Non-O157:H7 Shiga Toxin–ProducingEscherichia coliin Bovine Rectums and Surface Water Streams on a Beef Cattle Farm in Argentina

Abstract

The purposes of this study were to detect non-O157 Shiga toxin-producing Escherichia coli (STEC) in bovine rectums and water in a beef cattle farm in Argentina, and to determine the pathogenic potential of the circulating strains. During the study, 292 rectal swabs from healthy animals and 79 environmental water samples were collected. The rectal swabs and one loop of the Moore swabs, enriched in Escherichia coli broth for 24 h at 37°C, were streaked on MacConkey agar plates and incubated overnight at 37°C. The isolates were characterized by biochemical tests and serotyped. Nonmotile STEC strains were typed for their H-specific (fliC) antigens by polymerase chain reaction (PCR). Isolates were characterized by detection of stx1, stx2, and their variants, eae, ehxA, and saa genes. Macrorestriction fragment analysis by pulsed-field gel electrophoresis (PFGE) was performed using the PulseNet standardized protocol. From 371 samples analyzed, 36.6% of rectal swabs and 34.2% of water samples were non-O157 STEC-positive by PCR, and 110 strains from rectal swabs, but only three from water, were isolated. The strains were grouped into 24 different serotypes, from which, O103:[H2] (n = 12), O136:H12 (n = 8), O178:H19 (n = 8), and O103:NM (n = 5) were most prevalent, representing 29.2% of the isolates. Predominant genotypes were stx1/eae/ehxA (16.8%) and stx2/saa/ehxA (15.9%). PFGE analysis revealed 56 different patterns, with 65 strains grouped in 19 clusters of 100% similarity. Two STEC O124:H19 strains isolated from rectal swabs and water with a 5-month interval harbored the stx1/stx2/saa/ehxA genotype, and showed an indistinguishable PFGE profile. By comparison, some XbaI-PFGE patterns identified in the present study were identical to the profiles of strains isolated from human, food, and animal sources included in the Argentine PulseNet database. By PCR, similar non-O157 detection rates were found in rectal swabs and water. However, the methodology for water samples needs to be improved, since only three strains from the total number of positive samples were recovered.

Emerging types of Shiga toxin-producing E. coli (STEC) O178 present in cattle, deer, and humans from Argentina and Germany

“…Over the past years, STEC O178:H19 became one of the most prevalent serotypes isolated from dairy cows (Fernandez et al, 2010) and beef cattle (Tanaro et al, 2012) as well as in beef abattoirs (Masana et al, 2011) and in food of bovine origin in Argentina and Germany (Beutin et al, 2007; Sanz et al, 2007; Werber et al, 2008; Slanec et al, 2009; Kruger et al, 2011). Moreover, this serotype was prevalent in pets (Bentancor et al, 2012).…”

“…However, binding properties of saa -carrying STEC to epithelial cells exhibit marked variation with no correlation to the number of C-terminal repeats and to the Saa-expression (Toma et al, 2008). Clarification of the role of saa in human infections needs further investigation, however, its high prevalence in bovine and ovine STEC suggest a role in the attachment to bovine and ovine gut (Jenkins et al, 2003; Zweifel et al, 2004; Fernandez et al, 2010; Tanaro et al, 2012). …”

“…STEC O178:H19 strains were frequently isolated from beef in Germany (Beutin et al, 2007; Werber et al, 2008; Slanec et al, 2009) and Argentina (Sanz et al, 2007; Kruger et al, 2011). Cattle were identified as important reservoir for STEC O178:H19 in South America (Cergole-Novella et al, 2007; Oliveira et al, 2008; Fernandez et al, 2010; Kruger et al, 2011; Masana et al, 2011; Tanaro et al, 2012) and in Europe (Blanco et al, 2004; Aidar-Ugrinovich et al, 2007; European Food Safety Authority and European Centre for Disease Prevention and Control, 2012). Sporadic cases of human infections with STEC O178:H19 were reported from Germany (Bielaszewska et al, 2006; Werber et al, 2008) and Brazil (De Toni et al, 2009).…”

Summer and Winter Prevalence of Shiga Toxin–Producing Escherichia coli (STEC) O26, O45, O103, O111, O121, O145, and O157 in Feces of Feedlot Cattle

“…Non-O157 serogroup and STEC fecal prevalence estimates reported in cattle range from 0.0 to 90.7% and 0.9 to 16.9%, respectively, in the United States Cernicchiaro et al, 2013;Dargatz et al, 2013;Baltasar et al, 2014;Ekiri et al, 2014). However, only a few studies have assessed seasonality of non-O157 STEC shedding in cattle (Barkocy-Gallagher et al, 2003;Alexa et al, 2011;Tanaro et al, 2012). Often publications report combined prevalence estimates for all non-O157 STEC collectively, rather than reporting serogroup-specific prevalence estimates.…”

Update on non-O157 Shiga toxin-producing E. coli as a foodborne pathogen: analysis and control

“…The prevalence of STEC in the fecal samples was 37.7% (110/292). The STEC strains consisted of 24 serotypes and included O103:H2 ( n = 12), O136:H12 ( n = 8), O178:H19 ( n = 8), and O103:NM ( n = 5) (Tanaro et al ., 2012 ). Fecal samples obtained from beef cattle in 21 feedlots from four US states were tested by PCR for seven STEC serogroups (Dargatz et al ., 2013 ).…”