Enumeration of sublethally heated staphylococci in some dried foods

Hurst, A.; Hendry, G. S.; Hughes, A.; Paley, Beverly

doi:10.1139/m76-100

Cited by 36 publications

(15 citation statements)

References 32 publications

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“…The recovery process takes place in a step-wise manner (Maxcy 1973). Hurst et al (1976) found that dried-injured S. aureus cells fail to develop on the nonselective recovery media (TSA), but recover when pyruvate is added to the nonselective medium. Baird-Parker medium has been shown by Brewer et al (1977) to have greater efficacy in recovery of S. aureus because of its pyruvate content.…”

Section: Recovery Of the Sc-c02 Treatment Injured Cellsmentioning

confidence: 99%

Microbial Safety of Supercritical Carbon Dioxide Processes

Sirisee

Hsieh

Huff

1998

J Food Processing Preservation

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The effect of supercritical CO2 (SC‐CO2) processes on the population of Escherichia coli and Staphylococcus aureus was determined in both phosphate buffer solution and ground beef systems at 35, 42.5 and 50C/10.34, 20.67 and 31.03 MPa. Higher pressures and temperatures significantly decreased the D‐values of both bacteria. No cells survived at 50C. E. coli was more resistant to SC‐CO2 processes than was S. aureus in phosphate buffer solution at 35C and in ground beef at 42.5C. After applying SC‐CO2 at 35C for 1 h in a phosphate buffer solution, pH values dropped from 6.6–6.8 to 3.7–3.9 at each pressure and remained relatively constant at that level for 6 h. While the count of S. aureus recovered completely after 18 h of incubation, under similar conditions E. coli did not.

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Section: Recovery Of the Sc-c02 Treatment Injured Cellsmentioning

confidence: 99%

Microbial Safety of Supercritical Carbon Dioxide Processes

Sirisee

Hsieh

Huff

1998

J Food Processing Preservation

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“…Repaired cells become insensitive to rich agar medium and are able to multiply. Plating media supplemented with compounds that degrade H 2 O 2 or that have an antioxidant activity enhanced the recovery of stressed Salmonella typhimurium (Mackey and Derrick 1986), E. coli (Mackey and Seymour 1987;Calabrese and Bissonnette 1990), and Staphylococcus aureus cells (Hurst et al 1973(Hurst et al , 1976. Pyruvate also increases the number of E. coli O157:H7 cells recovered after freezing and heating (Sophia et al 1996).…”

Section: Introductionmentioning

confidence: 99%

Restoration of culturability of starvation-stressed and low-temperature-stressed Escherichia coli O157 cells by using H 2 O 2 -degrading compounds

Mizunoe

Wai²,

Takade³

et al. 1999

Archives of Microbiology

166

140

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Late-exponential-phase cells of Escherichia coli O157:H- strain E32511/HSC became nonculturable in sterilized distilled water microcosms at 4 degrees C. Plate counts declined from 3 x 10(6) to less than 0.1 CFU/ml in about 21 days. However, when samples of microcosms at 21 days were inoculated onto an agar medium amended with catalase or nonenzyme peroxide-degrading compounds such as sodium pyruvate or alpha-ketoglutaric acid, plate counts increased to 10(4)-10(5) CFU/ml within 48 h. The proposed mode of action of the catalase or pyruvate is via the degradation of the metabolic by-product H2O2, rather than through supplementation of a required nutrient in the recovery of nonculturable cells. Our studies were based on the assumption that E32511/HSC strain responds to starvation and a low temperature by entering a nonculturable state and that the correction of oxidative stress upon the inoculation of bacteria on agar plates promotes recovery of nonculturable cells.

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“…Pyruvate was first used as an agent for repair of stressed staphylococci (Baird-Parker and Davenport 1965) and has been used in many studies with selective (Smith 1990) and nonselective tnedia (Hurst et al 1976). Use of pyruvate for repair of heat-stressed Listeria cells in MMA has had both beneficial (Farber el al.…”

Section: Discussionmentioning

confidence: 99%

RECOVERY LIMITS OF HEAT‐INJURED LISTERIA MONOCYTOGENES FROM ENRICHMENT BROTH AND ENRICHED CULTURES OF INOCULATED FOODS

Tran

Hitchins

1993

Journal of Food Safety

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Recovery of heat‐injured Listeria monocytogenes strain LM82 was evaluated quantitatively in Listeria enrichment broth (LEB) and in enriched cultures of cooked shrimp and Brie cheese. LM82 cells [108 colony forming units (CFU)/ml] were heated for 60 min at 52C in phosphate‐buffered saline. After 24 and 48 h enrichment, injured LM82 (6 replicates at each of 5 inoculation levels) were isolated on 3 selective media: lithium chloride‐phenylethanol‐moxalactam agar (LPMA), modified McBride agar (MMA) and Oxford agar (OXA). The recovery limit was expressed as a 50% end point value (RL50), which is the calculated inoculation value necessary to recover LM82 on half of the replicates of each type of isolation agar plate after streaking from the enrichment of measured inoculum. The RL50 values for injured cells were comparable to those of uninjured cells after 48 h enrichment in LEB without food. The type of isolation agar did not affect the RL50 value, although with food, MMA gave consistently but not significantly higher values, i.e., recovery inferior to that of LPMA and OXA. RL50 values were higher in Brie and cooked shrimp, presumably because of the competitive microflora in those foods. Addition of lactose or pyruvate to LEB improved recovery but had little or no effect when foods were present.

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Enumeration of sublethally heated staphylococci in some dried foods

Cited by 36 publications

References 32 publications

Microbial Safety of Supercritical Carbon Dioxide Processes

Microbial Safety of Supercritical Carbon Dioxide Processes

Restoration of culturability of starvation-stressed and low-temperature-stressed Escherichia coli O157 cells by using H 2 O 2 -degrading compounds

RECOVERY LIMITS OF HEAT‐INJURED LISTERIA MONOCYTOGENES FROM ENRICHMENT BROTH AND ENRICHED CULTURES OF INOCULATED FOODS

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