Serotypes, virulence markers and cell invasion ability of Shiga toxin-producingEscherichia colistrains isolated from healthy dairy cattle

Abstract

Although reports of human disease associated with STEC are scarce in Brazil, the colonization of the animal reservoir by potentially pathogenic strains offers a significant risk to our population.

Diarrheagenic Escherichia coli

“…In fact, cell invasion and survival of some EHEC/STEC strains in cultured human intestinal epithelial cells has been previously described 171 . It should be mentioned that this invasive characteristic has been identified in some EHEC/STEC serotypes, many of which are responsible for human infections 170, 171, 172, 173. Therefore, it is conceivable that this virulence strategy may help bacteria to overcome host defense mechanisms and certainly contributes to their persistence in the zoonotic reservoir, ensuring efficient environmental and food transmission.…”

“…In general, these studies have shown that despite serotype diversity, the stx subtypes and the virulence profile identified among isolates from the animal reservoir and environment are similar to the isolates recovered from patients 173, 178, 179, 180. There has been particular interest in some STEC serotypes that have been responsible for causing severe human infections, such as O113:H21, but unlike others, they do not produce adhesins encoded by LEE.…”

“…The role of different animal species as asymptomatic carriers of EHEC/STEC has been extensively studied in the last years in Brazil. Besides cattle, which are their most common natural reservoir,173, 178 the presence of these pathogens has been identified in the feces of dairy buffaloes, 179 sheep,180, 181 pigs,182, 183 birds, 184 and fishes 185 . It is noteworthy that some relevant serotypes linked to human infections such as O103:H2 and O157:H7 have been recovered from the feces of sheep 186 and cattle 173 respectively.…”

“…Besides cattle, which are their most common natural reservoir,173, 178 the presence of these pathogens has been identified in the feces of dairy buffaloes, 179 sheep,180, 181 pigs,182, 183 birds, 184 and fishes 185 . It is noteworthy that some relevant serotypes linked to human infections such as O103:H2 and O157:H7 have been recovered from the feces of sheep 186 and cattle 173 respectively. Additionally, the high prevalence of O157:H7 EHEC/STEC strains identified in hides of cattle sent to slaughter in a Brazilian processing plant 178 certainly represents a relevant issue that should be considered when thinking about interventions targeting EHEC/STEC related to animal handling, from farm to slaughter, as well as the implementation of food safety throughout production and processing.…”

Shiga toxin‐producingEscherichia coliin the animal reservoir and food in Brazil

“…The northwest subregion of this state was associated with higher occurrences. Gonzalez et al () studied 105 STEC strains isolated from faecal samples in RJ, belonging to several serotypes, despite many rough or nontypeable STEC strains. More than half of the serotypes were identified as O8:H19, O22:H8, O22:H16, O113:H21, O157:H7, O171:H2 and NT:H21.…”