Brief report: biomarkers of aortic vascular prosthetic graft infection in a porcine model with Staphylococcus aureus

A Novel Mouse Model of Staphylococcus aureus Vascular Graft Infection: Noninvasive Imaging of Biofilm Development in Vivo

Staphylococcus aureus causes very serious infections of vascular grafts. Knowledge of the molecular mechanisms of this disease is largely lacking because of the absence of representable models. Therefore, the aim of this study was to set up a mouse model of vascular graft infections that closely mimics the human situation. A catheter was inserted into the right carotid artery of mice, which acted as a vascular graft. Mice were infected i.v. using 8 different S. aureus strains, and development of the infection was followed up. Although all strains had varying abilities to form biofilm in vitro and different levels of virulence in mice, they all caused biofilm formation on the grafts. This graft infection was monitored using magnetic resonance imaging (MRI) and ¹⁸F-fluordeoxyglucose positron emission tomography (FDG-PET). MRI allowed the quantification of blood flow through the arteries, which was decreased in the catheter after infection. FDG-PET revealed high inflammation levels at the site of the catheter after infection. This model closely resembles the situation in patients, which is characterized by a tight interplay between pathogen and host, and can therefore be used for the testing of novel treatment, diagnosis, and prevention strategies. In addition, combining MRI and PET with microscopic techniques provides an appropriate way to characterize the course of these infections and to precisely analyze biofilm development.

Multidisciplinary Treatment Approach for Prosthetic Vascular Graft Infection in the Thoracic Aortic Area

Prosthetic vascular graft infection in the thoracic aortic area is a rare but serious complication. Adequate management of the complication is essential to increase the chance of success of open surgery. While surgical site infection is suggested as the root cause of the complication, it is also related to decreased host tolerance, especially as found in elderly patients. The handling of prosthetic vascular graft infection has been widely discussed to date. This paper mainly provides a summary of literature reports published within the past 5 years to discuss issues related to multidisciplinary treatment approaches, including surgical site infection, timing of onset, diagnostic methods, causative pathogens, auxiliary diagnostic methods, antibiotic treatment, anti-infective structures of vascular prostheses, surgical treatment, treatment strategy against infectious aortic aneurysms, future surgical treatment, postoperative systemic therapy, and antimicrobial stewardship. A thorough understanding of these issues will enable us to prevent prosthetic vascular graft infection in the thoracic aortic area as far as possible. In the event of its occurrence, the early introduction of appropriate treatment is expected to cure the disease without worsening of the underlying pathological condition.

¹⁸F-FDG PET/CT for Therapy Control in Vascular Graft Infections: A First Feasibility Study

The aim of this study was to evaluate the clinical value of PET/CT with (18)F-FDG for therapy control in patients with prosthetic vascular graft infections (PVGIs).

METHODS

In this single-center, observational, prospective cohort study, 25 patients with a median age of 66 y (range, 48-81 y) who had a proven PVGI were included. Follow-up (18)F-FDG PET/CT was performed at a median of 170 d (range, 89-249 d) after baseline examination. Two independent and masked interpreters measured maximum standardized uptake values to quantify metabolic activity and analyzed whole-body datasets for a secondary diagnosis (i.e., infectious foci not near the graft). The metabolic activity of the graft was correlated with clinical information and 2 laboratory markers (C-reactive protein and white blood cell count).

RESULTS

(18)F-FDG PET/CT had an impact on management in all patients. In 19 of 25 patients (76%), antibiotic treatment was continued because of the results of follow-up (18)F-FDG PET/CT. Antibiotic treatment was stopped or changed in 8% and 16% of patients, respectively. In 8 patients (32%), additional incidental findings were detected on follow-up (18)F-FDG PET/CT and had a further impact on patient management. Only in a subgroup of patients with PVGI and no other sites of infection was a significant correlation found between the difference in C-reactive protein at the time of baseline and follow-up (18)F-FDG PET/CT and the difference in maximum standardized uptake value (n = 11; R(2) = 0.67; P = 0.002).

CONCLUSION

(18)F-FDG PET/CT represents a useful tool in therapy monitoring of PVGI and has an impact on patient management.