Vergleich der klinischen und immunologischen Auswirkungen einer Infektion mit Escherichia coli O104:H4 beziehungsweise enterohämorrhagischen Escherichia coli O157:H7 im gnotobiotischen Schweinemodell.
Comparison of clinical and immunological findings in gnotobiotic piglets infected with Escherichia coli O104:H4 outbreak strain and EHEC O157:H7
Dissertation, Vet. Med. Univ. Wien, pp. 50.
Data of 13 piglets delivered by caeseran section and kept under sterile conditions were included in this study. Piglets were assigned either to the control group or to two infection groups (E. coli O157:H7 and E. coli O104:H4, respectively). Animals were controlled frequently, clinical examination was regulary performed and samples were taken in specific time intervals (blood, faeces, urine). Immediately after euthanasia or death, necropsy was performed and further samples were taken for pathohistological examination according to a preassigned schedule. In contrast to animals infected with E. coli O157:H7, which partly developed severe neurological symptoms, animals infected with E. coli O104:H4 showed only mild signs of disease as dehydration and diarrhoea. No systemic disease was inducible by infection with E. coli O104:H4. This observation is in contrast to epidemiological data from the disease outbreak in 2011 in humans, which was characterised by a significantly higher prevalence of HUS patients than in outbreaks caused by other serotypes, for example by E. coli O157:H7. Some biochemical parameters considered as prognostic markers and predictors for the course of disease for HUS in humans were determined during the experiments. Expected changes in selected parameters, which were found in diseased humans with a high probability, were only found inconsistently in gnotobiotic piglets in both infection groups. Results of flowcytometry indicate that natural killer cells play a role in the host reaction during STEC-infection. This aspect of disease should be adressed in further studies. A/E lesions caused by E. coli O157:H7 were shown by electron microscopy, but not the typical stacked-brick adherence described for E. coli O104:H4. In conclusion, the gnotobiotic piglet model is time-consuming and expensive and has several limitations. Nevertheless, using this model, data can be collected and specific hypotheses can be answered, which could contribute to a better understanding of STEC-associated disease.