scholarly journals Impact of Acanthamoeba Cysts on Stress Resistance of Salmonella enterica Serovar Typhimurium, Yersinia enterocolitica 4/O:3, Listeria monocytogenes 1/2a, and Escherichia coli O:26

2017 ◽  
Vol 83 (14) ◽  
Author(s):  
Ellen Lambrecht ◽  
Julie Baré ◽  
Koen Sabbe ◽  
Kurt Houf
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Yersinia Enterocolitica ◽  
Sodium Hypochlorite ◽  
Salmonella Enterica ◽  
Bacterial Pathogens ◽  
Cross Tolerance ◽  
Free Living ◽  
Content Type ◽  
Physical And Chemical

ABSTRACT The formation of robust resting cysts enables Acanthamoeba to resist harsh environmental conditions. This study investigated to what extent these cysts are resistant to physical and chemical stresses as applied in food industry cleaning and disinfection procedures. Moreover, it was assessed whether certain intracystic meat-borne bacterial pathogens are more stress resistant than free-living bacterial monocultures and if intracystic passage and subsequent association with trophozoites induces cross-tolerance toward other stressors. Several physical and chemical stressors (NaCl, H2O2, benzalkonium chloride, 55°C, heating until boiling, ethanol, dishwashing detergent, and sodium hypochlorite) frequently used in domestic and industrial food-related environments were tested against (i) Acanthamoeba castellanii cysts, (ii) single strains of bacterial monocultures, (iii) intracystic bacteria, and (iv) bacteria after intracystic passage (cyst-primed bacteria). Only heating until boiling and hypochlorite treatment were cysticidal. After boiling, no viable trophozoites could be recovered from the cysts, and hypochlorite treatment caused a 1.34- to 4.72-log10 cells/ml reduction in cyst viability. All treatments were effective in reducing or even eliminating the tested bacterial monocultures, whereas bacteria residing inside cysts were more tolerant toward these stressors. All cyst-primed bacteria exhibited an increased tolerance toward subsequent H2O2 (>92% decrease in median log10 CFU/ml reduction) and 70% ethanol (>99% decrease) treatments. Moreover, intracystic passage significantly increased the survival of Yersinia enterocolitica (74% decrease in median log10 reduction), Escherichia coli (58%), and Salmonella enterica (48%) after NaCl treatment and of E. coli (96%), S. enterica (99%), and Listeria monocytogenes (99%) after sodium hypochlorite treatment compared with that of nonprimed bacteria. IMPORTANCE The results from this study demonstrated that both viable and nonviable amoebal cysts can protect internalized bacteria against stressful conditions. Moreover, cyst passage can induce cross-tolerance in bacteria, increasing their survival when exposed to selected stressors. These findings underscore the potential importance of free-living amoebae in food-related environments and their impact on the persistence of meat-borne bacterial pathogens.

scholarly journals Evaluation of Aerated Steam Treatment of Alfalfa and Mung Bean Seeds To Eliminate High Levels of Escherichia coli O157:H7 and O178:H12, Salmonella enterica, and Listeria monocytogenes

2013 ◽  
Vol 79 (15) ◽  
pp. 4613-4619 ◽  
Author(s):  
Patrick Studer ◽  
Werner E. Heller ◽  
Jörg Hummerjohann ◽  
David Drissner
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Salmonella Enterica ◽  
Mung Bean ◽  
Germination Rate ◽  
Steam Treatment ◽  
Heat Sensitivity ◽  
Human Pathogens ◽  
Content Type ◽  
E Coli

ABSTRACTSprouts contaminated with human pathogens are able to cause food-borne diseases due to the favorable growth conditions for bacteria during germination and because of minimal processing steps prior to consumption. We have investigated the potential of hot humid air, i.e., aerated steam, to treat alfalfa and mung bean seeds which have been artificially contaminated withEscherichia coliO157:H7,Salmonella entericasubsp.entericaserovar Weltevreden, andListeria monocytogenesScott A. In addition, a recently collectedE. coliO178:H12 isolate, characterized by a reduced heat sensitivity, was exposed to the treatment described. Populations ofE. coliO157:H7 andS. entericaon alfalfa and mung bean seeds could be completely eliminated by a 300-s treatment with steam at 70 ± 1°C as revealed by enrichment studies.L. monocytogenesandE. coliO178:H12 could not be completely eliminated from artificially inoculated seeds. However, bacterial populations were reduced by more than 5 log CFU/g on alfalfa and by more than 4 log CFU/g on mung bean seeds. The germination rate of mung beans was not affected by the 300-s treatment compared to the germination rate of untreated seeds whereas that of alfalfa seeds was significantly lower by 11.9%. This chemical-free method is an effective alternative to the 20,000-ppm hypochlorite treatment presently recommended by the U.S. Food and Drug Administration (FDA).

scholarly journals Modeling Stochastic Variability in the Numbers of Surviving Salmonella enterica, Enterohemorrhagic Escherichia coli, and Listeria monocytogenes Cells at the Single-Cell Level in a Desiccated Environment

2016 ◽  
Vol 83 (4) ◽  
Author(s):  
Kento Koyama ◽  
Hidekazu Hokunan ◽  
Mayumi Hasegawa ◽  
Shuso Kawamura ◽  
Shigenobu Koseki
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Probability Distribution ◽  
Poisson Process ◽  
Poisson Distribution ◽  
Salmonella Enterica ◽  
Bacterial Cells ◽  
Content Type ◽  
Cell Numbers ◽  
Inactivation Process

ABSTRACT Despite effective inactivation procedures, small numbers of bacterial cells may still remain in food samples. The risk that bacteria will survive these procedures has not been estimated precisely because deterministic models cannot be used to describe the uncertain behavior of bacterial populations. We used the Poisson distribution as a representative probability distribution to estimate the variability in bacterial numbers during the inactivation process. Strains of four serotypes of Salmonella enterica, three serotypes of enterohemorrhagic Escherichia coli, and one serotype of Listeria monocytogenes were evaluated for survival. We prepared bacterial cell numbers following a Poisson distribution (indicated by the parameter λ, which was equal to 2) and plated the cells in 96-well microplates, which were stored in a desiccated environment at 10% to 20% relative humidity and at 5, 15, and 25°C. The survival or death of the bacterial cells in each well was confirmed by adding tryptic soy broth as an enrichment culture. Changes in the Poisson distribution parameter during the inactivation process, which represent the variability in the numbers of surviving bacteria, were described by nonlinear regression with an exponential function based on a Weibull distribution. We also examined random changes in the number of surviving bacteria using a random number generator and computer simulations to determine whether the number of surviving bacteria followed a Poisson distribution during the bacterial death process by use of the Poisson process. For small initial cell numbers, more than 80% of the simulated distributions (λ = 2 or 10) followed a Poisson distribution. The results demonstrate that variability in the number of surviving bacteria can be described as a Poisson distribution by use of the model developed by use of the Poisson process. IMPORTANCE We developed a model to enable the quantitative assessment of bacterial survivors of inactivation procedures because the presence of even one bacterium can cause foodborne disease. The results demonstrate that the variability in the numbers of surviving bacteria was described as a Poisson distribution by use of the model developed by use of the Poisson process. Description of the number of surviving bacteria as a probability distribution rather than as the point estimates used in a deterministic approach can provide a more realistic estimation of risk. The probability model should be useful for estimating the quantitative risk of bacterial survival during inactivation.

scholarly journals Effect of Electropermeabilization by Ohmic Heating for Inactivation of Escherichia coli O157:H7, Salmonella enterica Serovar Typhimurium, and Listeria monocytogenes in Buffered Peptone Water and Apple Juice

2013 ◽  
Vol 79 (23) ◽  
pp. 7122-7129 ◽  
Author(s):  
Il-Kyu Park ◽  
Dong-Hyun Kang
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Electric Field ◽  
Salmonella Enterica ◽  
Apple Juice ◽  
Ohmic Heating ◽  
Conventional Heating ◽  
Content Type ◽  
Serovar Typhimurium ◽  
Peptone Water

ABSTRACTThe effect of electric field-induced ohmic heating for inactivation ofEscherichia coliO157:H7,Salmonella entericaserovar Typhimurium, andListeria monocytogenesin buffered peptone water (BPW) (pH 7.2) and apple juice (pH 3.5; 11.8 °Brix) was investigated in this study. BPW and apple juice were treated at different temperatures (55°C, 58°C, and 60°C) and for different times (0, 10, 20, 25, and 30 s) by ohmic heating compared with conventional heating. The electric field strength was fixed at 30 V/cm and 60 V/cm for BPW and apple juice, respectively. Bacterial reduction resulting from ohmic heating was significantly different (P< 0.05) from that resulting from conventional heating at 58°C and 60°C in BPW and at 55°C, 58°C, and 60°C in apple juice for intervals of 0, 10, 20, 25, and 30 s. These results show that electric field-induced ohmic heating led to additional bacterial inactivation at sublethal temperatures. Transmission electron microscopy (TEM) observations and the propidium iodide (PI) uptake test were conducted after treatment at 60°C for 0, 10, 20, 25 and 30 s in BPW to observe the effects on cell permeability due to electroporation-caused cell damage. PI values when ohmic and conventional heating were compared were significantly different (P< 0.05), and these differences increased with increasing levels of inactivation of three food-borne pathogens. These results demonstrate that ohmic heating can more effectively reduce bacterial populations at reduced temperatures and shorter time intervals, especially in acidic fruit juices such as apple juice. Therefore, loss of quality can be minimized in a pasteurization process incorporating ohmic heating.

Efficacy of Sodium Hypochlorite and Peroxyacetic Acid To Reduce Murine Norovirus 1, B40-8, Listeria monocytogenes, and Escherichia coli O157:H7 on Shredded Iceberg Lettuce and in Residual Wash Water

2009 ◽  
Vol 72 (5) ◽  
pp. 1047-1054 ◽  
Author(s):  
LEEN BAERT ◽  
ISABELLE VANDEKINDEREN ◽  
FRANK DEVLIEGHERE ◽  
ELS VAN COILLIE ◽  
JOHAN DEBEVERE ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Sodium Hypochlorite ◽  
Tap Water ◽  
Bacterial Pathogens ◽  
Wash Water ◽  
Escherichia Coli O157 ◽  
Murine Norovirus ◽  
Peroxyacetic Acid ◽  
Iceberg Lettuce

The efficiency of sodium hypochlorite (NaOCl) and peroxyacetic acid (PAA) to reduce murine norovirus 1 (MNV-1), a surrogate for human norovirus, and Bacteroides fragilis HSP40–infecting phage B40-8 on shredded iceberg lettuce was investigated. The levels of removal of viruses MNV-1 and B40-8 were compared with the reductions observed for bacterial pathogens Listeria monocytogenes and Escherichia coli O157:H7. Two inoculation levels, one with a high organic load and the other containing a 10-fold lower number of pathogens and organic matter, showed that the effectiveness of NaOClwas greatly influenced by the presence of organic material, which was not observed for PAA. Moreover, the present study showed that 200 mg/liter NaOCl or 250 mg/liter PAA is needed to obtain an additional reduction of 1 log (compared with tap water) of MNV-1 on shredded iceberg lettuce, whereas only 250 mg/liter PAA achieved this for bacterial pathogens. None of the treatments resulted in a supplementary 1-log PFU/g reduction of B40-8 compared with tap water. B40-8 could therefore be useful as an indicator of decontamination processes of shredded iceberg lettuce based on NaOCl or PAA. Neither MNV-1, B40-8, nor bacterial pathogens could be detected in residual wash water after shredded iceberg lettuce was treated with NaOCl and PAA, whereas considerable numbers of all these microorganisms were found in residual wash water consisting solely of tap water. This study illustrates the usefulness of PAA and NaOCl in preventing cross-contamination during the washing process rather than in causing a reduction of the number of pathogens present on lettuce.

Mixed culture enrichment of Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica, and Yersinia enterocolitica

Food Control ◽  
2012 ◽  
Vol 26 (2) ◽  
pp. 269-273 ◽  
Author(s):  
Andrew G. Gehring ◽  
David M. Albin ◽  
Arun K. Bhunia ◽  
Hyochin Kim ◽  
Sue A. Reed ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Mixed Culture ◽  
Yersinia Enterocolitica ◽  
Salmonella Enterica ◽  
Escherichia Coli O157 ◽  
Culture Enrichment

scholarly journals Fate of Salmonella enterica and Enterohemorrhagic Escherichia coli Cells Artificially Internalized into Vegetable Seeds during Germination

2017 ◽  
Vol 84 (1) ◽  
Author(s):  
Da Liu ◽  
Yue Cui ◽  
Ronald Walcott ◽  
Jinru Chen
Keyword(s):  
Escherichia Coli ◽  
Salmonella Enterica ◽  
Bacterial Pathogens ◽  
Bacterial Species ◽  
Enterohemorrhagic Escherichia Coli ◽  
Human Pathogens ◽  
Gastrointestinal Infections ◽  
Tissue Samples ◽  
Content Type ◽  
Vegetable Seed

ABSTRACTVegetable seeds contaminated with bacterial pathogens have been linked to fresh-produce-associated outbreaks of gastrointestinal infections. This study was undertaken to observe the physiological behavior ofSalmonella entericaand enterohemorrhagicEscherichia coli(EHEC) cells artificially internalized into vegetable seeds during the germination process. Surface-decontaminated seeds of alfalfa, fenugreek, lettuce, and tomato were vacuum-infiltrated with four individual strains ofSalmonellaor EHEC. Contaminated seeds were germinated at 25°C for 9 days, and different sprout/seedling tissues were microbiologically analyzed every other day. The internalization ofSalmonellaand EHEC cells into vegetable seeds was confirmed by the absence of pathogens in seed-rinsing water and the presence of pathogens in seed homogenates after postinternalization seed surface decontamination. Results show that 317 (62%) and 343 (67%) of the 512 collected sprout/seedling tissue samples were positive forSalmonellaand EHEC, respectively. The averageSalmonellapopulations were significantly larger (P< 0.05) than the EHEC populations. Significantly largerSalmonellapopulations were recovered from the cotyledon and seed coat tissues, followed by the root tissues, but the mean EHEC populations from all sampled tissue sections were statistically similar, except in pregerminated seeds. ThreeSalmonellaand two EHEC strains had significantly larger cell populations on sprout/seedling tissues than other strains used in the study.Salmonellaand EHEC populations from fenugreek and alfalfa tissues were significantly larger than those from tomato and lettuce tissues. The study showed the fate of internalized human pathogens on germinating vegetable seeds and sprout/seedling tissues and emphasized the importance of using pathogen-free seeds for sprout production.IMPORTANCEThe internalization of microorganisms into vegetable seeds could occur naturally and represents a possible pathway of vegetable seed contamination by human pathogens. The present study investigated the ability of two important bacterial pathogens,Salmonellaand enterohemorrhagicEscherichia coli(EHEC), when artificially internalized into vegetable seeds, to grow and disseminate along vegetable sprouts/seedlings during germination. The data from the study revealed that the pathogen cells artificially internalized into vegetable seeds caused the contamination of different tissues of sprouts/seedlings and that pathogen growth on germinating seeds is bacterial species and vegetable seed-type dependent. These results further stress the necessity of using pathogen-free vegetable seeds for edible sprout production.

scholarly journals Yersinia enterocolitica Inhibits Salmonella enterica Serovar Typhimurium and Listeria monocytogenes Cellular Uptake

2013 ◽  
Vol 82 (1) ◽  
pp. 174-183 ◽  
Author(s):  
Fabien Habyarimana ◽  
Matthew C. Swearingen ◽  
Glenn M. Young ◽  
Stephanie Seveau ◽  
Brian M. M. Ahmer
Keyword(s):  
Listeria Monocytogenes ◽  
Yersinia Enterocolitica ◽  
Salmonella Enterica ◽  
Effector Proteins ◽  
Cell Uptake ◽  
Secretion Systems ◽  
Content Type ◽  
T3ss Effector ◽  
Luxr Homolog ◽  
Serovar Typhimurium

ABSTRACTYersinia enterocoliticabiovar 1B employs two type three secretion systems (T3SS), Ysa and Ysc, which inject effector proteins into macrophages to prevent phagocytosis. Conversely,Salmonella entericaserovar Typhimurium uses a T3SS encoded bySalmonellapathogenicity island 1 (SPI1) to actively invade cells that are normally nonphagocytic and a second T3SS encoded by SPI2 to survive within macrophages. Given the distinctly different outcomes that occur with regard to host cell uptake ofS. Typhimurium andY. enterocolitica, we investigated how each pathogen influences the internalization outcome of the other.Y. enterocoliticareducesS. Typhimurium invasion of HeLa and Caco-2 cells to a level similar to that observed using anS. Typhimurium SPI1 mutant alone. However,Y. enterocoliticahad no effect onS. Typhimurium uptake by J774.1 or RAW264.7 macrophage-like cells.Y. enterocoliticawas also able to inhibit the invasion of epithelial and macrophage-like cells byListeria monocytogenes.Y. enterocoliticamutants lacking either the Ysa or Ysc T3SS were partially defective, while double mutants were completely defective, in blockingS. Typhimurium uptake by epithelial cells.S. Typhimurium encodes a LuxR homolog, SdiA, which detectsN-acylhomoserine lactones (AHLs) produced byY. enterocoliticaand upregulates the expression of an invasin (Rck) and a putative T3SS effector (SrgE). Two different methods of constitutively activating theS. Typhimurium SdiA regulon failed to reverse the uptake blockade imposed byY. enterocolitica.

scholarly journals Formation of Sublethally InjuredYersinia enterocolitica,Escherichia coliO157:H7, andSalmonella entericaSerovar Enteritidis Cells after Neutral Electrolyzed Oxidizing Water Treatments

2018 ◽  
Vol 84 (17) ◽  
Author(s):  
Dong Han ◽  
Yen-Con Hung ◽  
Christy L. Bratcher ◽  
Emefa A. Monu ◽  
Yifen Wang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Heat Treatment ◽  
Bile Salt ◽  
Yersinia Enterocolitica ◽  
Salmonella Enterica ◽  
Antimicrobial Treatment ◽  
Cross Protection ◽  
Content Type ◽  
Sublethal Injury ◽  
Water Treatments

ABSTRACTThe impact of neutral electrolyzed oxidizing (NEO) water treatments on the formation of sublethally injuredYersinia enterocolitica,Escherichia coliO157:H7, andSalmonella entericaserovar Enteritidis cells was evaluated. When pathogens were treated with 6% NEO water, approximately 38% of the treatedYersiniapopulation and 25% of the treatedSalmonellapopulation became sublethally injured. The highest sublethally injured population was found whenSalmonellacultures were treated with 3% NEO water. Regardless of the NEO water concentration used, no sublethally injuredE. coliO157:H7 cells were found. To evaluate the sensitivity of NEO water-treated cells, four additional stresses (heat treatment, pH, NaCl, and bile salt) were tested. NEO water treatments did not generate any cross protection of treated cells against the other stresses. The diluted NEO water treatments in combination with heat treatment at 51°C for 10 min led to the best synergistic antimicrobial effects with a combined reduction of 7 logs. The gene expression results showed that NEO water treatments led to the upregulation ofompR,ail, andycfR. These genes are known for their involvement in cells' environmental stress responses. In summary, this study investigated the sublethal injury in pathogenic cells caused by NEO water treatments. Although sublethal injury was discovered, when combined with other mild stresses, the synergistic antimicrobial effects were able to further reduce the numbers of viable pathogenic cells. These results demonstrate the great application potential of NEO water as a nonthermal and less corrosive antimicrobial treatment.IMPORTANCENeutral electrolyzed oxidizing (NEO) water is a nonthermal and less corrosive antimicrobial treatment that has been demonstrated to have efficacy in reducing microbial contamination in food, including meat, fresh fruit, and vegetables. However, NEO water treatments can cause sublethal injury to pathogenic cells, resulting in cells that retain their viability. Consequently, these sublethally injured pathogenic cells become a serious food safety concern. This study evaluated the formation of sublethally injuredYersinia enterocolitica,Escherichia coliO157:H7, andSalmonella entericaserovar Enteritidis cells by NEO water treatments and the potential cross protection against heat, pH, NaCl, or bile salt stresses that it may generate. No cross protection was observed. By combining NEO water treatments with sublethal levels of additional stresses, significant synergistic antimicrobial outcomes were achieved. These results indicate that mild processing treatments, when combined, can effectively reduce pathogen populations while minimizing the negative impacts on food quality.

scholarly journals Dissemination of IncI2 Plasmids That Harbor theblaCTX-MElement among Clinical Salmonella Isolates

2015 ◽  
Vol 59 (8) ◽  
pp. 5026-5028 ◽  
Author(s):  
Marcus Ho-yin Wong ◽  
Lizhang Liu ◽  
Meiying Yan ◽  
Edward Wai-chi Chan ◽  
Sheng Chen
Keyword(s):  
Escherichia Coli ◽  
Salmonella Enterica ◽  
Bacterial Pathogens ◽  
Content Type ◽  
E Coli ◽  
Species Migration ◽  
Typhimurium Strain ◽  
Extended Spectrum ◽  
Multiple Antibiotics

ABSTRACTThe extended-spectrum-β-lactamase (ESBL) determinant CTX-M-55 is increasingly prevalent inEscherichia colibut remains extremely rare inSalmonella. This study reports the isolation of a plasmid harboring theblaCTX-M-55element in a clinicalSalmonella entericaserotype Typhimurium strain resistant to multiple antibiotics. This plasmid is genetically identical to several known IncI2-type elements harbored byE. colistrains recovered from animals. This finding indicates that IncI2 plasmids harboring theblaCTX-Mgenes may undergo cross-species migration among potential bacterial pathogens, withE. colias the major source of such elements.

Searching for high pressure processing parameters for Escherichia coli O157:H7, Salmonella enterica and Listeria monocytogenes reduction in Concord grape juice

2019 ◽  
Vol 122 (1) ◽  
pp. 170-180 ◽  
Author(s):  
Rodrigo Petrus ◽  
John Churey ◽  
Randy Worobo
Keyword(s):  
Escherichia Coli ◽  
High Pressure ◽  
Listeria Monocytogenes ◽  
Salmonella Enterica ◽  
Grape Juice ◽  
Processing Parameters ◽  
High Pressure Processing ◽  
Content Type ◽  
Log Reduction ◽  
Concord Grape

Purpose High pressure processing (HPP) has been widely used for high-acid (pH<4.6) juices. The purpose of this study was to investigate optimal parameters aimed at achieving 5-log reduction of the pathogens of reference in Concord grape juice (pH 3.39). Design/methodology/approach Grape juice was inoculated with five strain cocktails of Escherichia coli O157:H7, Salmonella enterica and Listeria monocytogenes. In total, 11 trials were carried out based on a Central Composite Rotational Design (CCRD). The pressure (P), ranging from 319 to 531 MPa, and dwell time (t), from 35 to 205 s, were tested. The performance of the combinations (P × t) was evaluated by pathogen challenge microbiological assays. Findings E. coli O157:H7 was more resistant to HPP than S. enterica. L. monocytogenes did not grow in unprocessed juice (before HPP). Findings demonstrated that moderate pressures (~400 MPa) and short dwell times (~2 min) were effective in achieving a greater than 5-log reduction in the pathogens of reference. Practical implications Because the maintenance costs of equipment exponentially increase with pressure beyond 600 MPa, significant reductions in process pressure are highly desirable. Originality/value The results of this study can supplement the dearth of information on the applicability of high pressure as a Concord grape juice processing technology in terms of the pathogens inactivation. Furthermore, the use of a cocktail of five strains of pathogens inoculated in Concord grape juice to challenge different HPP parameters has not been reported.

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