Effectiveness of a Commercial Lactic Acid Bacteria Intervention Applied to Inhibit Shiga Toxin-Producing Escherichia coli on Refrigerated Vacuum-Aged Beef

Abstract

Because of their antagonistic activity towards pathogenic and spoilage bacteria, some members of the lactic acid bacteria (LAB) have been evaluated for use as food biopreservatives. The objectives of this study were to assess the antimicrobial utility of a commercial LAB intervention against O157 and non-O157 Shiga-toxigenic E. coli (STEC) on intact beef strip loins during refrigerated vacuum aging and determine intervention efficacy as a function of mode of intervention application. Prerigor strip loins were inoculated with a cocktail (8.9 ± 0.1 log10 CFU/ml) of rifampicin-resistant (100.0 μg/ml; RifR) O157 and non-O157 STEC. Inoculated loins were chilled to ≤4°C and treated with 8.7 ± 0.1 log10 CFU/ml LAB intervention using either a pressurized tank air sprayer (conventional application) or air-assisted electrostatic sprayer (ESS). Surviving STEC were enumerated on tryptic soy agar supplemented with 100.0 μg/ml rifampicin (TSAR) to determine STEC inhibition as a function of intervention application method (conventional, ESS) and refrigerated aging period (14, 28 days). Intervention application reduced STEC by 0.4 log10 CFU/cm2 (p < 0.05), although application method did not impact STEC reductions (p > 0.05). Data indicate that the LAB biopreservative may assist beef safety protection when utilized within a multi-intervention beef harvest, fabrication, and aging process.

Evaluation of Commercial Prototype Bacteriophage Intervention Designed for Reducing O157 and Non-O157 Shiga-Toxigenic Escherichia coli (STEC) on Beef Cattle Hide

“…Measurements beyond phage infection efficiency via methods such as EOP and/or MOI are likely required to develop, deploy, and maintain effective phage interventions. STEC isolates used in the current study were harvested from differing sources, including multiple isolates recovered from human stool samples from sporadic or outbreak-associated disease cases, and from beef products [ 30 ]. While the use of only one isolate per serogroup limits the opportunity for generalization of experimentally-obtained STEC reductions to the broader STEC ecology in beef production, data presented do indicate the usefulness of STEC-infecting phages in combination with other food safety interventions applied within the beef chain.…”

Evaluating disinfectant efficacy on mixed biofilms comprising Shiga toxigenic Escherichia coli, lactic acid bacteria, and spoilage microorganisms

“…For instance a study aiming to asses a LAB commercial product, composed of a mixture of Lactobacillus, Lactococcus, and Pediococcus spp. to reduce STEC on beef strip loins found a modest reduction of 0.4 log10 CFU/cm 2 ( Kirsch et al, 2017 ). Other research that showed that Lactobacillus plantarum and Lactobacillus rhamnosus , were able to displace generic E. coli pre-established biofilms from medical-grade silicone ( Carvalho et al, 2021 ).…”