ORIGINAL PAPER Staphylococcal toxins in sudden unexpected death in infancy: experience from a single specialist centre M. A. Weber • J. C. Hartley • N. J. Klein • R. A. Risdon • M. Malone • N. J. Sebire Accepted: 5 October 2010 / Published online: 10 November 2010 Ó Springer Science+Business Media, LLC 2010 Abstract Around two thirds of sudden unexpected deaths in infancy (SUDI) remain unexplained following post- mortem examination. It has been postulated that a subset of unexplained SUDI may be caused by toxigenic Staphylo- coccus aureus. The aim of this study was to compare the prevalence of toxigenic S aureus strains in unexplained and explained SUDI (those in whom a cause of death is determined at autopsy). A retrospective review was per- formed of 546 SUDI autopsies as part of a larger review of [ 1,500 pediatric autopsies over a 10-year period, 1996–2005 inclusive. SUDI was defined as the sudden and unexpected death of an infant aged 7–365 days, and cate- gorized into unexplained, explained with histological evi- dence of infection (bacterial infection group) or explained due to non-infective causes. Toxin gene profiling was carried out by PCR in cases in whom S aureus was isolated as part of clinical investigation. Of the 507 SUDI included in this analysis, bacteriological investigations were per- formed in 470, and S aureus was isolated on post-mortem culture from at least one site in 173 (37%). There were significantly more cases with S aureus isolated in unex- plained SUDI (40%) compared to non-infective SUDI (21%; difference 19.0%, 95% CI 5.4% to 29.3%, P = 0.006). 46% of all cases with S aureus isolated underwent routine testing for a panel of staphylococcal toxin genes (including SEA to SEE, SEG to SEJ, TSST-1, and exfoliative toxins A and B). There were more cases with at least one toxigenic strain of S aureus in the unex- plained SUDI (81%) and bacterial infection groups (77%) than in the non-infection group (63%), but these differ- ences were not statistically significant (Fisher exact test, P = 0.44). Toxin gene-carrying S aureus is commonly detected at autopsy in SUDI, accounting for 78% of S aureus isolates submitted for toxin gene profiling in this series. There is a significantly higher prevalence of S aureus in unexplained SUDI compared to non-infective SUDI, but no significant difference in the proportion with toxigenic S aureus strains isolated between the groups. These data are consistent with the hypothesis that a subset of otherwise unexplained SUDI may be related to the presence of S aureus colonization/infection, but do not indicate routine testing for toxin-associated genotypes. Keywords SUDI Á Sudden unexpected death Á Infancy Á Autopsy Á Infection Á Sepsis Á Staphylococcus aureus Á Toxins Á Microbiology Introduction Sudden unexpected death in infancy (SUDI) is defined as the sudden death of an infant aged less than 1 year (usually limited to infants aged 7–365 days) in whom death occurs suddenly and unexpectedly. It comprises a heterogeneous group of infant deaths, including those in which a review of the death scene and complete post-mortem examination (autopsy) will disclose the cause of death (explained SUDI) and those in whom a cause of death is not determined M. A. Weber (&) Á R. A. Risdon Á M. Malone Á N. J. Sebire Department of Paediatric Histopathology, Great Ormond Street Hospital for Children and UCL Institute of Child Health, Great Ormond Street, London WC1N 3JH, UK e-mail: WeberM1@gosh.nhs.uk J. C. Hartley Á N. J. Klein Department of Infectious Diseases and Microbiology, Great Ormond Street Hospital for Children and UCL Institute of Child Health, London, UK 123 Forensic Sci Med Pathol (2011) 7:141–147 DOI 10.1007/s12024-010-9199-0