BACKGROUND: Iliacus muscle abscess is a rare condition that frequently presents with nonspecific clinical symptoms. Abscesses in the iliacus muscle can arise from contiguous spread from adjacent structures or from distant sites via hematogenous or lymphatic routes.

CASE REPORT: We report a case of iliacus muscle abscess in a 22-year-old female microbiologist who presented to the emergency department with severe back pain and lower-extremity weakness after returning from a trip to Mexico. She was found to have urinary tract infection due to Salmonella. The patient was found to have left iliacus muscle abscess and septic arthritis of the sacroiliac joint. She was initially treated with piperacillin-tazobactam, vancomycin, and metronidazole, which were later switched to intravenous ceftriaxone and oral levofloxacin. She was successfully treated with antibiotics, with a complete resolution of the multiple tiny abscesses.

CONCLUSIONS: Iliacus muscle abscess presents with nonspecific symptoms that can mimic neurologic diseases such as spinal cord compression. A high index of suspicion is required to make an early diagnosis and initiate prompt treatment with antibiotics and abscess drainage, if accessible. A detailed history is essential to assess risk factors and establish likely causative organisms. Delay in treatment can lead to an increase in morbidity and mortality. Long-term follow-up is crucial, as the incidence of relapse is high.

Keywords: Early Diagnosis, Psoas Abscess, Salmonella, Abscess, Anti-Bacterial Agents, Arthritis, Infectious, Drug Therapy, Combination, Mexico, Salmonella Infections, Travel, Urinary Tract Infections, young adult