Mode of Salmonella and Escherichia coli O157:H7 inactivation by a stabilized oxychloro-based sanitizer

Development of benchmark datasets for text mining and sentiment analysis to accelerate regulatory literature review

In the field of regulatory science, reviewing literature is an essential and important step, which most of the time is conducted by manually reading hundreds of articles. Although this process is highly time-consuming and labor-intensive, most output of this process is not well transformed into machine-readable format. The limited availability of data has largely constrained the artificial intelligence (AI) system development to facilitate this literature reviewing in the regulatory process. In the past decade, AI has revolutionized the area of text mining as many deep learning approaches have been developed to search, annotate, and classify relevant documents. After the great advancement of AI algorithms, a lack of high-quality data instead of the algorithms has recently become the bottleneck of AI system development. Herein, we constructed two large benchmark datasets, Chlorine Efficacy dataset (CHE) and Chlorine Safety dataset (CHS), under a regulatory scenario that sought to assess the antiseptic efficacy and toxicity of chlorine. For each dataset, ∼10,000 scientific articles were initially collected, manually reviewed, and their relevance to the review task were labeled. To ensure high data quality, each paper was labeled by a consensus among multiple experienced reviewers. The overall relevance rate was 27.21% (2,663 of 9,788) for CHE and 7.50% (761 of 10,153) for CHS, respectively. Furthermore, the relevant articles were categorized into five subgroups based on the focus of their content. Next, we developed an attention-based classification language model using these two datasets. The proposed classification model yielded 0.857 and 0.908 of Area Under the Curve (AUC) for CHE and CHS dataset, respectively. This performance was significantly better than permutation test (p < 10E-9), demonstrating that the labeling processes were valid. To conclude, our datasets can be used as benchmark to develop AI systems, which can further facilitate the literature review process in regulatory science.

On mechanism behind UV-A light enhanced antibacterial activity of gallic acid and propyl gallate against Escherichia coli O157:H7

Possible mechanisms behind the enhanced antimicrobial activity of gallic acid (GA) and its ester propyl gallate (PG) in the presence of UV-A light against Escherichia coli O157:H7 were investigated. GA by itself is a mild antimicrobial and has a pro-oxidant ability. We found that the presence of UV-A light increases the uptake of GA by the bacteria. Once GA is internalized, the interaction between GA and UV-A induces intracellular ROS formation, leading to oxidative damage. Concurrently, GA + UV-A also inhibits the activity of superoxide dismutase (SOD), magnifying the imbalance of redox status of E. coli O157:H7. In addition to ROS induced damage, UV-A light and GA also cause injury to the cell membrane of E. coli O157:H7. UV-A exposed PG caused oxidative damage to the cell and significantly higher damage to the cell membrane than GA + UV-A treatment, explaining its higher effectiveness than GA + UV-A treatment. The findings presented here may be useful in developing new antimicrobial sanitation technologies for food and pharmaceutical industries.

Antimicrobial activity and stability of weakly acidified chlorous acid water

The antimicrobial activity of weakly acidified chlorous acid water (WACAW) against Staphylococcus aureus, non-pathogenic Escherichia coli, enterohemorrhagic E. coli (EHEC O157:H7), Candida albicans, and spore-forming Bacillus and Paenibacillus species was evaluated in vitro. The antiviral activity was also examined using feline calicivirus (FCV). Diluted WACAW (>100 ppm) effectively reduced the number of non-spore-forming bacteria (>4 log10 CFU reductions) within 5 min. Treatment with this sanitizer at 400 ppm for 30 min achieved>5 log10 CFU reductions in spore-forming Bacillus and Paenibacillus species while an equivalent concentration of sodium hypochlorite (NaClO) resulted in only a 0.98 and 2.72 log10 CFU reduction, respectively. The effect of this sanitizer against FCV was equivalent to that of NaClO. Immersion in WACAW (400 ppm) achieved >4 and 2.26 log10 CFU reductions in Campylobacter jejuni and EHEC, respectively, on artificially contaminated broiler carcass pieces. Finally, theantimicrobial activity of this sanitizer was shown to be maintained for at least 28 d when in contact with nonwoven fabric (100% cotton). This study showed that pH control of chlorous acid is expected to modify its antimicrobial activity and stability. WACAW is expected to have applications in various settings such as the food processing and healthcare industries.

Current intervention strategies for the microbial safety of sprouts

Sprouts have gained popularity worldwide due to their nutritional values and health benefits. The fact that their consumption has been associated with numerous outbreaks of foodborne illness threatens the $250 million market that this industry has established in the United States. Therefore, sprout manufacturers have utilized the U.S. Food and Drug Administration recommended application of 20,000 ppm of calcium hypochlorite solution to seeds before germination as a preventative method. Concentrations of up to 200 ppm of chlorine wash are also commonly used on sprouts. However, chlorine-based treatment achieves on average only 1- to 3-log reductions in bacteria and is associated with negative health and environmental issues. The search for alternative strategies has been widespread, involving chemical, biological, physical, and hurdle processes that can achieve up to 7-log reductions in bacteria in some cases. The compilation here of the current scientific data related to these techniques is used to compare their efficacy for ensuring the microbial safety of sprouts and their practicality for commercial producers. Of specific importance for alternative seed and sprout treatments is maintaining the industry-accepted germination rate of 95% and the sensorial attributes of the final product. This review provides an evaluation of suggested decontamination technologies for seeds and sprouts before, during, and after germination and concludes that thermal inactivation of seeds and irradiation of sprouts are the most practical stand-alone microbial safety interventions for sprout production.

Efficacy of levulinic acid-sodium dodecyl sulfate against Encephalitozoon intestinalis, Escherichia coli O157:H7, and Cryptosporidium parvum

Foodborne parasites are characterized as being highly resistant to sanitizers used by the food industry. In 2009, a study reported the effectiveness of levulinic acid in combination with sodium dodecyl sulfate (SDS) in killing foodborne bacteria. Because of their innocuous properties, we studied the effects of levulinic acid and SDS at various concentrations appropriate for use in foods, on the viability of Cryptosporidium parvum and Encephalitozoon intestinalis. The viability of Cryptosporidium and E. intestinalis was determined by in vitro cultivation using the HCT-8 and RK-13 cell lines, respectively. Two Escherichia coli O157:H7 isolates were also used in the present study: strain 932 (a human isolate from a 1992 Oregon meat outbreak) and strain E 0018 (isolated from calf feces). Different concentrations and combinations of levulinic acid and SDS were tested for their ability to reduce infectivity of C. parvum oocysts (10(5)), E. intestinalis spores (10(6)), and E. coli O157:H7 (10(7)/ml) when in suspension. Microsporidian spores were treated for 30 and 60 min at 20 ± 2°C. None of the combinations of levulinic acid and SDS were effective at inactivating the spores or oocysts. When Cryptosporidium oocysts were treated with higher concentrations (3% levulinic acid-2% SDS and 2% levulinic acid-1% SDS) for 30, 60, and 120 min, viability was unaffected. E. coli O157:H7, used as a control, was highly sensitive to the various concentrations and exposure times tested. SDS and levulinic acid alone had very limited effect on E. coli O157:H7 viability, but in combination they were highly effective at 30 and 60 min of incubation. In conclusion, Cryptosporidium and microsporidia are not inactivated when treated for various periods of time with 2% levulinic acid-1% SDS or 3% levulinic acid-2% SDS at 20°C, suggesting that this novel sanitizer cannot be used to eliminate parasitic contaminants in foods.

Comparison of the effectiveness of acidified sodium chlorite and sodium hypochlorite in reducing Escherichia coli

This study was designed to compare the effectiveness of acidified sodium chlorite (ASC) and sodium hypochlorite (NaClO) in reducing several Escherichia coli strains isolated from different retail meat and fresh produce. Forty nonpathogenic E. coli strains were isolated and used in this study. A type strain of E. coli (JCM 1649) and four O157:H7 serotypes of E. coli (CR-3, MN-28, MY-29, and DT-66) were used as reference. In vitro assay results revealed that the viable cell counts of each isolated E. coli strain and control strains exhibited a reduction of ∼ 4.3 ± 0.9 log and 7.8 ± 1.7 log CFU/mL after a 3-minute exposure to 100 mg/L NaClO and 20 mg/L ASC (pH 4.6), respectively, at 25°C, when compared with the viable bacterial counts obtained from phosphate-buffered saline. The one exception was the flocs-forming strain, which showed a reduction of only 1.0 log CFU/mL with both disinfectants. However, reductions of only 1.7 ± 0.3 log and 1.9 ± 0.4 log CFU/g were observed in lettuce after 5 minutes of washing with NaClO and ASC, respectively. On the other hand, reductions of 1.6 ± 0.2 log and 1.6 ± 0.4 log CFU/g were observed in spinach after 5 minutes of washing with NaClO and ASC, respectively. No reduction in the population was observed after washing the inoculated, fresh-cut vegetables with distilled water only. No significant difference in the reduction of E. coli was observed among all the tested strains with both sanitizers in the in vivo assay. These data suggest that the tested sanitizers exhibit a similar reduction of the surface-attached E. coli on leafy vegetables irrespective of the strain source.