P2959 - Spontaneous Peritonitis From Actinomyces: A Rare Cause for Chronic Abdominal Pain

Xixi Xu, MD, MS, Dionne Rebello, MD, Michelle Long, MD, MSc
Boston Medical Center, Boston, MA

Introduction: Actinomycosis is an uncommon, chronic granulomatous disease caused by filamentous gram-positive anaerobic bacteria Actinomyces. The presentation of abdominal actinomycosis is usually nonspecific, chronic, and indolent. Due to the low suspicion and nonspecific clinical features, abdominal actinomycosis is very difficult to diagnose. Most of the reported abdominal actinomycosis cases in the literature described localized masses, pseudotumors, or abscesses. There are very few reported cases of spontaneous peritonitis caused by actinomycetes. We report a case of symptomatic spontaneous bacterial peritonitis (SBP) found incidentally on peritoneal fluid culture.

Case Description/Methods: The patient is a 51-year-old female with alcoholic cirrhosis complicated by ascites, previous SBP, active alcohol use disorder who was admitted to our hospital for chronic abdominal pain with worsening ascites. She was afebrile with stable vital signs. The physical exam showed a distended abdomen with diffuse tenderness on palpation. Laboratory tests showed leukocytosis with elevated liver function tests. At baseline, the patient had chronically elevated WBC and liver function tests. Chest, abdomen, and pelvis CT showed a diffuse liver parenchymal abnormality with nonspecific, innumerable hypoattenuating lesions throughout the liver. There were also innumerable bilateral stable punctate pulmonary nodules compatible with granulomatous disease. Paracentesis was performed and the ascetic peritoneal fluid analysis showed the absolute neutrophil count 25/UL. Aerobic culture grew gram-positive bacilli which speciated to Actinomyces species. She started treatment for abdominal actinomycosis with Amoxicillin 1g, 3 times every day for 6 months.

Discussion: Actinomyces are normal commensal bacteria found in the bronchial and gastrointestinal tracts. Actinomyces become pathologic when they penetrate the mucosal barrier resulting in granulomatous and suppurative inflammation. Diagnosis is usually made with histologic identification of actinomycotic sulfur granules or culture of Actinomyces. The diagnosis of SBP caused by Actinomyces is especially challenging given the lack of mass or abscesses identifiable on imaging to biopsy. The diagnosis is solely dependent on the culture or cytology of ascetic fluid. Less than 50% of the abdominal actinomycosis cases are confirmed by culture, making the diagnosis of SBP due to Actinomyces even more challenging. Thus a high index of suspicion is needed to avoid delay in diagnosis.


Disclosures:


Xixi Xu, MD, MS, Dionne Rebello, MD, Michelle Long, MD, MSc. P2959 - Spontaneous Peritonitis From Actinomyces: A Rare Cause for Chronic Abdominal Pain, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.