Prevalence, Characterization, and Genotypic Analysis of Escherichia coli O157:H7/NM fromSelected Beef Exporting Abattoirs of Argentina

Abstract

In Argentina, Escherichia coli O157:H7/NM (STEC O157) is the prevalent serotype associated with hemolytic uremic syndrome (HUS), which is endemic in the country with more than 400 cases per year. In order to estimate the prevalence and characteristics of STEC O157 in beef cattle at slaughter, a survey of 1,622 fecal and carcass samples was conducted in nine beef exporting abattoirs from November 2006 to April 2008. A total of 54 samples were found positive for STEC O157, with an average prevalence of 4.1% in fecal content and 2.6% in carcasses. Calves and heifers presented higher percentages of prevalence in feces, 10.5 and 8.5%, respectively. All STEC O157 isolates harbored stx(2) (Shiga toxin 2), eae (intimin), ehxA (enterohemolysin), and fliC(H7) (H7 flagellin) genes, while stx(1) (Shiga toxin 1) was present in 16.7% of the strains. The prevalent (56%) stx genotype identified was stx(2) combined with variant stx(2c (vh-a)), the combination of which is also prevalent (>90%) in STEC O157 post-enteric HUS cases in Argentina. The clonal relatedness of STEC O157 strains was established by phage typing and pulsed-field gel electrophoresis (PFGE). The 54 STEC isolates were categorized into 12 different phage types and in 29 XbaI-PFGE patterns distributed in 27 different lots. STEC O157 strains isolated from 5 of 21 carcasses were identical by PFGE (100% similarity) to strains of the fecal content of the same or a contiguous bovine in the lot. Five phage type-PFGE-stx profiles of 10 strains isolated in this study matched with the profiles of the strains recovered from 18 of 122 HUS cases that occurred in the same period.

Phylogenetically Related Argentinean and Australian Escherichia coli O157 Isolates Are Distinguished by Virulence Clades and Alternative Shiga Toxin 1 and 2 Prophages

“…Consistent with previous studies (8,25), we also observed a significant difference in the motility of O157 from Argentina (predominantly motile strains) and Australia (predominantly nonmotile strains), further supporting potential differentiation of the O157 populations in each country.…”

“…Fegan and Desmarchelier (8) tested 102 Australian E. coli O157 isolates from human and animal sources for the pres- (22,25). Isolates in the current study represented multiple genotypes in proportions similar to the diversity previously demonstrated in Argentina and Australia.…”

“…The prevalences of particular stx genotypes in E. coli O157 isolates from different geographic origins have previously been reported (8,22,25). Fegan and Desmarchelier (8) tested 102 Australian E. coli O157 isolates from human and animal sources for the pres- (22,25).…”

Microbiological Properties of Beef in Various Meat Shops at Semarang, Indonesia

“…Aslam et al (2009) was successfully isolated E. coli bacteria from the slaughtering equipments and cow hide that have been skined. Masana et al (2010) reported that 54 samples of beef that come from the slaughterhouse in Argentina (slaughtering period of November 2006 up to April 2008) were containing E. coli bacteria. Ingham et al (2010) reported that beef has potential to get E. coli bacteria and non fecal coliform bacteria contamination Indonesia government's regulation on beef and carcass quality defined five strictly requirements as follows: TPC for a maximum 10 6 CFU/g, total coliform bacteria for a maximum 10 2 CFU/g, total E. coli bacteria up to 10 CFU/g, total S. aureus bacteria for a maximum of 10 2 CFU/g and zero tolerant for Salmonella bacteria per 25 g samples (SNI 3932, 2008).…”

Virulence genes of Shiga toxin-producing Escherichia coli O157:H7 strains isolated from calves and cattle

“…It has been reported that cattle are main reservoir for STEC (2,20,26). Investigations carried out in different part of Europe, Asia, North America have showed that 10-80% cattle were infected with STEC (1,2,5,8,27,39).…”