Category Archives: Food Microbiology Research

Research – Acidic environment could boost power of harmful pathogens

Posted on January 14, 2020 by | Leave a comment

Science Daily

When food we’ve swallowed reaches our stomachs, it finds an acidic environment. The low pH in the stomach helps to begin digestion — and has been thought to kill the bacteria that hides in food that otherwise could harm our bodies.

However, recent work from the Ackley and Chandler labs in the Department of Molecular Biosciences at the University of Kansas runs counter to this idea, instead suggesting lower pH in the digestive tract may make some bacterial pathogens even more harmful.

Their findings, published in the peer-reviewed journal PLOS Pathogens, could have implications for addressing the crisis of antibiotic resistance in bacterial infections around the world.

The investigation was performed using small, bacteria-eating organisms called Caenorhabditis elegans.

Leave a comment

Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, microbial contamination, Microbiology, Research, Uncategorized

Research – Treatment of fresh produce with a Salmonella‐targeted bacteriophage cocktail is compatible with chlorine or peracetic acid and more consistently preserves the microbial community on produce

Posted on January 14, 2020 by | Leave a comment

Wiley Online

Diets rich in minimally processed foods are associated with numerous health benefits, in part, due to their diverse, natural microbiota. However, antimicrobials, such as chlorine and peracetic acid (PAA), that are used to address food safety concerns may damage the natural microflora of fresh produce. One promising approach for targeting pathogenic bacteria in foods without impacting the normal food microbiota are bacteriophages. In this study, we observed that combinational treatment of conventional antimicrobials (PAA and chlorine) and bacteriophages, specifically the Salmonella‐targeted preparation SalmoFresh, retained the bactericidal effectiveness of individual interventions, and in some cases, achieved substantially increased efficacy. Additionally, the bacterial microbiomes of farm fresh and organic produce were less affected after phage treatment compared to PAA and chlorine. Finally, our study revealed that resistance rates against SalmoFresh were relatively minor and unaffected by the stresses introduced after chemical washes and/or bacteriophage treatment.

Leave a comment

Posted in Antimicrobials, Bacteriophage, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Technology, microbial contamination, Microbiology, Research, Salmonella, Technology, Uncategorized

Research-Nisin-Based Organic Acid Inactivation of Salmonella on Grape Tomatoes: Efficacy of Treatment with Bioluminescence ATP Assay

Posted on January 12, 2020 by | Leave a comment

Journal of Food Protection

ABSTRACT

The antimicrobial activity of a new nisin-based organic acid sanitizer (NOAS), developed in our laboratory, was tested against viable aerobic mesophilic bacteria and Salmonella populations inoculated on produce surfaces. The activity of NOAS was compared with 200 ppm of chlorinated wash water and a bioluminescence ATP technique to determine the efficacy of treatments compared with plate count methods. The activity of the 10% final concentration of NOAS against viable populations of 109 CFU/mL Salmonella in phosphate-buffered saline (PBS), sterile deionized distilled water, and buffered peptone water was tested in vitro and on grape tomatoes inoculated with Salmonella at 2.5 log CFU/g. A similar batch of inoculated tomatoes were treated with 200 ppm of total available chlorinated water. All treatments for inactivation of viable Salmonella in vitro was tested up to 30 min and 5 min for the attached populations on tomatoes. Inactivation of viable Salmonella at 109 log CFU/mL by 10% the NOAS solution averaged >107 log CFU/mL in PBS, sterile deionized distilled water, and buffered peptone water. Similarly, Salmonella bacteria inactivated on tomato surfaces by the NOAS solution was significantly (P < 0.05) greater than numbers on chlorinated washed tomatoes, and surviving bacterial populations on NOAS and chlorine-treated tomatoes were <1 and 4 CFU/g, respectively. A significant linear correlation coefficient (r2 = 0.99) between the bioluminescence ATP assay and aerobic plate counts of inoculated and untreated grape tomatoes were recorded but not with NOAS and chlorine-treated tomatoes, as bacterial populations were less than the minimum baseline for determination. Also, the results indicated that the NOAS solution is a better alternative antimicrobial wash solution than 200 ppm of chlorinated water.

HIGHLIGHTS

  • The antimicrobial activity of NOAS was compared with chlorinated water.

  • Salmonella bacteria were more susceptible to NOAS than chlorinated water.

  • Assay correlated with aerobic plate count of inoculated and untreated tomatoes, not treated ones.

  • NOAS is an excellent alternative antimicrobial wash solution compared with chlorinated wash water.

Leave a comment

Posted in Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Technology, microbial contamination, Microbiology, Nisin, Research, Salmonella, Technology, Uncategorized

Research – Inactivation of Murine Norovirus on Fruit and Vegetable Surfaces by Vapor Phase Hydrogen Peroxide

Posted on January 12, 2020 by | Leave a comment

Journal of Food Protection

ABSTRACT

Vapor phase hydrogen peroxide (H2O2) can be utilized to inactivate murine norovirus (MNV), a surrogate of human norovirus, on surface areas. However, vapor phase H2O2 inactivation of virus on fruits and vegetables has not been characterized. In this study, MNV was used to determine whether vaporized H2O2 inactivates virus on surfaces of various fruits and vegetables (apples, blueberries, cucumbers, and strawberries). The effect of vapor phase H2O2 decontamination was investigated with two application systems. Plaque assays were performed after virus recovery from untreated and treated fresh produce to compare the quantity of infective MNV. The Mann-Whitney U test was applied to the test results to evaluate the virus titer reductions of treated food samples, with significance set at P ≤ 0.05. The infective MNV populations were significantly reduced on smooth surfaces by 4.3 log PFU (apples, P < 0.00001) and 4 log PFU or below the detection limit (blueberries, P = 0.0074) by treatment with vapor phase H2O2 (60 min, maximum of 214 ppm of H2O2). Similar treatments of artificially contaminated cucumbers resulted in a virus titer reduction of 1.9 log PFU. Treatment of inoculated strawberries resulted in 0.1- and 2.8-log reductions of MNV. However, MNV reduction rates on cucumbers (P = 0.3809) and strawberries (P = 0,7414) were not significant. Triangle tests and color measurements of untreated and treated apples, cucumbers, blueberries, and strawberries revealed no differences in color and consistency after H2O2 treatment. No increase of the H2O2 concentration in treated fruits and vegetables compared with untreated produce was observed. This study reveals for the first time the conditions under which vapor phase H2O2 inactivates MNV on selected fresh fruit and vegetable surfaces.

HIGHLIGHTS

  • Produce was treated with vapor phase H2O2 for 60 min (maximum of 260 ppm of H2O2).

  • A 4-log reduction in MNV was achieved by H2O2 treatment on apples and blueberries.

  • Reductions of MNV on treated strawberries and cucumbers were not significant.

Leave a comment

Posted in Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Technology, Food Virus, microbial contamination, Microbiology, Norovirus, Research, Technology, Uncategorized, Virus

Research- Survival Evaluation of Salmonella and Listeria monocytogenes on Selective and Nonselective Media in Ground Chicken Meat Subjected to High Hydrostatic Pressure and Carvacrol

Posted on January 11, 2020 by | Leave a comment

Journal of Food Protection

ABSTRACT

High pressure processing (HPP) and treatment with the essential oil extract carvacrol had synergistic inactivation effects on Salmonella and Listeria monocytogenes in fresh ground chicken meat. Seven days after HPP treatment at 350 MPa for 10 min, Salmonella treated with 0.75% carvacrol was reduced to below the detection limit (1 log CFU/g) at 4°C and was reduced by ca. 6 log CFU at 10°C. L. monocytogenes was more sensitive to these imposed stressors, remaining below the detection limit during storage at both 4 and 10°C after HPP treatment at 350 MPa for 10 min following treatment with 0.45% carvacrol. However, pressure-injured bacterial cells may recover and lead to an overestimation of process lethality when a selective medium is used without proper justification. For HPP-stressed Salmonella, a 1- to 2-log difference was found between viable counts on xylose lysine Tergitol 4 agar and aerobic plate counts, but no significant difference was found for HPP-stressed L. monocytogenes between polymyxin–acriflavine–lithium chloride–ceftazidime–esculin–mannitol (PALCAM) agar and aerobic plate counts. HPP-induced bacterial injury and its recovery have been investigated by comparing selective and nonselective agar plate counts; however, few investigations have addressed this issue in the presence of essential oil extracts, taking into account the effect of high pressure and natural antimicrobial compounds (e.g., carvacrol) on bacterial survival in various growth media. Use of selective media may overestimate the efficacy of bacterial inactivation in food processing evaluation and validation studies, and the effects of various media should be systematically investigated.

HIGHLIGHTS

  • HPP and carvacrol had synergistic pathogen inactivation effects in ground chicken meat.

  • HPP at 350 MPa for 10 min with 0.60% carvacrol treatment resulted in a >5-log pathogen reduction.

  • A 1- to 2-log difference was found for counts of HPP-treated Salmonella on two growth media.

  • Counts of HPP-treated L. monocytogenes were similar on selective and nonselective media.

  • Carvacrol suppressed the growth and recovery of the HPP-treated bacterial cells.

Leave a comment

Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Technology, Listeria, Listeria monocytogenes, microbial contamination, Microbiology, Research, Salmonella, Technology, Uncategorized

Research -Inactivation of Bacillus cereus Spores on Stainless Steel by Combined Superheated Steam and UV-C Irradiation Treatment

Posted on January 11, 2020 by | Leave a comment

Journal of Food Protection

ABSTRACT

Bacillus cereus spore contamination on food contact surfaces is of great concern in the food industry. Thus, in the present study, superheated steam (SHS) was used alone or combined with UV-C irradiation for inactivation of B. cereus spores inoculated on stainless steel coupons. Temperatures higher than 250°C were needed to effectively inactivate B. cereus spores by SHS treatment alone, while a synergistic bactericidal effect resulted from the sequential treatment of SHS before or after UV-C irradiation. The increased dipicolinic acid ratio obtained by the combined treatment had a significant role in the synergistic bactericidal effect. Therefore, the combined treatment of SHS and UV-C could be used effectively to inactivate B. cereus on stainless steel. It is recommended to use hurdle technology with reduced energy consumption to ensure microbiological safety on food contact surfaces.

HIGHLIGHTS

  • Inactivation of Bacillus cereus spores on stainless steel was identified in this study.

  • Superheated steam (SHS) was applied solely or combined with UV-C irradiation.

  • A synergistic effect was observed by combination treatment for spore inactivation.

  • The dipicolinic acid (DPA) release level increased significantly by combination treatment.

  • The combination treatment can be applied to sanitize food processing equipment.

Leave a comment

Posted in Bacillus, Bacillus cereus, Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Technology, microbial contamination, Microbiology, Research, Technology, Uncategorized

Information USA – What Are the Symptoms of Common Foodborne Pathogens?

Posted on January 10, 2020 by | Leave a comment

CDC

Burden of Foodborne Illness: Findings

CDC estimates that each year roughly 1 in 6 Americans (or 48 million people) gets sick, 128,000 are hospitalized, and 3,000 die of foodborne diseases.

 

These estimates provide the most accurate estimates yet of which known foodborne pathogens (bacteria, viruses, and parasites) are causing the most illnesses in the United States, and how many foodborne illnesses are caused by unspecified agents. The estimates also show that much work remains to be done—specifically in focusing efforts on the top known pathogens and identifying the additional causes of foodborne illness and death.

CDC provides estimates for two major groups of foodborne illnesses

Known foodborne pathogens — 31 pathogens known to cause foodborne illness. Many of these pathogens are tracked by public health systems that track diseases and outbreaks. Read the report >

Unspecified agents — Agents with insufficient data to estimate agent-specific burden; known agents not yet identified as causing foodborne illness; microbes, chemicals, or other substances known to be in food whose ability to cause illness is unproven; and agents not yet identified. Because you can’t “track” what isn’t yet identified, estimates for this group of agents started with the health effects or symptoms that they are most likely to cause, such as acute gastroenteritis. Read the report >

Total number of foodborne illnesses each year

CDC estimated the number of illnesses, hospitalizations, and deaths caused by both known and unspecified agents. CDC then estimated what proportion of each were foodborne. The first table below provides estimates for domestically acquired foodborne illnesses, and the second table provides estimates for domestically acquired illnesses caused by all transmission routes (foodborne, waterborne, person-to-person contact, animal contact, environmental contamination, and others).

Estimated annual number of domestically acquired, foodborne illnesses, hospitalizations, and deaths due to 31 pathogens and the unspecified agents transmitted through food, United States
Foodborne agents Estimated annual number of illnesses Estimated annual number of hospitalizations Estimated annual number of deaths
Number (90% credible interval) % Number (90% credible interval) % Number (90% credible interval) %
31 known pathogens 9.4 million
(6.6–12.7 million)		 20 55,961
(39,534–75,741)		 44 1,351
(712–2,268)		 44
Unspecified agents 38.4 million
(19.8–61.2 million)		 80 71,878
(9,924–157,340)		 56 1,686
(369–3,338)		 56
Total 47.8 million
(28.7–71.1 million)		 100 127,839
(62,529–215,562)		 100 3,037
(1,492–4,983)		 100
Estimated annual number of illnesses, hospitalizations, and deaths due to 31 pathogens and the unspecified agents, United States
Foodborne agents Estimated annual number of illnesses Estimated annual number of hospitalizations Estimated annual number of deaths
Number (90% credible interval) % Number (90% credible interval) % Number (90% credible interval) %
31 known pathogens 37.2 million
(28.4–47.6 million)		 21 228,744
(188,326–275,601)		 47 2,612
(1,723–3,819)		 42
Unspecified agents 141.8 million 79 258,033 53 3,574 58
Total 179 million 100 486,777 100 6,186 100

 

Pathogens causing the most foodborne illnesses, hospitalizations, and deaths each year

Top five pathogens contributing to domestically acquired foodborne illnesses
Pathogen Estimated number of illnesses 90% credible interval %
Norovirus 5,461,731 3,227,078–8,309,480 58
Salmonella, nontyphoidal 1,027,561 644,786–1,679,667 11
Clostridium perfringens 965,958 192,316–2,483,309 10
Campylobacter spp. 845,024 337,031–1,611,083 9
Staphylococcus aureus 241,148 72,341–529,417 3
Subtotal 91

 Top of Page

Top five pathogens contributing to domestically acquired foodborne illnesses resulting in hospitalization
Pathogen Estimated number of hospitalizations 90% credible interval %
Salmonella, nontyphoidal 19,336 8,545–37,490 35
Norovirus 14,663 8,097–23,323 26
Campylobacter spp. 8,463 4,300–15,227 15
Toxoplasma gondii 4,428 2,634–6,674 8
E. coli (STEC) O157 2,138 549–4,614 4
Subtotal 88
Top five pathogens contributing to domestically acquired foodborne illnesses resulting in death
Pathogen Estimated number of deaths 90% credible interval %
Salmonella, nontyphoidal 378 0–1,011 28
Toxoplasma gondii 327 200–482 24
Listeria monocytogenes 255 0–733 19
Norovirus 149 84–237 11
Campylobacter spp. 76 0–332 6
Subtotal 88
References

Scallan E, Hoekstra RM, Angulo FJ, Tauxe RV, Widdowson M, Roy SL, et al. Foodborne illness acquired in the United States—major pathogens. Emerg Infect Dis. 2011;17(1):7-15. https://dx.doi.org/10.3201/eid1701.p11101External

Leave a comment

Posted in Campylobacter, Clostridium perfringens, food contamination, food death, 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 Poisoning Death, Food Safety, Food Toxin, Listeria monocytogenes, Norovirus, Research, Salmonella, Staphylococcus aureus, STEC, STEC E.coli, Toxoplasma gondii, Toxoplasmosis, Uncategorized

Research -Enumeration and Survival of Salmonella enterica in Live Oyster Shellstock Harvested from Canadian Waters

Posted on January 8, 2020 by | Leave a comment

Journal of Food Protection

ABSTRACT

Since 2015, 11 recalls of live oyster shellstock have been issued in Canada due to the presence of Salmonella enterica. Six of those recalls took place in 2018. To understand this increase, fundamental information is needed on the relationship between S. enterica and oysters. The aims of this study were to address important data gaps concerning the levels of Salmonella in naturally contaminated oysters and the ability of this pathogen to survive in live oyster shellstock. Enumeration data were evaluated for five oyster and clam samples collected from the east coast of Canada from 2015 to 2018. The reported levels were <0.0015 to 0.064 most probable number per g of oyster tissue. The S. enterica isolates recovered from these animals belonged to serovars Typhimurium, Infantis, Enteritidis, and I 4,5:i:−. Filter feeding by the oysters was exploited to assess the Salmonella accumulation that would occur following a natural contamination event. Detectable levels of the pathogen were observed after 30 min of exposure and began to plateau at 60 min. A survival study in live oyster shellstock indicated that after 4 days of storage at ambient temperatures, the Salmonella level declined slightly from 4.3 to 3.7 log CFU/g. These data indicate that the levels of Salmonella found in naturally contaminated oysters are low and are not expected to increase between the point of harvest and the point of consumption. The changing ecology of shellfish environments requires continued monitoring and testing to safeguard public health. The data presented here will be useful for the evaluation and design of sampling plans and risk management approaches for the control of Salmonella in live oyster shellstock.

HIGHLIGHTS

  • Salmonella levels in naturally contaminated clams and oysters were <0.1 to 6.4 MPN/100 g.

  • Salmonella was detected in oysters after 30 min of exposure.

  • Salmonella did not grow in live oyster shellstock.

  • Salmonella was able to survive for at least 7 days in live oyster shellstock.

Leave a comment

Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, microbial contamination, Microbiology, Research, Salmonella, Uncategorized

Research – Edible films containing carvacrol and cinnamaldehyde inactivate Escherichia coli O157:H7 on organic leafy greens in sealed plastic bags

Posted on January 7, 2020 by | Leave a comment

Wiley Online Eurofins Food Testing UK

The antimicrobial effects of apple‐, carrot‐, and hibiscus‐based edible films containing carvacrol and cinnamaldehyde against Escherichia coli O157:H7 on organic leafy greens in sealed plastic bags were investigated. Fresh‐cut Romaine and Iceberg lettuce, and mature and baby spinach leaves were inoculated with E. coli O157:H7 and placed into Ziploc® bags. Edible films were then added to the bags, which were stored at 4°C. The evaluation of samples taken at days 0, 3, and 7 showed that on all leafy greens, 3% carvacrol‐containing films had the greatest effect against E. coli O157:H7, reducing the bacterial population by about 5 log CFU/g on day 0. All three types of 3% carvacrol‐containing films reduced E. coli O157:H7 by about 5 log CFU/g at day 0. The 1.5% carvacrol‐containing films reduced E. coli O157:H7 by 1–4 logs CFU/g at day 7. Films with 3% cinnamaldehyde showed reduction of 0.6–3 logs CFU/g on different leafy greens.

Leave a comment

Posted in E.coli, E.coli O157, E.coli O157:H7, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiology, Research, STEC E.coli, Technology, Uncategorized

Research – Control of Listeria monocytogenes in boned dry‐cured ham by E‐beam treatment

Posted on January 6, 2020 by | Leave a comment

Wiley Online listeria

Boning of dry‐cured hams involves additional handling which increases the risk of contamination with Listeria monocytogenes. This work studies the ability of E‐beam to eliminate this pathogen from boned dry‐cured ham (BDH). The destruction kinetics of four L. monocytogenes strains (S2, S4‐2, S12‐1, and S7‐2) and L. innocua NCTC 11288 as a surrogate were determined at doses up to 3 kGy. L. innocua and L. monocytogenes S4‐2 were the most radioresistant (D‐value = 0.55 kGy). E‐beam penetration was studied in blocks extracted from BDH and irradiated with 2–6 kGy. The bilateral treatment of 2 kGy allows the required dose (1.32 kGy) to be absorbed in the innermost part of the block to achieve the food safety objective of “zero tolerance” for this microorganism. This listericidal treatment was also confirmed in whole BDH intentionally contaminated with L. innocua. The sensory analysis of irradiated BDH showed off‐odors that were imperceptible after 15 days of storage at 4°C.

Leave a comment

Posted in Food Hygiene, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Pathogen, Food Safety, Food Technology, Food Testing, Listeria, Listeria monocytogenes, Research, Uncategorized