According to an announcement in the Federal Register, the USDA will expand non-O157 STEC (Shiga toxin-producing E. coli) testing to ground beef, bench trim, and other raw ground beef components. The non-O157 strains include what’s called the “Big Six” E. coli strains: E. coli O26, O45, O103, O111, O121, and O145.
In vitro studies have demonstrated antibacterial activity of essential oils (EOs) against Listeria monocytogenes, Salmonella typhimurium, Escherichia coli O157:H7, Shigella dysenteria, Bacillus cereus and Staphylococcus aureus at levels between 0.2 and 10 microl ml(-1). Gram-negative organisms are slightly less susceptible than gram-positive bacteria. A number of EO components has been identified as effective antibacterials, e.g. carvacrol, thymol, eugenol, perillaldehyde, cinnamaldehyde and cinnamic acid, having minimum inhibitory concentrations (MICs) of 0.05-5 microl ml(-1) in vitro. A higher concentration is needed to achieve the same effect in foods. Studies with fresh meat, meat products, fish, milk, dairy products, vegetables, fruit and cooked rice have shown that the concentration needed to achieve a significant antibacterial effect is around 0.5-20 microl g(-1) in foods and about 0.1-10 microl ml(-1) in solutions for washing fruit and vegetables. EOs comprise a large number of components and it is likely that their mode of action involves several targets in the bacterial cell. The hydrophobicity of EOs enables them to partition in the lipids of the cell membrane and mitochondria, rendering them permeable and leading to leakage of cell contents. Physical conditions that improve the action of EOs are low pH, low temperature and low oxygen levels. Synergism has been observed between carvacrol and its precursor p-cymene and between cinnamaldehyde and eugenol. Synergy between EO components and mild preservation methods has also been observed. Some EO components are legally registered flavourings in the EU and the USA. Undesirable organoleptic effects can be limited by careful selection of EOs according to the type of food.
As the nation grapples with the COVID-19 public health emergency, the U.S. Food and Drug Administration is grateful for all that the food and agricultural sector is doing to provide safe and available food to consumers during this difficult time. As we work to get through the current challenge together, the FDA remains committed to protecting both the safety of workers and consumers from foodborne illness as we strive to ensure that America’s food supply remains resilient and among the safest in the world. As part of our ongoing efforts to combat foodborne illness, the FDA released the findings of an investigation into three outbreaks of E. coli O157:H7 illnesses that occurred in Fall 2019, all tied to romaine lettuce, that suggests the proximity of cattle to produce fields may have been a contributing factor.
Investigational Findings
The FDA worked with the Centers for Disease Control and Prevention (CDC) and state partners to investigate the contamination of romaine lettuce with several strains of E. coli O157:H7 that caused three outbreaks of foodborne illness beginning in September 2019 and which were declared over in January 2020. Some clusters (but not all) within each of these outbreaks were traced back to a common grower with multiple ranches/fields located in the Salinas, CA, growing region. Together, the outbreaks made 188 people ill.
During the course of on-farm investigations, one of the outbreak strains of E. coli O157:H7 was detected in a sample on public land less than two miles upslope from a produce farm with multiple fields that were identified during the traceback investigations. Other Shiga toxin-producing strains of E. coli (STEC) were found in closer proximity to where romaine lettuce crops were grown, including two samples from the border area of a farm immediately next to cattle grazing land in the hills above leafy greens fields and two samples from on-farm water drainage basins.
While these strains were not tied to the outbreaks, they do offer insight into the survival and movement of pathogens in this growing region. These findings, together with the findings from earlier leafy greens outbreaks, suggest that a potential contributing factor has been the proximity of cattle to the produce fields identified in traceback investigations. This is especially true when cattle are adjacent to and at higher elevations than produce fields.
In the report, “Investigation Report: Factors Potentially Contributing to the Contamination of Romaine Lettuce Implicated in the Three Outbreaks of E. coli O157:H7 During the Fall of 2019,” we’re calling on leafy greens growers to assess and mitigate risks associated with adjacent and nearby land uses, including grazing lands and animal operations. Of note, the number of cattle observed on nearby lands during the 2019 investigations was far lower than the volume of a large Concentrated Animal Feeding Operation, offering a useful reminder that high-density animal operations are not the only factor to consider. These key findings reinforce our concern about the possible impact of nearby and adjacent land use on the safety of leafy green crops and further underscore the importance of reviewing current operations and implementing appropriate risk mitigation strategies.
Posted in E.coli, E.coli O157, E.coli O157:H7, food contamination, Food Hygiene, Food Illness, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, Food Poisoning, food recall, Food Safety, Food Safety Alert, Food Testing, Food Toxin, Research, STEC E.coli, Uncategorized
Litsea cubeba essential oil (LC‐EO) has been reported as antibacterial agents, but there are few studies about its possible antibacterial mechanism. The antibacterial activities and the underlying mechanisms of LC‐EO against Escherichia coli O157: H7 and Salmonella enterica were investigated. The results showed that the LC‐EO was more effective against gram‐negative bacteria. The inhibition zone for E. coli O157: H7 and S. enterica were 3.1 ± 0.8 and 4.5 ± 0.6 mm, respectively. The minimum inhibitory concentration of LC‐EO against both bacteria was 0.9 μg/ml, while the minimum bactericidal concentrations were 4.5 and 9 μg/ml. Gas chromatography–mass spectrometry analysis confirmed that citral (86.8%) was the main component of LC‐EO. The results of a time–kill analysis illustrated that treatment with LC‐EO led to a rapid decrease in viable bacterial cell number. The release of electrolytes and nucleic acids from the bacterial cells increased with the dose of LC‐EO. Propidium iodide uptake revealed that LC‐EO caused cell membrane damage. Scanning electron and transmission electron microscopy showed that LC‐EO caused damage to the cell walls and membranes, resulting in cell deformation, atrophy, and large central voids. Thus, LC‐EO may provide the basis for the development of new natural food preservatives.
Biofilm formation by Escherichia coli O157:H7 and Salmonella enterica at meat processing plants poses a potential risk of meat product contamination. Many common sanitizers are unable to completely eradicate biofilms formed by these foodborne pathogens because of the three-dimensional biofilm structure and the presence of bacterial extracellular polymeric substances (EPSs). A novel multifaceted approach combining multiple chemical reagents with various functional mechanisms was used to enhance the effectiveness of biofilm control. We tested a multicomponent sanitizer consisting of a quaternary ammonium compound (QAC), hydrogen peroxide, and the accelerator diacetin for its effectiveness in inactivating and removing Escherichia coli O157:H7 and Salmonella enterica biofilms under meat processing conditions. E. coli O157:H7 and Salmonella biofilms on common contact surfaces were treated with 10, 20, or 100% concentrations of the multicomponent sanitizer solution for 10 min, 1 h, or 6 h, and log reductions in biofilm mass were measured. Scanning electron microscopy (SEM) was used to directly observe the effect of sanitizer treatment on biofilm removal and bacterial morphology. After treatment with the multicomponent sanitizer, viable E. coli O157:H7 and Salmonella biofilm cells were below the limit of detection, and the prevalence of both pathogens was low. After treatment with a QAC-based control sanitizer, surviving bacterial cells were countable, and pathogen prevalence was higher. SEM analysis of water-treated control samples revealed the three-dimensional biofilm structure with a strong EPS matrix connecting bacteria and the contact surface. Treatment with 20% multicomponent sanitizer for 10 min significantly reduced biofilm mass and weakened the EPS connection. The majority of the bacterial cells had altered morphology and compromised membrane integrity. Treatment with 100% multicomponent sanitizer for 10 min dissolved the EPS matrix, and no intact biofilm structure was observed; instead, scattered clusters of bacterial aggregates were detected, indicating the loss of cell viability and biofilm removal. These results indicate that the multicomponent sanitizer is effective, even after short exposure with dilute concentrations, against E. coli O157:H7 and S. enterica biofilms.
Tahini is a common food product in the Mediterranean area that is used as a main ingredient in variety of ready-to-eat foods. The objective of the current study was to investigate the inhibitory effect of thyme oil (TO) or cinnamon oil (CO) on E. coli O157:H7 viability in tahini and diluted tahini at different storage temperatures. Addition of 2.0% CO to tahini reduced E. coli O157:H7 numbers by 1.38, 1.79 or 2.20 log10 CFU/mL at 10, 25 or 37 °C, respectively, by 28d. In diluted tahini at 10 °C, no viable cells of E. coli O157:H7 by 21d were detected when 1.0% CO was used. However, at 25 and 37 °C, no viable cells were detected by 14d when CO was added at 0.5% level. Addition of 2.0% TO to tahini, resulted in 1.82, 2.01 or 1.65 log10 CFU/mL reduction in E. coli O 157:H7 numbers was noted at 37, 25 or 10 °C, respectively, by 28d. In diluted tahini, TO at 0.5% or 1.0% induced complete reduction in the viability of E. coli O157:H7 by 28d storage at 37 or 25 °C. At 10 °C, a 3.02 log10 CFU/mL reduction was observed by 28d compared to the initial inoculation level in samples treated with 2.0% TO.
The U.S. Department of Agriculture’s Food Safety and Inspection Service (FSIS) is issuing a public health alert because approximately 70 pounds of raw beef ravioli products, produced by P&S Ravioli Company, a Philadelphia, Pa. establishment, may be contaminated with E. coli O157:H7. A recall was not requested because the affected product is no longer available for purchase.
Posted in E.coli, E.coli O157, E.coli O157:H7, food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Testing, Food Pathogen, Food Poisoning, food recall, Food Safety, Food Safety Alert, Food Testing, Food Toxin, STEC E.coli, Uncategorized
Contamination of fresh produce with the foodborne pathogens Salmonella enterica, Listeria monocytogenes, and Escherichia coli O157:H7 continues to be problematic, resulting in outbreaks of foodborne illness and costly corporate recalls. Various individual concentrations of citric or lactic acids (0.35 to 0.61%) or isopropyl citrate (0.16 to 0.54%) combined with two generally recognized as safe surfactants, 0.025% sodium-2-ethyl-hexyl sulfate and 0.025% sodium dodecylbenzene-sulfonate, were tested against these three pathogens in suspension and when inoculated and dried on the surface of grape tomatoes. The efficacy of sodium hypochlorite (NaClO; at 46 ppm) was also evaluated under dirty and clean conditions in suspension after addition of 0.3 or 0.03% bovine serum albumin, respectively, as an organic load. NaClO (46 ppm) inactivated the three pathogens in suspension by <0.76 log CFU/mL after 5 min in the presence of 0.3% bovine serum albumin, whereas 9 and 15 ppm of free chlorine inactivated the pathogens by 0.64 and 2.77 log CFU/mL, respectively, after 5 min under clean conditions. Isopropyl citrate (0.16% acidulant) plus 0.05% total concentration of the two surfactants inactivated the pathogens in suspension by up to 7.0 log CFU/mL within 2 min. When applied to grape tomatoes for 2 min, 0.54% isopropyl citrate plus 0.025% concentrations of each of the two surfactants reduced Salmonella, E. coli O157:H7, and L. monocytogenes by as much as ca. 5.47, 4.89, and 4.19 log CFU/g, respectively. These reductions were significantly greater than those achieved with 49 ppm of free chlorine. Citric acid and lactic acid plus surfactant washes achieved greater inactivation than water-only washes, reducing Salmonella, E. coli O157:H7, and L. monocytogenes on tomatoes by up to 4.90, 4.37, and 3.98 log CFU/g, respectively. These results suggest that these combinations of acidulants and surfactants may be an effective tool for preventing cross-contamination during the washing of grape tomatoes, for reducing pathogens on the fruit itself, and as an alternative to chlorine for washing fresh produce.
Management of Shiga toxin–producing Escherichia coli (STEC), including E. coli O157:H7, in food products is a major challenge for the food industry. Several interventions, such as irradiation, chemical disinfection, and pasteurization, have had variable success controlling STEC contamination. However, these interventions also indiscriminately kill beneficial bacteria in foods, may impact organoleptic properties of foods, and are not always environmentally friendly. Biocontrol using bacteriophage-based products to reduce or eliminate specific foodborne pathogens in food products has been gaining attention due to the specificity, safety, and environmentally friendly properties of lytic bacteriophages. We developed EcoShield PX, a cocktail of lytic bacteriophages, that specifically targets STEC. This study was conducted to examine the efficacy of this bacteriophage cocktail for reducing the levels of E. coli O157:H7 in eight food products: beef chuck roast, ground beef, chicken breast, cooked chicken, salmon, cheese, cantaloupe, and romaine lettuce. The food products were challenged with E. coli O157:H7 at ca. 3.0 log CFU/g and treated with the bacteriophage preparation at ca. 1 × 106, 5 × 106, or 1 × 107 PFU/g. Application of 5 × 106 and 1 × 107 PFU/g resulted in significant reductions (P < 0.05) in E. coli O157:H7 levels of up to 97% in all foods. When bacteriophages (ca. 1 × 106 PFU/g) were used to treat lower levels of E. coli O157:H7 (ca. 1 to 10 CFU/10 g) on beef chuck roast samples, mimicking the levels of STEC found under real-life conditions in food processing plants, the prevalence of STEC in the samples was significantly reduced (P < 0.05) by ≥80%. Our results suggest that this STEC-targeting bacteriophage preparation can result in significant reduction of both the levels and prevalence of STEC in various foods and, therefore, may help improve the safety and reduce the risk of recalls of foods at high risk for STEC contamination.
The food recall warning for raw beef and veal for E. coli O157:H7 in Canada that was issued on October 17, 2020 and many other dates has been updated with more information. This information was discovered during the Canadian Food InspectionAgency’s food safety investigation. The investigation has been closed.
You can see the long list of recalled products at the CFIA web site. The products include beef bone-in hind shank, beef back ribs, fresh beef, choice grain-fed veal scallopine (frozen), ground beef, boneless veal shank, flat iron, rump roast, beef liver, beef top sirloin, and boneless beef brisket, among others.
Posted in E.coli, E.coli O157, E.coli O157:H7, food contamination, Food Hygiene, Food Illness, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Testing, Food Pathogen, food recall, Food Safety, Food Safety Alert, Food Testing, foodborne disease, Foodborne Illness, foodborne outbreak, foodbourne outbreak, STEC E.coli, Uncategorized
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