Reduction of Shiga toxin-producing Escherichia coli in a beef abattoir.

The aim of this work was to reinforce actions tending to reduce Shiga toxin-producing Escherichia coli (STEC) in beef products from an Argentinean commercial abattoir implementing Hazard Analysis and Critical Control Point (HACCP) practices. An environmental stx map was built with 421 environmental samples from the slaughter, quartering, cool chamber and deboning sectors (February-May 2013). For stx determination, 125 carcass and 572 anatomical cut samples were used. Based on the environmental stx mapping results, improvement actions were designed and implemented (June and July 2013). After implementing improvement actions, 160 carcass and 477 anatomical cut samples were collected to identify stx and verify the impact of improvement actions (August-December 2013). Our results showed stx-positivity in pre-operational (10.1%) and operational (15.5%) environmental samples and in carcass and beef cut samples before (4.8 and 10.1%; p = 0.144) and after (1.2 and 4.8%; p = 0.0448) implementing improvement actions, respectively. Although improvement actions reduced stx in beef cuts, it is difficult to implement and sustain a system based on stx zero-tolerance only by reinforcing Good Manufacturing Practices, Sanitation Standard Operating Procedures and HACCP practices. The application of combined intervention strategies to reduce STEC in carcasses and beef cuts should be therefore considered.

Evaluation of intervention measures at different stages of the production chain in Argentinian exporting abattoirs.

Antimicrobial treatments could help to decrease the transmission of microorganisms to beef carcasses and abattoir environments. The aim of this study was to evaluate the effectiveness of interventions in reducing Shiga toxin genes (stx1 and stx2) presence in a commercial abattoir. Intervention measures included the application of electrolytically generated hypochlorous acid to steer pens (experiment 1), chlorinated water, electrolytically generated hypochlorous acid, and isoclor to steer pens (experiment 2), electrolytically generated hypochlorous acid to knocking pens (experiment 3), and aqueous ozone and electrolytically generated hypochlorous acid onto beef carcasses (experiment 4). Detection of stx in samples was performed with BAX® System Real-Time PCR Assay. Our results showed that treatment with pressurized electrolytically generated hypochlorous acid and isoclor were effective to reduce stx presence from hides on steer pens. Although there is no single strategy to ensure the reduction of stx presence in a commercial abattoir, the combined application of several antimicrobial interventions would be ideal.

Evaluation of decontamination efficacy of commonly used antimicrobial interventions for beef carcasses against Shiga toxin-producing Escherichia coli.

In Argentina, Shiga toxin producing Escherichia coli (STEC) serogroups O157, O26, O103, O111, O145 and O121 are adulterant in ground beef. In other countries, the zero-tolerance approach to all STEC is implemented for chilled beef. Argentinean abattoirs are interested in implementing effective interventions against STEC on carcasses. Pre-rigor beef carcasses were used to determine whether nine antimicrobial strategies effectively reduced aerobic plate, coliform and E. coli counts and stx and eae gene prevalence. These strategies were: citric acid (2%; automated), acetic acid (2%; manual and automated), lactic acid (LA 2%; manual and automated), LA (3%; automated), electrolytically-generated hypochlorous acid (400 ppm; manual), hot water (82 °C; automated) and INSPEXX (0.2%; automated). Automated application of 2% LA after 30-60-min aeration and 3% LA at 55 °C were the most effective interventions. Automated application was more effective than manual application. Decontamination of beef carcasses through automated application of lactic acid and hot water would reduce public health risks associated with STEC contamination.

Isolation and characterization of non-O157 Shiga toxin-producing Escherichia coli from beef carcasses, cuts and trimmings of abattoirs in Argentina.

Several foods contaminated with Shiga toxin-producing Escherichia coli (STEC) are associated with human diseases. Some countries have established microbiological criteria for non-O157 STEC, thus, the absence of serogroups O26, O45, O103, O104, O111, O121, and O145 in sprouts from the European Union or ground beef and beef trimmings from the United States is mandatory. While in Argentina screening for O26, O103, O111, O145 and O121 in ground beef, ready-to-eat food, sausages and vegetables is mandatory, other countries have zero-tolerance for all STEC in chilled beef. The aim of this study was to provide data on the prevalence of non-O157 STEC isolated from beef processed in eight Argentinean cattle slaughterhouses producing beef for export and local markets, and to know the non-O157 STEC profiles through strain characterization and genotypic analysis. Samples (n = 15,965) from 3,205 beef carcasses, 9,570 cuts and 3,190 trimmings collected between March and September 2014 were processed in pools of five samples each. Pools of samples (n = 3,193) from 641 carcasses, 1,914 cuts and 638 trimming were analyzed for non-O157 STEC isolation according to ISO/CEN 13136:2012. Of these, 37 pools of carcasses (5.8%), 111 pools of cuts (5.8%) and 45 pools of trimmings (7.0%) were positive for non-O157 STEC. STEC strains (n = 200) were isolated from 193 pools of samples. The most prevalent serotypes were O174:H21, O185:H7, O8:H19, O178:H19 and O130:H11, and the most prevalent genotypes were stx2c(vh-b) and stx2a/saa/ehxA. O103:H21 strain was eae-positive and one O178:H19 strain was aggR/aaiC-positive. The prevalence of non-O157 STEC in beef carcasses reported here was low. None of the non-O157 STEC strains isolated corresponded to the non-O157 STEC serotypes and virulence profiles isolated from human cases in Argentina in the same study period. The application of microbiological criteria for each foodstuff should be determined by risk analysis in order to have a stringent monitoring system. Likewise, zero-tolerance intervention measures should be applied in beef, together with GMP and HACCP. Further, collaborative efforts for risk assessment, management and communication are extremely important to improve the safety of foodstuffs.