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BACKGROUND: The isolation of Propionibacterium acnes in blood cultures is often considered a contaminant. On rare occasions, P. acnes can cause severe infections, including endocarditis and intravascular prosthesis-associated infections. To evaluate the discrimination between a contaminant and a clinically relevant infection we used an Ouchterlony test system to quantify the antibody response to P. acnes in a patient with a proven P. acnes endocarditis. CASE PRESENTATION: We report on a 64-year-old Caucasian man who developed P. acnes endocarditis four years following a composite valve-graft conduit replacement of the aortic root. Bacterial growth in blood cultures was detected after an incubation period of 6 days. However, the antibody titer to P. acnes was 1:8 at the time of diagnosis and declined slowly thereafter over 2½ years. The patient's response to the antibiotic treatment was excellent, and no surgical re-intervention was necessary. CONCLUSION: The working hypothesis of infective endocarditis can be substantiated by serologic testing, which, if positive, provides one additional minor criterion. Moreover, quantification of the antibody response to P. acnes, though not specific, may assist in the differentiation between contaminants and an infection. This quantification may have implications for the patient management, e.g. indication for and choice of the antibiotic therapy.

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AIM: of the study was to evaluate the influence of an extra corporal perfusion (cardiopulmonary bypass operation - cpb) on activation and biodistribution of (99m)Tc labelled granulocytes in pigs with and without inhibition of the granulocytes by a leukocyte inhibition module (LIM). The cpb is often related to an activation of granulocytes resulting in an inflammatory answer. The biological mechanisms are unsolved yet. First trials of our group showed that LIM may inhibit the activation of neutrophils and therefore antagonize a cpb-caused impairment of cardiac function. This study is the continuation of these experiments with a higher number of animals and the focus on scintigraphic imaging. ANIMALS, MATERIAL, METHODS: 39 German landrace pigs were subdivided into three groups: group A (control) median sternotomy without cpb, group B with cpb, group C with LIM in addition to cpb. After labelling with (99m)Tc-HMPAO autologues granulocytes were reinjected. Subsequently to cpb, the animals underwent scintigraphic imaging. Quantification was performed with ROI evaluation and with tissue samples (section analysis) examined in a well counter. RESULTS: A high uptake of (99m)Tc-HMPAO was found in the liver. The count rates in brain, heart, lung, spleen and kidneys were far below. The amount of 99mTc-activity in the organ related to the half life corrected administered activity [%] was for the tissue samples (group A/B/C): brain 0.01/0.02/0.03; lung 12.1/8.3/11.5; heart 0.35/0.54/0.42; kidney 1.24/0.87/1.02; spleen 4.0/4.0/4.5, liver 16.8/20.9/19.6. The count rates determined by ROI-evaluation of the scintigraphic images related to the total count rate in the image [%] were (group A/B/C): brain 1.1/0.9/1.0; lung 15.6/10.4/12.2; heart 4.0/3.5/3.4; kidney 4.0/2.9/3.2; spleen 7.6/7.7/9.5, liver 23.1/36.7/31.4. A significant difference in the tracer uptake between the groups could neither be detected by scintigraphic imaging nor evaluation of tissue samples. CONCLUSION: Scintigraphic imaging as well as section analysis showed a comparable biodistribution of the tracer. Therefore, the initial results of our group were not confirmed with a considerably higher number of animals. Neither cpb nor the use of the LIM influenced distribution of 99mTc-labelled granulocytes in pigs significantly.

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AIM: The aim of this study was to retrospectively analyse the value of positron emission tomography (PET) with a radiolabelled somatostatin analogue, [(68)Ga]DOTATOC, in recurrent radioiodine positive and negative differentiated thyroid cancer (DTC) compared to [(18)F]FDG PET. METHODS: Seventeen patients with known or suspected recurrent DTC were enrolled in this study. All patients underwent PET with [(68)Ga]DOTATOC and [(18)F]FDG under TSH suppressive therapy and whole-body scintigraphy (WBS) after administration of [(131)I] following TSH stimulation. The total number of tumour lesions was defined as the sum of the lesions detected by at least one of these three imaging techniques. Pathologic findings were confirmed histopathologically or by follow-up and conventional radiological imaging. RESULTS: Both PET tracers consistently detected metastases in 12 patients. In two cases, only [(131)I] WBS and computed tomography revealed metastatic disease; in the remaining three patients with an increased thyroglobulin no correlate could be found. From a total of 104 tumour lesions, [(18)F]FDG PET showed only slightly higher detection rate than [(68)Ga]DOTATOC PET in radioiodine positive patients (28/31 versus 25/31), whereas significant differences were seen in the group with negative [(131)I] WBS (70/73 versus 26/73, P<0.01). Three out of 104 lesions were only visible using [(68)Ga]DOTATOC PET. CONCLUSIONS: [(68)Ga]DOTATOC and [(18)F]FDG PET showed comparable diagnostic performance in recurrent, radioiodine positive DTC. Due to much higher lesion detection rates, [(18)F]FDG PET should be preferred to [(68)Ga]DOTATOC PET in the work-up of radioiodine negative DTC relapse. These preliminary results have to be confirmed by more extensive data in further studies.

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