18F-FDG PET/CT for detection of metastatic infection in gram-positive bacteremia.
The timely detection of metastatic infectious foci in gram-positive bacteremia is crucial, because these foci often require prolonged antibiotic treatment or drainage. The diagnosis of metastatic infectious foci is difficult because localizing symptoms are often absent. We investigated whether (18)F-FDG PET/CT was able to detect such foci and whether detection influenced clinical outcome.


METHODS
One hundred fifteen nonneutropenic patients with gram-positive bacteremia were prospectively included. Patients with positive blood cultures growing Staphylococcus aureus, Streptococcus species, or Enterococcus species were eligible when a risk factor for developing metastatic infectious foci was present. (18)F-FDG PET/CT was performed within 2 wk after the first positive blood culture. Abnormal (18)F-FDG uptake had to be confirmed by radiologic, microbiologic, or pathologic studies. Results were compared with a matched historical control group of 230 patients in whom no (18)F-FDG PET/CT was performed.


RESULTS
Significantly more patients were diagnosed with metastatic foci in the study group (67.8% vs. 35.7%). Of the imaging investigations performed, (18)F-FDG PET/CT was the first to delineate infectious foci in 35 patients (30%). In the remaining 70%, either symptoms on physical examination or other imaging techniques first revealed infectious foci. The sensitivity, specificity, negative predictive value, and positive predictive value of (18)F-FDG PET/CT were 100%, 87%, 100%, and 89%, respectively. Relapse rates decreased from 7.4% to 2.6% among study patients (P = 0.09) and from 8.9% to 1.4% in patients with S. aureus (P = 0.04). Overall mortality after 6 mo decreased from 32.2% to 19.1% in the (18)F-FDG PET/CT group (P = 0.014).


CONCLUSIONS
In the diagnostic work-up of high-risk patients with gram-positive bacteremia, (18)F-FDG PET/CT is a valuable technique that results in lower mortality rates. In patients with S. aureus bacteremia, relapse rates decreased significantly after the addition of (18)F-FDG PET/CT.
Vos
Fidel J
FJ
Department of Internal Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. f.vos@aig.umcn.nl
Bleeker-Rovers
Chantal P
CP
Sturm
Patrick D
PD
Krabbe
Paul F M
PF
van Dijk
Arie P J
AP
Cuijpers
Maria L H
ML
Adang
Eddy M M
EM
Wanten
Geert J A
GJ
Kullberg
Bart-Jan
BJ
Oyen
Wim J G
WJ
D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D016470:Bacteremia / Q000000981:diagnostic imaging* / Q000382:microbiology; D003428:Cross Infection / Q000000981:diagnostic imaging; D023381:Endpoint Determination; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D016908:Gram-Positive Bacterial Infections / Q000000981:diagnostic imaging* / Q000382:microbiology; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D012307:Risk Factors; D013203:Staphylococcal Infections / Q000000981:diagnostic imaging / Q000382:microbiology; D013290:Streptococcal Infections / Q000000981:diagnostic imaging / Q000382:microbiology; D014055:Tomography, Emission-Computed; D016896:Treatment Outcome
D000900:Anti-Bacterial Agents; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18