No abstract

Antibodies provide a sensitive indicator of proteins displayed by bacteria during sepsis. Because signals produced by infection are naturally amplified during the antibody response, host immunity can be used to identify biomarkers for proteins that are present at levels currently below detectable limits. We developed a microarray comprising ϳ70% of the 4066 proteins contained within the Yersinia pestis proteome to identify antibody biomarkers distinguishing plague from infections caused by other bacterial pathogens that may initially present similar clinical symptoms. We first examined rabbit antibodies produced against proteomes extracted from Y. pestis, Burkholderia mallei, Burkholderia cepecia, Burkholderia pseudomallei, Pseudomonas aeruginosa, Salmonella typhimurium, Shigella flexneri, and Escherichia coli, all pathogenic Gram-negative bacteria. These antibodies enabled detection of shared cross-reactive proteins, fingerprint proteins common for two or more bacteria, and signature proteins specific to each pathogen. Recognition by rabbit and non-human primate antibodies involved less than 100 of the thousands of proteins present within the Y. pestis proteome. Further antigen binding patterns were revealed that could distinguish plague from anthrax, caused by the Gram-positive bacterium Bacillus anthracis, using sera from acutely infected or convalescent primates. Thus, our results demonstrate potential biomarkers that are either specific to one strain or common to several species of pathogenic bacteria. Molecular & Cellular Proteomics 8:924 -935, 2009.

A commercial plant extract (prepared from olive, garlic, onion and citrus extracts with sodium acetate (SA) as a carrier) was evaluated to extend the viability of yogurt starter and probiotic bacteria as a means to enhance the shelf life of live and active culture, probiotic nonfat yogurt. Yogurts prepared from three different formulas (0.5* plant extract, 0.25* SA, or no supplement) and cultures (yogurt starter plus Bifidobacterium animalis,Lactobacillus acidophilus, or both probiotics) were assessed weekly during 29 days of storage at 5°C. Supplemented yogurt mixes had greater buffering capacities than non-supplemented yogurt mixes. At the end of storage, Lactobacillus bulgaricus and L. acidophilus counts in supplemented yogurts were greater compared with non-supplemented yogurts. Supplementation did not affect Streptococcus thermophilus and B. animalis counts. Hence the greater buffering capacity of yogurt containing plant extract could enhance the longevity of the probiotics, L. bulgaricus and L. acidophilus, during storage.

This research investigates the potential risk of Salmonella in muffins when contamination is introduced via flour, the main ingredient. Flour was inoculated with a 3-strain cocktail of Salmonella serovars (Newport, Typhimurium, and Senftenberg) and re-dried to achieve a target concentration of ~8logCFU/g. The inoculated flour was then used to prepare muffin batter following a standard commercial recipe. The survival of Salmonella during and after baking at 190.6°C for 21min was analyzed by plating samples on selective and injury-recovery media at regular intervals. The thermal inactivation parameters (D and z values) of the 3-strain Salmonella cocktail were determined. A ≥5logCFU/g reduction in Salmonella population was demonstrated by 17min of baking, and a 6.1logCFU/g reduction in Salmonella population by 21min of baking. The D-values of Salmonella serovar cocktail in muffin batter were 62.2±3.0, 40.1±0.9 and 16.5±1.7min at 55, 58 and 61°C, respectively; and the z-value was 10.4±0.6°C. The water activity (a) of the muffin crumb (0.928) after baking and 30min of cooling was similar to that of pre-baked muffin batter, whereas the a of the muffin crust decreased to (0.700). This study validates a typical commercial muffin baking process utilizing an oven temperature of 190.6°C for at least 17min as an effective kill-step in reducing a Salmonella serovar population by ≥5logCFU/g.

Hyperspectral imaging (HSI) provides both spatial and spectral information of a sample by combining imaging with spectroscopy. The objective of this study was to generate hyperspectral graphs of common foodborne pathogens and to develop and validate prediction models for the classification of these pathogens. Four strains of Cronobacter sakazakii , five strains of Salmonella spp., eight strains of Escherichia coli , and one strain each of Listeria monocytogenes and Staphylococcus aureus were used in the study. Principal component analysis and k NN ( k ‐nearest neighbor) classifier model were used for the classification of hyperspectra of various bacterial cells, which were then validated using the cross‐validation technique. Classification accuracy of various strains within genera including C. sakazakii , Salmonella spp., and E. coli , respectively, was 100%; except within C. sakazakii , strain BAA‐894, and E. coli , strains O26, O45, and O121 had 66.67% accuracy. When all strains were studied together (irrespective of their genus) for the classification, only C. sakazakii P1, E. coli O104, O111, and O145, S . Montevideo, and L. monocytogenes had 100% classification accuracy, whereas E. coli O45 and S . Tennessee were not classified (classification accuracy of 0%). Lauric arginate treatment of C. sakazakii BAA‐894, E. coli O157, S . Senftenberg, L. monocytogenes , and S. aureus significantly affected their hyperspectral signatures, and treated cells could be differentiated from the healthy, nontreated cells.

This study was conducted to validate a simulated commercial baking process for hamburger buns to destroy Salmonella serovars and to determine the appropriateness of using nonpathogenic surrogates (Enterococcus faecium ATCC 8459 or Saccharomyces cerevisiae) for in-plant process validation studies. Wheat flour was inoculated (∼6 log CFU/g) with three Salmonella serovars (Typhimurium, Newport, or Senftenberg 775W) or with E. faecium. Dough was formed, proofed, and baked to mimic commercial manufacturing conditions. Buns were baked for up to 13 min in a conventional oven (218.3°C), with internal crumb temperature increasing to ∼100°C during the first 8 min of baking and remaining at this temperature until removal from the oven. Salmonella and E. faecium populations were undetectable by enrichment (>6-log CFU/g reductions) after 9.0 and 11.5 min of baking, respectively, and ≥5-log-cycle reductions were achieved by 6.0 and 7.75 min, respectively. D-values of Salmonella (three-serovar cocktail) and E. faecium 8459 in dough were 28.64 and 133.33, 7.61 and 55.67, and 3.14 and 14.72 min at 55, 58, and 61°C, respectively, whereas D-values of S. cerevisiae were 18.73, 5.67, and 1.03 min at 52, 55, and 58°C, respectivly. The z-values of Salmonella, E. faecium, and S. cerevisiae were 6.58, 6.25, and 4.74°C, respectively. A high level of thermal lethality was observed for baking of typical hamburger bun dough, resulting in rapid elimination of high levels of the three-strain Salmonella cocktail; however, the lethality and microbial destruction kinetics should not be extrapolated to other bakery products without further research. E. faecium demonstrated greater thermal resistance compared with Salmonella during bun baking and could serve as a conservative surrogate to validate thermal process lethality in commercial bun baking operations. Low thermal tolerance of S. cerevisiae relative to Salmonella serovars limits its usefulness as a surrogate for process validations.

The objective of this foundational study was to develop and evaluate the efficacy of an affordable hyperspectral imaging (HSI) system to identify single and mixed strains of foodborne pathogens in dairy products. This study was designed as a completely randomized design with three replications. Three strains each of Escherichia coli O157:H7 and Listeria monocytogenes were evaluated either as single or mixed strains with the HSI system in growth media and selected dairy products (whole milk, and cottage and cheddar cheeses). Test samples from freshly prepared single or mixed strains of pathogens in growth media or inoculated dairy products were streaked onto selective media (PALCAM and/or Sorbitol MacConkey agar) for isolation. An isolated colony was selected and mixed with 1 ml of HPLC grade water, vortexed for 1 min, and spread over a microscope slide. Images were captured at 2000× magnification on the built HSI system at wavelengths ranging from 400 nm to 1100 nm with 5‐nm band intervals. For each image, three cells were selected as regions of interest (ROIs) to obtain hyperspectral signatures of respective bacteria. Reference pathogen libraries were created using growth media, and then test pathogenic cells were classified by their hyperspectral signatures as either L. monocytogenes or E. coli O157:H7 using k‐nearest neighbor (kNN) and cross‐validation technique in R‐software. With the implementation of kNN (k = 3), overall classification accuracies of 58.97% and 61.53% were obtained for E. coli O157:H7 and L. monocytogenes, respectively.

Aim To study the impact of incorporating micro‐nano‐bubbles (MNBs) in commonly used food antimicrobials (AMs) against Escherichia coli O157:H7 (EC) and Listeria monocytogenes (LM). Methods and Results Air, carbon dioxide (CO2) and nitrogen (N2) were used to incorporate MNBs in city water. AM solution (with or without MNBs) of 9 ml was individually taken into sterile test tubes and mixed with 1 ml of inoculum grown in brain heart infusion (BHI) broth to get the net AM concentrations of 28·4 ppm peracetic acid (PAA), 200 ppm chlorine (Cl2), 5·4% citric acid (CA) and 4·5% lactic acid (LA). After treatment time of 1·5 and 3·0 min, 1 ml of sample was neutralized using Dey–Engley neutralizing broth and plated on BHI agar. For EC, Cl2‐CO2 solutions resulted in significantly greater log reductions (5·2 logs) compared to that of Cl2 solutions without MNBs (3·8 logs). For LM, PAA‐CO2 solutions resulted in significantly greater log reductions (4·4 logs) compared to that of PAA solutions without MNBs (1·7 logs). Conclusions This study demonstrated that the efficacy of Cl2 and PAA AM solutions could be increased by incorporating CO2‐MNBs against EC and LM in microbiological growth medium. Significance and Impact of the Study Incorporation of CO2‐MNBs in AM solutions could increase the efficacy of AMs against pathogens on/in food matrices, which should be tested in future research.