Influence of strain-dependent characteristics on the Stx2e secretion by porcine Shiga toxin-producing Escherichia coli

Korte beschrijving

In this PhD thesis, the primary focus is on investigating the production and secretion of Shiga toxin subtype 2e (Stx2e) by Shiga toxin-producing Escherichia coli (STEC) strains, which are major pathogens responsible for diarrhoea and oedema disease in post-weaning piglets. Despite being a well-established cause of disease, the mechanisms that regulate Stx2e production and its variable effects under different environmental and physiological conditions remain insufficiently understood. Additionally, the reasons behind the variability in clinical outcomes—ranging from subclinical infections to severe symptoms—are unclear, with contributing factors potentially including bacterial strain differences, host immunity, and external stressors such as diet, co-infections, and farm hygiene. To address these knowledge gaps, this thesis presents a comprehensive approach. Wild-type STEC strains from farms with a history of oedema disease were collected and characterized to investigate strain-specific differences. Furthermore, recombinant Stx2e was produced and purified to facilitate experimental investigations of the environmental and physiological factors influencing toxin secretion. Specifically, the effects of bile acids, catecholamines, and antibiotics on Stx2e secretion were examined.