Behavior of an Emetic Bacillus cereus Strain in Rice Food (original) (raw)
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Foodborne Pathogens and Disease, 2012
Whereas the prevalence of Bacillus cereus emetic strains in the environment has been shown to be very low, there is a lack of information on the prevalence of its toxin, cereulide, in food. Yet, the rice leftovers of a family outbreak which occurred after the consumption of dishes taken away from an Asian restaurant revealed significant amounts of cereulide, reaching up to 13,200 ng/g of food. The occurrence of cereulide in rice dishes collected from various restaurants was therefore evaluated using the liquid chromatography coupled with tandem mass spectrometry method, which allows for the direct quantification of the toxin in food. The cereulide prevalence was found to be 7.4% when samples were analyzed at the day of sampling, but reached 12.9% when exposed to temperature abuse conditions (25°C). The cereulide concentrations observed in cooked rice dishes were low (approximately 4 ng/g of food). However, since little is known yet about the potential chronic toxicity of cereulide, one needs to be very careful and vigilant.
International Journal of PharmTech Research, 2015
The aim of this study has been an investigation of the presence of Bacillus cereus and detection of enterotoxigenic genes in cooked rice samples through utilizing a PCR technique. In this study the providence of B.cereus was carried out to cooked rice samples and the B.cereus isolates were investigated for enterotoxigenic gene. The cooked rice samples were purchased from several restaurants in the area of (Bangi, Kajang and UKM) Selangor, Malaysia. A total of 70 samples have been analyzed. B. cereus contamination has been formed between 1.2 × 10 4 to 1.6 × 10 6 cfu/g cooked of 110 colonies of tentative B. cereus have been tested onto mannitol egg yolk polymyxin agar and Chromogenic Bacillus cereus Agar, and 35 colonies have been detected as B. cereus using biochemical test and partial sequence of 16s r DNA sequences analysis. The B. cereus isolates that are BC1 to BC35 have been distinguished for hemolytic enterotoxin (HBL complex encoding gene (hblD), and ematic (ces) gene toxin. 12 isolates have been reported to be positive towards hblD, None of the B. cereus isolates have been found positive towards ematic(ces) gene. Therefore, the presence of B. cereus and their enterotoxigenic genes in cooked rice samples can be regarded as a potential risk for public health.
International journal of …, 2006
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.
Identification of emetic toxin producingBacillus cereusstrains by a novel molecular assay
Fems Microbiology Letters, 2004
Bacillus cereus causes two types of gastrointestinal diseases: emesis and diarrhea. The emetic type of the disease is attributed to the heat-stable depsipeptide cereulide and symptoms resemble Staphylococcus aureus intoxication, but there is no rapid method available to detect B. cereus strains causing this type of disease. In this study, a polymerase chain reaction (PCR) fragment of unknown function was identified, which was shown to be specific for emetic toxin producing strains of B. cereus. The sequence of this amplicon was determined and a PCR assay was developed on this basis. One hundred B. cereus isolates obtained from different food poisoning outbreaks and diverse food sources from various geographical locations and 29 strains from other species belonging to the B. cereus group were tested by this assay. In addition, 49 non-B. cereus group strains, with special emphasis on food pathogens, were used to show that the assay is specific for emetic toxin producing B. cereus strains. The presented PCR assay is the first molecular tool for the rapid detection of emetic toxin producing B. cereus strains.
Determination of Bacillus cereus Emetic Toxin in Food Products by Means of LC–MS²
Food Analytical Methods, 2011
Cereulide is the heat-stable toxin produced by certain strains of Bacillus cereus. It is the main virulence factor of emetic B. cereus strains, which causes the emetic food poisoning syndrome, including rare fatal cases of food intoxications. Due to presumably low intoxication doses, a sensitive, specific, and robust technique is needed for its detection. In 2002, a LC-MS method was developed which allowed absolute quantification of cereulide using valinomycin as standard. This study describes the validation, according to the Commission Decision 2002/657/EC, of the LC-MS² method, a tandem mass spectrometry technique, which guarantees lower detection limit and higher specificity. The LC-MS² method, calibrated with valinomycin, was validated in rice and tested on various matrices (i.e., red beans, spices, and chili con carne) containing cereulide. The process combines a simple extraction step from the food matrix followed by LC-MS² analysis and detection by ion trap mass spectrometer. The detection limit for cereulide in rice was 0.5 ng eq/g, which is 20 to 2,500 times lower than currently understood intoxicative doses between 10 and 1.280 ng/g previously reported for cereulide. The validated method was specific, sensitive, repeatable, and reproducible with recoveries ranging from 77% to 101%.
Identification of emetic toxin producing Bacillus cereus strains by a novel molecular assay
FEMS microbiology …, 2004
Bacillus cereus causes two types of gastrointestinal diseases: emesis and diarrhea. The emetic type of the disease is attributed to the heat-stable depsipeptide cereulide and symptoms resemble Staphylococcus aureus intoxication, but there is no rapid method available to detect B. cereus strains causing this type of disease. In this study, a polymerase chain reaction (PCR) fragment of unknown function was identified, which was shown to be specific for emetic toxin producing strains of B. cereus. The sequence of this amplicon was determined and a PCR assay was developed on this basis. One hundred B. cereus isolates obtained from different food poisoning outbreaks and diverse food sources from various geographical locations and 29 strains from other species belonging to the B. cereus group were tested by this assay. In addition, 49 non-B. cereus group strains, with special emphasis on food pathogens, were used to show that the assay is specific for emetic toxin producing B. cereus strains. The presented PCR assay is the first molecular tool for the rapid detection of emetic toxin producing B. cereus strains.
Contaminated Bacillus cereus in Lao and Thai fermented soybean “Tua Nao”
Japan Agricultural Research Quarterly: JARQ
A spontaneous remission is observed after 24 hrs. in most cases, and one fatal case caused by polluted pasta salad has been described (Dierick et al. 2005). According to Mikami et al. (1995), 66% and 3.1% of 524 B. cereus strains isolated from the environment and foods produced diarrheal and emetic toxins (cereulide), respectively. A higher (12%) ratio of emetic toxin positive strains was isolated from starch foods made from cereal powders (Kashiwagi et al. 2005). B. cereus grows well at room temperature in starch foods to produce heatresistant emetic toxin (Agata 1997, 2002). For these reasons, many B. cereus food poisoning incidents are caused by the intake of cooked rice, noodles or sticky rice cakes (Shinagawa 1990). In December 2001, 346 people who ate sweet red bean paste covered with sticky rice cake (An-iri-mochi) in Kumamoto prefecture in Japan suffered food poisoning caused by cereulide (Huruse et al. 2004, Matsuoka et al. 2003). Fermentation during Tua Nao production occurs due
Risk of Bacillus cereus in Relation to Rice and Derivatives
Foods, 2021
Rice is a very popular food throughout the world and the basis of the diet of the citizens of many countries. It is used as a raw material for the preparation of many complex dishes in which different ingredients are involved. Rice, as a consequence of their cultivation, harvesting, and handling, is often contaminated with spores of Bacillus cereus, a ubiquitous microorganism found mainly in the soil. B. cereus can multiply under temperature conditions as low as 4 °C in foods that contain rice and have been cooked or subjected to treatments that do not produce commercial sterility. B. cereus produces diarrhoeal or emetic foodborne toxin when the consumer eats food in which a sufficient number of cells have grown. These circumstances mean that every year many outbreaks of intoxication or intestinal problems related to this microorganism are reported. This work is a review from the perspective of risk assessment of the risk posed by B. cereus to the health of consumers and of some con...
Food microbiology, 2011
Two outbreak-related Bacillus cereus emetic strains were investigated for their growth and cereulide production potential in penne pasta at 4, 8 and 25 C during 7-day storage. Cereulide production was detected and quantified by LC-MS method (LOD of 1 ng/ml, LOQ of 5 ng/ml) and growth was determined by culture-based enumeration. Inoculated B. cereus strains (10 5 CFU/g) were able to reach counts of more than 10 8 CFU/g and cereulide production of about 500 ng/g already after 3 days of storage at 25 C. Interestingly, a constant increase of the toxin was noticed during incubation at ambient temperature storage: the cereulide was continuously produced during the bacterial stationary growth phase reaching maximal amounts at the end of the experiment (7 days, concentration of about 1000 ng/g). Strictly respected cold chain temperature as 4 C did not allow any detectable cereulide production for any of the two tested strains. At the limited temperature abuse of 8 C, a detectable amount of cereulide was observed after two days for one of the strain (TIAC303) (<LOQ). These results confirm that cereulide production is controlled by multiple factors (from type of strain to temperature) and that prolonged storage time plays a crucial role for consumer safety.