S3526 Parvimonas Micra Liver Abscess and Diverticulitis in an Immunocompetent Host: A Case Report

Abstract

INTRODUCTION: Parvimonas micra (P.micra) is a Gram-positive (GP) anaerobic species, known as a commensal of the oral cavity and a common cause of periodontitis. It is reported twice in the literature as the infectious agent causing hepatic abscesses. Herein we present the case of multiloculated liver abscess and diverticulitis caused by P.micra. CASE DESCRIPTION/METHODS: A 54-year-old healthy man presented to the hospital for fever, malaise, and fifteen lbs weight loss for two weeks. Initial evaluation revealed a temperature of 102.9F, heart rate of 108, and blood pressure of 124/60mmHg. The physical examination was non-contributory. Laboratory studies revealed leukocytosis 23.67k/uL, AST 50U/L, ALT 80U/L, ALP 1015U/L, total bilirubin 0.5mg/dL. A CT-scan of the abdomen with intravenous contrast showed two multiloculated liver abscesses with sigmoid diverticulitis (Figure). Empiric antibiotics therapy with ceftriaxone and metronidazole was started. Blood cultures at admission were negative. The patient underwent ultrasound-guided drainage of the abscesses with the placement of 2 drainage catheters. The culture revealed P.micra. Antibiotics were switched to oral Amoxicillin/Clavulanic-acid. Follow-up colonoscopy showed sigmoid diverticulosis without evidence of malignancy. A repeat CT-scan confirmed abscesses resolution. DISCUSSION: Pyogenic liver abscess is a rare disease in the US, with an annual incidence of 2.9–3.6 cases/100,000 individuals. Biliary tract infections are the most common etiology. Seeding from diverticulitis or appendicitis through the portal vein is the second. PLA is often polymicrobial. Parvimonas micra is an anaerobic GP coccus. It is known to cause periodontitis in immunocompromised patients. Only 2 cases of liver abscesses secondary to P.micra have been reported, but none was associated with diverticulitis. Blood cultures are positive in half of the cases of PLA, with lower rates in anaerobes. Abscess culture has higher sensitivities (up to 80%). CT scan is the preferred imaging modality. Therapy includes antibiotics, percutaneous drainage of the abscess, and treatment of the underlying cause. Empiric antibiotic should cover GP cocci, gram-negative bacilli, and anaerobes. P.micra is highly susceptible to antibiotics. Surgical drainage is reserved for multilocular and larger abscesses. PLA remains a challenging disease despite advancements in diagnostic imaging and treatment. It is vital to screen for the associated conditions and rare organisms for successful therapy.Figure 1.: Liver abscess.Figure 2.: diverticulitis.