Utility of 18F-FDG PET/CT in Evaluation of Staphylococcus aureus Bacteremia

Abstract Background Staphylococcus aureus bacteremia (SAB) is often complicated by metastatic infection. Prompt diagnosis of distant sites of infection is key to appropriate and timely intervention, and guiding duration of antimicrobial therapy. Methods All patients with SAB who underwent 18F-FDG PET/CT as part of the evaluation at Mayo Clinic Rochester from 2015–2016 were reviewed. Primary outcomes were new findings of infection on PET/CT with resulting modification to therapy. Results Eleven patients with SAB underwent PET/CT are summarized in table 1. Median symptom duration prior to PET/CT was 13 days (IQR 9–25). All patients were on antibiotics (median 10 days, IQR 7–18) prior to PET/CT scan. PET/CT was positive for infection in 10/11 patients; unique sites of infection were noted in 7/10 patients and clinical suspicion of infectious foci was confirmed in 5/10 patients. Clinically unsuspected spine infection was found in 3 patients, leading to longer duration of antibiotic therapy and 1 patient had spine infection and psoas abscess on PET/CT with negative prior CT and MRI. Intra-abdominal and deep soft-tissue infection were found in 2 patients, requiring drainage procedures. An unsuspected cardiac device lead infection was found in 1 patient prompting device explantation. An alternative diagnosis of pancreatitis accounted for recurrent leucocytosis and fever in a critically ill patient, leading to antimicrobial deescalation. An asymptomatic prostate abscess was found in another patient. Conclusion 18F‐FDG‐PET/CT is a useful tool for detection of metastatic foci of infection in SAB, with subsequent impact on management interventions for source control and duration of antibiotic therapy. Table 1. Summary of patient characteristics Median age 67 years (IQR 59–79) Female gender 45% (N = 5/11) Median BMI 30 (IQR 28–34) Comorbidities CKD 27% (N = 3/11); ESRD on HD 18% (N = 2/11) Mean Charlson Comorbidity Index 4.5 (SD 2.9) Initial presentation Sepsis/shock 55% (N = 6/11); spinal osteomyelitis 18% (N = 2/11); SSTI 9% (N = 1/11); UTI 9% (N = 1/11); meningitis 9% (N = 1/11) Mean peak white cell count 23.8 x109/L (SD 10.5) Mean peak CRP 173 (SD 121.2) Blood cultures MSSA 55% (N = 6/11), MRSA 45% (N = 5/11) Positive TEE 9% (N = 1/11) Median length of stay 15 days (IQR 9–37) Disclosures All authors: No reported disclosures.