Micreos’ PhageGuard team to present novel food safety technology

IAFP 2019 – Louisville, Kentucky     July 21-24

Each year, the International Association for Food Protection hosts an Annual Meeting, providing attendees with information on current and emerging food safety issues, the latest science, innovative solutions to new and recurring problems, and the opportunity to network with thousands of food safety professionals from around the globe. Held in various locations throughout North America, this meeting has grown over the years to become the leading food safety conference worldwide.  IAFP 2019 will be held at the Kentucky International Convention Center in Louisville, Kentucky. 

The IAFP Annual Meeting is attended by more than 3,600 of the top industry, academic and governmental food safety professionals from six continents. This renowned event owes its reputation and success to the quantity, quality, and diversity of each year’s program; the quality and relevance of exhibits sharing the latest in available technologies; leading experts speaking on a variety of timely topics; and special recognition of outstanding professionals and students for their contributions in the food safety field.

Abstract 1: P2-71: Efficiency of a Phage Intervention against Salmonella on Lean Pork, Pork Trim and Bacon

Sonali Sirdesai¹, Giovanni Eraclio¹, Robin Peterson², Steven Hagens¹, Joël van Mierlo¹ and Bert de Vegt¹, (1)Micreos Food Safety B.V., Wageningen, Netherlands, (2)Micreos Food Safety B.V., Atlanta, GA

Introduction: An ongoing baseline sampling program by the Food Safety Inspection Service (FSIS), the Raw Pork Products Exploratory Sampling Program (2015), will provide direction to FSIS to develop a better risk profile and refine the present food safety guidelines for pork products. Thus, new impending regulatory standards will likely prompt establishments to seek interventions that can help in reducing the most probable number of Salmonella in their products.

Purpose: To determine the efficacy of a commercially available bacteriophage product, PhageGuard S, against Salmonella on several types of pork meat.

Methods: Overnight cultures of Salmonella Se13 (streptomycin resistant strain) were inoculated at a concentration of 2×10⁴ CFU/cm² or CFU/g on lean pork, bacon or pork trims (duplicate samples per treatment). Subsequently, contaminated samples were treated with phage concentrations of 5×10⁶, 1×10⁷, 2×10⁷ or 5×10⁷ PFU/cm² or PFU/g, or water (negative control). After treatment, samples were stored at 40°F for 18 h before retrieval and enumeration of bacteria on selective agar plates. Reduction values of two individual experiments were used for statistical analysis (ANOVA).

Results: The application of phages at 10⁷ and 5×10⁷ PFU/cm² on lean pork resulted in 1.1 log CFU/cm² and 1.6-logCFU/cm² (P<0.05) reductions of Salmonella, respectively. On bacon, 5×10⁷ PFU/cm² showed Salmonella reduction of 1.3 log CFU/cm² and the 5×10⁶ PFU/cm² resulted in 0.8-log CFU/cm² reduction (P<0.05). When applied on pork trim, phage concentrations of 2×10⁷ and 5×10⁷ PFU/g showed Salmonella kill of 1.3 and 1.7 log CFU/g, respectively. Overall, a dose-response was observed where increasing phage concentration resulted in an increasing Salmonella kill on different pork meat.

Significance: The above results indicate that the tested phage solution can reduce Salmonella contamination on pork by 1.3 to 1.7 log. This shows that bacteriophages are an effective Salmonella intervention for processors to reduce risks and allow an increase in consumer safety.

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Abstract 2: T2-07: Application of Bacteriophages on Beef and Leafy Greens as a Natural Intervention against E. coli O157

Joël van Mierlo, Sander Witte, Linda Huijboom, Leoni van de Straat, Steven Hagens and Bert de Vegt, Micreos Food Safety B.V., Wageningen, Netherlands

Monday, July 22, 2019 10:00 AM – 10:15 AM Kentucky International Convention Center – ROOM M112

Introduction: Escherichia coli O157 remains a great concern for the beef and leafy greens industry. Bacteriophages have the potential to be an additional safe and effective intervention against E. coli O157.

Purpose: The objective was to determine the efficacy of a commercially available bacteriophage cocktail (PhageGuard E) as an intervention against E. coli O157 on refrigerated beef and vegetables.

Methods: Lysis activity of natural phage isolates was assessed by spotting serial dilutions on 88 E. coli O157 strains. For beef, two cold (4°C) beef cuts of nine cm² were contaminated with 1×10⁵ CFU/cm² E. coli O157, while for romaine lettuce, zucchini and spinach 18 cm² areas were contaminated with 1×10⁶ CFU/cm² E. coli O157. Subsequently, samples were treated with 3×10⁷ or 3×10⁸ PFU/cm². Controls were treated with tap water. Samples were then incubated at 4°C, after which bacteria were retrieved at two, six, 24, 30, and 54 hours post phage treatment. Bacterial reductions on phage-treated samples were calculated relative to controls at the corresponding time point. Reductions in three independent experiments were used for statistical analysis (Unpaired t-test).

Results: A cocktail of two selected phages, lysing 90% of all E. coli O157 strains tested, showed bacterial reductions from 1.5 to 1.9 log_­ (P<0.05) on three different strains when cold beef was treated with 3×10⁸ PFU/cm², while 0.8 to 1.5 log₁₀ (P<0.05) reductions were observed with 3×10⁷ PFU/cm² at 24 hours post phage treatment. Similarly, reductions between 1.45 to 2.97 log (P<0.05) and 2.33 to 3.86 log (P<0.05) were observed after 24 hours on contaminated vegetables treated with 3×10⁷ or 3×10⁸ PFU/cm², respectively. In all experiments, the maximum reduction was already achieved six hours post phage application.

Significance: The phage cocktail described above can be used by the industry as a natural, safe, and effective intervention to fight E. coli O157.

Abstract 3: T4-06: Synergistic Effect of Bacteriophages and Buffered Vinegar on Listeria-contaminated Ready-to-Eat Products

Sonali Sirdesai¹, Giovanni Eraclio¹, Alessandra Moncho¹, Robin Peterson², Joël van Mierlo¹, Steven Hagens¹ and Bert de Vegt¹, (1)Micreos Food Safety B.V., Wageningen, Netherlands, (2)Micreos Food Safety B.V., Atlanta, GA

Monday, July 22, 2019 02:45 PM – 03:00 PM Kentucky International Convention Center – ROOM M107

Introduction: RTE product producers seek ways to comply with FSIS Listeria rules for delivering Listeria-free foods. This forces the industry to test and implement new microbial intervention strategies.

Purpose: To assess the use of PhageGuard Listex (a natural bacteriophage solution against Listeria) with buffered vinegar as antimicrobial agents of addressing post-lethality Listeria contaminations in RTE foods.

Methods: Cooked turkey slices were inoculated with a cocktail of four Listeria monocytogenes strains at 10 CFU/g (detection limit 10 CFU/g). Similarly, whole quiches with and without added buffered vinegar were inoculated at two CFU/g (detection limit two CFU/g). Both contaminated products were either surface spray treated with phages (2×10⁷ PFU/cm²) or phages and buffered vinegar. Samples treated with either buffered vinegar or tap water were used as negative controls. Subsequently, samples were vacuum packed and stored at 40°F. During the shelf-life of 21 and 120 days for quiche and turkey slices respectively, samples were retrieved to detect and enumerate Listeria. Data presented are the mean value of two individual experiments.

Results: On contaminated turkey slices, phage solution or buffered vinegar alone kept Listeria concentration below the detection limit for 10 and 30 days respectively. A clear synergistic effect was observed when combining phages with buffered vinegar, as Listeria was below the detection limit for almost 120 days. For contaminated quiche, phages alone kept Listeria below a two-log outgrowth level for up to 21 days. A similar, though stronger effect, was observed with phages plus buffered vinegar as this treatment suppressed the growth of Listeria throughout the shelf life of quiche.

Significance: These results establish PhageGuard Listex when applied along with buffered vinegar as an effective combination of antimicrobials to control Listeria during processing of RTE foods, thus leading to an increase in consumer safety.

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