Primary Abdominal Wall Abscess by Actinomyces and Eikenella corrodens : A First Report

To the Editor:

A 45-year-old male presented with a history of abdominal pain, hyporexia, and weight loss for one month. He had hyperemia and referred increase of temperature (37.5°C). Medical history was blank and he denied any history of trauma, abdominal surgery, or local injections. The umbilical region was tender and revealed a non-movable 10 × 7 cm solid mass fixed to the abdominal wall with spontaneous suppuration. Laboratory results showed a leukocyte count of 18.8 × 10⁹/L and C-reactive protein of 25 mg/L. Computed tomography revealed an irregular mass in the umbilical area occupying bilaterally musculus rectus and extending through subcutaneous adipose tissue (Fig. 1). The patient was admitted with a broad-spectrum intravenous antibiotic (amoxicillin/clavulanate 1 g per 8 h). Culture of pus showed Eikenella corrodens and Actinomyces odontolyticus. The antibiotic was replaced with parenteral ceftriaxone 2 g/d for one month, followed by oral amoxicillin 1 g per eight hours for six months, with notable improvement. At the end of the follow-up, a computed tomography revealed no mass (Fig. 2) and the patient had no further complications.

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FIG. 1.

Computed tomography: irregular mass in the umbilical area measuring 10 × 7 cm, occupying bilaterally musculus rectus and extending through subcutaneous adipose tissue.

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FIG. 2.

Computed tomography: no masses are present at the end of the follow-up.

Primary abdominal wall actinomycosis is an uncommon entity. Actinomycosis usually presents as a mass lesion and sometimes can mimic malignancy [1]. The gold standard for diagnosis is microbiologic culture, althouth it is negative in 75% of cases. In many patients surgery is necessary and diagnosis is confirmed by pathologic examination [1,2]. The adequate treatment is long-term penicillin therapy for 6–12 months [2]. Physicians should keep actinomycosis in mind as a possible diagnosis for unknown abdominal wall masses.

Eikenella corrodens is a gram-negative facultative anaerobic bacillus, which is a commensal of the mouth and upper respiratory tract. It is more commonly associated with head and neck infections (periodontal), however, intra-abdominal infections have been reported rarely. Eikenella corrodens has not been isolated previously from abdominal wall infections [3]. The adequate treatment is penicillin for 7–10 days (other options are macrolides or quinolons).