Abdominal Actinomycosis

Introduction

Actinomyces spp. are gram positive, non-motile, unencapsulated, non-spore-forming, anaerobic bacterias which colonize in the normal flora of the oral cavity, the gastro-intestinal system and the female genital tract. Actinomyces spp. cause a chronic suppurative, granulomatous disease, which is characterized clinically by extensive abscess formation, recurrent draining of sinuses and fistulae. The histological hall-mark is the presence of so-called “sulphur granules” . There are six types of actinomyces defined that cause actinomycosis in humans.

A.israelii is the most common Actinomyces spp. Actinomycosis presents in different clinical forms : cervicofacial, thoracic, abdominal and cerebral actinomycosis. The most common clinical forms are cervicofacial and abdominal actinomycosis. The patients with abdominal actinomycosis may present with abdominal mass and/or abscess. We present two actinomycosis cases, which were initially diagnosed as ovarian torsion and colon tumour before surgery. Definite diagnosis of abdominal actinomycosis was onlymade postoperatively.

Discussion

The most causative pathogen for actinomycosis in humans is A.israelii. The other less common agents are A. meyeri, A. gerencseriae, A. naeslundii, A. viscosus, A. odontolyticus. The prevalance of human actinomycosis is 5/100000. It is ten times more frequent in rural areas. Male/female rate is 3/1. Although the first identification of actinomycosis was made nearly a hundred years ago, the factors that initiate the infection are not well known. Patients with immune, deficiency previous abdominal surgery, trauma, inserted IUD, and oropharygeal surgery are prone to abdominal
actinomycosis.

Abdominal Actinomycosis In our first case there was a history of IUD use, which can be regarded as a predisposing factor. On the other hand, in the second case, predisposing factors were absent. Since Actinomyces spp., have low virulence, they
cause disease only when the normal mucosal barrier is broken, leading to abscess formation, fistula or mass lesions. Abdominal actinomycosis is a persistant infectious disease that presents with clinical features of tumoral masses, inflammatory bowel disease and diverticulitis. In general, it is characterized by the involvement of the caecum and the right colon, retroperitoneal fibrosis and fistulisation to the skin in the right iliac region. Hence, intestinal tuberculosis, amoeboma,
chronic appendicitis, regional enteritis and colon carcinoma must be considered in the differential diagnosis.
The diagnosis of abdominal actinomycosis remains difficult. Radiological findings are nonspecific. In one study made by LEE et al, CT scan revealed thickening of the bowel wall, perirectal, pericolic or perienteric infiltration, peritoneal or pelvic mass, minimal lymphadenopathy, hydronephrosis and hydro-ureter. In our first case, abdominal ultrasonography revealed a
cystic mass (measuring 4 x 5 x 4 cm) in the right ovary. In the second case, a mass-like wall thickness was also detected.
Since malignancy and acute abdomen present similar clinical pictures to abdominal actinomycosis, the definite
diagnosis is usually achieved by histopathological examination, showing the pathognomic sulphur granules. A pre-operative clinical or radiological diagnosis could be performed, but definitive diagnosis of the present two cases was only made after surgery, as in some other cases reported in the literature. Penicillin G and ampicillin are the first choice therapy for actinomycosis. Initial treatment with parenteral penicillin G, 18-24 million units for 4-6 weeks can be followed by penicillin V or oral ampicillin for at least 6-12 months. For penicillin-allergic cases, tetracyclines, erythromycin, clindamycin or cephalosporines are suitable alternatives. In our first case this treatment was administered succesfully without any relapse.
However, in the second case, we administered ceftriaxon at 3 gr/day for 2 weeks due to penicillin allergy and continued with doxicycline 100 mg twice a day. After three months follow-up, there was no relapse.