Individualizing the use of [18F]FDG-PET/CT in patients with complicated Staphylococcus aureus bacteremia: experiences from a tertiary care center.

PURPOSE: [18F]FDG-PET/CT scanning can help detect metastatic infectious foci and reduce mortality in patients with Staphylococcus aureus bacteremia (SAB), but it is unknown if patients with SAB and an indication for prolonged treatment because of possible endovascular, orthopaedic implant, or other metastatic infection still need [18F]FDG-PET/CT. METHODS: In a retrospective single-center cohort study, we included all consecutive adult patients with SAB between 2013 and 2020 if an [18F]FDG-PET/CT scan was performed and antibiotic treatment was planned for ≥ 6 weeks prior to [18F]FDG-PET/CT. We aimed to identify patients for whom treatment was adjusted due to the results of [18F]FDG-PET/CT, and assessed concordance of [18F]FDG-PET/CT and clinical diagnosis for infected prosthetic material. RESULTS: Among 132 patients included, the original treatment plan was changed after [18F]FDG-PET/CT in 22 patients (16.7%), in the majority (n = 20) due to diagnosing or rejecting endovascular (graft) infection. Antibiotic treatment modifications were shortening in 2, iv-oral switch in 3, extension in 13, and addition of rifampicin in 4 patients. Ninety additional metastatic foci based on [18F]FDG-PET/CT results were found in 69/132 patients (52.3%). [18F]FDG-PET/CT suggested vascular graft infection in 7/14 patients who lacked clinical signs of infection, but showed no infection of prosthetic joints or osteosynthesis material in eight patients who lacked clinical signs of such an infection. CONCLUSION: [18F]FDG-PET/CT can help refine treatment for SAB in patients with clinically suspected endovascular infection or vascular grafts, even if 6 weeks treatment is already indicated, but can be safely omitted in other patients who are clinically stable.

The diagnostic value of [18F]FDG-PET/CT in detecting septic thrombosis in patients with central venous catheter-related Staphylococcus aureus bacteremia.

PURPOSE: Septic thrombosis often complicates Staphylococcus aureus bacteremia (SAB) in patients with a central venous catheter. Currently there is no reference standard for diagnosis. We describe the diagnostic value of [18F]FDG-PET/CT imaging in a patient cohort and the potential contribution of quantitative measurements in detecting septic thrombosis. METHODS: We selected patients with catheter-related SAB from our institutional database (2013-2020). The contribution of [18F]FDG-PET/CT on clinical diagnosis of septic thrombosis was evaluated. Standardized Uptake Values (SUV) were measured and compared with a composite reference standard (clinical signs, initial [18F]FDG-PET/CT result, Multidisciplinary Team (MDT) meeting outcome) to identify a cut-off value for detecting septic thrombosis. RESULTS: We identified 93 patients with a catheter-related SAB. Quantitative measurements were possible for 43/56 patients in whom a [18F]FDG-PET/CT scan was performed. Septic thrombosis was clinically diagnosed in 30% (13/43) of the cases. In 85% of these cases, significant [18F]FDG-PET/CT uptake at the site of the thrombus was the deciding factor for diagnosis of septic thrombosis during the MDT meeting. All mean SUV's of thrombotic lesions were higher in patients with clinically proven septic thrombosis compared to patients in whom this diagnosis was rejected (p < 0.001). A SUVpeak thrombus/SUVmean blood ratio of 1.6 (AUC-ROC value 0.982) as cut-off to differentiate between septic thrombosis and non-septic thrombosis had a sensitivity of 92% (95% CI 64-100) and specificity of 89% (95% CI 65-99). An algorithm was designed to guide diagnosis of septic thrombosis. CONCLUSION: Quantitative [18F]FDG-PET/CT-derived parameters seem helpful to differentiate between septic and non-septic thrombosis in patients with catheter-related SAB.

Intravenous to Oral Switch in Complicated Staphylococcus aureus Bacteremia Without Endovascular Infection: A Retrospective Single-Center Cohort Study.

In this retrospective cohort study, selected patients with disseminated Staphylococcus aureus bacteremia, but without endovascular infection on echocardiography and 18F-FDG-PET/CT, were free of relapse after IV-oral switch. Mortality was low and similar to patients who received prolonged intravenous treatment. IV-oral switch was associated with a shorter length of hospital stay.

Clinical Characteristics and Outcomes of S. Aureus Bacteremia in Patients Receiving Total Parenteral Nutrition.

Background: Patients on total parenteral nutrition (TPN) are at risk of developing central line-associated infections. Specifically, Staphylococcus aureus bacteremia (SAB) is feared for its high complication rates. This prospective cohort study compares characteristics, clinical course and outcome of SAB in patients with and without TPN support. Methods: Clinical and microbiological data from all patients with positive blood cultures for S. aureus from two facilities, including our referral center for TPN support, were retrieved (period 2013-2020). Primary outcome was overall mortality, and included survival analysis using a multivariate Cox regression model. Secondary outcomes comprised a comparison of clinical characteristics and outcomes between both patient groups and analysis of factors associated with complicated outcome (e.g., endocarditis, deep-seated foci, relapse and death) in patients on TPN specifically. Results: A total of 620 SAB cases were analyzed, of which 53 cases received TPN at the moment the blood culture was taken. Patients in the TPN group were more frequently female, younger and had less comorbidity (p < 0.001). In-hospital death and overall mortality were significantly lower in TPN patients (4% vs. 18%, p = 0.004 and 10% vs. 34%, p < 0.001, respectively). Positive follow-up blood cultures, delayed onset of therapy and previous catheter problems were associated with a higher incidence of complicated SAB outcome in patients on TPN. Conclusion: Our data show that patients on TPN have a milder course of SAB with lower mortality rates compared to non-TPN SAB patients.