Prioritization of Chicken Meat Processing Interventions on the Basis of Reducing the Salmonella Residual Relative Risk.

Protecting public health by controlling Salmonella in chicken meat products continues to be a challenge to both industry and policymakers. Studies evaluating the combined use of commercially available antimicrobial interventions are scarce. The aim of this work was to develop a risk-based prioritization framework to rank chicken meat processing interventions that achieve the greatest Salmonella relative risk reduction. A baseline model characterizing the current U.S. broiler industry food safety intervention practices was created from direct observation of processes and expert elicitation. Results showed the combination of chlorine at the bird wash station and peroxyacetic acid at the on-line reprocessing and chill stages as the most common U.S. processing scenario. Irradiation at packaging and acidified sodium chlorite at evisceration were the most effective single processing interventions (98.8 and 91.6% risk reduction, respectively); however, no single intervention was able to comply with the current Food Safety and Inspection Service Salmonella postchill performance standards. The combination of peroxyacetic acid in at least one of the chicken processing stages with the current set of U.S. baseline interventions achieved >99% Salmonella relative risk reduction and ensured Food Safety and Inspection Service compliance. Adding more than one intervention to the U.S. current practice did not enhance (<2%) the overall Salmonella risk reduction. This study can help poultry processors to prioritize food safety interventions to maximize Salmonella reduction and public health protection.

Improved Positive Predictive Performance of Listeria Indicator Broth: A Sensitive Environmental Screening Test to Identify Presumptively Positive Swab Samples.

PDX-LIB, Listeria Indicator Broth, was developed as a proprietary sensitive screening test to identify presumptively positive environmental swab samples for Listeria sp. The original formulation, while sensitive, initially proved to exhibit acceptable levels of false positive test results. Paradigm Diagnostics has been undertaken to modify the medium formulation to render it more selective while not sacrificing its sensitivity. After identification of a candidate formulation through laboratory studies, a field trial was conducted to validate the test performance parameters, including the true positive frequency and false positive frequency in several different food-processing facilities. Identical swab samples were enriched in both the original medium formulation and the new formulation. Presumptive positive samples were confirmed by plating on selective differential agar and qPCR analysis. The field trial data demonstrate that the new formulation significantly reduces the frequency of false positive samples compared to the original Listeria Indicator Broth formulation, without compromising the sensitivity of the original formulation. The new medium formulation resulted in no false positive samples compared to the 54% increased presumptive positive samples obtained with the original medium formulation.

A Novel Selective Medium for Simultaneous Enrichment of Shiga Toxin-Producing Escherichia coli and Salmonella in Ground Beef.

Microbiological analysis of ground beef for contamination by both Salmonella and Shiga toxin-producing Escherichia coli (STEC) is performed by the U.S. Department of Agriculture, Food Safety Inspection Service (FSIS), as part of its Performance Standards Verification Testing program. FSIS has established a zero tolerance for STEC serotype O157:H7 and serogroups O26, O45, O103, O111, O121, and O145 because they are regarded as adulterants. The detection and isolation of these specific serogroups presents a technical challenge necessitating time-consuming and costly laboratory procedures that often exceed the technical capabilities of many small internal and reference laboratories. We describe here a method using a novel STEC and Salmonella selective (SSS) broth that allows for simultaneous selective enrichment of STEC and Salmonella sp., providing isolation and detection from the same broth. The method only involves direct plating from beef enrichments to detect suspect isolates that can be easily confirmed by using immunoassays or PCR, rendering the isolation simpler and less costly than the current described methods. In a side-by-side comparison with modified tryptic soy broth (mTSB), the use of SSS broth resulted in primarily isolating STEC and Salmonella sp., while substantially suppressing the growth of other gram-negative Enterobacteriacae by 90%. Significantly more (χ2 < 3.84) samples containing E. coli O157:H7 and STEC O26, O111, O121, and O145 and a nondifferent (χ2 > 3.84) number of samples containing STEC O103 and O45 were identified when enriching in SSS broth. Coenrichment using six different Salmonella serovars showed numerically greater but not significant (χ2 < 3.84) positive samples by using SSS broth compared with mTSB for a majority of serotypes.

Consumption of Lactobacillus acidophilus and Bifidobacterium longum does not alter phytoestrogen metabolism and plasma hormones in men: a pilot study.

OBJECTIVE: The aim of this study was to determine whether equol excretion status and plasma hormone and leptin concentrations can be influenced by consumption of a probiotic supplement. A secondary focus was to investigate whether male equol excretors have a hormone profile consistent with reduced prostate cancer risk. DESIGN: The design was a randomized, single-blinded, placebo-controlled, parallel-arm trial. SUBJECTS: Thirty-one (31) of the initially enrolled 39 subjects, 18 to 37 years old, completed all study requirements. INTERVENTION: Subjects consumed either probiotic capsules (containing Lactobacillus acidophilus and Bifidobacterium longum) or placebo capsules for 2 months. Fasting plasma concentrations of testosterone (T), dihydrotestosterone (DHT), androstanediol glucuronide (AAG), androstenedione (A), dehydroepiandrosterone sulfate (DHEAS), sex hormone-binding globulin (SHBG), and leptin were measured on days 1 and 57. Urinary excretion of genistein, glycitein, daidzein, O-desmethylangolensin (O-Dma), and equol was measured on days 4 and 61 following a 4-day soy challenge. RESULTS: Probiotic consumption did not significantly alter equol excretor status, plasma hormone, or leptin concentrations in these subjects. At baseline, there were no differences in plasma hormone concentrations between equol excretors and nonexcretors; however, the low number of equol excretors included in this study limits the strength of this finding. CONCLUSIONS: The 2-month intervention with probiotic capsules did not significantly alter equol excretion, plasma hormone, or leptin concentrations in these subjects. A secondary finding was that male equol excretors in this study did not exhibit a hormone profile consistent with reduced prostate cancer risk, although this result should be interpreted with caution.

Economic analysis of feeding pasteurized nonsaleable milk versus conventional milk replacer to dairy calves.

OBJECTIVE: To determine growth, morbidity, and mortality rates in dairy calves fed pasteurized nonsaleable milk versus commercial milk replacer and compare economics of feeding pasteurized nonsaleable milk versus commercial milk replacer in dairy calves. DESIGN: Clinical trial. ANIMALS: 438 dairy calves. PROCEDURE: Calves were assigned at 1 to 2 days of age to be fed pasteurized nonsaleable milk or a commercial milk replacer until weaned. Body weight was measured at the time of study enrollment and at the time of weaning, and any medical treatments administered and deaths that occurred prior to weaning were recorded. A partial budget model was developed to examine the economics of feeding pasteurized nonsaleable milk versus commercial milk replacer. RESULTS: Calves fed conventional milk replacer had significantly lower rates of gain (-0.12 kg/d [-0.26 lb/d]), lower weaning weights (-5.6 kg [-12.3 lb]), higher risk for treatment during the summer and winter months (odds ratio [OR], 3.99), and higher risk of death during the winter months (OR, 29.81) than did calves fed pasteurized nonsaleable milk. The estimated savings of feeding pasteurized nonsaleable milk, compared with milk replacer, was dollars 0.69/calf per day. The estimated number of calves needed to economically justify the nonsaleable milk pasteurization system was 23 calves/d. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that dairy calves fed pasteurized nonsaleable milk have a higher growth rate and lower morbidity and mortality rates than do calves fed conventional milk replacer. Feeding pasteurized nonsaleable milk could be an economically viable strategy for dairy calf producers.

Quenching and Enhancement Effects of ATP Extractants, Cleansers, and Sanitizers on the Detection of the ATP Bioluminescence Signal †.

Techniques for measuring ATP bioluminescence are being used widely as rapid methods for the assessment of the cleanliness of food-processing plants. Sanitizer or cleanser residues could present a potential problem in the use of these ATP bioluminescence techniques due to the degradation of the firefly luciferin-luciferase substrate-enzyme system by these cleaning chemicals. The objectives of this study were the evaluation of the quenching and enhancement effects on the detection of the ATP bioluminescence signal using various ATP extractants, commercial cleansers, and sanitizers, and the determination of the antimicrobial properties of different concentrations of cleansers and sanitizers on Escherichia coli OI57:H7, Listeria monocytogenes , Staphylococcus aureus , and Pseudomonasfragi . Extractants evaluated were benzalkonium chloride, Triton X-100,benzethonium chloride, cetylpyridinium chloride, and trichloroacetic acid. Cleansers evaluated were an alkaline foam and an acid foam. Also evaluated were a quaternary ammonium sanitizer, a d-limolene sanitizer, commercial sodium hypochlorite, and household bleach (sodium hypochlorite). The extractant cetylpyridinium chloride (0.0125%) did not have a statistically significant effect on the detection of the ATP bioluminescence signal at a 95% confidence level. A transition from enhancement to quenching as a concentration-dependent phenomenon was observed for the alkaline foam, acid foam, commercial sodiumhypochlorite,d-limolene,and household bleach. An enhancement effect that did not appear to be concentration-dependent was observed for the quaternary ammonium sanitizer. Antimicrobial disc assays demonstrated that in some cases the cleanser or sanitizer concentration was not effective against the bacteria, but enhanced or quenched the detection of the bioluminescence signal, leading to false-positive or false-negative results respectively.

Isolation and Partial Physiological Characterization of Commercial Strains of Bifidobacteria.

The genus Bifidobacterium has been suggested to be capable of performing gastrointestinal modifications, providing nutritional value when added to the diet as a probiotic and having an inducing effect on the immune system by enhancing cytokine production. As a consequence, the dairy food industry is introducing bifidobacteria to such products as yogurt, flavored milk, and cottage cheese. The objectives of this project were to characterize isolates of bifidobacteria from commercial suppliers, to isolate and characterize bifidobacteria from dairy products, and to establish and compare their physiological characteristics. Physiological characterization was performed based on phenotypic characteristics, carbohydrate fermentation patterns, enzyme profiles, fructose-6-phosphate phosphoketolase (F6PPK) assays, and antibiotic sensitivities. The results demonstrated that commercial bifidobacteria strains and those strains isolated from dairy products were physiologically different. This demonstrates that some bifidobacteria present in dairy products may be mischaracterized when identifying their presence based solely on phenotypic characteristics. The difficulty in growth, rapid assessment, and isolation of bifidobacteria from a mixed culture in dairy products was evaluated in this study. X-α-Gal medium was selected as the most suitable for isolation of bifidobacteria from mixed culture products and modified lactobacilli MRS medium for growing pure isolates of bifidobacteria.