Posterior Splenic Abscess Leak Causing Salmonella Group B Peritonitis in an Immunocompetent Young Adult

Splenic abscess is an uncommon intra-abdominal abscess, typically associated with immunocompromised states. This report highlights a case where the abscess was caused by Salmonella species in an immunocompetent individual, which is a very rare occurrence with limited prior documentation. We report a previously healthy 24-year-old male who presented with high-grade fever and diffuse abdominal pain. Preoperative CT imaging demonstrated hepatosplenomegaly and a 5.6 × 3.8 cm posterior splenic lesion. Exploratory laparoscopy revealed four-quadrant purulent peritonitis without hollow-viscus perforation and a posterior splenic capsular tear with oozing. Cultures from blood, peritoneal fluid, and a subsequent percutaneous splenic drain all grew Salmonella enterica serogroup B. Spontaneous leak of a splenic abscess causing diffuse peritonitis without gastrointestinal perforation is extremely rare. While most reported cases involve comorbidities, Salmonella splenic abscesses have been documented in healthy individuals. Management requires prompt source control, either percutaneous drainage or splenectomy, plus targeted antimicrobials. Our patient was successfully treated with laparoscopic washout, targeted antibiotic therapy after allergy-related adjustment, and image-guided drainage, preserving splenic function. This case highlights one of the few documented instances of Salmonella Group B splenic abscess rupture in an immunocompetent adult. Clinicians should maintain high suspicion for splenic pathology in Salmonella bacteremia with peritonitis, even without classic risk factors. Organ-sparing approaches can be effective when combined with multidisciplinary care.