Studies on the role of the pyrogenic staphylococcal toxins in sudden infant death syndrome

• Main Author: Essery, Stephen D
• Format: Dissertation
• Language: English
• Published: University of Edinburgh 1998

The aim of this study was to examine how infection might play a role in SIDS in relation to developmental and environmental risk factors identified in epidemiological studies by examining the binding of bacterial toxins to human cells and their effects, singly and in combination on induction of inflammatory mediators. There is a correlation between the incidence of SIDS, isolation of Staphylococcus aureus and expression of the Lewisa blood group antigen in the 2 to 4 month age range. Lewisa has previously been shown to act as a surface receptor for certain bacteria on human epithelial cells, the first stage of this study was to develop a screening method to detect adhesions that bind Lewisa on toxigenic strains of S. aureus and other bacteria isolated from SIDS infants. Additional experiments indicated that some of the superantigenic toxins of S. aureus utilise this antigen as a receptor on monocytes and are capable of stimulating the production of inflammatory mediators from these cells. The pertussis toxin of B. pertussis is capable of binding to Lewisa and Lewisx and it has been suggested that asymptomatic whooping is one cause of SIDS. Changes in the age range of SIDS infants were observed between 1988 and 1994, after the DPT immunisation schedule was changed from 3 months to 2 months of age in October 1990. The protective effect of DPT immunisation suggested in several large epidemiological studies was examined with reference to antigenic cross reactivity between the DPT vaccine and the staphylococcal toxins. Results obtained in enzyme linked immunosorbent assays (ELISA) indicated that antibodies cross-reactive with the staphylococcal toxins were produced by rabbits in response to DPT immunisation. Assays for nitric oxide production by human monocytes in response to the toxins indicated that the antibodies were able to neutralise partially some of the inflammatory activities of the toxins.