Methicillin-resistant Staphylococcus aureus (MRSA) Colitis: A Rare Cause of Communityacquired Infectious Colitis

Abstract

Introduction: Community acquired MRSA colitis in an otherwise healthy individual is rare and only a few cases have been reported in the United States to our knowledge. We report a case of MRSA colitis in an otherwise healthy individual presenting with hematochezia.Figure: Diffuse moderate inflammation characterized by congestion (edema), erythema and friability in descending colon.Figure: Interface between normal epithelium and erosion with mixed inflammatory cells- neutrophils, plasma cells, eosinophils, lymphocytes.Figure: Dilated crypt with enclosed polymorphonuclear neutrophils (PMNs) with inflammation representing exudative process.Case presentation: A 63 year old female with no significant past medical or surgical history presented with complaints of new onset hematochezia with associated left lower quadrant abdominal pain and distention for one day. Patient denied sick contacts, travel, antibiotic use, recent hospitalization, use of blood thinners, personal or family history of colon cancer. Patient was tachycardic, hypotensive and febrile. Physical exam was normal. Laboratory findings showed WBC 20K/mcl, ESR 23mm/hr, CRP 327mg/L, lactic acid 3.4mmol/L. Stool clostridium difficle toxin polymerase chain reaction (PCR), Ova and parasites panel were negative. CT abdomen/pelvis with contrast showed descending and proximal sigmoid bowel wall thickening and colitis. Empiric therapy with oral metronidazole was initiated. With an unclear etiology and possibility of ischemic colitis or inflammatory disease, colonoscopy was performed which showed diffuse moderate inflammation characterized by congestion, erythema and friability in proximal and descending colon.[1] Biopsy yielded findings of mucosal ulceration with underlying granulation tissue- both chronic and acute inflammation.[2] Findings of intact mucosa with edema, moderate chronic inflammation and focal cryptitis with crypt abscess formation were found in descending colon.[3] Inflammatory bowel disease was considered however with stool cultures positive for heavy growth of MRSA, infectious colitis was concluded as cause. Patient was treated with course of oral vancomycin for 14 days with complete resolution of symptoms. Patient was followed over one year of time without recurrence of symptoms. Discussion: MRSA is one of the leading cause of deaths in hospitalized patients in the Unites States. MRSA primarily colonizes in the nares, however colonization in rectum and intestine have been shown primarily in patients with history of IBD or history of gastric surgery with rare occurrence in a otherwise healthy patient. Stool gram stain and culture are mainstay for diagnosis and treatment with oral vancomycin for 10-14 days has been shown effective. It is imperative to consider MRSA as cause of infectious colitis, especially with rise of MRSA isolates in the community.