scholarly journals Prior Exposure to Dry-Cured Meat Promotes Resistance to Simulated Gastric Fluid in Salmonella Typhimurium

Foods ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 603 ◽  
Author(s):  
Yhan S. Mutz ◽  
Denes K. A. Rosario ◽  
Vinicius S. Castro ◽  
Patricia C. Bernardes ◽  
Vania M. F. Paschoalin ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Salmonella Enterica ◽  
Meat Product ◽  
Foodborne Pathogen ◽  
Acid Tolerance ◽  
Gastric Fluid ◽  
Simulated Gastric Fluid ◽  
Pathogen Inactivation ◽  
Cured Meat

This study assessed if exposure of foodborne Salmonella enterica in Brazilian dry-cured loin (BDL) affects pathogen inactivation in simulated gastric fluid (SGF). The acid tolerance responses of three Salmonella enterica serovars, Typhimurium, Derby and Panama, were assessed by an acid challenge trial at pH 3.0 for 4 h following pre-adaptation to three conditions: neutral pH, acidic pH (4.5) or BDL matrix. The influence of Salmonella exposure temperature and time in the BDL on pathogen gastric fluid resistance was evaluated by the response surface methodology. The Salmonella serovars acquired acid tolerance when exposed to the BDL matrix and their response to acid stress was strain-dependent, with S. Typhimurium being the most tolerant strain. S. Typhimuirum exposed to temperatures >25 °C in the BDL matrix displayed increased resistance to SGF. By using the response surface methodology, it was determined that S. Typhimurium becomes less resistant against SGF if maintained in the BDL matrix at temperatures <7 °C, reinforcing the recommendation to store dry-cured meat under refrigeration in order to minimize consumer risks. The results presented herein point to a novel aspect of hurdle technology that should be taken into account to further understand the risks associated with hurdle-stable meat product, such as dry-cured meats, concerning foodborne pathogen contamination.

Survival of Salmonella enterica Serotype Tennessee during Simulated Gastric Passage Is Improved by Low Water Activity and High Fat Content

2013 ◽  
Vol 76 (2) ◽  
pp. 333-337 ◽  
Author(s):  
BRYAN AVILES ◽  
COURTNEY KLOTZ ◽  
TWYLA SMITH ◽  
ROBERT WILLIAMS ◽  
MONICA PONDER
Keyword(s):  
Water Activity ◽  
Salmonella Enterica ◽  
Peanut Butter ◽  
Gastric Fluid ◽  
Fat Content ◽  
Simulated Gastric Fluid ◽  
Food Matrix ◽  
High Fat ◽  
Low Fat ◽  
Infectious Dose

The low water activity (aw 0.3) of peanut butter prohibits the growth of Salmonella in a product; however, illnesses are reported from peanut butter contaminated with very small doses, suggesting the food matrix itself influences the infectious dose of Salmonella, potentially by improving Salmonella's survival in the gastrointestinal tract. The purpose of our study was to quantify the survival of a peanut butter outbreak–associated strain of Salmonella enterica serotype Tennessee when inoculated into peanut butters with different fat contents and aw (high fat, high aw; high fat, low aw; low fat, high aw; low fat, low aw) and then challenged with a simulated gastrointestinal system. Exposures to increased fat content and decreased aw both were associated with a protective effect on the survival of Salmonella Tennessee in the simulated gastric fluid compared with control cells. After a simulated intestinal phase, the populations of Salmonella Tennessee in the control and low-fat formulations were not significantly different; however, a 2-log CFU/g increase occurred in high-fat formulations. This study demonstrates that cross-protection from low-aw stress and the presence of high fat results in improved survival in the low pH of the stomach. The potential for interaction of food matrix and stress adaptations could influence the virulence of Salmonella and should be considered for risk analysis.

scholarly journals Identification of Salmonella enterica Serovar Typhimurium Genes Important for Survival in the Swine Gastric Environment

2006 ◽  
Vol 72 (4) ◽  
pp. 2829-2836 ◽  
Author(s):  
Shawn M. D. Bearson ◽  
Bradley L. Bearson ◽  
Mark A. Rasmussen
Keyword(s):  
Lactic Acid ◽  
Salmonella Enterica ◽  
Ex Vivo ◽  
Stomach Contents ◽  
Acid Tolerance ◽  
Lethal Effect ◽  
Gastric Fluid ◽  
Low Ph ◽  
Chromatography Analysis ◽  
Serovar Typhimurium

ABSTRACT Since the stomach is a first line of defense for the host against ingested microorganisms, an ex vivo swine stomach contents (SSC) assay was developed to search for genes important for Salmonella enterica serovar Typhimurium survival in the hostile gastric environment. Initial characterization of the SSC assay (pH 3.87) using previously identified, acid-sensitive serovar Typhimurium mutants revealed a 10-fold decrease in survival for a phoP mutant following 20 min of challenge and no survival for mutants of rpoS or fur. To identify additional genes, a signature-tagged mutagenesis bank was constructed and screened in the SSC assay. Nineteen mutants were identified and individually analyzed in the SSC and acid tolerance response assays; 13 mutants exhibited a 10-fold or greater sensitivity in the SSC assay compared to the wild-type strain, but only 3 mutants displayed a 10-fold or greater decrease in survival following pH 3.0 acidic challenge. Further examination determined that the lethal effects of the SSC are pH dependent but that low pH is not the sole killing mechanism(s). Gas chromatography analysis of the SSC revealed lactic acid levels of 126 mM. Upon investigating the effects of lactic acid on serovar Typhimurium survival in a synthetic gastric fluid, not only was a concentration- and time-dependent lethal effect observed, but the phoP, rpoS, fur, and pnp genes were identified as involved in protection against lactic acid exposure. These studies indicate a role in gastric survival for several serovar Typhimurium genes and imply that the stomach environment is defined by more than low pH.

scholarly journals Effects of 405 ± 5-nm LED Illumination on Environmental Stress Tolerance of Salmonella Typhimurium in Sliced Beef

Foods ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 136
Author(s):  
Du Guo ◽  
Yichen Bai ◽  
Shengyi Fei ◽  
Yanpeng Yang ◽  
Jiahui Li ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Environmental Stress ◽  
Salmonella Typhimurium ◽  
Bile Salts ◽  
Foodborne Pathogen ◽  
Acid Stress ◽  
Gastric Fluid ◽  
Simulated Gastric Fluid ◽  
Pressure Oxidation ◽  
Light Emitting

Salmonella Typhimurium is a widely distributed foodborne pathogen and is tolerant of various environmental conditions. It can cause intestinal fever, gastroenteritis and bacteremia. The aim of this research was to explore the effect of illumination with 405 nm light-emitting diodes (LEDs) on the resistance of S. Typhimurium to environmental stress. Beef slices contaminated with S. Typhimurium were illuminated by 405 nm LEDs (18.9 ± 1.4 mW/cm2) for 8 h at 4 °C; controls were incubated in darkness at 7 °C. Then, the illuminated or non-illuminated (control) cells were exposed to thermal stress (50, 55, 60 or 65 °C); oxidative stress (0.01% H2O2 [v/v]); acid stress (simulated gastric fluid [SGF] at pH 2 or 3); or bile salts (1%, 2%, or 3% [w/v]). S. Typhimurium treated by 405 nm LED irradiation showed decreased resistance to thermal stress, osmotic pressure, oxidation, SGF and bile salts. The transcription of eight environmental tolerance-related genes were downregulated by the illumination. Our findings suggest the potential of applying 405 nm LED-illumination technology in the control of pathogens in food processing, production and storage, and in decreasing infection and disease related to S. Typhimurium.

scholarly journals Impact of Inoculum Preparation and Storage Conditions on the Response of Escherichia coli O157:H7 Populations to Undercooking and Simulated Exposure to Gastric Fluid

2006 ◽  
Vol 72 (1) ◽  
pp. 672-679 ◽  
Author(s):  
Jarret D. Stopforth ◽  
Panagiotis N. Skandamis ◽  
Laura V. Ashton ◽  
Ifigenia Geornaras ◽  
Patricia A. Kendall ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Acid Tolerance ◽  
Storage Conditions ◽  
Gastric Fluid ◽  
Simulated Gastric Fluid ◽  
Tissue Samples ◽  
E Coli ◽  
Inoculum Preparation ◽  
The Impact ◽  
And Storage

ABSTRACT This study evaluated the impact of inoculum preparation and storage conditions on the response of Escherichia coli O157:H7 exposed to consumer-induced stresses simulating undercooking and digestion. Lean beef tissue samples were inoculated with E. coli O157:H7 cultures prepared in tryptic soy broth or meat decontamination runoff fluids (WASH) or detached from moist biofilms or dried biofilms formed on stainless steel coupons immersed in inoculated WASH. After inoculation, the samples were left untreated or dipped for 30 s each in hot (75°C) water followed by lactic acid (2%, 55°C), vacuum packaged, stored at 4 (28 days) or 12°C (16 days), and periodically transferred to aerobic storage (7°C for 5 days). During storage, samples were exposed to sequential heat (55°C; 20 min) and simulated gastric fluid (adjusted to pH 1.0 with HCl; 90 min) stresses simulating consumption of undercooked beef. Under the conditions of this study, cells originating from inocula of planktonic cells were, in general, more resistant to heat and acid than cells from cultures grown as biofilms and detached prior to meat inoculation. Heat and acid tolerance of cells on meat stored at 4°C was lower than that of cells on nondecontaminated meat stored at 12°C, where growth occurred during storage. Decontamination of fresh beef resulted in injury that inhibited subsequent growth of surviving cells at 12°C, as well as in decreases in resistance to subsequent heat and acid stresses. The shift of pathogen cells on beef stored under vacuum at 4°C to aerobic storage did not affect cell populations or subsequent survival after sequential exposure to heat and simulated gastric fluid. However, the transfer of meat stored under vacuum at 12°C to aerobic storage resulted in reduction in pathogen counts during aerobic storage and sensitization of survivors to the effects of sequential heat and acid exposure.

Dietary Proteins Extend the Survival of Salmonella Dublin in a Gastric Acid Environment

2012 ◽  
Vol 75 (2) ◽  
pp. 353-358 ◽  
Author(s):  
TINA BIRK ◽  
KIM KRISTENSEN ◽  
ANNE HARBOE ◽  
TINA BECK HANSEN ◽  
HANNE INGMER ◽  
...  
Keyword(s):  
Gastric Acid ◽  
Foodborne Pathogen ◽  
Gastric Fluid ◽  
Human Stomach ◽  
Pathogen Inactivation ◽  
Related Factors ◽  
Salmonella Dublin ◽  
Food Components ◽  
Set Up ◽  
The Impact

The pH of the human stomach is dynamic and changes over time, depending on the composition of the food ingested and a number of host-related factors such as age. To evaluate the number of bacteria surviving the gastric acid barrier, we have developed a simple gastric acid model, in which we mimicked the dynamic pH changes in the human stomach. In the present study, model gastric fluid was set up to imitate pH dynamics in the stomachs of young and elderly people after ingestion of a standard meal. To model a serious foodborne pathogen, we followed the survival of Salmonella enterica serotype Dublin, and found that the addition of proteins such as pepsin, ovalbumin, and blended turkey meat to the simple gastric acid model significantly delayed pathogen inactivation compared with the control, for which no proteins were added. In contrast, no delay in inactivation was observed in the presence of bovine serum albumin, indicating that protection could be protein specific. The simple gastric acid model was validated against a more laborious and complex fermenter model, and similar survival of Salmonella Dublin was observed in both models. Our gastric acid model allowed us to evaluate the influence of food components on survival of pathogens under gastric conditions, and the model could contribute to a broader understanding of the impact of specific food components on the inactivation of pathogens during gastric passage.

scholarly journals Growth and Survival of Acid-Resistant and Non-Acid-Resistant Shiga-Toxin-ProducingEscherichia coliStrains during the Manufacture and Ripening of Camembert Cheese

2009 ◽  
Vol 2009 ◽  
pp. 1-10 ◽  
Author(s):  
M. P. Montet ◽  
E. Jamet ◽  
S. Ganet ◽  
M. Dizin ◽  
S. Miszczycha ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Acid Tolerance ◽  
Acid Resistance ◽  
Gastric Fluid ◽  
Simulated Gastric Fluid ◽  
Growth And Survival ◽  
Cheese Making ◽  
Early Stages ◽  
Camembert Cheese

Growth and survival of acid-resistant (AR) and non-acid-resistant (NAR) Shiga-toxin-producingEscherichia coli(STEC) strains were investigated during the manufacture and ripening of microfiltered milk Camembert cheeses. The induction of acid resistance of the STEC strains in cheeses was also studied. Six different mixtures of AR and/or NAR STEC strains were inoculated separately into microfiltered milk at a level of103CFUmL−1. The STEC counts (AR and NAR) initially increased by 1 to 2log⁡10CFUg−1during cheese-making. Thereafter, the populations stabilized during salting/drying and then decreased during the early stages of ripening. Exposing the STEC strains in artificially inoculated cheeses to simulated gastric fluid (SGF - pH: 2.0) reduced the number of NAR strains to undetectable levels within 40 minutes, versus 120 minutes for the AR STEC strains. AR and NAR STEC were able to survive during the manufacture and ripening of Camembert cheese prepared from microfiltered milk with no evidence of induced acid tolerance in NAR STEC strains.

Listeria monocytogenes ArcA contributes to acid tolerance

2013 ◽  
Vol 62 (6) ◽  
pp. 813-821 ◽  
Author(s):  
Changyong Cheng ◽  
Jianshun Chen ◽  
Ying Shan ◽  
Chun Fang ◽  
Yuan Liu ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Bacterial Load ◽  
Foodborne Pathogen ◽  
Acid Stress ◽  
Intestinal Barrier ◽  
Systemic Infection ◽  
Acid Tolerance ◽  
Gastric Fluid ◽  
Arginine Deiminase

The foodborne pathogen Listeria monocytogenes is able to colonize the human and animal intestinal tracts and subsequently crosses the intestinal barrier, causing systemic infection. For successful establishment of infection, L. monocytogenes must survive and adapt to the low pH environment of the stomach. Gene sequence analysis indicates that lmo0043, an orthologue of arcA, encodes a protein containing conserved motifs and critical active amino acids characteristic of arginine deiminase that mediates an arginine deimination reaction. We attempted to characterize the role of ArcA in acid tolerance in vitro and in mice models. Transcription of arcA was significantly increased in L. monocytogenes culture subjected to acid stress at pH 4.8, as compared with that at pH 7.0. Deletion of arcA impaired growth of L. monocytogenes under mild acidic conditions at pH 5.5, and reduced its survival in synthetic human gastric fluid at pH 2.5 and in the murine stomach. Bacterial load in the spleen of mice intraperitoneally inoculated with an arcA deletion mutant was significantly lower than that of the wild-type strain. These phenotypic changes were recoverable by genetic complementation. Thus, we conclude that L. monocytogenes arcA not only mediates acid tolerance in vitro but also participates in gastric survival and virulence in mice.

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