Category Archives: microbial contamination

Research – Cold plasma enhances the efficacy of aerosolized hydrogen peroxide in reducing populations of Salmonella Typhimurium and Listeria innocua on grape tomatoes, apples, cantaloupe and romaine lettuce

Posted on December 26, 2019 by | Leave a comment

Science Direct

In the present study, we investigated whether cold plasma activation affected the efficacy of aerosolized hydrogen peroxide against S. Typhimurium and L. innocua. Stem scars and smooth surfaces of grape tomatoes, surfaces of Granny Smith apples and Romaine lettuce (both midrib and upper leaves) and cantaloupe rinds were inoculated with two-strain cocktails of S. Typhimurium and 3-strain cocktails of L. innocua. The inoculated samples were treated with 7.8% aerosolized H2O2 with and without cold plasma for various times. For all fresh produce items and surfaces, cold plasma significantly (P < 0.05) improved the efficacy of aerosolized H2O2 against Salmonella and L. innocua. Without cold plasma activation, H2O2 aerosols only reduced populations of Salmonella by 1.54–3.17 log CFU/piece while H2O2 with cold plasma achieved 2.35–5.50 log CFU/piece reductions of Salmonella. L. innocua was more sensitive to the cold plasma-activated H2O2 than Salmonella. Cold plasma activated H2O2 aerosols reduced Listeria populations by more than 5 log CFU/piece on all types and surfaces of fresh produce except for the tomato stem scar area. Without cold plasma, the reductions by H2O2 were only 1.35–3.77 log CFU/piece. Overall, our results demonstrated that cold plasma activation significantly enhanced the efficacy of H2O2 mist against bacteria on fresh produce.

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

Research -Vertical transmission of Salmonella Enteritidis with heterogeneous antimicrobial resistance from breeding chickens to commercial chickens in China

Posted on December 25, 2019 by | Leave a comment

Science Direct

Human salmonellosis caused by the consumption of eggs and chicken meat contaminated with Salmonella Enteritidis has become a continuing public health concern worldwide. In this study we adopted whole genome sequencing (WGS) to determine the genetic relationship and antimicrobial resistance of S. enterica strains isolated from a poultry breeding enterprise that consists of one breeding chicken farm, one egg hatchery and one commercial chicken farm. A total of 148 S. enterica including 147 S. Enteritidis strains were isolated from 2100 fecal swab samples, with 16 (5.3 %, 16/300) from breeding chicken farm, 38 (4.2 %, 38/900) from egg hatchery and 94 (10.4 %, 94/900) from commercial chicken farm. WGS revealed that all 147 S. Enteritidis strains belonged to ST11, and further divided into 4 different ribosomal STs and 64 core genome STs. Single nucleotide polymorphism typing suggested the presence of the vertical transmission of S. Enteritidis from breeding chicken to commercial chicken. Three different antimicrobial-resistant plasmids including one blaCTX-M-14-carrying plasmid and two virulence-resistance plasmids were characterized, resulting in the heterogeneous antimicrobial resistance of clonally related S. Enteritidis strains. Routine surveillance in breeding chicken farms is conducive to the control of S. Enteritidis from farm to fork.

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

Research – Effect of high hydrostatic pressure on Salmonella spp inactivation and meat-quality of frozen chicken breast

Posted on December 24, 2019 by | Leave a comment

Science Direct

The aim of this study was to evaluate the effect of the pressure level and holding time on the Salmonella spp inactivation during HHP processing in frozen chicken breast fillets. Once identified the most effective process, meat quality (color and texture) was evaluated. Results showed that the treatments at 500 MPa for 1 min and 400 MPa for 5 min were enough to guarantee Salmonella spp inactivation in frozen chicken breast fillets. With respect to quality parameters, an extension of shelf life is expected with both treatments, as counts of indigenous microbiota were below the detectable level (<2 logs CFU/g). However, chromatic parameters and texture profile of the fillets treated with HHP suffered significant changes. Even so, the treatment of 500 MPa for 1 min was more effective at preserving chromatic parameters than treatment of 400 MPa for 5 min. The texture profile between fillets treated was not significantly different.

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

Research – Environmental persistence and virulence of Salmonella spp. isolated from a poultry slaughterhouse

Posted on December 23, 2019 by | Leave a comment

Science Direct

Salmonella spp. is responsible for severe foodborne disease, and is one of the main agents involved in foodborne outbreaks worldwide. Contamination occurs mainly as a result of poultry and egg consumption since they can carry some serotypes pathogenic to humans. The aim of the study was to evaluate the persistence and pathogenic potential of Salmonella spp. (n = 40) isolated from poultry slaughterhouse mats, using adhesion and invasion assays, antimicrobial susceptibility by disc diffusion, and biofilm production as phenotypic tests and genotypic analyses. Polystyrene mats presented 3.2 times greater chance of isolating Salmonella than canvas mats. Besides, we observed resistance to tetracycline (17.5%), ampicillin (10%), cefotaxime (7.5%), trimethoprim-sulfamethoxazole (5%), and chloramphenicol (2.5%). All strains possessed the invA, sipB, sipD, ssaR, sifA, sitC, iroN, tolC, flgK, fljB, and flgL genes. The genes sopB and sipA were both present in 92.5% of the isolates, while sopD and spvB were observed in 90% and 32.5% of strains, respectively. All strains adhered to and invaded HeLa cells. Regarding biofilm production, 31 (77.5%) strains were able to produce biofilm on polystyrene microplates. Using PFGE, we detected the persistence of clones in the environment for up to 18 fromthe 20 weeks. The ability of these strains to produce a biofilm and thus persist in the environment and disperse through contact surfaces in the processing plant favors the contamination of food, aggravated by the pathogenic potential of these isolates demonstrated by their adhesion capacity, invasion and resistance to various antibiotic agents.

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

Research -Salmonella on Australian cage egg farms: observations from hatching to end of lay

Posted on December 22, 2019 by | Leave a comment

Science Direct

Single-aged caged layer hen flocks were monitored for Salmonella over the course of their lifetime. Chicks from both flocks were Salmonella negative at hatch and remained negative during rearing. Pullets were transported to production farms at 15 weeks of age. Pre-population dust swabs collected from both production sheds had a high percentage of Salmonella positive samples (80 and 90%). Flocks were sampled at regular intervals until 70-72 weeks of age. The proportion of Salmonella positive samples and mean load detected on eggs was low on both farms. Analysis of dust samples revealed that Salmonella persisted in dust over 8 weeks. Dust total moisture content and water activity appears to influence bacterial persistence. On egg grading equipment, only suction cups prior to egg washing were Salmonella positive (mean proportion Salmonella positive samples 0.13 ± 0.07; mean load of 18.6 ± 12.31 MPN/ml). An egg washing experiment demonstrated that while washing reduced the total Salmonella load from eggshell surfaces, no effect was observed for shell pores. These results demonstrate that despite environmental contamination on farm, Salmonella contamination of eggs is low and is further minimized by washing.

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

Research – Prevalence and identification of Aspergillus and Penicillium species isolated from peanut kernels in central Myanmar

Posted on December 21, 2019 by | Leave a comment

Wiley Online

Abstract

The objective of the present study was to conduct a survey to evaluate the postharvest handling of peanuts at farm level and to screen and identify the strains of Aspergillus and Penicillium species from peanut kernels in central Myanmar. A total of 640 samples from the stores of farmers, collectors, and wholesalers were collected and seeded for growth, isolation, and characterization of fungi. Out of 85 isolates, Aspergillus flavus (38), A. niger (20), A. terreus (15), and Penicillium citrinum (12) were identified and confirmed by molecular techniques including DNA sequencing using internal transcribed spacer (ITS5/4) and beta‐tubulin (Bt2a/2b) primer sets. The study indicates different factors associated with fungal contamination at farm level peanut storage and warrants an immediate attention of food safety regulatory authorities to design and implement strategies for postharvest handling and storage practice in developing countries to minimize fungal contamination.

Practical applications

In developing countries like Myanmar, there are lack of food safety practices and policies regarding the food storage, handling, and farmer education. The current study indicates the different storage methods for peanut kernels at farm level and their influence on prevalence of fungi. The study will give a deep insight to the policy makers to design food safety practices at farm level and educate the farmers to adopt the better practices to assure the consumer health and satisfaction in developing countries.

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Posted in Aflatoxin, Aspergillus, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Toxin, microbial contamination, Microbiology, Mould Toxin, Mycotoxin, Penicillium citrinium, Research, Uncategorized

RASFF Alert – Animal Feed – Salmonella – Pet Food

Posted on December 20, 2019 by | Leave a comment

RASFF-Logo

RASFF – Salmonella (presence /25g) in pet food from Poland in Poland

 

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Posted in Animal Feed, Food Micro Blog, Food Microbiology, Food Microbiology Blog, microbial contamination, Microbiology, Pet Food, Salmonella, Uncategorized

Research -The probiotic, Leuconostoc mesenteroides, inhibits Listeria monocytogenes biofilm formation

Posted on December 19, 2019 by | Leave a comment

Wiley Online listeria

Listeria monocytogenes biofilm formation renders these cells highly resistant to current sanitation methods, and probiotics may be a promising approach to the efficient inhibition of Listeria biofilms. In the present study, three Leuconostoc mesenteroides strains of lactic acid bacteria isolated from kimchi were shown to be effective probiotics for inhibiting Listeria biofilm formation. Biofilms of two L. monocytogenes serotypes, 1/2a (ATCC15313) and 4b (ATCC19115), in dual‐species culture with each probiotic strain were decreased by more than 40‐fold as compared with single‐species Listeria biofilms; for instance, a reduction from 5.4 × 106 colony forming units (CFU)/cm2 L. monocytogenes ATCC19115 in single‐species biofilms to 1.1 × 105 CFU/cm2 in dual‐species biofilms. Most likely, one of the Leuconostoc strains, L. mesenteroides W51, led to the highest Listeria biofilm inhibition without affecting the growth of L. monocytogenes. The cell‐free supernatant from the L. mesenteroides W51 culture containing large protein molecules (>30 kDa) also inhibited Listeria biofilms. These data indicate that Leuconostoc probiotics can be used to repress L. monocytogenes biofilm contamination on surfaces at food processing facilities.

 

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Posted in Biofilm, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Leuconostoc mesenteroides, Listeria, Listeria monocytogenes, microbial contamination, Microbiology, Research, Uncategorized

Research – Inactivating foodborne pathogens in apple juice by combined treatment with fumaric acid and ultraviolet-A light, and mechanisms of their synergistic bactericidal action

Posted on December 19, 2019 by | Leave a comment

Science Direct

We evaluated the bactericidal efficacy of the simultaneous application of ultraviolet-A (UV-A) irradiation and fumaric acid (FA) against Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes in apple juice and as well as investigated the effects of this treatment on product quality. Further, we elucidated the mechanisms underlying their synergistic bactericidal action. Simultaneous UV-A light irradiation and 0.1% FA treatment for 30 min resulted in 6.65-, 6.27-, and 6.49-log CFU/ml reductions in E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively, which involved 3.15, 2.21, and 3.43 log CFU reductions, respectively, and these were attributed to the synergistic action of the combined treatments. Mechanistic investigations suggested that the combined UVA-FA treatment resulted in significantly greater bacterial cell membrane damage and intracellular reactive oxygen species (ROS) generation. UVA-FA treatment for 30 min did not cause significant changes to the color, nonenzymatic browning index, pH, and total phenolic content of apple juice. These results suggest that combined UVA-FA treatment can be effectively used to control foodborne pathogens in apple juice without affecting its quality.

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Posted in E.coli, E.coli O157, E.coli O157:H7, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Pathogen, Food Technology, Listeria, Listeria monocytogenes, microbial contamination, Microbiology, Pathogen, pathogenic, Research, Salmonella, Technology, Uncategorized

Research – Eugenol as an antimicrobial wash treatment reduces Campylobacter jejuni in postharvest poultry

Posted on December 18, 2019 by | Leave a comment

Wiley Online

Abstract

The efficacy of the natural plant‐derived compound, eugenol (EG), as an antimicrobial wash treatment to reduce Campylobacter jejuni in postharvest poultry was investigated. The antimicrobial efficacy of EG was studied as a suspension, emulsion, or nanoemulsion treatment (two trials each). In each trial, chicken skin samples were inoculated with C. jejuni (∼7.2 Log CFU/sample), washed with treatments (0, 0.125, 0.25, 0.5, 1, or 2% EG corresponds to 0, 7.61, 15.22, 30.45, 60.90, or 121.8 mM, respectively) for 1 min, drip dried for 2 min, and then processed at 0, 8, and 24 hr of refrigerated storage (n = 5 samples/treatment/time point). All doses of the EG suspension consistently reduced C. jejuni counts with the greatest reduction (>2.0 Log CFU/sample) for the 2% dose when compared with controls (p < .05). EG emulsions or nanoemulsions did not provide any additional reduction in C. jejuni when compared to EG suspension. Our results suggest that EG could be an effective postharvest intervention strategy for reducing C. jejuni contamination on poultry products.

Practical Applications

Campylobacter jejuni, a leading cause of foodborne illness in humans, is strongly associated with the consumption of contaminated poultry products. Interventions reducing C. jejuni contamination in poultry would reduce the risk of subsequent human infections. In this study, the antimicrobial efficacy of eugenol was studied in three different delivery systems; suspension, emulsion, or nanoemulsion. Our results demonstrated that eugenol was effective in reducing C. jejuni counts on chicken skin and can be used as a potential strategy to reduce Campylobacter on poultry products.

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