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A total of 38 Citrobacter freundii strains was isolated from patients and their environment at a neonatal intensive care unit of a large hospital where colonization and clinical diseases due to the agent had been observed. Epidemiological investigations were carried out by subtyping, for which a combination of allozyme, whole-cell protein and resistance pattern analysis was used. Infant formula was identified as a vehicle of nosocomial spread. This shows that the role of foods in the transmission of hospital infections should not be underestimated. The combination of methods applied, in particular a limited enzyme set, is recommended also for epidemiological investigations of food-borne infections and establishment of their causes.

In June 1998, an increased number of persons with Salmonella blockley infection were reported from one German state. Because S. blockley is extremely uncommon in Germany, a case-control study was performed in order to find the source. A total of 13 patients met the case definition. Nine of 12 cases and 2 of 21 controls with food consumption histories reported eating smoked eel (OR 28.5; 95% CI 3.9-235.3). The consumed eel came from four different local smokeries, but could be traced back to fish farms in Italy. This outbreak indicates that eel may be a vehicle for salmonella infection and that the smoking process may not eliminate bacterial contamination from raw fish.

SummaryIsolation and characterization of shigatoxin producing E. coli strains isolated from stool samples: results of a Sentinel-study In order to record the incidence and clonal types of shigatoxin-producing E. coli of human origin (EHEC) and to evaluate the feasibility, sensitivity and specificity of a protocol for screening and isolation of EHEC under conditions clinical stool diagnostics a pilot study (Sentinel-study) was carried out with private clinical laboratory (covering 1.1 Mio. inhabitants). 3 % EHEC bacteria were detected among 3835 stool samples investigated from patients suffering with watery and bloody diarrhoea. These isolates belong to a broad range of serovars and clones with a spectrum of various virulence factors. Thus, about 10 % of the isolates have been identified as E. coil O157:H7/-, only, but with the same frequency E. coli O103:H2, O26:Hll/-, O8:H or Ont. The protocol of combined bacterial enrichment and molecular methods turned out to be valuable and feasible under conditions and economic requests of private diagnostic laboratories covering ca. 85 % of primary diagnostics.

Existing solar thermal power plants are based on steam turbine cycles. While their process temperature is limited, solar gas turbine (GT) systems provide the opportunity to utilize solar heat at a much higher temperature. Therefore there is potential to improve the efficiency of future solar thermal power plants. Solar based heat input to substitute fuel requires specific GT features. Currently the portfolio of available GTs with these features is restricted. Only small capacity research plants are in service or in planning. Process layout and technology studies for high solar share GT systems have been carried out and have already been reported by the authors. While these investigations are based on a commercial 10MW class GT, this paper addresses the parameterization of high solar share GT systems and is not restricted to any type of commercial GT. Three configurations of solar hybrid GT cycles are analyzed. Besides recuperated and simple GT with bottoming Organic Rankine Cycle (ORC), a conventional combined cycle is considered. The study addresses the GT parameterization. Therefore parametric process models are used for simulation. Maximum electrical efficiency and associated optimum compressor pressure ratio πC are derived at design conditions. The pressure losses of the additional solar components of solar hybrid GTs have a different adversely effect on the investigated systems. Further aspects like high ambient temperature, availability of water and influence of compressor pressure level on component design are discussed as well. The present study is part of the R&D project Hybrid High Solar Share Gas Turbine Systems (HYGATE) which is funded by the German Ministry for the Environment, Nature and Nuclear Safety and the Ministry of Economics and Technology.