Category Archives: pathogenic

Research – Consumer Knowledge and Behaviors Regarding Food Safety Risks Associated with Wheat Flour

Journal of Food Protection

Consumers do not consider flour, a low-moisture food product, a high risk for microbial contamination. In the past 10 years, however, flour has been identified as a source of pathogenic bacteria, including Salmonella and Escherichia coli. Online surveys were conducted to study consumers’ flour handling practices and knowledge about food safety risks related to flour. The survey also evaluated message impact on three food safety messages in communicating information and convincing consumers to adopt safe flour handling practices. Flour-using consumers (n = 1,045) from the United States reported they used flour to make cakes, cookies, and bread. Most consumers stored flour in sealed containers. Less than 1% kept a record of product identification numbers, such as lot numbers, and less than 11% kept brand and use-by date information. Many consumers (85%) were unaware of flour recalls, or outbreaks, and few (17%) believed they would be affected by flour recalls or outbreaks. If the recall affected the flour they bought, nearly half of the consumers (47%) would buy the same product from a different brand for a few months before they returned to the recalled brand. Among consumers who use flour to bake, 66% said they ate raw cookie dough or batter. Raw dough “eaters” were more difficult to convince to avoid eating and playing with raw flour than “noneaters.” Food safety messages were less impactful on those raw dough eaters than noneaters. Compared with the food safety message with only recommendations, those messages with recommendations and an explanation as to the benefits of the practice were more effective in convincing consumers to change their practices. These findings provide insight into effective consumer education about safe flour handling practices and could assist in the accurate development of risk assessment models related to flour handling.

USA – Timeline for Identifying and Reporting Illnesses in Foodborne Outbreaks


Ever wonder why the number of illnesses in a foodborne outbreak can increase for weeks, even after the contaminated food is off the market?

A series of events happen before public health officials can report that a case of illness is linked to an outbreak. Each event takes a certain amount of time. This time is known as the “reporting lag” or “lag window” of an outbreak. It is usually 3–4 weeks. For illnesses caused by some bacteria, such as Listeria, it may be longer. Public health officials work to speed up this process when possible.

The steps below outline what typically happens from the day someone eats a contaminated food to the day their illness is linked to a multistate foodborne outbreak investigated by CDC.*

Day 1: You eat a food containing harmful bacteria.
Day 3: You start to feel sick.
  • Symptoms of food poisoning (such as nausea and diarrhea) could start anywhere from a few hours to a few weeks later, depending on the bacteria you ingested. The following chart describes how long it typically takes for someone to have symptoms after being infected with some of the most common foodborne bacteria.
How long it typically takes for someone to have symptoms after being infected with some of the most common foodborne bacteria.
Bacteria Typical start of symptoms
Campylobacter 2–5 days
E. coli 3–4 days
Listeria 1–4 weeks
Salmonella 6 hours–6 days
Vibrio 1-2 days
Should I call the doctor?

Find out when some common food poisoning symptoms are severe enough to need medical attention. See the list

Day 5: You still feel sick with nausea or diarrhea, so you decide to see a healthcare provider.
  • To learn which germ is making you sick, the healthcare provider collects a sample of your stool (poop), urine (pee), or blood.
  • The provider sends your sample to a clinical laboratory for testing.
Day 6: The clinical laboratory tests your sample.
  • After receiving your sample, the laboratory takes 1–3 days to run tests, depending on their capacity.
Day 9: Clinical laboratory test results show what germ is causing your illness.
  • The clinical laboratory identifies the germ making you sick and reports the test results to your healthcare provider.
  • The clinical laboratory should also report test results to the state or local public health department, and they notify CDC.
Days 9–16: The clinical laboratory sends a sample of your bacteria to a public health laboratory.
  • The clinical laboratory ships the bacteria found in your sample to a public health laboratory for whole genome sequencing (WGS) analysis.
  • Shipping can take up to a week, depending on transportation arrangements in your state and the distance between the two laboratories.
Days 16–21: The public health laboratory performs WGS analysis and other tests on the bacteria.
  • The public health laboratory performs tests to determine the bacteria’s DNA fingerprint and other characteristics.
  • WGS testing and analysis of the results, including whether the bacteria is resistant to any antibiotics, can take 2–10 days depending on the bacteria.
What Is Whole Genome Sequencing?

CDC and public health laboratories use a technology called whole genome sequencing (WGS) to generate DNA fingerprints of bacteria causing illness. When bacteria have nearly identical DNA fingerprints, we consider them “genetically closely related.” Illnesses caused by bacteria that are genetically closely related are more likely to have a common source, such as a contaminated food. An outbreak is an event in which a group of people get similar illnesses from a common source. Disease detectives investigate outbreaks to find out what is making people sick.

Find out how CDC uses WGS to detect and solve foodborne outbreaks.

Day 22: The public health laboratory sends WGS results to CDC.
  • Within a day of analyzing the WGS results, state public health officials add the DNA fingerprint from the bacteria to PulseNet, a national laboratory network coordinated by CDC. PulseNet connects foodborne illnesses in order to identify outbreaks.
Day 23: CDC determines if your illness is related to other recent illnesses.
  • CDC scientists determine whether the bacteria causing your illness is closely related genetically to any other recent WGS results from other people in PulseNet.
  • If it is closely related to bacteria causing recent illnesses in other people, CDC may begin an outbreak investigation or add your illness to an ongoing investigation.

Total time: 34 weeks

*Most cases of illness, even those caused by common foodborne germs, are not linked to a foodborne outbreak. This can happen for many reasons. A major reason is that most illnesses are not part of an outbreak. Another reason is that germs that cause foodborne illness can also be spread in other ways, such as by water or directly from one person to another. Also, if an illness is diagnosed by a culture-independent diagnostic test, that case may not be linked to an outbreak because these tests do not provide the information needed to link it to an outbreak. In addition, many people do not seek medical care for foodborne illnesses, so their illnesses cannot be diagnosed or reported to public health officials.

Norway – Research – Risk ranking and source attribution of food- and waterborne pathogens for surveillance purposes – Toxoplasma the top risk!



Providing risk managers with the information that they need for decision making is an important element in food-safety management. The present risk assessment was undertaken to establish a scientific basis that could be used to assist the Norwegian Food Safety Authority (NFSA) in implementing risk-based surveillance, monitoring, and control programmes for pathogens in food and water. The assessment approach used here consisted of two steps:(1) risk ranking of 20 selected pathogens based on the incidence and severity of their associated diseases following infection with the pathogens via food or water, and(2) a source attribution process aimed at identifying the main pathogen-food combinations that may pose a risk to human health for each of the ranked pathogens. We used an expert knowledge elicitation (EKE) procedure with a panel of nine experts, including all eight members of the Panel on Biological Hazards of the Norwegian Scientific Committee for Food and Environment (NSCFE) and one invited expert on food/water-borne viral infections.
Risk Ranking
The 20 pathogens selected for risk ranking were defined in the terms of reference (ToR) received from NFSA. We performed a multicriteria-based ranking of the pathogens in terms of their public health impact from food/water-borne transmission in Norway. The risk ranking utilized six criteria that estimated the incidence of food- and waterborne illness attributable to each pathogen, the severity of acute and chronic illness, the fraction of chronic illness, fatality rate, and the probability for future increased disease burden. For each pathogen, all criteria were scored by the expert panel members, and individual criterion scores were combined into an overall score for every pathogen. To achieve this, each criterion was weighted in terms of its relative importance, as judged by the expert panel. The overall scores so calculated were the basis for the ranking.
Source attribution
For each of the ranked pathogens, the subsequent source-attribution process aimed to identify the main food vehicles, reservoirs, and sources of infection for outbreak-related and sporadic cases of illness, the relative importance of food sources, and preventable risk factors in Norway. To achieve this, both microbiological and epidemiological data were scrutinized. These encompassed results from national surveillance and monitoring programmes, prevalence surveys, outbreak investigations, and research, including analytic epidemiological studies. When Norwegian data were sparse or absent, international reports and research were used.
The six highest-ranked pathogens were, in descending order: Toxoplasma gondii, Campylobacter spp., Echinococcus multilocularis, enterohaemorrhagic E. coli (EHEC), Listeria monocytogenes, and non-typhoid Salmonella. It should be emphasized, however, that confidence intervals revealed considerable overlaps between the scores. The food vehicles associated with the pathogens varied widely. It is notable, however, that fresh produce was identified as being among the main food vehicles for 12 of the 20 pathogens, drinking water was associated with 8, and 5 were linked to raw milk or products thereof

Research – Antimicrobial effect of tea polyphenols against foodborne pathogens

Journal of Food Protection

In recent years, science and technology have developed to a considerable level. However, food contamination by food-borne pathogens is still widespread in many countries around the world, and food safety is a major global public health issue. Therefore, novel preservatives that can guarantee safer food are high in demand. Contrary to artificial food preservatives, tea polyphenols (TP) are getting wide attention as food additives for being “green”, “safe” and “healthy”. The sources of TP are wide, and the purification technology is sophisticated. Compared with other natural antibacterial agents, its antibacterial effect is more stable. It is an excellent natural antibacterial agent. Here, this review systematically summarizes the important chemical components of TP and discusses their antibacterial mechanisms against various foodborne pathogens. In addition, the potential application areas of TP are also discussed. It can provide a theoretical basis for the in-depth study of TP.

Research – Effect of UVC light-emitting diodes on pathogenic bacteria and quality attributes of chicken breast

Journal of Food Protection

This study aimed to investigate the inactivation of foodborne pathogens and the quality characteristics of fresh chicken breasts after Ultraviolet-C light-emitting diode (UVC-LED) treatment. Fresh chicken breasts were separately inoculated with Salmonella Typhimurium, Escherichia coli O157:H7, and Listeria monocytogenes at an initia population of 6.01, 5.80, and 6.22 log 10 CFU/cm 2 , respectively, then were treated by UVC-LED at 1000 to 4000 mJ/cm 2 . UVC-LED irradiation could inactivate the tested bacteria in a dose-dependent manner. After UVC-LED treatment at 4000 mJ/cm 2 , the populations of S . Typhimurium, E . coli O157:H7, and L . monocytogenes on chicken breasts were decreased by 1.90, 2.25, and 2.18 log 10 CFU/cm 2 , respectively. No significant ( P > 0.05) changes were found in the color, pH value, texture properties, and thiobarbituric acid reactive substances (TBARS) values of chicken breasts following the UVC-LED radiation at doses up to 4000 mJ/cm 2 . Overall, this study indicates that UVC-LED is a promising technology to reduce the number of microorganisms while maintaining the physico-chemical characteristics of poultry meat.

Research – Bacteriophages for detection and control of foodborne bacterial pathogens—The case of Bacillus cereus and their phages

Wiley Online

Bacillus cereus is among the primary food‐poisoning pathogenic bacterium that causes diarrhea and emetic types of diseases throughout the world. Recent advances show that bacteriophages become important tools in detection and control of foodborne bacterial pathogens in foods. They gain the interest of researchers for the food industries mainly because they are host‐specific and harmless to humans. Studies showed that bacteriophages could be employed as natural or engineered, whole or part, and temperate or virulent type in designing a range of tools for the detection and control of foodborne bacterial pathogens. This article discusses the recent methods and advances in the utilization strategies of bacteriophages in detection and control of foodborne pathogens, with particular focus on B. cereus pathogen. Moreover, the article presents the latest and relevant information of B. cereus‐infecting phages with respect to their potential applications in foods to address food safety issues. It also reflects future research directions by indicating gap of studies on the area.

Research – Contamination of ready-to-eat street food in Pakistan with Salmonella spp.: Implications for consumers and food safety

IJID Online

kswfoodworld salmonella


  • Microbial contamination of street food sold in Quetta.
  • 38% (121/320) of ready-to-eat food samples were contaminated with microbial pathogens.
  • Food quality was worse in summer months.
  • Salmonella enteritidis and Salmonella typhimurium were identified by multiplex polymerase chain reaction.
  • Isolated pathogens showed antibiotic resistance.



Ready-to-eat (RTE) food sold in Quetta, Pakistan was assessed for microbial contamination.


Equal numbers of samples were collected from four categories of RTE food – burgers, shawarma, pizza and sandwiches – from January 2018 to December 2018. Microbial contamination of individual food samples was assessed by quantifying the total aerobic count obtained from plating samples on bacterial growth medium. Salmonella spp. serovars were identified using polymerase chain reaction.


Approximately 38% (121/320) of RTE food samples were not fit for human consumption. The most contaminated type of RTE food was shawarma (49%). Microbial contamination of food samples was higher in summer compared with the other seasons. Approximately 40% (49/121) of food samples that were not fit for human consumption were contamined with Salmonella spp. Salmonella enteritidis (69%) and Salmonella typhimurium (31%) were the only serovars among the samples testing positive for Salmonella spp. Of the 49 samples with high microbial counts, S. enteritidis was present in 34 samples and S. typhimurium was present in 15 samples. The antibiotic sensitivity results demonstrated that both S. enteritidis and S. typhimurium were resistant to amoxicillin. In addition, S. enteritidis was resistant to chloramphenicol and erythromycin, and S. typhimurium presented high resistance to erythromycin. Both S. typhimurium and S. enteritidis were highly sensitive to kanamycin.


RTE food sold by street vendors in Quetta was found to be contaminated with Salmonella spp. and poses a great health risk to consumers. As such, consumption should be avoided, and the health authorities should take stringent action to ensure the quality of street food in order to reduce the healthcare burden.

Research – Effect of Chlorine Dioxide Treatment on Human Pathogens on Iceberg Lettuce


In the vegetable processing industry, the application of chlorine dioxide (ClO2) as a disinfectant solved in washing water to eliminate undesirable microorganisms harmful to consumers’ health and the shelf life of produce has been discussed for years. The disinfection efficacy depends on various factors, e.g., the location of microorganisms and the organic load of the washing water. The present study analyzed the sanitation efficacy of various concentrations of water-solved ClO2 (cClO2: 20 and 30 mg L−1) on Escherichia coli (1.1 × 104 cfu mL−1), Salmonella enterica (2.0 × 104 cfu mL−1) and Listeria monocytogenes (1.7 × 105 cfu mL−1) loads, located on the leaf surface of iceberg lettuce assigned for fresh-cut salads. In addition, it examined the potential of ClO2 to prevent the cross-contamination of these microbes in lettuce washing water containing a chemical oxygen demand (COD) content of 350 mg L−1 after practice-relevant washing times of 1 and 2 min. On iceberg leaves, washing with 30 mg L−1 ClO2 pronouncedly (1 log) reduced loads of E. coli and S. enterica, while it only insignificantly (<0.5 × log) diminished the loads of L. monocytogenes, irrespective of the ClO2 concentration used. Although the sanitation efficacy of ClO2 washing was only limited, the addition of ClO2 to the washing water avoided cross-contamination even at high organic loads. Thus, the application of ClO2 to the lettuce washing water can improve product quality and consumer safety. View Full-Text

Research – Persistence of Foodborne Pathogens on Farmers Market Fomites

Journal of Food Protection

The number of farmers markets registered by the U. S. Department of Agriculture (USDA) has seen a significant increase, jumping from 1,755 in 1994 to 8,771 in 2019. Microbial studies have found evidence that produce sold at farmers can yield higher microbial counts than their retail counterparts; however, no previous literature explored the efficacy of microbial (bacteria and virus) persistence on a variety of different farmers market fomites over a 2-month period. The objectives of the current study were to conduct observations to determine the most commonly used food contact surface fomites at farmers markets and to investigate the persistence of key foodborne pathogens ( Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp., Staphylococcus aureus, and MS2 bacteriophage) on these fomites. A repeated-measures analysis of variance was used to compare the persistence rates of foodborne pathogens on cardboard, plastic, tablecloth, molded pulp fiber, and wicker baskets used to store, transport, and display produce at farmers markets. In general, molded pulp fiber, plastic and wicker surface materials supported the persistence of foodborne pathogens the most, with S. aureus demonstrating the highest log concentrations over the longest period of time. Additionally, Salmonella and E. coli strains also persisted for a significant period of time (approximately 32-days) on all fomites with the exception of tablecloth. The results suggest that foodborne pathogens on these fomites pose a high-risk of cross-contamination particularly if the fomites cannot be washed, rinsed, and sanitized effectively (e.g. cardboard). The results highlight the need avoid using porous, single-use storage containers such as cardboard, molded pulp fiber and wicker containers for extended periods of time and suggest the use of easily cleanable materials such as plastic containers.

Research – Case–control study of gastro-intestinal outbreak in a rural village, Philippines – 2017

IJID Online

On March 21, 2017, field investigating team was sent to Cayapa Village, Abra, Philippines due to an increasing cases of foodborne illness. An epidemiologic investigation was conducted to verify the diagnosis, establish existence of outbreak, identify risk factors, and recommend control and prevention measures.

The epidemic curve indicates a point source outbreak of gastrointestinal Anthrax. We found valid statistical and temporal association of eating by-product of dead water buffalo and gastrointestinal Anthrax. Though, bacterial isolation were both negative for human specimen and environmental sample, all clinical manifestations were consistent with Bacillus anthracis rather than other foodborne bacterial pathogens. Hence, we conducted massive information education campaign sick or dead animal by-product should not be sold or eaten and properly handled and disposed.