Acid Resistance of Non-O157 Shiga Toxin-Producing Escherichia coli Adapted in Fruit Juices in Simulated Gastric Fluid

2016 ◽  
Vol 45 (4) ◽  
pp. 577-584
Author(s):  
Gwang-Hee Kim ◽  
Deog-Hwan Oh
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Acid Resistance ◽  
Gastric Fluid ◽  
Fruit Juices ◽  
Simulated Gastric Fluid

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.

scholarly journals Adaptation of Escherichia coli O157:H7 to pH Alters Membrane Lipid Composition, Verotoxin Secretion, and Resistance to Simulated Gastric Fluid Acid

2004 ◽  
Vol 70 (6) ◽  
pp. 3500-3505 ◽  
Author(s):  
Hyun-Gyun Yuk ◽  
Douglas L. Marshall
Keyword(s):  
Escherichia Coli ◽  
Membrane Fluidity ◽  
Lipid Composition ◽  
Vaccenic Acid ◽  
Acid Resistance ◽  
Gastric Fluid ◽  
Membrane Lipid ◽  
Simulated Gastric Fluid ◽  
Acidic Ph ◽  
Membrane Lipid Composition

ABSTRACT The influence of adaptation to pH (from pH 5.0 to 9.0) on membrane lipid composition, verotoxin concentration, and resistance to acidic conditions in simulated gastric fluid (SGF) (pH 1.5, 37�C) was determined for Escherichia coli O157:H7 (HEC, ATCC 43895), an rpoS-deficient mutant of ATCC 43895 (HEC-RM, FRIK 816-3), and nonpathogenic E. coli (NPEC, ATCC 25922). Regardless of the strain, D values (in SGF) of acid-adapted cells were higher than those of non-acid-adapted cells, with HEC adapted at pH 5.0 having the greatest D value, i.e., 25.6 min. Acid adaptation increased the amounts of palmitic acid (C16:0) and decreased cis-vaccenic acid (C18:1ω7c) in the membrane lipids of all strains. The ratio of cis-vaccenic acid to palmitic acid increased at acidic pH, causing a decrease in membrane fluidity. HEC adapted to pH 8.3 and HEC-RM adapted to pH 7.3 exhibited the greatest verotoxin concentrations (2,470 and 1,460 ng/ml, respectively) at approximately 108 CFU/ml. In addition, the ratio of extracellular to intracellular verotoxin concentration decreased at acidic pH, possibly due to the decrease of membrane fluidity. These results suggest that while the rpoS gene does not influence acid resistance in acid-adapted cells it does confer decreased membrane fluidity, which may increase acid resistance and decrease verotoxin secretion.

scholarly journals Stress Resistance Development and Genome-Wide Transcriptional Response ofEscherichia coliO157:H7 Adapted to Sublethal Thymol, Carvacrol, andtrans-Cinnamaldehyde

2018 ◽  
Vol 84 (22) ◽  
Author(s):  
Wenqian Yuan ◽  
Zi Jing Seng ◽  
Gurjeet Singh Kohli ◽  
Liang Yang ◽  
Hyun-Gyun Yuk
Keyword(s):  
Escherichia Coli ◽  
Stress Resistance ◽  
Virulence Genes ◽  
Acid Resistance ◽  
Gastric Fluid ◽  
Simulated Gastric Fluid ◽  
Cross Resistance ◽  
Resistance Development ◽  
Content Type ◽  
E Coli

ABSTRACTThymol, carvacrol, andtrans-cinnamaldehyde are essential oil (EO) compounds with broad-spectrum antimicrobial activities against foodborne pathogens, includingEscherichia coliO157:H7. However, little is known regarding direct resistance and cross-resistance development inE. coliO157:H7 after adaptation to sublethal levels of these compounds, and information is scarce on microbial adaptive responses at a molecular level. The present study demonstrated thatE. coliO157:H7 was able to grow in the presence of sublethal thymol (1/2T), carvacrol (1/2C), ortrans-cinnamaldehyde (1/2TC), displaying an extended lag phase duration and a lower maximum growth rate. EO-adapted cells developed direct resistance against lethal EO treatments and cross-resistance against heat (58°C) and oxidative (50 mM H2O2) stresses. However, no induction of acid resistance (simulated gastric fluid, pH 1.5) was observed. RNA sequencing revealed a large number (310 to 338) of differentially expressed (adjustedPvalue [Padj], <0.05; fold change, ≥5) genes in 1/2T and 1/2C cells, while 1/2TC cells only showed 27 genes with altered expression. In accordance with resistance phenotypes, the genes related to membrane, heat, and oxidative stress responses and genes related to iron uptake and metabolism were upregulated. Conversely, virulence genes associated with motility, biofilm formation, and efflux pumps were repressed. This study demonstrated the development of direct resistance and cross-resistance and characterized whole-genome transcriptional responses inE. coliO157:H7 adapted to sublethal thymol, carvacrol, ortrans-cinnamaldehyde. The data suggested that caution should be exercised when using EO compounds as food antimicrobials, due to the potential stress resistance development inE. coliO157:H7.IMPORTANCEThe present study was designed to understand transcriptomic changes and the potential development of direct and cross-resistance in essential oil (EO)-adaptedEscherichia coliO157:H7. The results demonstrated altered growth behaviors ofE. coliO157:H7 during adaptation in sublethal thymol, carvacrol, andtrans-cinnamaldehyde. Generally, EO-adapted bacteria showed enhanced resistance against subsequent lethal EO, heat, and oxidative stresses, with no induction of acid resistance in simulated gastric fluid. A transcriptomic analysis revealed the upregulation of related stress resistance genes and a downregulation of various virulence genes in EO-adapted cells. This study provides new insights into microbial EO adaptation behaviors and highlights the risk of resistance development in adapted bacteria.

Modelling inactivation of wild‐type and clinical Escherichia coli O26 strains using UV‐C and thermal treatment and subsequent persistence in simulated gastric fluid

2019 ◽  
Vol 127 (5) ◽  
pp. 1564-1575 ◽  
Author(s):  
V.S. Castro ◽  
D.K.A. Rosario ◽  
Y.S. Mutz ◽  
A.C.C. Paletta ◽  
E.E.S. Figueiredo ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Thermal Treatment ◽  
Gastric Fluid ◽  
Simulated Gastric Fluid ◽  
Wild Type ◽  
Uv C

scholarly journals Selective Isolation of eae-Positive Strains of Shiga Toxin-Producing Escherichia coli

2000 ◽  
Vol 38 (4) ◽  
pp. 1684-1687 ◽  
Author(s):  
Hiroshi Fukushima ◽  
Ken Hoshina ◽  
Manabu Gomyoda
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Acid Resistance ◽  
Selective Isolation ◽  
Macconkey Agar ◽  
Tellurite Resistance ◽  
E Coli

Culture on cefixime, tellurite, and sorbitol-MacConkey agar after HCl treatment facilitated the growth of 410 (94%) of 436eae-positive Shiga toxin-producing Escherichia coli (STEC) strains and 17 (16%) of 107 eae-negative STEC strains. This selectivity was closely related to acid resistance in E. coli and tellurite resistance ineae-positive STEC strains.

scholarly journals Variation in Acid Resistance among Shiga Toxin-Producing Clones of Pathogenic Escherichia coli

2005 ◽  
Vol 71 (5) ◽  
pp. 2493-2500 ◽  
Author(s):  
Teresa M. Large ◽  
Seth T. Walk ◽  
Thomas S. Whittam
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Survival Rates ◽  
Acid Resistance ◽  
Acid Decarboxylase ◽  
Infectious Dose ◽  
Clonal Group ◽  
E Coli ◽  
Log Reduction ◽  
Oxidative System

ABSTRACT Pathogenic strains of Escherichia coli, such as E. coli O157:H7, have a low infectious dose and an ability to survive in acidic foods. These bacteria have evolved at least three distinct mechanisms of acid resistance (AR), including two amino acid decarboxylase-dependent systems (arginine and glutamate) and a glucose catabolite-repressed system. We quantified the survival rates for each AR mechanism separately in clinical isolates representing three groups of Shiga toxin-producing E. coli (STEC) clones (O157:H7, O26:H11/O111:H8, and O121:H19) and six commensal strains from ECOR group A. Members of the STEC clones were not significantly more acid resistant than the commensal strains when analyzed using any individual AR mechanism. The glutamate system provided the best protection in a highly acidic environment for all groups of isolates (<0.1 log reduction in CFU/ml per hour at pH 2.0). Under these conditions, there was notable variation in survival rates among the 30 O157:H7 strains, which depended in part on Mg2+ concentration. The arginine system provided better protection at pH 2.5, with a range of 0.03 to 0.41 log reduction per hour, compared to the oxidative system, with a range of 0.13 to 0.64 log reduction per hour. The average survival rate for the O157:H7 clonal group was significantly less than that of the other STEC clones in the glutamate and arginine systems and significantly less than that of the O26/O111 clone in the oxidative system, indicating that this clonal group is not exceptionally acid resistant with these specific mechanisms.

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