Publications by authors named "Stephen Dietrich"

Shiga toxin-producing (STEC) causes high frequencies of foodborne infections worldwide and has been linked to numerous outbreaks each year. Pulsed-field gel electrophoresis (PFGE) has been the gold standard for surveillance until the recent transition to whole-genome sequencing (WGS). To further understand the genetic diversity and relatedness of outbreak isolates, a retrospective analysis of 510 clinical STEC isolates was conducted.

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A cluster of five human Salmonella Guinea cases was identified among Ohio residents through core genome multilocus sequence typing of clinical isolates. An investigation was conducted to characterize illnesses and identify common exposures. Four patients were aged ≤5 years and three of four patients with information available regarding exposure to animals reported prior exposure to bearded dragons.

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In 2018, Michigan public health officials determined that a single restaurant in southwest Michigan was the source for a protracted, intermittent outbreak of Salmonella enterica serotype Mbandaka infections occurring since 2008. Isolates from 36 infected persons shared two highly related pulsed-field gel electrophoresis (PFGE) patterns and highly related whole genome sequencing (WGS) subtypes. The initial focus of the local public health investigation on food items rather than food sources (i.

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Non-O157 STEC are increasingly linked to foodborne infections, yet little is known about the diversity and molecular epidemiology across locations. Herein, we used whole genome sequencing to examine genetic variation in 894 isolates collected from Michigan patients between 2001 and 2018. In all, 67 serotypes representing 69 multilocus sequence types were identified.

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To investigate a shigellosis outbreak in Genesee County, Michigan (including the City of Flint), and Saginaw County, Michigan, in 2016 and address community concerns about the role of the Flint water system. We met frequently with community members to understand concerns and develop the investigation. We surveyed households affected by the outbreak, analyzed isolate data, examined the geospatial distribution of cases, and reviewed available water quality data.

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Listeriosis is a serious foodborne infection that disproportionately affects elderly adults, pregnant women, newborns, and immunocompromised individuals. Diagnosis is made by culturing Listeria monocytogenes from sterile body fluids or from products of conception. This report describes the investigations of two listeriosis pseudo-outbreaks caused by contaminated laboratory media made from sheep blood.

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Temporal changes in the distribution of Salmonella subtypes in livestock populations may have important impacts on human health. The first objective of this research was to determine the within-farm changes in the population of subtypes of Salmonella on Michigan dairy farms that were sampled longitudinally in 2000-2001 and again in 2009. The second objective was to determine the yearly frequency (2001 through 2012) of reported human illnesses in Michigan associated with the same subtypes.

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Hydrogen sulfide (H2S) is an important signaling molecule that exerts action on various bioinorganic targets. Despite this importance, few studies have investigated the differential reactivity of the physiologically relevant H2S and HS(-) protonation states with metal complexes. Here we report the distinct reactivity of H2S and HS(-) with zinc(II) and cobalt(II) phthalocyanine (Pc) complexes and highlight the chemical reversibility and cyclability of each metal.

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Escherichia coli O157:H7, a toxin-producing food and waterborne bacterial pathogen, has been linked to large outbreaks of gastrointestinal illness for more than two decades. E. coli O157 causes a wide range of clinical illness that varies by outbreak, although factors that contribute to variation in disease severity are poorly understood.

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A surveillance system used different detection methods to estimate prevalence of Shiga toxin-producing Escherichia coli during 2003-2005 and 2001-2002. More non-O157 serotypes were detected by enzyme immunoassay than by evaluation of non-sorbitol-fermenting E. coli isolates.

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We investigated a multistate cluster of Escherichia coli O157:H7 isolates; pulsed-field gel electrophoresis subtyping, using a single enzyme, suggested an epidemiologic association. An investigation and additional subtyping, however, did not support the association. Confirmating E.

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