Seasonal variation of Shiga toxin-encoding genes (stx) and detection ofE. coliO157 in dairy cattle from Argentina

Abstract

Aims: To study the seasonal variation of Shiga toxin‐encoding genes (stx) and to investigate the presence of Shiga toxin‐producing Escherichia coli (STEC) O157 in cattle belonging to five dairy farms from Argentina. Methods and Results: Rectal swab samples were collected from 360 dairy cows in each season and 115 and 137 calves in autumn and in spring, respectively. The stx were investigated by multiplex PCR and it was used as the indicator for STEC. Samples positives for stx were tested by PCR for eae‐γ1 of E. coli O157 and then subjected to IMS (immunomagnetic separation). In positive animals significant differences in the prevalence of stx between warm and cold seasons were detected. In warm seasons, stx1 + stx2 increased and stx1 decreased, independently of the animal category. The prevalence of STEC O157 in cows and calves were 0·2% and 0·8%, respectively. Conclusions: This work provides new data about the occurrence of stx and STEC O157 in dairy herds from Argentina and suggests a relationship between the type of stx and season of year. Significance and Impact of Study: The detection of STEC O157 and the seasonality of stx and its types provide an opportunity to improve control strategies designed to prevent contamination of food products and transmission animal‐person.

Molecular Characterization of Escherichia coli O157:H7 and non-O157 Shiga Toxin Producing E. coli from Retail Meat and Humans

“…The higher frequency of stx2 isolation in STEC isolates from beef was in accordance with other studies [23,55,57,58]. However, in beef, eaeA gene was reported in 100% of STEC O157:H7 and 19% of non-O157 isolates [31].In contrary, all STEC strains from meat products in Australia were negative for eaeA gene [59].…”

Prevalence and molecular detection of shiga toxin producing Escherichia coli from diarrheic cattle

“…STEC O157 has also been isolated in India from foods of cattle origin namely raw minced beef samples (9%; n=22) (Dutta et al, 2000), beef surface swabs (3.7%; n=27), and milk samples (2.4%; n=81) (Manna et al, 2006). In China, STEC O157:H7 was isolated from 10 to 20% of the animals in the villages, including pigs, cattle, goats, and chickens (Zheng et al, 2005;Fernández et al, 2009). When buffalo samples were tested for the presence of Stx1 genes by PCR, around 80% of the samples were positive.…”

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

“…Similarly in the Svalbard reindeer, mating season and gathering in snow-free areas during the winter, may favour the stx gene horizontal transfer. Fernández et al (2009) are suggesting that the type of the stx gene is not only influenced by the age of the cattle, but also by the season in which samples were collected. In this study, no stx sequence was detected in sample 9, which originated from either a young individual with unknown sex or an adult female.…”

“…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).…”