Survival of acid-adapted and non-adapted Shiga toxin-producing Escherichia coli using an in vitro model

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Abstract

Shiga toxin-producing Escherichia coli (STEC) are known to adapt and survive acidic conditions. Acid-adaptation also may result in cross-protection against other stressors present in foods, such as reduced water activity (aw), refrigeration conditions, or the presence of antimicrobials. Three independent experiments were conducted with non-adapted (control) and acid-adapted E. coli O157:H7 and non-O157:H7 serogroups (E. coli O26, O45, O103, O111, O121 and O145) in vitro and in situ. Experiment 1: STEC cocktails in media were left untreated (non-adapted; control) or adapted (pH 5.0), exposed to mild acidic conditions (pH 4.5) or reduced aw (0.88 and 0.75) for 4 days at 24 °C, and evaluated for survival. Experiment 2: Non-adapted and acid-adapted STEC cocktails were subjected to desiccation (28 days at 24 °C) on sterile paper disks, and remaining pathogen populations were determined. Experiment 3: Control and acid-adapted STEC were subjected to mild acidic conditions (pH 4.5) and low aw (0.88 or 0.78) in ground beef slurries (GBS; 4 days at 24 °C) and surviving populations enumerated. Results from experiment 1 demonstrated that populations of non-O157:H7 STEC serogroups O45, O103, O111 and O121 were significantly different from populations of E. coli O157:H7, and non-O157:H7 STEC serogroups O26 and O145. In contrast, when STEC serogroups were acid-adapted, all populations of non-O157:H7 STEC were significantly different from populations of E. coli O157:H7. Results of experiments in media with aw of 0.88 or 0.78 demonstrated that there was no significant difference between E. coli O157:H7 and any of the non-O157:H7 STEC, regardless of acid-adaptation. In experiment 2, exposure to desiccation resulted in no significant difference in survival between E. coli O157:H7 and non-O157:H7 STEC, regardless of acid-adaptation. Experiment 3 in acidified GBS demonstrated that all non-O157:H7 STEC behaved similarly to E. coli O157:H7, except for E. coli O145, which had a higher reduction than O157:H7. There were no significant differences in bacterial populations associated with GBS with modified aw. Collectively, these results suggest than non-O157:H7 STEC behave similarly to E. coli O157:H7 when exposed to low pH (<4.5) and low aw (0.88 or 0.78) under laboratory conditions.

Original languageEnglish (US)
Pages (from-to)28-33
Number of pages6
JournalFood Control
Volume104
DOIs
StatePublished - Oct 1 2019

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Shiga-Toxigenic Escherichia coli
Shiga toxin-producing Escherichia coli
Escherichia coli O157
Acids
acids
serotypes
Population
Desiccation
In Vitro Techniques
Escherichia coli O26
Cross Protection
Escherichia coli
Refrigeration
slurries
ground beef
refrigeration
water activity

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Food Science

Cite this

@article{37e4d9eba6de404cbcce528b92c9ba35,
title = "Survival of acid-adapted and non-adapted Shiga toxin-producing Escherichia coli using an in vitro model",
abstract = "Shiga toxin-producing Escherichia coli (STEC) are known to adapt and survive acidic conditions. Acid-adaptation also may result in cross-protection against other stressors present in foods, such as reduced water activity (aw), refrigeration conditions, or the presence of antimicrobials. Three independent experiments were conducted with non-adapted (control) and acid-adapted E. coli O157:H7 and non-O157:H7 serogroups (E. coli O26, O45, O103, O111, O121 and O145) in vitro and in situ. Experiment 1: STEC cocktails in media were left untreated (non-adapted; control) or adapted (pH 5.0), exposed to mild acidic conditions (pH 4.5) or reduced aw (0.88 and 0.75) for 4 days at 24 °C, and evaluated for survival. Experiment 2: Non-adapted and acid-adapted STEC cocktails were subjected to desiccation (28 days at 24 °C) on sterile paper disks, and remaining pathogen populations were determined. Experiment 3: Control and acid-adapted STEC were subjected to mild acidic conditions (pH 4.5) and low aw (0.88 or 0.78) in ground beef slurries (GBS; 4 days at 24 °C) and surviving populations enumerated. Results from experiment 1 demonstrated that populations of non-O157:H7 STEC serogroups O45, O103, O111 and O121 were significantly different from populations of E. coli O157:H7, and non-O157:H7 STEC serogroups O26 and O145. In contrast, when STEC serogroups were acid-adapted, all populations of non-O157:H7 STEC were significantly different from populations of E. coli O157:H7. Results of experiments in media with aw of 0.88 or 0.78 demonstrated that there was no significant difference between E. coli O157:H7 and any of the non-O157:H7 STEC, regardless of acid-adaptation. In experiment 2, exposure to desiccation resulted in no significant difference in survival between E. coli O157:H7 and non-O157:H7 STEC, regardless of acid-adaptation. Experiment 3 in acidified GBS demonstrated that all non-O157:H7 STEC behaved similarly to E. coli O157:H7, except for E. coli O145, which had a higher reduction than O157:H7. There were no significant differences in bacterial populations associated with GBS with modified aw. Collectively, these results suggest than non-O157:H7 STEC behave similarly to E. coli O157:H7 when exposed to low pH (<4.5) and low aw (0.88 or 0.78) under laboratory conditions.",
author = "Minerva Rivera-Reyes and Campbell, {Jonathan Alexander} and Cutter, {Catherine Nettles}",
year = "2019",
month = "10",
day = "1",
doi = "10.1016/j.foodcont.2019.04.009",
language = "English (US)",
volume = "104",
pages = "28--33",
journal = "Food Control",
issn = "0956-7135",
publisher = "Elsevier BV",

}

TY - JOUR

T1 - Survival of acid-adapted and non-adapted Shiga toxin-producing Escherichia coli using an in vitro model

AU - Rivera-Reyes, Minerva

AU - Campbell, Jonathan Alexander

AU - Cutter, Catherine Nettles

PY - 2019/10/1

Y1 - 2019/10/1

N2 - Shiga toxin-producing Escherichia coli (STEC) are known to adapt and survive acidic conditions. Acid-adaptation also may result in cross-protection against other stressors present in foods, such as reduced water activity (aw), refrigeration conditions, or the presence of antimicrobials. Three independent experiments were conducted with non-adapted (control) and acid-adapted E. coli O157:H7 and non-O157:H7 serogroups (E. coli O26, O45, O103, O111, O121 and O145) in vitro and in situ. Experiment 1: STEC cocktails in media were left untreated (non-adapted; control) or adapted (pH 5.0), exposed to mild acidic conditions (pH 4.5) or reduced aw (0.88 and 0.75) for 4 days at 24 °C, and evaluated for survival. Experiment 2: Non-adapted and acid-adapted STEC cocktails were subjected to desiccation (28 days at 24 °C) on sterile paper disks, and remaining pathogen populations were determined. Experiment 3: Control and acid-adapted STEC were subjected to mild acidic conditions (pH 4.5) and low aw (0.88 or 0.78) in ground beef slurries (GBS; 4 days at 24 °C) and surviving populations enumerated. Results from experiment 1 demonstrated that populations of non-O157:H7 STEC serogroups O45, O103, O111 and O121 were significantly different from populations of E. coli O157:H7, and non-O157:H7 STEC serogroups O26 and O145. In contrast, when STEC serogroups were acid-adapted, all populations of non-O157:H7 STEC were significantly different from populations of E. coli O157:H7. Results of experiments in media with aw of 0.88 or 0.78 demonstrated that there was no significant difference between E. coli O157:H7 and any of the non-O157:H7 STEC, regardless of acid-adaptation. In experiment 2, exposure to desiccation resulted in no significant difference in survival between E. coli O157:H7 and non-O157:H7 STEC, regardless of acid-adaptation. Experiment 3 in acidified GBS demonstrated that all non-O157:H7 STEC behaved similarly to E. coli O157:H7, except for E. coli O145, which had a higher reduction than O157:H7. There were no significant differences in bacterial populations associated with GBS with modified aw. Collectively, these results suggest than non-O157:H7 STEC behave similarly to E. coli O157:H7 when exposed to low pH (<4.5) and low aw (0.88 or 0.78) under laboratory conditions.

AB - Shiga toxin-producing Escherichia coli (STEC) are known to adapt and survive acidic conditions. Acid-adaptation also may result in cross-protection against other stressors present in foods, such as reduced water activity (aw), refrigeration conditions, or the presence of antimicrobials. Three independent experiments were conducted with non-adapted (control) and acid-adapted E. coli O157:H7 and non-O157:H7 serogroups (E. coli O26, O45, O103, O111, O121 and O145) in vitro and in situ. Experiment 1: STEC cocktails in media were left untreated (non-adapted; control) or adapted (pH 5.0), exposed to mild acidic conditions (pH 4.5) or reduced aw (0.88 and 0.75) for 4 days at 24 °C, and evaluated for survival. Experiment 2: Non-adapted and acid-adapted STEC cocktails were subjected to desiccation (28 days at 24 °C) on sterile paper disks, and remaining pathogen populations were determined. Experiment 3: Control and acid-adapted STEC were subjected to mild acidic conditions (pH 4.5) and low aw (0.88 or 0.78) in ground beef slurries (GBS; 4 days at 24 °C) and surviving populations enumerated. Results from experiment 1 demonstrated that populations of non-O157:H7 STEC serogroups O45, O103, O111 and O121 were significantly different from populations of E. coli O157:H7, and non-O157:H7 STEC serogroups O26 and O145. In contrast, when STEC serogroups were acid-adapted, all populations of non-O157:H7 STEC were significantly different from populations of E. coli O157:H7. Results of experiments in media with aw of 0.88 or 0.78 demonstrated that there was no significant difference between E. coli O157:H7 and any of the non-O157:H7 STEC, regardless of acid-adaptation. In experiment 2, exposure to desiccation resulted in no significant difference in survival between E. coli O157:H7 and non-O157:H7 STEC, regardless of acid-adaptation. Experiment 3 in acidified GBS demonstrated that all non-O157:H7 STEC behaved similarly to E. coli O157:H7, except for E. coli O145, which had a higher reduction than O157:H7. There were no significant differences in bacterial populations associated with GBS with modified aw. Collectively, these results suggest than non-O157:H7 STEC behave similarly to E. coli O157:H7 when exposed to low pH (<4.5) and low aw (0.88 or 0.78) under laboratory conditions.

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