A 43-year-old female with a medical history of nonsteroid dependent asthma presented to an outside hospital complaining of one-month frequent bloody diarrhea, body aches, loss of appetite, and 15 kg weight loss. Upon admission she was febrile (39 C); however the rest of the physical examination was reportedly benign. Laboratory findings were remarkable for leukocytosis (18.2 k/mm3; reference value: 4.5-11) and hypokalemia (2.6 meq/L; reference value: 3.3-5.3); the hemoglobin level was within normal range (13.9 g/dL; reference value: 12-16 g/dL). Although the initial workup for infectious etiologies was nondiagnostic, she was empirically treated with piperacillin-tazobactam. Two days later, she was transferred to our hospital for a higher level of care. Upon arrival, she was febrile (39.3 C) and tachycardic (125 bpm); moreover, she was found to have polyarthritis, involving the distal joints of her upper extremities. Significant laboratory findings included a low hemoglobin level (8.9 g/dL; reference value: 12-16), hypoalbuminemia (1.2 g/dL; reference value: 3.5-5), elevated C-reactive protein (40.3 mg/L; reference value: <3), and elevated erythrocyte sedimentation rate (104 mm/hr; reference value: <20). Repeated blood cultures in our facility were negative for bacteremia; however antibiotic therapy with piperacillin-tazobactam was continued as the computed tomography scan of the abdomen and pelvis showed evidence of colitis. Studies for infectious colitis were negative. On day three of admission, a peripherally inserted central catheter (PICC) was placed for total parenteral nutrition. One day later, the patient underwent colonoscopy which showed diffuse mucosal inflammation with numerous deep, clean-based ulcers from the rectum to the distal ascending colon. The differential diagnosis included cytomegalovirus (CMV) colitis versus IBD. Empiric ganciclovir was started; however it was discontinued once CMV colitis was ruled out by serology, quantitative polymerase chain reaction, and immunohistochemistry studies. Histopathology revealed subacute colitis, small crypt abscesses, fragments of granulation tissue, and neutrophilic exudate. An extensive rheumatologic workup for her seronegative polyarthritis led to the diagnosis of enteropathic arthritis. On day eight of hospitalization, once the serology for human immunodeficiency virus was confirmed as negative, intravenous methylprednisolone and oral mesalamine were initiated. On the same day, an episode of massive rectal bleeding was reported by the patient. The hemoglobin decreased from 7.8 to 6.7 g/dL and the patient was transferred to the intensive care unit and transfused with packed red blood cells. Two sets of blood cultures obtained at that time showed growth of gram-negative rods in aerobic bottles only. The methylprednisolone was held due to sepsis and the PICC was removed and sent for culture, which was negative. The microorganism was identified as L. adecarboxylata, using the fully automated Vitek 2 Compact 60 system (bioMerieux, Inc. Hazelwood, MO). The microorganism showed a pan-sensitive antimicrobial profile (Table 1), so the antibiotic regimen was changed to intravenous ceftriaxone and repeated blood cultures were negative. Therapy with methylprednisolone was resumed, achieving resolution of her bloody diarrhea and partial improvement of her polyarthritis. In light of the aforementioned clinical and paraclinical findings, the patient was diagnosed with ulcerative colitis with severe disease activity (ulcerative colitis disease activity index of 11), responsive to steroids and mesalamine. After a negative workup for latent tuberculosis and completion of the antibiotic course, treatment with infliximab was initiated which resulted in a complete recovery of the polyarthritis and normalization of the inflammatory markers. She was subsequently discharged to an acute rehabilitation facility with a gradual taper of oral prednisone and infliximab infusions every eight weeks.