Abstract
RATIONALE: Multiple myeloma (MM), ranking as the second most prevalent hematologic malignancy. Despite prolonged survival in MM due to novel therapies, infections remain a leading cause of mortality. While bacterial pneumonias and viral reactivations are well-documented, Listeria monocytogenes (L monocytogenes) (a rare but aggressive pathogen) is underrecognized in MM. PATIENT CONCERNS: In this report, we report a 60-year-old male patient with newly diagnosed IgA-λ MM (Durie-Salmon stage IIIA, ISS stage III with 1q21 amplification) who developed high-grade fever (39.8 °C) and expressive aphasia during the second cycle of bortezomib-lenalidomide-dexamethasone induction therapy. Initial workup revealed neutrophilia (absolute neutrophil count 1.94 × 10⁹/L) with elevated inflammatory markers (C-reactive protein 118.14 mg/L). Cerebrospinal fluid analysis showed albuminocytologic dissociation (protein 1116.3 mg/L, glucose 1.77 mmol/L, chloride 114.75 mmol/L) without positive cultures. Contrast-enhanced brain MRI demonstrated neither abscess formation nor acute ischemia. DIAGNOSES: Repeated blood cultures drawn at fever onset, L monocytogenes bacteremia was confirmed 48 hours after-afebrile through blood culture. The patient has been diagnosed MM with bacteremia and meningitis caused by L monocytogenes infection. INTERVENTIONS: Empiric meropenem was initiated promptly, achieving defervescence within 72 hours. Upon availability of antimicrobial susceptibility testing (intravenous penicillin G 8 million units every 8 hours), with documented blood culture clearance at 72 hours. OUTCOMES: On the second day of medication, the patient's aphasia symptoms were resolved, the fever subsided on the 3rd day, and the blood culture turned negative on the 10th day. The patient completed a 21-day targeted antibiotic course without neurologic sequelae and was discharged with planned resumption of anti-myeloma therapy. LESSONS: This case underscores the need for early empiric coverage for Listeria in MM patients with unexplained fever or neurological symptoms, particularly given its high mortality in immunocompromised hosts.