S5073 Breaking Down the Abscess: Nocardia farcinica Behind an Abdominal Mystery

Introduction: Nocardia farcinica is a gram-positive, aerobic, filamentous bacteria. According to the NIH there are only 50-100 cases of Nocardia per year. N. farcinica is distinct from other Nocardia species by its high degree of antibiotic resistance and virulence, particularly in predisposing conditions. Nocardia spp. usually causes primary pulmonary infections, but it can cause infections in other sites resulting from hematogenous dissemination. The central nervous system is the second most frequently involved, but it can lead to rare infections in the abdomen, cornea, heart, joints and bones. Nocardia can lead to significant morbidity, particularly if disseminated and immunosuppressed. This case presents a 39-year-old man with a complex medical history who developed nocardiosis identified in an intrabdominal wall abscess. Case Description/Methods: A 39-year-old incarcerated man with large-vessel arteritis (inconsistently on prednisone and methotrexate leading to a complicated vascular history now on rivaroxaban), multiple DVT’s requiring an IVC filter, pyoderma gangrenosum and chronic mesenteric ischemia presented to the Emergency Department for 2 months of hematochezia, 70-lb weight loss, hand rashes with abdominal and leg pain. Computed tomography (CT) of chest/abdomen found a 1.2 cm nodular area with cavitation in the right middle lobe, development of a complicated left transversalis intramuscular fluid collection, complete occlusion of SMA and other vascular changes. He was started on vancomycin and piperacillin/tazobactam. He underwent abdominal fluid drainage which expressed purulent drainage. The culture had no growth until day 9, resulting positive for N. farcinica. MRI brain showed multifocal enhancing lesions. He was then changed to imipenem-cilastatin and trimethoprim/sulfamethoxazole; however, resistances returned to imipenem-cilastatin and switched to linezolid. He subsequently underwent a native vein SMA bypass. He clinically improved slowly overtime. Discharge plan included intravenous antibiotics for 6 weeks then switch to PO for 1 year. Discussion: This case highlights the complexity of diagnosing and managing nocardial infections in immunocompromised patients. The delayed identification of N. farcinica emphasizes the importance of considering atypical pathogens when standard antimicrobial regimens fail. Targeted antibiotic therapy with surgical intervention led to the patient's clinical improvement. This case demonstrates the necessity for multidisciplinary care in managing complex infections in immunocompromised patients.