Invasive Listeriosis in an Older Adult With a History of Raw Crab Consumption: A Case Report.

Listeria monocytogenes can cause severe invasive infection in older and medically vulnerable patients, and pinpointing a potential exposure may require a detailed dietary history. We report the case of an 84-year-old woman with end-stage renal disease on hemodialysis, type 2 diabetes mellitus, cardiovascular disease, and vascular dementia who presented with chest pain and mild dyspnea and then developed fever, hypotension, tachycardia, and a single episode of diarrhea, which prompted evaluation for sepsis. Blood cultures turned positive in both aerobic and anaerobic bottles after approximately 22 hours of incubation and were subsequently identified as Listeria monocytogenes. Empiric vancomycin was stopped, and targeted therapy with intravenous ampicillin and adjunctive gentamicin was started. Repeat blood cultures remained negative during Infectious Diseases follow-up. There were no local signs of infection at her left upper-extremity arteriovenous fistula, transthoracic echocardiography showed no reported valvular vegetations, and no clinical evidence of central nervous system involvement was found. Collateral dietary history obtained during hospitalization revealed that she had eaten raw crab before admission. Because the interval between consumption and symptom onset could not be established and the implicated food was unavailable for microbiological testing, the exposure was considered plausible but unconfirmed. The patient improved clinically and was discharged in stable condition. This case highlights the importance of considering invasive listeriosis in older, medically vulnerable patients with bacteremia or sepsis, evaluating for possible invasive complications, and obtaining detailed collateral dietary histories, while avoiding unsupported attribution of causality to a suspected food exposure.