Characteristics of some psychrotrophic Bacillus cereus isolates

Dufrenne, J.; Bijwaard, M.; Giffel, Meike te; Beumer, R.R.; Notermans, S.

doi:10.1016/0168-1605(94)00163-z

Cited by 98 publications

(53 citation statements)

References 12 publications

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“…Although several studies provide data on inactivation and germination of B. cereus spores (e.g. Johnson et al, 1982;Dufrenne et al, 1995;Pol et al, 2001), quantitative models to predict the number of spores after growth are not available to our knowledge. Therefore, in this study the spore load after growth is expressed as a simple nongermination fraction P sng , estimated by expert opinion, based on these data.…”

Section: Spore Germinationmentioning

confidence: 99%

A retail and consumer phase model for exposure assessment of Bacillus cereus

Nauta

2003

International Journal of Food Microbiology

106

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An exposure assessment is conducted for psychrotrophic and mesophilic Bacillus cereus in a cooked chilled vegetable product. A model is constructed that covers the retail and consumer phase of the food pathway, using the output of a similar model on the industrial process as input. Microbial growth is the predominant process in the model. Variability in time and temperature during transport and storage is included in the model and different domestic refrigerator temperature distributions are compared. As an end point, probable levels of B. cereus colony forming units (cfu) in packages of vegetable purée are predicted at the moment the consumer takes the product from its refrigerator, that is prior to a cooking process. The psychrotrophic strain is predicted to end up above a threshold level of 10 5 cfu/g in 0.9% to 6.3% of the vegetable purée packages, depending on domestic refrigerator temperature. Accounting for spoilage this reduces to 0.3% to 2.4%. Even if the purée is stored at 4 jC in the domestic refrigerator and use-by-date (UBD) is respected, the threshold level may be passed. For the mesophilic strain the threshold level is rarely passed, but in contrast to the total viable count, the spore load at the end point is predicted to be higher than in the psychrotrophic strain. Our study illustrates how an exposure assessment model, which may be used in quantitative risk assessment, can integrate expertise in modelling, food processing and microbiology over the food pathway, and thus evaluate food safety, identify gaps in knowledge and compare risk management measures. As important gaps in knowledge, the lack of sporulation and germination models and data, validated non-isothermal growth models and a spoilage model useful for risk assessment are identified. Knowledge of the dose -response relationship is limited and does not allow a full risk assessment. It is shown that exposure can be lowered by lowering domestic refrigerator temperatures, and less so much by monitoring and withdrawing contaminated products at the end of industrial processing. D

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Section: Spore Germinationmentioning

confidence: 99%

A retail and consumer phase model for exposure assessment of Bacillus cereus

Nauta

2003

International Journal of Food Microbiology

106

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“…The species B. cereus covers a huge diversity in genetic characters (Guinebretière and Sanchis, 2003, Helgason et al, 2004and Hill et al, 2004, virulence factors (Beattie and Williams, 1999, Choma et al, 2000, Helgason et al, 2004and Hill et al, 2004 and survival or growth characteristics (Dufrenne et al, 1994, Dufrenne et al, 1995, Choma et al, 2000and Nguyen-the et al, 2003. However there is some evidence that emetic toxin-producing strains form a distinct cluster within B. cereus with some specific characters (such as the inability to hydrolyse starch) (Shinagawa, 1990, Agata et al, 1996, Pirttijarvi et al, 1999and EhlingSchulz et al, 2005b.…”

Section: Introductionmentioning

confidence: 99%

Emetic toxin-producing strains of Bacillus cereus show distinct characteristics within the Bacillus cereus group

Carlin

Fricker

Pielaat

et al. 2006

International Journal of Food Microbiology

146

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One hundred representative strains of Bacillus cereus were selected from a total collection of 372 B. cereus strains using two typing methods (RAPD and FT-IR) to investigate if emetic toxin-producing hazardous B. cereus strains possess characteristic growth and heat resistance profiles. The strains were classified into three groups: emetic toxin (cereulide)-producing strains (n = 17), strains connected to diarrheal foodborne outbreaks (n = 40) and food-environment strains (n = 43), these latter not producing the emetic toxin. Our study revealed a shift in growth limits towards higher temperatures for the emetic strains, regardless of their origin. None of the emetic toxin-producing strains were able to grow below 10 °C. In contrast, 11% (9 food-environment strains) out of the 83 non-emetic toxin-producing strains were able to grow at 4 °C and 49% at 7 °C (28 diarrheal and 13 food-environment strains). non-emetic toxin-producing strains. All emetic toxin-producing strains were able to grow at 48 °C, but only 39% (16 diarrheal and 16 food-environment strains) of the non-emetic toxinproducing strains grew at this temperature. Spores from the emetic toxin-producing strains showed, on average, a higher heat resistance at 90 °C and a lower germination, particularly at 7 °C, than spores from the other strains. No difference between the three groups in their growth kinetics at 24 °C, 37 °C, and pH 5.0, 7.0, and 8.0 was observed. Our survey shows that emetic toxin-producing strains of B. cereus have distinct characteristics, which could have important implication for the risk assessment of the emetic type of B. cereus caused food poisoning. For instance, emetic strains still represent a special risk in heat-processed foods or preheated foods that are kept warm (in restaurants and cafeterias), but should not pose a risk in refrigerated foods.

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“…Diarrheal outbreaks are caused by the enterotoxins produced during vegetative growth of the bacterium in the small intestine, and a wide variety of foods, including meat and vegetable dishes, soups, and dairy products, have been implicated in such outbreaks (16). Furthermore, observations that toxin-producing psychrotrophic strains have been implicated in outbreaks of food-borne illness (9,10,18,21) have raised concerns about their growth and toxin production in refrigerated foods.…”

mentioning

confidence: 99%

“…Samples of each culture were removed at different times (6,10,24,48, and 72 h) after bacteriocin addition, centrifuged, filter sterilized, and tested to determine the reciprocal toxin titer by using a B. cereus reverse passive latex agglutination diarrheic enterotoxin detection kit (BCET-RPLA; Oxoid). Control cultures released high titers of enterotoxin after 6 h of cultivation, and the titers reached a maximum at 24 h (Fig.…”

mentioning

confidence: 99%

Inhibition of Bacterial Growth, Enterotoxin Production, and Spore Outgrowth in Strains of Bacillus cereus by Bacteriocin AS-48

Abriouel

Maqueda

Gálvez

et al. 2002

Appl Environ Microbiol

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Bacteriocin AS-48 showed high bactericidal activity for mesophilic and psychrotrophic strains of Bacillus cereus over a broad pH range. AS-48 inhibition of the enterotoxin-producing strain LWL1 was enhanced by sodium nitrite, sodium lactate, and sodium chloride. The latter also enhanced AS-48 activity against strain CECT 131. Bacterial growth and enterotoxin production by strain LWL1 were completely inhibited at bacteriocin concentrations of 7.5 g/ml. At subinhibitory bacteriocin concentrations, enterotoxin production decreased markedly and sporulation was delayed. Intact spores were resistant to AS-48 but became gradually sensitive to AS-48 during the course of germination.

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Characteristics of some psychrotrophic Bacillus cereus isolates

Cited by 98 publications

References 12 publications

A retail and consumer phase model for exposure assessment of Bacillus cereus

A retail and consumer phase model for exposure assessment of Bacillus cereus

Emetic toxin-producing strains of Bacillus cereus show distinct characteristics within the Bacillus cereus group

Inhibition of Bacterial Growth, Enterotoxin Production, and Spore Outgrowth in Strains of Bacillus cereus by Bacteriocin AS-48

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