A50-17 Septic Shock Due to Capnocytophaga Bacteremia in a Patient With Dual Primary Malignancies: A Diagnostic Challenge

Abstract Background Patients with simultaneous solid and hematologic malignancies represent a rare population. Profound immunosuppression and overlapping oncologic complications obscure typical clinical and laboratory signs of infection. In this context, Capnocytophaga, rare gram-negative bacilli, can cause rapidly progressive, often fatal bacteremia, often presenting atypically, further complicating timely diagnosis and management. Case Presentation A 61-year-old man with stage IV esophageal squamous cell carcinoma metastatic to bronchus and concurrent stage IV T-cell lymphoma with bone marrow involvement presented with dyspnea 2 weeks after chemotherapy with carboplatin/paclitaxel. He had recently undergone esophageal stenting and gastrostomy placement for obstruction one month prior. On arrival, he was hypotensive and hypoxic, but afebrile with normal lactate. Imaging demonstrated multifocal consolidations, with a broad differential including aspiration pneumonia, metastatic progression, and chemotherapy-related lung injury. Standard laboratory markers were unreliable due to pancytopenia, impaired T-cell immune function, and recent chemotherapy, obscuring the recognition of severe infection. He was treated with broad coverage for pseudomonal pneumonia and gram-negative rod bacteremia. Despite aggressive measures, he clinically declined and transitioned to comfort-focused care. Unfortunately, the species, Capnocytophaga, was identified after more than 48 hours, delaying appropriate antibiotic coverage. Discussion This case highlights the diagnostic complexity of septic shock in immunocompromised patients. Dual primary malignancies increase disease burden and diminish physiologic reserve, while hematologic malignancies and recent chemotherapy further impair immune function. Capnocytophaga species is a rare, slow growing, highly virulent pathogen associated with immunosuppression, aspiration, mucosal injury, animal bites, cirrhosis, and polymicrobial infections of the head and neck. Capnocytophaga species cause opportunistic infections and specifically have been reported with T-cell lymphoma. Antimicrobial resistance is an emerging concern with clinical implications for empiric therapy. Capnocytophaga bacteremia, although rare, is lethal if unrecognized, and should be considered in immunocompromised patients with esophageal lesions, aspiration risk, or mucosal disruption, which placed him at an increased risk. This case further highlights reliance on classic sepsis markers alone may miss life-threatening infections. His complex clinical picture masked infection and delayed diagnosis and thus, timing of pancytopenia should be considered in consultation with hematology-oncology to determine etiology and appropriate interpretation. Recent publications support the use of capillary refill to determine tissue hypoperfusion in early septic shock which has shown improved outcomes. A broad diagnostic approach with aggressive individualized empiric antimicrobial therapy, in combination with techniques such as capillary refill, can be crucial for identifying atypical pathogens and may ultimately improve outcomes in complex oncologic patients with septic shock. This abstract is funded by: None