China Aortic Infection and Graft Infection Study: An Ambispective Cohort

Vascular infections are uncommon but severe infections involving the arterial wall, vascular grafts, or endografts, and their diagnosis and management remain challenging. The CAIGIS Cohort is an ambispective observational cohort established at Zhongshan Hospital, Fudan University, to create an integrated clinical research platform and biobank for patients with suspected or confirmed vascular infections. The primary research focus is the diagnosis and characterization of causative pathogens. Conventional microbiological methods and emerging molecular diagnostic technologies will be systematically evaluated, with particular emphasis on blood-based pathogen detection as a form of liquid biopsy and its diagnostic value compared with local tissue or operative specimens. Serial blood samples and tissue specimens, when available, will also be used to investigate biomarkers associated with treatment response and clinical outcomes. Another major focus is the role of molecular imaging, particularly 18F-FDG PET/CT, in the diagnosis and longitudinal assessment of vascular infections. The study will evaluate its diagnostic performance, its added value in patients with inconclusive conventional imaging, and the potential significance of changes in metabolic activity during follow-up for assessing treatment response, residual infection, recurrence, and prognosis. The cohort will further support nested translational studies addressing specific pathogen- and disease-related questions. These include longitudinal characterization of microbial communities in patients with vascular-enteric fistulas; evaluation of the clinical significance and invasive potential of Candida species; investigation of the clinical and biological characteristics of mycobacterial vascular infections; and exploration of pathogen-host interactions within infected vascular tissues. By integrating longitudinal clinical data, microbiological results, molecular diagnostics, PET/CT findings, treatment information, outcomes, and biospecimens, the cohort aims to improve etiological diagnosis, disease stratification, treatment monitoring, prognostic assessment, and understanding of the pathogenesis of vascular infections.

Inclusion Criteria: 1. Adults aged 18 years or older. 2. Patients with suspected or confirmed vascular infection involving the native arterial wall, vascular graft, or endograft, including but not limited to infectious aortitis, infected arterial aneurysm, vascular graft or endograft infection, and fistula-associated vascular infection. 3. Patients evaluated or treated at Zhongshan Hospital, Fudan University, with sufficient clinical information to allow diagnostic adjudication and outcome assessment. 4. For the prospective cohort, willingness to participate and provide informed consent when required. 5. For the retrospective cohort, availability of relevant clinical records meeting the requirements approved by the institutional ethics committee. Exclusion Criteria: 1. Isolated superficial surgical-site infection without evidence of involvement of the arterial wall, vascular graft, or endograft. 2. Insufficient clinical data to permit diagnostic adjudication or longitudinal outcome assessment. 3. Refusal to participate in the prospective component when informed consent is required.