Bacterial skin flora and contamination of blood components: do we defer blood donors wisely?

BACKGROUND AND OBJECTIVES: Bacterial infection through contaminated blood is currently the greatest infection risk in relation to a transfusion. Deferral of prospective blood donors with a skin disorder is a common practise, because bacteria usually originate from the donor's skin. The effectiveness of current deferral guidelines to prevent the bacterial contamination of blood has not been assessed. MATERIALS AND METHODS: We recruited 55 blood donors with a skin disorder that prevented donation, and matched three controls for each case. The donors filled out a questionnaire and one bacterial culture sample was taken from venepuncture forearm skin. RESULTS: The median total number of colony forming skin bacteria was significantly higher in the cases (224 CFUs per sample) than controls (105 CFU per sample). Staphylococcus aureus was significantly more often present on the skin in cases (49%) as compared to controls (7%). Regarding other bacterial genera, no difference between cases and controls was found. CONCLUSIONS: This study shows that our current guidelines for deferral of blood donors with skin disorders effectively identifies individuals with a high number of bacteria on their skin, as well as S. aureus carriers. However, deferral due to skin disorders had only a minor impact on blood product contamination when compared to other actions.

Sweden beyond oil: nuclear commitments and solar options.

The project "Energy and Society," sponsored by the Swedish Secretariat for Futures Studies, has studied different indigenous energy sources as alternatives to imported oil in Sweden. One alternative is nuclear energy, antoer is renewable energy. Large uncertainties are associated with both alternatives today. The main characteristics of an energy policy for the rest of the century that does not foreclose either of these options have been identified. Such a policy will have to be based on an understanding of similarities and differences between the alternatives. A nuclear and a solar energy system have been outlined as a basis for an analysis of technical, economic, and institutional issues.

Dependence of Staphylococcus epidermidis on non-transferrin-bound iron for growth.

The ability of Staphylococcus epidermidis strains to grow in the presence of human transferrin and varying amounts of ferric iron was studied. At initial bacterial densities up to 10(4) cfu ml(-1), none of the three strains grew when transferrin iron saturation was below the full saturation point, whereas the bacteria grew consistently when transferrin was fully iron-saturated and there was non-transferrin-bound iron in the medium. Precultivation of the bacteria under iron-restricted conditions to induce siderophore production did not abolish the growth dependence on non-transferrin-bound iron. At initial bacterial densities of 10(6) cfu ml(-1), the bacteria proliferated consistently also in the presence of partially saturated transferrin. The results indicate that at low bacterial densities, S. epidermidis cannot utilise transferrin-bound iron for growth and that its proliferation is dependent on non-transferrin-bound iron.

Characteristics of an unusual anaerobic pigmented gram-negative rod isolated from normal and inflamed appendices.

During our studies of the bacterial etiology of appendicitis, we often isolated a previously undescribed anaerobic gram-negative rod. This organism resembled the Bacteroides fragilis group because it was resistant to bile and because of its special-potency-disk pattern (resistant to vancomycin, kanamycin, and colistin), but unlike the B. fragilis group, this bacterium produced brown pigment on media containing hemolysed blood. The cellular fatty acid pattern, with iso-C15:0 being the predominant acid, was most closely related to the fatty acid profile of Porphyromonas species; however, this organism differed from Porphyromonas species by being bile-resistant and by not producing butyrate as a metabolic endproduct. Enzymatic activities of 31 isolates were determined with use of the API ZYM system and Rosco diagnostic tablets. These profiles were different from those of Prevotella, Porphyromonas, and related species. This organism was isolated from 40% of appendiceal tissue samples; no obvious qualitative or quantitative difference in rates of isolation from patients with inflamed or normal appendices was observed.