Category Archives: pathogenic

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.

Research – Genome evolution and the emergence of pathogenicity in avian Escherichia coli


Chickens are the most common birds on Earth and colibacillosis is among the most common diseases affecting them. This major threat to animal welfare and safe sustainable food production is difficult to combat because the etiological agent, avian pathogenic Escherichia coli (APEC), emerges from ubiquitous commensal gut bacteria, with no single virulence gene present in all disease-causing isolates. Here, we address the underlying evolutionary mechanisms of extraintestinal spread and systemic infection in poultry. Combining population scale comparative genomics and pangenome-wide association studies, we compare E. coli from commensal carriage and systemic infections. We identify phylogroup-specific and species-wide genetic elements that are enriched in APEC, including pathogenicity-associated variation in 143 genes that have diverse functions, including genes involved in metabolism, lipopolysaccharide synthesis, heat shock response, antimicrobial resistance and toxicity. We find that horizontal gene transfer spreads pathogenicity elements, allowing divergent clones to cause infection. Finally, a Random Forest model prediction of disease status (carriage vs. disease) identifies pathogenic strains in the emergent ST-117 poultry-associated lineage with 73% accuracy, demonstrating the potential for early identification of emergent APEC in healthy flocks.

Research – Evaluation of foodborne pathogen die-off in back-sweetened wine and apple cider models

Journal of Food Protection

Wine and alcoholic apple cider are commonly back-sweetened with unpasteurized juice to produce fresh, natural, and palatable sweetened alcoholic beverages. Foodborne pathogens may be introduced from unpasteurized juice into alcoholic beverages through this back-sweetening process. Although pathogens generally do not survive under low pH conditions or high alcohol environment, the die-off of these pathogens has not been established to ensure the safety of the products. To determine the safety of these back-sweetened beverages, we evaluated the survival of three common foodborne pathogens, E. coli O157:H7, Salmonella enterica , and Listeria monocytogenes in modified white grape juice and apple juice models. White grape juice and apple juice were modified with hydrochloric acid/sodium hydroxide and ethanol to achieve conditions that are similar to the back-sweetened white wine and alcoholic apple cider. Pathogen cocktails were inoculated separately into modified juice models and their survival in the juice models were recorded over a 96-hour period. Our results show that a combination of low pH and high ethanol content resulted in a faster pathogen die-off compared to higher pH and lower ethanol conditions. The holding times required for different combinations of pH and ethanol concentration for each juice model to achieve 5-log reduction were reported. This research provides data to validate pathogen die-off to comply with Juice HACCP 5-log pathogen inactivation requirements for back-sweetened wine and alcoholic apple cider.

Research – Application of a Novel Lytic Podoviridae Phage Pu20 for Biological Control of Drug-Resistant Salmonella in Liquid Eggs


kswfoodworld Salmonella

Salmonella is a globally distributed zoonotic pathogen. Among them, S. Pullorum is a host-specific pathogen that seriously affects the development of the poultry breeding industry in China. It mainly infects chickens and can cause white scabs, and the mortality rate after infection is almost 100%. As antibiotics are widely used in animal feed and other production processes, Salmonella resistance has gradually increased. Therefore, there is an increasing need to develop new technologies to control multi-drug resistant (MDR) pathogens and confirm their actual effectiveness in the target food matrix. Bacteriophage can efficiently and specifically lyse bacteria, and will be a potential bactericide to replace antibiotics. In this study, 34 strains of Salmonella bacteriophages were isolated from environmental resources. Therein, phage Pu20 with the widest host spectrum had the strongest ability to lyse tested Salmonella strains. Further studies showed that Pu20 had high pH tolerance and heat resistance, short incubation period. Pu20 can effectively inhibit the growth of two strains of MDR Salmonella in liquid egg white and yolk at 4 ℃ and 25 ℃, respectively. According to morphological and phylogenetic analysis, Pu20 belongs to the Podoviridae family. Genomic analysis of Pu20 indicates a linear 59435 bp dsDNA sequence with no homology to virulence or antibiotic resistance-related genes. Together, these results sheds light on the potential biocontrol application value of Pu20 in food products.

Research – Special Issue: Shiga Toxin-Producing Escherichia coli


Globally, Shiga toxin-producing Escherichia coli (STEC) is an important cause of diarrheal disease, most notably hemorrhagic colitis, and post-diarrheal sequela, such as hemolytic-uremic syndrome (HUS) [1]. Cattle are a major reservoir of STEC, with approximately half of the cases in humans attributable to foodborne exposure [2]. Prevention of human illness has mainly been through food safety measures [2]. Despite extensive research, no other generally accepted and effective preventive measures or therapies for STEC infections in human patients are available [3]. Many questions remain about STEC virulence factors, pathogenesis, detection, and other aspects that necessitate a continuation of basic and applied research on a wide front. This Special Issue includes 14 papers (nine articles, two communications, one review, one comment, and one reply) that collectively provide novel information on the epidemiology [4,5,6,7], virulence factors [7,8,9,10], and pathogenesis [11,12,13] of STEC, and the molecular structure or toxicity [14,15,16] and immunodetection [17] of Shiga toxin.

Research – Growth and Survival of Foodborne Pathogens during Soaking and Drying of Almond (Prunus dulcis) Kernels

Journal of Food Protection


The practice of soaking almonds prior to consumption is popular both commercially and at home. The food safety implications of soaking almonds was investigated through analysis of blogs and videos (n = 85 recipes) to identify both the reasons for soaking almonds and the common practices employed. Among the recipes analyzed, the most common reasons for soaking almonds (94.1%) were perceived benefits such as improved digestion and nutrient uptake. Most recipes (34.1%) suggested soaking at “room temperature” for times that ranged from 4 to 24 h or, more commonly, “overnight” (51.8%). Postsoaking drying instructions were provided in 40 recipes (47.1%). Among those providing a drying temperature (31.8%), 85% specified 66°C and lower. To evaluate the growth of foodborne pathogens during almond soaking, separate cocktails of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica were inoculated onto raw almonds or into the soak water (almonds-to-water ratios of 1:1 and 1:3 [w/v]). Populations were monitored during soaking at 15, 18, and 23°C for up to 24 h, and during postsoak drying at 66°C for 14 h (for Salmonella only). At 15°C and a 1:1 almond:water ratio, no significant population increase (P > 0.05) was observed between 0 and 24 h for any of the pathogens. At 18°C, increases of 0.63, 1.70, and 0.88 log CFU per sample were observed over 24 h for populations of E. coli O157:H7, L. monocytogenes, and Salmonella, respectively. Populations of E. coli O157:H7, L. monocytogenes, and Salmonella increased by 3.48, 3.22, and 3.94 log CFU per sample, respectively, after 24 h at 23°C. When soaked almonds were dried for 14 h at 66°C, moisture and water activity decreased from 40 to ∼6% and 0.99 to 0.60, respectively, but no significant reduction in Salmonella populations was observed. Recommendations for using shorter times (<8 h) and cooler temperatures (≤15°C) should reduce the potential for foodborne pathogens, if present, to grow during soaking of almonds.

  • Online recipes described soaking conditions that would support growth of pathogens.
  • Foodborne pathogens were able to multiply in almonds soaked at 18 and 23°C.
  • Pathogen populations significantly increased after 8 h of soaking at 23°C.
  • Foodborne pathogens did not multiply in almonds soaked at 15°C for 24 h.
  • Drying soaked almonds at 66°C for 14 h did not reduce populations of Salmonella.

RASFF Alerts – Salmonella – Chilled Fuet – Thyme – Chicken Products – Frozen Tenders – Black Pepper

European Food Alerts


Salmonella (presence /25g) in chilled fuet from Spain in the Netherlands


Salmonella enterica ser. Amberg (presence /25g) and Salmonella enterica ser. Charity (presence /25g) in thyme from Turkey in Lithuania


Salmonella enterica ser. Infantis (presence /25g) in chilled chicken wings from Poland in Poland


Salmonella enterica ser. Infantis (in 2 out of 5 samples /25g) in frozen chicken drumsticks from Slovakia in Lithuania


Salmonella (presence /25g) in frozen chicken products from Poland in France


Salmonella enterica ser. Enteritidis (presence /25g) in chilled chicken meat from Poland, with raw material from Hungary in Poland


Salmonella enterica ser. Enteritidis (presence /25g) in chilled poultry carcasses from unknown origin in Slovakia


Salmonella enterica ser. Infantis (presence /25g) in frozen tenders from Poland in France


Salmonella enterica ser. Infantis (in 5 out of 5 samples /25g) in chilled chicken fillets from Poland in Poland


Salmonella enterica ser. Infantis (present /25g) and Salmonella enterica ser. Panama (present /25g) in black pepper from Brazil in Germany

USA – Most Listeria Cases Are in Massachusetts in Deli Meat Listeria Outbreak

Food Poisoning Bulletin

Most Listeria cases are in Massachusetts in the deli meat Listeria monocytogenes outbreak announced last week by the Centers for Disease Control and Prevention (CDC). All ten patients have been hospitalized, and one person, who  lived in Florida, has died.