of the foot are most uncommon and the mechanism of infection unclear, E. corrodens should not be ruled out as a causative factor. We, therefore recommend including E. corrodens in the spectrum of causative pathogens in diabetic foot infections.

Acknowledgements

Karin Lee Ovadia and Mary Rozenberg for translation and editing.