Control of Foodborne Staphylococcus aureus by Shikonin, a Natural Extract

Foodborne Staphylococcus aureus (S. aureus) has attracted widespread attention due to its foodborne infection and food poisoning in human. Shikonin exhibits antibacterial activity against a variety of microorganisms, but there are few studies on its antibacterial activity against S. aureus. This study aims to explore the antibacterial activity and mechanism of shikonin against foodborne S. aureus. The results show that the minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) of shikonin were equal for all tested strains ranging from 35 μg/mL to 70 μg/mL. Shikonin inhibited the growth of S. aureus by reducing intracellular ATP concentrations, hyperpolarizing cell membrane, destroying the integrity of cell membrane, and changing cell morphology. At the non-inhibitory concentrations (NICs), shikonin significantly inhibited biofilm formation of S. aureus, which was attributed to inhibiting the expression of cidA and sarA genes. Moreover, shikonin also markedly inhibited the transcription and expression of virulence genes (sea and hla) in S. aureus. In addition, shikonin has exhibited antibacterial ability against both planktonic and biofilm forms of S. aureus. Importantly, in vivo results show that shikonin has excellent biocompatibility. Moreover, both the heat stability of shikonin and the antimicrobial activity of shikonin against S. aureus were excellent in food. Our findings suggest that shikonin are promising for use as a natural food additive, and it also has great potential in effectively controlling the contamination of S. aureus in food and reducing the number of illnesses associated with S. aureus.

Assessing Existing Food Safety Resources with UK-Based Chemotherapy Patients and Family Caregivers for Future Learning Purposes

As incidence of foodborne infection is more prevalent among cancer patients, and the domestic kitchen reported to be a contributor to foodborne infection; there is a need to ensure appropriate domestic food safety practices to safeguard this ‘at-risk’ population. Although patients are aware of the increased risk of infection, previous self-reported data indicate potential food safety malpractices among patients and family caregivers; thus suggesting the need for targeted food safety information. However, existing UK resources provide inconsistent and insufficient food safety information. Involvement of intended end-users in the co-creation of interventions increases potential effectiveness. Qualitative data was collated from in-depth interviews and a focus group with UK chemotherapy patients and family caregivers (n=35) to determine perceptions and preferences for food safety information, by evaluating existing food safety resources from international providers (n=12). Although participants liked digital interventions (e.g. websites/videos), traditional paper-based leaflets were perceived to be the most beneficial as they could be referred to on repeated occasions. Despite identifying drawbacks with some resources, combining approaches in a multi-resource intervention was favored by patients and family caregivers. Ensuring patients are not overwhelmed with excessive information was important. Short, logical, engaging, educational and entertaining information to evoke an interest in the topic was preferred. Utilization of graphics to supplement descriptive information may enhance comprehensibility. Interventions need to be appropriate for patients and caregivers and delivery by trusted healthcare professionals may enhance the credibility of the message. The study identifies preferred approaches to facilitate targeted food safety communication. Findings can be utilized to co-create targeted food safety interventions for chemotherapy patients and family caregivers.

A Review of Microbial Contamination in Processed and Street Foods

As a basic physiology need threat to sufficient food, production is threat to human survival food security was a main issue that has gained global concern. This paper looks at the food borne contamination by assessing the availability of food and accessibility of the available food from a food as a microbiologist’s perspective, there are several microorganisms similarly viruses, bacteria, fungi, protozoans, and parasites for which foods serve as vehicles of transmission. Among these agents, several bacteria are most commonly implicated in foodborne outbreak episodes. Foodborne diseases in human beings are caused either by straight contact with infested food animals/animal products (zoonotic) or humans, such as a food handler, or by direct absorption of polluted foods. There are three important terms with regard to foodborne diseases foodborne infections, foodborne toxicoinfections and foodborne intoxications. Foodborne infection is the condition caused by the incorporation of viable cells of a pathogen. For example, Salmonella Enteritidis and Escherichia coli infections are brought about by the ingestion of food contaminated with living cells of these pathogens. Finally, foodborne toxicoinfection is that in which the ingestion of viable pathogenic cells causes the toxins productions inside the human body, leading to infection episodes. For example, Vibrio cholerae produces cholera toxin inside the body after being ingested by the host. The morphology, Gram’s reaction, biochemical properties, and associated foods with important foodborne bacteria.

Hepatitis E Virus in Croatia in the “One-Health” Context

Hepatitis E virus (HEV) is the most common cause of viral hepatitis globally. The first human case of autochthonous HEV infection in Croatia was reported in 2012, with the undefined zoonotic transmission of HEV genotype 3. This narrative review comprehensively addresses the current knowledge on the HEV epidemiology in humans and animals in Croatia. Published studies showed the presence of HEV antibodies in different population groups, such as chronic patients, healthcare professionals, voluntary blood donors and professionally exposed and pregnant women. The highest seroprevalence in humans was found in patients on hemodialysis in a study conducted in 2018 (27.9%). Apart from humans, different studies have confirmed the infection in pigs, wild boars and a mouse, indicating the interspecies transmission of HEV due to direct or indirect contact or as a foodborne infection. Continued periodical surveys in humans and animals are needed to identify the possible changes in the epidemiology of HEV infections.

Precursor abundance influences divergent antigen specific CD8+ T cell responses after Yersinia pseudotuberculosis foodborne infection

Primary infection of C57BL/6 mice with the bacterial pathogen Yersinia pseudotuberculosis elicits an unusually large H-2Kb-restricted CD8+ T cell response to the endogenous and protective bacterial epitope YopE69-77. To better understand the basis for this large response, the model OVA257-264 epitope was inserted into YopE in Y. pseudotuberculosis and antigen specific CD8+ T cells in mice were characterized after foodborne infection with the resulting strain. The epitope YopE69-77 elicited significantly larger CD8+ T cell populations in the small intestine, mesenteric lymph nodes (MLNs), spleen and liver between 7- and 30-days post infection, despite residing in the same protein and having a similar affinity for H-2Kb as OVA257-264. YopE-specific CD8+ T cell precursors were ∼4.6 times as abundant as OVA-specific precursors in the MLNs, spleen and other lymph nodes of naïve mice, explaining the dominance of YopE69-77 over OVA257-264 at early infection times. However, other factors contributed to this dominance as the ratio of YopE-specific to OVA-specific CD8+ T cells increased between 7- and 30-days post infection. We also compared the YopE-specific and OVA-specific CD8+ T cells generated during infection for effector and memory phenotypes. Significantly higher percentages of YopE-specific cells were characterized as short short-lived effectors while higher percentages of OVA-specific cells were memory precursor effectors at day 30 post infection in spleen and liver. Our results suggest that a large precursor number contributes to the dominance and effector and memory functions of CD8+ T cells generated to the protective YopE69-77 epitope during Y. pseudotuberculosis infection of C57BL/6 mice.

Precursor abundance influences divergent antigen specific CD8+ T cell responses after Yersinia pseudotuberculosis foodborne infection

Primary infection of C57BL/6 mice with the bacterial pathogen Yersinia pseudotuberculosis elicits an unusually large H-2Kb-restricted CD8+ T cell response to the endogenous and protective bacterial epitope YopE69-77. To better understand the basis for this large response, the model OVA257-264 epitope was inserted into YopE in Y. pseudotuberculosis and antigen specific CD8+ T cells in mice were characterized after foodborne infection with the resulting strain. The epitope YopE69-77 elicited significantly larger CD8+ T cell populations in the small intestine, mesenteric lymph nodes (MLNs), spleen and liver between 7- and 30-days post infection, despite residing in the same protein and having a similar affinity for H-2Kb as OVA257-264. YopE-specific CD8+ T cell precursors were ~4.6 times as abundant as OVA-specific precursors in the MLNs, spleen and other lymph nodes of naïve mice, explaining the dominance of YopE69-77 over OVA257-264 at early infection times. However, other factors contributed to this dominance as the ratio of YopE-specific to OVA-specific CD8+ T cells increased between 7- and 30-days post infection. We also compared the YopE-specific and OVA-specific CD8+ T cells generated during infection for effector and memory phenotypes. Significantly higher percentages of YopE-specific cells were characterized as short short-lived effectors while higher percentages of OVA-specific cells were memory precursor effectors at day 30 post infection in spleen and liver. Our results suggest that a large precursor number contributes to the dominance and effector and memory functions of CD8+ T cells generated to the protective YopE69-77 epitope during Y. pseudotuberculosis infection of C57BL/6 mice.

Exposure Profile of SARS-CoV-2 in Canadian Food Sources.

A new coronavirus strain known as SARS-CoV-2 has spread throughout the world. This virus is the causative agent for the Coronavirus Disease 2019 (COVID-19) and spreads primarily through human-to-human transmission via infected droplets and aerosols generated by infected persons. While COVID-19 is a respiratory virus, the potential for transmission of SARS-CoV-2 via food is considered theoretically possible and remains a concern for Canadian consumers. We have conducted an exposure assessment of the likelihood of exposure of SARS-CoV-2 in Canadian food sources at the time of consumption. This article describes the exposure routes considered most relevant in the context of food contamination with SARS-CoV-2, including contaminated food of animal origin, other contaminated fresh foods, fomites and SARS-CoV-2 contaminated feces. The likelihood of foodborne infection of SARS-CoV-2 via the human digestive tract was also considered. Our analysis indicates that there is no evidence that foodborne transmission of SARS-CoV-2 has occurred and we consider the likelihood of contracting COVID-19 via food and food packaging in Canada as low to remote. Adherence to safe food practices and cleaning procedures would in any case prevent a potential foodborne infection with SARS-CoV-2.

Probiotic Bacilli Inhibit Salmonella Biofilm Formation Without Killing Planktonic Cells

Salmonellosis is a foodborne infection caused by Salmonella. Domestic poultry species are one of the main reservoirs of Salmonella, which causes the foodborne infection salmonellosis, and are responsible for many cases of animal-to-human transmission. Keeping backyard chickens is now a growing trend, increasing the frequency of direct contact with the flock and, by consequence, the incidence of Salmonella infections. Bacillus subtilis KATMIRA1933 and Bacillus amyloliquefaciens B-1895 are probiotic bacilli that produce the bacteriocins subtilosin A and subtilin, respectively. The antimicrobial activity of the two strains was determined against the reference strain Micrococcus luteus ATCC 10420. The cell-free supernatant of B. subtilis KATMIRA1933 inhibited biofilm formation by Salmonella enterica subsp. enterica serovar Hadar, Salmonella enterica subsp. enterica serovar Enteritidis phage type 4, and Salmonella enterica subsp. enterica serovar Thompson by 51.1, 48.3, and 56.9%, respectively. The cell-free supernatant of B. amyloliquefaciens B-1895 inhibited the biofilm formation of these Salmonella strains by 30.4, 28.6, and 35.5%, respectively. These findings suggest that the bacillus strains may have the potential to be used as probiotics and antibiotic alternatives for the control of Salmonella in poultry. The number of planktonic cells was unaffected by treatment with the cell-free supernatant. A co-culture of the Salmonella strains with either bacilli showed no signs of growth inhibition, suggesting that it might have been quorum sensing that is affected by the two Bacillus strains.