Isolation, prevalence, and risk factors for infection by shiga toxin-producing Escherichia coli (STEC) in dairy cattle

Abstract

Rectal swabs of 198 Holstein × Gir crossbred beef cattle from 34 milk farms in the central west of Brazil were analyzed from August 2010 to February 2011. Strains of shiga toxin-producing Escherichia coli (STEC) were isolated from 72.73% (144/198) of the animals, on over 97% of the surveyed properties. The molecular characterization indicated the most common toxin gene stx1 in 70.88% of the animals (202/285), followed by 18.95% (54/285) stx1/sxt2, and 10.18% (29/285) stx2. The presence of STEC in animals together with the probable risk factors based on a questionnaire was evaluated in the owners of the evaluated animals. Results showed that the animal category "calves" and production/technification scale "low" of the farm were related to high STEC prevalence in cattle. The season did not significantly affect the presence of STEC in cattle. The STEC strains are considered a major pathogen, causing severe and potentially lethal diseases in humans such as hemorrhagic colitis and hemolytic uremic syndrome. This high prevalence of STEC in dairy cattle poses a significant risk to public health, since these microorganisms can contaminate products intended for human consumption, e.g., water, raw and pasteurized milk, meat products, dairy products, and/or products of plant origin.

Climate, lactation, and treatment factors influence faecal shedding ofEscherichia coliO157 pathotypes in dairy cows

“…Although studies to date have not assessed aEPEC prevalence, other studies of stx and O157:H7 dairy prevalence have shown both higher (72·7%, 11·1-32·3%) [15,18] and lower (1%) levels [10]. Importantly, high-shedding cattle have been hypothesized to influence herd EHEC propagation, and only one was observed in the current study [21,22].…”

“…Even though O157 is ubiquitous in dairy herds across the United States, risk factors for colonization and shedding dynamics have more commonly been studied in beef herds [12,13]. Dairy studies are especially relevant due to the increasing popularity of drinking raw milk, and the fact that high prevalence levels of O157 have been noted in the few published studies [14][15][16][17]. Previous work has shown several environmental risk factors for dairy O157 shedding, including season, temperature, humidity, rainfall and solar exposure [17].…”

Detection of virulence factors and antimicrobial resistance patterns in shiga toxin-producing Escherichia coli isolates from sheep

“…Studies by Ferreira et al (2014) and Freitas-Filho et al (2014) were pioneering in determining the prevalence of STEC and STEC/O157:H7 in healthy cattle in the State of Goiás, Brazil, while our study evaluated the virulence factors and antimicrobial resistance in STEC isolates obtained from healthy sheep in this State. On the contrary, Blanco et al (2003) found a higher prevalence of non-O157 STEC in sheep compared to cattle, where our study did not reveal the difference between sheep (78.3%) and cattle (72.7%) .…”

Molecular characterisation of Shiga toxin-producing Escherichia coli O157:H7 isolates from cattle in eastern Turkey

“…STEC O157:H7 is commonly found in the intestines of cattle and it can contaminate carcasses at slaughter (Hussein and Bollinger 2005). Humans can be infected by consumption of food and water contaminated with animal faeces (Ferreira et al 2014). STEC O157:H7 causes diarrhoea, haemorrhagic colitis, haemolytic-uremic syndrome (HUS) and thrombotic thrombocytopenic purpura in humans (D'Astek et al 2012;Chui et al 2015).…”