Abstract
Introduction: Infection can be difficult to recognize in immunosuppressed patients as their ability to mount an immune response is blunted. Furthermore, an intraabdominal abscess can progress rapidly, leading to complications, septic shock, and mortality. We present a case of delayed recognition and intervention of an abdominal abscess leading to surgical complications in an immunocompromised lung transplant (LT) recipient. Description: A 63-year-old man with idiopathic pulmonary fibrosis presented to our center 18 months after bilateral LT endorsing ongoing vague malaise and abdominal pain. His immunosuppressive regimen consisted of mycophenolic acid, prednisone, and tacrolimus, along with prophylactic acyclovir/letermovir, bactrim, and itraconazole. He was seen in clinic 2 months prior for diarrhea without constitutional signs of infection. A comprehensive pathogen panel was negative. On admission, he met sepsis criteria with leukopenia (WBC count 2,700 cells/μL). Abdominal CT revealed severe sigmoid diverticulitis with contained perforation and a peri-colonic abscess eroding into the superior bladder wall. Interventional Radiology and General Surgery deemed the abscess too small to drain. The patient was treated with levaquin and metronidazole and discharged with close follow up. He returned to the hospital 1 month later endorsing pneumaturia, at which time significant adhesions from the sigmoid colon to the bladder and a colovesicular fistula were found. General Surgery and Urology evaluated the patient, and he underwent laparoscopic sigmoidectomy with end colostomy and colovesicular fistula takedown. He was empirically treated with piperacillin and tazobactam, which was transitioned to amoxicillin/clavulanate on discharge. Blood cultures were negative on both admissions. The patient responded well to surgical management and subsequently underwent ostomy reversal. Discussion: This case highlights significant diagnostic and therapeutic challenges that immunocompromised patients, particularly lung transplant recipients, present when managing intra-abdominal infections. Recognizing infection in immunosuppressed patients is inherently challenging, as immunosuppression often masks classic symptoms such as fever and elevated inflammatory markers. Subtle or vague symptoms, like the patient's initial malaise and mild abdominal pain need prompt intervention. Source control is an important factor in the treatment of infections requiring prompt intervention including surgery as the risk of disease progression, bacterial translocation, and complications including septic shock increase over time. Broad spectrum antibiotics alone are often insufficient. Our patient recognized pneumaturia quickly, leading to a timely intervention with a good outcome.