Detection of stx1 and stx2 Genes in Pennsylvanian White-Tailed Deer

Abstract

Shiga toxin-producing E. coli carrying the stx1 and/or stx2 genes can cause multi-symptomatic illness in humans. A variety of terrestrial and aquatic environmental reservoirs of stx have been described. Culture based detection of microbes in deer species have found a low percentage of samples that have tested positive for Stx-producing microbes, suggesting that while deer may contain these microbes, their overall abundance in deer is low. In this study, quantitative PCR (qPCR) was utilized to test for the presence of stx genes in white-tailed deer fecal matter in western Pennsylvania. In this culture independent screening, nearly half of the samples tested positive for the stx2 gene, with a bias towards samples that were concentrated with stx2. This study, while limited in scope, suggests that deer may be a greater reservoir for stx than was previously thought.

Animal Reservoirs of Shiga Toxin-ProducingEscherichia coli

“…Other species of deer, including red deer (Cervus elaphus), fallow deer (Dama dama), and roe deer (Capreolus capreolus), have also been identified as capable of shedding STEC serotypes (65,66). Almost 50% of Pennsylvanian white-tailed deer fecal samples screened tested positive for stx genes; however, only 8% possessed the eae gene, which is necessary for colonization of the human intestine (67).…”

DNA extracted from faeces as a source of information about endemic reindeer from the High Arctic: detection of Shiga toxin genes and the analysis of reindeer male-specific DNA

“…In this study, we detected the stx1 gene in 90 % of the tested faecal samples and in 50 % of the tested samples the stx2 gene was determined to be present, which is a considerably high percentage of detection frequency when compared to the Norwegian reindeer (Rangifer tarandus tarandus; Aschfalk et al 2003) or a white-tailed deer (Odocoileus virginianus) from Louisiana (Dunn et al 2004) and Pennsylvania (Kistler et al 2011). Lillehaug et al (2005 reported that no E. coli O157 isolates, both Shiga toxins producing as well as not Shiga toxins producing, were observed in four different wild cervid species: red deer (Cervus elaphus), roe deer (Capreolus capreolus), moose (Alces alces) and reindeer from the central Norway.…”

“…However, in many studies regarding ruminants, stx2 was shown to be detected more often than stx1 (Sán-chez et al 2009;Kistler et al 2011). In contrast, only the stx1 gene was detected in samples taken from a reindeer cadaver found in Norway, but no association with mortality was established (Aschfalk et al 2003).…”

“…In Pennsylvanian white-tailed deer, the presence of stx2 was detected at a similar percentage (46 %) as in the study presented here; however, the number of the tested samples was five times higher and was based on a different sampling method. On the other hand, stx1, which was detected in majority of the tested faecal samples, was detected only in 10 % of the Pennsylvanian deer samples, but every sample positive for stx1 was also positive for stx2 (Kistler et al 2011). In an extensive study of four different species of free-living ruminants, including red deer, roe deer, fallow deer Dama dama and mouflon Ovis musimon in the south-western Spain, both stx genes were detected in Table 2 Occurrence of stx1 and stx2 gene and sex identification among Svalbard reindeer population Sample no.…”

“…The main reservoir for Shiga toxin pathogens is ruminants, mainly cattle, which are their asymptomatic carriers, but they can be also found in other domestic and wild animals (Gyles 2007;Fernández et al 2009;Franklin et al 2013). Natural occurrence of the stx (Shiga) genes in deer faeces samples from different parts of the world has been reported (Asakura et al 1998;Aschfalk et al 2003;Lillehaug et al 2005;Kistler et al 2011;Hofer et al 2012;Eggert et al 2013). One of the virulence factors of STEC is Shiga toxins (Stx) encoded on lambdoid prophage genomes (Łoś et al 2013).…”