Survival of Escherichia coli O157:H7 in broth and processed salami as influenced by pH, water activity, and temperature and suitability of media for its recovery

Clavero, M. R. S.; Beuchat, Larry R.

doi:10.1128/aem.62.8.2735-2740.1996

Cited by 138 publications

(62 citation statements)

References 23 publications

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“…Survival of E. coli O157:H7 and Salmonella typhimurium in model brines (23% salt and pH 7) and cheese brine (22-29% salt and pH 5AE3 or 5AE7) was significantly increased when stored at 8°C compared to 15°C (Ingham et al 2000). Clavero and Beuchat (1996) observed, that regardless of the pH (6AE0, 5AE4, and 4AE8) and a w (0AE99, 0AE95, and 0AE90) of TSB, survival of E. coli O157:H7 was better at 5°C than at 20 or 30°C. Breidt et al (2004) investigated the effect of acetic acid on survival of E. coli in simulated acidified pickled products.…”

Section: Discussionmentioning

confidence: 93%

Antagonistic effect of acetic acid and salt for inactivatingEscherichia coliO157:H7 in cucumber puree

Lee

Rhee

Dougherty

et al. 2010

Journal of Applied Microbiology

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Aim: This study was conducted to investigate the effects of acetic acid alone or combined with salt for inhibiting Escherichia coli O157:H7 in cucumber puree during storage time at 5 and 22°C. Methods and Results: Samples at various concentrations were prepared by the addition of acetic acid (0%, 0·25%, 0·5%, 0·75%, 1%, 2%, 2·5%, or 3%) along with NaCl (0% or 3%) and pureed cucumber (50% or 94%). The effect of storage temperature (5 and 22°C) on the survival of E. coli O157:H7 was also tested. The numbers of E. coli O157:H7 were reduced as the amount of acetic acid increased (P < 0·01) and rate of reduction was more rapid at 22°C than at 5°C. Combinations of acetic acid and salt were less effective at killing E. coli O157:H7 in simulated pickled cucumber samples stored at 5 and 22°C than did treatment of acetic acid alone. The concentration of pureed cucumber affected the reduction rate of E. coli O157:H7. When stored at 5°C, E. coli O157:H7 survived for up to 23 days in a mixture of 94% cucumber puree, 1% acetic acid, and 3% NaCl. Conclusions: There was the antagonistic effect of acetic acid and 3% NaCl with regard to the reduction of E. coli O157:H7. Significance and Impact of the Study: Our results suggest that pickled cucumbers prepared with at least 2% acetic acid and stored at room temperature (22°C) after 3 days storage can free from E. coli O157:H7 without heating.

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Section: Discussionmentioning

confidence: 93%

Antagonistic effect of acetic acid and salt for inactivatingEscherichia coliO157:H7 in cucumber puree

Lee

Rhee

Dougherty

et al. 2010

Journal of Applied Microbiology

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“…Tzannetis and Papavassiliou (1975) reported that the death rate of Shigella sonnei and Salmonella Typhimurium in acidic Greek cheeses (pH 4AE0) increased with storage temperature. E. coli O157:H7 has been shown to survive better in acid environment (pH 4AE5) at 7°C than at 22°C (Uyttendaele et al 2001b) and survival of E. coli O157:H7 in acid foods stored at refrigeration temperatures was prolonged compared to survival at ambient temperature (Zhao and Doyle 1994;Clavero and Beuchat 1996). The application of a combination of suboptimal intrinsic and extrinsic factors (hurdle concept) such as reduced pH and reduced temperature, can indeed inhibit the outgrowth of pathogens in foods but may induce prolonged survival of highly virulent pathogens such as Shigella spp.…”

Section: Discussionmentioning

confidence: 99%

Acid tolerance of Shigella sonnei and Shigella flexneri

2002

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Aims: Determination of the behaviour of Shigella sonnei and Sh. flexneri under acid conditions.  Methods and results: The growth and survival of Shigella spp. (9 isolates) in acidified Brain Heart Infusion (BHI) (pH 5·0–3·25 with pH intervals of 0·25) was determined after 6, 24 and 30 h incubation at 37°C. Subsequently, survival of shigellae was studied in apple juice and tomato juice stored at 7°C and 22°C for up to 14 days and in strawberries and a fresh fruit salad, kept at 4°C for 4 and 48 h.  Conclusions: The minimum pH for growth in acidified BHI for Sh. flexneri and Sh. sonnei was, respectively, pH 4·75 and pH 4·50. Survival in fruit juices and fresh fruits depended upon their pH, the type of strain and the incubation temperature. Shigella spp. Survived for up to 14 days in tomato juice and apple juice stored at 7°C. The shortest survival time (2–8 d) was observed in apple juice at 22°C. Sh. sonnei but not Sh. flexneri was recovered after 48 h from strawberries and fruit salad kept at 4°C.  Significance and Impact of the Study: Acid foods, especially if kept at refrigeration temperatures, suppport survival of Shigella spp. and may cause Shigella food poisoning.

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“…Several studies have reported that low temperature enhances the survival of E. coli O157:H7 in acid foods (Zhao et al 1993;Conner and Kotrola 1995;Clavero and Beuchat 1996). Abdul-Raouf et al (1993) reported that various organic acids have different inhibitory effects on E. coli O157:H7 in acidified beef.…”

Section: Acidified Tsa Studymentioning

confidence: 99%

Tolerance of acid‐adapted and non‐adaptedEscherichia coliO157:H7 cells to reduced pH as affected by type of acidulant

Deng

Ryu

Beuchat

1999

Journal of Applied Microbiology

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A study was carried out to determine if three strains of Escherichia coli O157:H7 grown (18 h) in Tryptic Soy Broth (TSB) and TSB supplemented with 1.25% glucose (TSBG), i.e. unadapted and acid-adapted cells, respectively, exhibited changes in tolerance to reduced pH when plated on Tryptic Soy Agar (TSA) acidified (pH 3.9, 4.2, 4.5, 4.8, 5.1 and 5.4) with acetic, citric or malic acids. All test strains grew well on TSA acidified with acetic acid at pH > or = 5.4 or malic acid at pH > or = 4.5; two strains grew on TSA acidified with citric acid at pH > or = 4.5, while the third strain grew at pH > or = 4.8. Acid-adapted and control (unadapted) cells differed little in their ability to form visible colonies on TSA containing the same acid at the same pH. However, on plates not showing visible colonies, acid-adapted cells retained higher viability than unadapted cells when plated on acidified TSA. Growth of acid-adapted and control cells of E. coli O157:H7 inoculated into TSB containing acetic acid (pH 5.4 and 5.7) and citric or malic acids (pH 4.2 and 4.5) was also studied. There was essentially no difference in growth characteristics of the two types of cells in TSB acidified at the same pH with a given acid. Tolerance of acid-adapted and control cells on subsequent exposure to low pH is influenced by the type of acidulant. The order of sensitivity at a given pH is acetic > citric > malic acid. When performing acid challenge studies to determine survival and growth characteristics of E. coli O157:H7 in foods, consideration should be given to the type of acid to which cells have been exposed previously, the procedure used to achieve acidic environments and possible differences in response among strains. The use of strains less affected by pH than type of acidulant or vice versa could result in an underestimation of the potential for survival and growth of E. coli O157:H7 in acid foods.

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Survival of Escherichia coli O157:H7 in broth and processed salami as influenced by pH, water activity, and temperature and suitability of media for its recovery

Cited by 138 publications

References 23 publications

Antagonistic effect of acetic acid and salt for inactivatingEscherichia coliO157:H7 in cucumber puree

Antagonistic effect of acetic acid and salt for inactivatingEscherichia coliO157:H7 in cucumber puree

Acid tolerance of Shigella sonnei and Shigella flexneri

Tolerance of acid‐adapted and non‐adaptedEscherichia coliO157:H7 cells to reduced pH as affected by type of acidulant

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