**2. Pathogenic** *Bacillus cereus* **transmitted through rice**

#### **2.1 Characteristics and diseases caused by** *Bacillus cereus*

*Bacillus cereus* is a spore-forming bacteria that produces a toxin that causes vomiting or diarrhea. Symptoms are generally mild and short-lived (up to 24 h). *Bacillus cereus* commonly found in the environment (e.g., soil) and various foods. Spores are able to withstand harsh environments, including average cooking temperatures. *Bacillus cereus* is a Gram-positive, motile (flagellated), spore-forming, rod-shaped bacterium belonging to the genus Bacillus. Species in this genus include *Bacillus anthracis, Bacillus cereus, Bacillus mycoides, Bacillus thuringiensis, Bacillus pseudomycoides, and Bacillus weihenstephanensis* [17, 20].

*Bacillus cereus* is widespread and easy to find in the soil, where it adopts a saprophytic life cycle, germinate, grow, and sporulate in this environment [21]. Spores are more resistant to environmental stress than vegetative cells because of their metabolic dormancy and hard physical properties [22].

*Bacillus cereus* causes two types of diseases, namely emetic syndrome and diarrhea syndrome. Emetic syndrome causes by emetic toxins produced by bacteria during the growth phase in food, a diarrheal syndrome caused by diarrheal toxins produced during bacterial growth in the small intestine [23].

*Bacillus cereus* has a mesophilic or psychrotrophic strain. Mesophilic strains grow well at 37°C but do not grow below 10°C, whereas psychrotrophic strains grow well at cold temperatures but grow poorly at 37°C [24]. All *Bacillus cereus* isolates associated with emetic toxin production have found to be mesophilic [25]. *Bacillus cereus* growth is optimal in the presence of oxygen, although it continues to grow under anaerobic conditions. *Bacillus cereus* cells grown in aerobic conditions were less resistant to heat and acid than *Bacillus cereus* cells that grew anaerobically or microaerobically [26]. *Bacillus cereus*' mesophilic strains have shown to have higher acid resistance than psychotropic strains [25].

Spores are more resistant to dry heat than humid heat, with heat resistance usually higher in foods with lower water activity. Spores are also more resistant to radiation than vegetative cells [22]. Nisin is a preservative that used to inhibit germination and spore growth. Antimicrobials that inhibit the growth of *Bacillus cereus* include benzoic, sorbic, and ethylenediaminetetraacetic acids [22].

Symptoms of *Bacillus cereus* disease cause two types of foodborne illness, namely emetic syndrome (vomiting) and diarrhea. Vomiting syndrome is poisoning caused by the ingestion of a cyclic peptide toxin called cereulide that has been pre-formed

**125**

*Pathogens Transmitted through Contaminated Rice DOI: http://dx.doi.org/10.5772/intechopen.93757*

infections in humans [29].

to 56°C for 5 min [22].

enterotoxins [35].

lial cells plays a role in causing diarrhea [27].

**2.2 Mode of transmission** *Bacillus cereus* **food poisoning**

in food during growth by *Bacillus cereus*. This syndrome has a short incubation period and recovery time. Symptoms of nausea, vomiting, and stomach cramps occur within 1–5 h after ingestion, with recovery usually within 6–24 h [27].

The diarrheal syndrome caused by enterotoxins produced by *Bacillus cereus* in the host body, the incubation period before the onset of the disease is 8–16 h, and infection usually lasts 12–14 h. However, it can continue for several days. Symptoms are generally mild, with stomach cramps, watery diarrhea, and nausea [28]. In a small number of cases, both toxins produced, and vomiting and diarrhea develop [17]. No form of the disease is considered life-threatening for normal healthy individuals, with few fatal cases reported [22]. *Bacillus cereus* has been associated with the non-food-related illness, although this is rare. These bacteria have been found in postoperative and traumatic wounds and can cause opportunistic infections, especially in individuals with immune system disorders, such as septicemia, meningitis, and pneumonia. *Bacillus cereus* has also known to occasionally cause localized eye

The pathogenic mechanisms for *Bacillus cereus* emetic disease are well known. Emetic toxins (cereulide) cause vacuole formation in HEp-2 cells in the laboratory [29]. Cereulide in experimental animals caused vomiting, potentially by binding to 5-HT3 receptors in the stomach/small intestine to stimulate the vagus nerve and brain [30]. Cereulide produced by the Non-Ribosomal Peptide Synthetase Complex (NRPS) [31]. All NRPS clusters have characterized [23], resulting in a precise method for detecting cereulide-producing *Bacillus cereus* strains [32]. Emetic toxin production has shown to occur in skim milk in the temperature range of 12–37°C, with more toxins produced at 12 and 15°C than at higher temperatures [33]. Emetic toxins are highly resistant to environmental factors, exhibiting stability from a pH

Three types of enterotoxins are associated with a form of diarrhea syndrome, namely three components of the enterotoxin Hemolysin BL (HBL), three parts of Non-Hemolytic Enterotoxin (NHE) and one element of cytotoxin K. Enterotoxins are released into the small intestine by the surviving vegetative cells of *Bacillus cereus* [34]. Diarrheal enterotoxins are stable at pH 4–11 and deactivated by heating

Up to 26% of the vegetative cells of *Bacillus cereus* can survive as they travel through the stomach. Diarrheal enterotoxins are unstable at low pH in the stomach and degraded by digestive enzymes. Any previously formed enterotoxins in food are destroyed during passage through the stomach so that they do not cause disease if ingested [22]. In contrast, *Bacillus cereus* spores can pass unaffected by the gastric barrier. Spores need to be triggered by nutrients and intestinal epithelial cells to initiate germination. In the small intestine, spores germinate, grow and produce

A vital virulence factor required to cause diarrhea symptoms is the ability of vegetative cells and *Bacillus cereus* spores to adhere to the small intestine's epithelial cell walls. Spore and cell adhesion efficiency show to be low, around 1% [35]. Enterotoxins' ability to damage tissue and damage the plasma membrane of small intestinal epithe-

The pattern of transmission *Bacillus cereus* food poisoning can be caused by ingesting large numbers of bacterial cells and spores in contaminated food (diarrhea type) or by ingesting food contaminated with pre-formed toxins (emetic type). Transmission of this disease caused by the consumption of contaminated food, improper handling/storage of food, and inadequate cooling of cooked food [36].

of 2–11 and heating to 100°C for 150 min (pH 8.7–10.6) [22].

#### *Pathogens Transmitted through Contaminated Rice DOI: http://dx.doi.org/10.5772/intechopen.93757*

*Recent Advances in Rice Research*

*Staphylococcus aureus* is naturally present in the human body, so these bacteria are one of the essential agents causing food poisoning that often occurs in society. The most significant cause of *Staphylococcus aureus* entry into the food chain (which then causes staphylococcal poisoning) is the low sanitation of workers handling food [18]. According to the Food Standards Agency (FSA), there are nearly 900,000 food poisoning cases each year. The lifestyle that has changed in recent years has resulted in an increasing dependence on ready-to-eat food, eating out more than cooking, busyness results in having less time to prepare and cook food. This habit is the reason that increases the number of cases of food poisoning [19]. Apart from that, environmental factors also influence the level of contamination. Food prepared under unfavorable conditions and environment implies a higher incidence of food poisoning than others [18]. Food poisoning occurs more frequently in developing countries than in developed countries. This situation is due to differences in the

*Bacillus cereus* is a spore-forming bacteria that produces a toxin that causes vomiting or diarrhea. Symptoms are generally mild and short-lived (up to 24 h). *Bacillus cereus* commonly found in the environment (e.g., soil) and various foods. Spores are able to withstand harsh environments, including average cooking temperatures. *Bacillus cereus* is a Gram-positive, motile (flagellated), spore-forming, rod-shaped bacterium belonging to the genus Bacillus. Species in this genus include *Bacillus anthracis, Bacillus cereus, Bacillus mycoides, Bacillus thuringiensis, Bacillus pseudomy-*

*Bacillus cereus* is widespread and easy to find in the soil, where it adopts a saprophytic life cycle, germinate, grow, and sporulate in this environment [21]. Spores are more resistant to environmental stress than vegetative cells because of their

*Bacillus cereus* causes two types of diseases, namely emetic syndrome and diarrhea syndrome. Emetic syndrome causes by emetic toxins produced by bacteria during the growth phase in food, a diarrheal syndrome caused by diarrheal toxins

*Bacillus cereus* has a mesophilic or psychrotrophic strain. Mesophilic strains grow well at 37°C but do not grow below 10°C, whereas psychrotrophic strains grow well at cold temperatures but grow poorly at 37°C [24]. All *Bacillus cereus* isolates associated with emetic toxin production have found to be mesophilic [25]. *Bacillus cereus* growth is optimal in the presence of oxygen, although it continues to grow under anaerobic conditions. *Bacillus cereus* cells grown in aerobic conditions were less resistant to heat and acid than *Bacillus cereus* cells that grew anaerobically or microaerobically [26]. *Bacillus cereus*' mesophilic strains have shown to have higher

Spores are more resistant to dry heat than humid heat, with heat resistance usually higher in foods with lower water activity. Spores are also more resistant to radiation than vegetative cells [22]. Nisin is a preservative that used to inhibit germination and spore growth. Antimicrobials that inhibit the growth of *Bacillus* 

Symptoms of *Bacillus cereus* disease cause two types of foodborne illness, namely emetic syndrome (vomiting) and diarrhea. Vomiting syndrome is poisoning caused by the ingestion of a cyclic peptide toxin called cereulide that has been pre-formed

*cereus* include benzoic, sorbic, and ethylenediaminetetraacetic acids [22].

level of sanitation between developed and developing countries [18].

**2. Pathogenic** *Bacillus cereus* **transmitted through rice**

**2.1 Characteristics and diseases caused by** *Bacillus cereus*

*coides, and Bacillus weihenstephanensis* [17, 20].

acid resistance than psychotropic strains [25].

metabolic dormancy and hard physical properties [22].

produced during bacterial growth in the small intestine [23].

**124**

in food during growth by *Bacillus cereus*. This syndrome has a short incubation period and recovery time. Symptoms of nausea, vomiting, and stomach cramps occur within 1–5 h after ingestion, with recovery usually within 6–24 h [27].

The diarrheal syndrome caused by enterotoxins produced by *Bacillus cereus* in the host body, the incubation period before the onset of the disease is 8–16 h, and infection usually lasts 12–14 h. However, it can continue for several days. Symptoms are generally mild, with stomach cramps, watery diarrhea, and nausea [28]. In a small number of cases, both toxins produced, and vomiting and diarrhea develop [17].

No form of the disease is considered life-threatening for normal healthy individuals, with few fatal cases reported [22]. *Bacillus cereus* has been associated with the non-food-related illness, although this is rare. These bacteria have been found in postoperative and traumatic wounds and can cause opportunistic infections, especially in individuals with immune system disorders, such as septicemia, meningitis, and pneumonia. *Bacillus cereus* has also known to occasionally cause localized eye infections in humans [29].

The pathogenic mechanisms for *Bacillus cereus* emetic disease are well known. Emetic toxins (cereulide) cause vacuole formation in HEp-2 cells in the laboratory [29]. Cereulide in experimental animals caused vomiting, potentially by binding to 5-HT3 receptors in the stomach/small intestine to stimulate the vagus nerve and brain [30]. Cereulide produced by the Non-Ribosomal Peptide Synthetase Complex (NRPS) [31]. All NRPS clusters have characterized [23], resulting in a precise method for detecting cereulide-producing *Bacillus cereus* strains [32]. Emetic toxin production has shown to occur in skim milk in the temperature range of 12–37°C, with more toxins produced at 12 and 15°C than at higher temperatures [33]. Emetic toxins are highly resistant to environmental factors, exhibiting stability from a pH of 2–11 and heating to 100°C for 150 min (pH 8.7–10.6) [22].

Three types of enterotoxins are associated with a form of diarrhea syndrome, namely three components of the enterotoxin Hemolysin BL (HBL), three parts of Non-Hemolytic Enterotoxin (NHE) and one element of cytotoxin K. Enterotoxins are released into the small intestine by the surviving vegetative cells of *Bacillus cereus* [34]. Diarrheal enterotoxins are stable at pH 4–11 and deactivated by heating to 56°C for 5 min [22].

Up to 26% of the vegetative cells of *Bacillus cereus* can survive as they travel through the stomach. Diarrheal enterotoxins are unstable at low pH in the stomach and degraded by digestive enzymes. Any previously formed enterotoxins in food are destroyed during passage through the stomach so that they do not cause disease if ingested [22]. In contrast, *Bacillus cereus* spores can pass unaffected by the gastric barrier. Spores need to be triggered by nutrients and intestinal epithelial cells to initiate germination. In the small intestine, spores germinate, grow and produce enterotoxins [35].

A vital virulence factor required to cause diarrhea symptoms is the ability of vegetative cells and *Bacillus cereus* spores to adhere to the small intestine's epithelial cell walls. Spore and cell adhesion efficiency show to be low, around 1% [35]. Enterotoxins' ability to damage tissue and damage the plasma membrane of small intestinal epithelial cells plays a role in causing diarrhea [27].

#### **2.2 Mode of transmission** *Bacillus cereus* **food poisoning**

The pattern of transmission *Bacillus cereus* food poisoning can be caused by ingesting large numbers of bacterial cells and spores in contaminated food (diarrhea type) or by ingesting food contaminated with pre-formed toxins (emetic type). Transmission of this disease caused by the consumption of contaminated food, improper handling/storage of food, and inadequate cooling of cooked food [36].


#### **Table 1.**

*Cases of* Bacillus cereus *contamination in rice (rice-based food).*

#### **2.3 Case contamination and precautions for** *Bacillus cereus* **in rice**

Cases of contamination of *Staphylococcus aureus* on rice, either in the form of raw rice or cooked rice and other processed rice products, are found in several countries. Further explanations can see in **Table 1**.

Precautions for contamination of *Bacillus cereus* in rice:

1.Processing (thoroughly cooked and quickly cooled) is one of the easiest ways to prevent foodborne illness associated with Bacillus spp. [37].

**127**

poisoning [45, 46].

*Pathogens Transmitted through Contaminated Rice DOI: http://dx.doi.org/10.5772/intechopen.93757*

Staphylococcal Enterotoxin (SE) [39, 40].

toxins [38].

optimum of 6–7 [41].

outbreaks in India [42].

4.If frozen food is allowed to thaw, it must remain at 41°F/5°C or lower [37].

5.Steaming under pressure, roasting, frying, and grilling foods will destroy the vegetative cells and spores if temperatures within foods are ≥ 145ºF/63ºC [38].

6.Foods that contain emetic toxins need to be heated to 259°F/126°C for more than 90 min—reheating food until steaming is not sufficient to kill emetic

**3. Pathogenic** *Staphylococcus aureus* **transmitted through rice**

*Staphylococcus aureus* is one of the bacteria that cause food poisoning. *Staphylococcus aureus* is commonly found in the environment (soil, water, and air) and located on humans' nose and skin. *Staphylococcus aureus* is a spherical, Gram-positive, non-spore bacteria. The genus Staphylococcus divided into 32 species and subspecies. *Staphylococcus aureus* causes food poisoning by producing

*Staphylococcus aureus*'s growth and survival depend on several environmental factors such as temperature, water activity (aw), pH, presence of oxygen, and food composition. These physical growth parameters varied for different strains of *Staphylococcus aureus* [41]. The temperature range for *Staphylococcus aureus* growth is 7–48°C, with an optimum temperature of 37°C. *Staphylococcus aureus* is resistant to freezing and does well in foods stored below −20°C; however, viability is reduced at −10 to 0°C. *Staphylococcus aureus* easily killed during pasteurization or cooking. *Staphylococcus aureus* growth occurs in the pH range 4.0–10.0, with an

*Staphylococcus aureus* is a facultative anaerobe so it can grow in both aerobic and anaerobic conditions. However, growth occurs at a much slower rate under anaerobic conditions [41]. For non-sporing mesophilic bacteria, *Staphylococcus aureus* has relatively high heat resistance [41]. A highly heat resistant *Staphylococcus aureus* strain (D-value at 60°C > 15 min in broth) has identified from foodborne

Several chemical preservatives, including sorbate and benzoate, inhibit the growth of *Staphylococcus aureus*. The effectiveness of this preservative increases as

Symptoms of staphylococcal food poisoning generally have a rapid onset, appearing approximately 3 h after ingestion (range 1–6 h). Common symptoms include nausea, vomiting, stomach cramps, and diarrhea. The individual may not show all the signs associated with the disease. In severe cases, headaches, muscle cramps, and temporary changes in blood pressure and pulse may occur. Recovery is usually between 1 and 3 days [39, 41]. Death is rare (0.03% for the general population) but occasionally reported in children and the elderly (death rate 4.4%) [40]. *Staphylococcus aureus* can cause various health problems not related to food such as skin inflammation (e.g., ulcers and style), mastitis, respiratory tract infections,

Staphylococcal food poisoning caused by the ingestion of foods containing pre-formed SE [44], there are several types of SE; enterotoxin A is most commonly associated with staphylococcal food poisoning. Enterotoxins D, E, and H, and to a lesser extent B, G, and I have also associated with staphylococcal food

the pH decreases. Methyl and propyl parabens are also useful [41, 43].

wound sepsis, and toxic shock syndrome [40, 41].

**3.1 Characteristics and diseases caused by** *Staphylococcus aureus*


*Recent Advances in Rice Research*

rice and glutinous rice

2009 Brown

2012 Cooked rice (white rice, fried rice)

2012 Cooked

2013 Baby food (made from rice)

2018 Local

2019 Cooked rice (yellow rice)

2020 Rice/

**Table 1.**

and raw rice

unhulled (coarse) rice

noodles

**Year Food Country Findings Article title**

2009 Raw rice Amerika *Bacillus* species spores

Korea 15 (37%) of 83 samples of brown rice, 23 (37%) of 63 samples of glutinous rice

> found in 94 (52.8%) rice samples with an average concentration of

cereulide found in rice dishes is around four

the presence of *Bacillus cereus*, the highest number: 3.34 × 101

enterotoxigenic genes have found in infant diets in Iran

*cereus* bacteria in all samples found to be more than 1100 MPN/g

contaminated with *Bacillus cereus*

samples (50%) were positive for *Bacillus* 

32.6 CFU/g

Belgia The concentration of

ng/g

Pakistan All rice samples showed

CFU/ml

Malaysia The number of *Bacillus* 

Indonesia 21% of yellow rice

China 59 out of 119 rice/noodle

*cereus*

Iran *Bacillus cereus* and its

Prevalence, Genetic diversity, and Antibiotic Susceptibility of *Bacillus cereus* Strains Isolated from Rice and Cereals Collected

Detection of Toxigenic *Bacillus cereus* and *Bacillus thuringiensis* in

Prevalence and Levels of *Bacillus cereus* Emetic Toxin in Rice Dishes Randomly Collected from Restaurants and Comparison with the Levels Measured in a Recent Foodborne Outbreak [4]

Microbial Assessment of Uncooked and Cooked Rice Samples Available in Local Markets of Lahore [5]

*Bacillus cereus* in Infant Foods: Prevalence Study and Distribution of Enterotoxigenic Virulence Factors in Isfahan Province, Iran [6]

Presence of *Bacillus cereus* from Local Unhusked (Rough) Rice Samples in Sarawak, Malaysia [7]

*Staphylococcus aureus* and *Bacillus cereus* in Yellow Rice [8]

A Study on Prevalence and Characterization of *Bacillus cereus* in Ready-to-Eat Foods in

China [9]

in Korea [2]

US Rice [3]

**126**

**2.3 Case contamination and precautions for** *Bacillus cereus* **in rice**

to prevent foodborne illness associated with Bacillus spp. [37].

3.Reheating cooked food should be stored at 165°F/74°C [37].

Precautions for contamination of *Bacillus cereus* in rice:

2.Hot foods should store at 140°F/60°C or higher [37].

Further explanations can see in **Table 1**.

*Cases of* Bacillus cereus *contamination in rice (rice-based food).*

Cases of contamination of *Staphylococcus aureus* on rice, either in the form of raw rice or cooked rice and other processed rice products, are found in several countries.

1.Processing (thoroughly cooked and quickly cooled) is one of the easiest ways

4.If frozen food is allowed to thaw, it must remain at 41°F/5°C or lower [37].

