Fried Rice Syndrome

Prehospital evaluation & treatment 

On arrival, the crew is met at the front door by a 13-year-old girl who reports that she called 9-1-1 for her mother, whom she found vomiting in the bathroom. The child indicates that she had arrived home from school 20 minutes prior, at around 4:30 p.m., and found her mother in this condition. She then states that while she was waiting for the ambulance to arrive, her 53-year-old grandmother also began vomiting by the sink.

With multiple patients complaining of similar symptoms, unusually cold weather over the past few days and the presence of a space heater in the apartment, the crew is initially concerned about possible carbon monoxide (CO) poisoning. However, the 13-year-old doesn't have symptoms, and the patients report that no heat source has been used during the previous 24 hours. Although CO poisoning remains a consideration, the crew prioritizes it as lower on their list of differential diagnoses.

One crew member evaluates the 35-year-old mother and finds out that the nausea and vomiting began about two hours ago, with six episodes of vomiting food-like, non-blood-tinged material. Her abdominal pain is found to be a generalized cramping that began approximately 20–30 minutes ago.

This patient has no significant past medical history, does not take any medications and is not allergic to any medications. The patient looks well hydrated and well nourished despite the multiple vomiting episodes. Approximately 100–150 cc of food-like emesis is evident in the toilet.

The second crew member evaluates the grandmother. This patient reveals that although she felt nauseated just after lunch about three hours ago, she didn't begin vomiting until a few minutes prior to the ambulance's arrival. She reports two episodes of vomiting food-like emesis. Approximately 60 cc of vomited material is evident in the sink.

Bacillus cereus, an aerobic, spore-forming rod, can survive cooking and then germinate, producing toxins and causing food poisoning.

This patient reports a history of high blood pressure, for which she takes an unknown medication. She denies any other history, medications or allergies. Although she denies any abdominal cramping, this patient does report one episode of a watery stool approximately one hour prior. She's also well nourished and well hydrated.

Both family members deny any recent trips outside of the country or exposure to industrial/chemical areas, but both admit to having symptoms after eating leftover pork fried rice at approximately 1 p.m. (It was later revealed at the hospital that the rice may have been left out overnight, unrefrigerated.) Both family members have stable vital signs.

With this information, the crew moves both patients to the ambulance, continues to monitor both victims, and transports them to the local emergency department for further medical care.

Case review 

Diarrheal and emetic complaints from patients are encountered by emergency care providers on a daily basis. The goal of providers is more to categorize the patient's condition into one of the major types rather than to find a specific cause, all while attempting to identify the life threats associated with the condition and treating them appropriately.

Infectious agents (e.g., viruses, bacteria and parasites) and medical conditions, such as inflammatory bowel diseases (e.g., Crohn's disease and ulcerative colitis), as well as surgical abdominal conditions (e.g., small bowel obstruction, diverticulitis and mesenteric infarction) can all cause some degree of diarrhea and/or vomiting, making the case that much more difficult.

Another cause of diarrhea and vomiting is food poisoning. In this particular case, food poisoning from the organism Bacillus cereus germinating in the consumed fried rice was the culprit.

Bacillus cereus is an aerobic (oxygen-requiring), spore-forming, gram-positive rod often found in soil and in raw, dried and processed foods. Ingestion of these spores is often associated with improperly handled food.

Bacillus cereus is found in uncooked rice. Even after boiling during the initial cooking process, the heat-stable spores survive and then germinate when subsequently left unrefrigerated. In this condition, the bacteria further multiply and produce toxins. When the rice is then flash-fried in the preparation of the meal, the spores remain intact and further germinate until ingested.

Clinically, it's believed that Bacillus cereus causes two distinct clinical syndromes: an emetic syndrome, thought to be caused by a heat-stable enterotoxin, and a diarrheal syndrome, thought to be caused by a heat-labile enterotoxin.

The more commonly recognized form occurs with the first condition, with the ingestion of heat-stable or heat-resistant spores. Most often this condition is associated with the ingestion of fried rice in which the spores have germinated during a prolonged period of cooling at room temperature. In fact, this condition has so often been associated with fried rice that it has been reported in some literature as “Fried Rice Syndrome” or “Chinese Restaurant Syndrome.” In this condition, abdominal pain and vomiting usually occur within three hours of ingestion. Diarrhea may or may not be present (reportedly found in 25–30% of these patients).

The latter condition (the ingestion of heat-labile enterotoxin) more often occurs after the ingestion of improperly handled vegetables and meats. In this condition, symptoms, such as diarrhea, occur six to 14 hours after ingestion of the heat-labile spores. Approximately 75% of these patients develop some form of abdominal cramping.

Whether producing the emetic or diarrheal condition, the symptoms of both syndromes are self-limiting. The literature reports that the emetic condition usually lasts less than 10 hours while the diarrheal condition can last anywhere from 20–36 hours.

The diagnosis can be confirmed by laboratory isolation of 10 or more organisms from the ingested food source. Stool cultures may also be positive for the organism, but it should be noted that the organism may also be inherently present in the stools of the healthy population.

As previously mentioned, both syndromes are generally mild and self-limited. As far as management of these patients, because enterotoxins produce the symptoms, antibiotics are not necessary or indicated. Preventing dehydration, attempting to control the emesis and diarrhea, and supportive care are the mainstays of therapy.

Food poisoning by Bacillus cereus can be prevented if boiled rice and other susceptible foods are promptly eaten or refrigerated to avoid sitting at room temperatures, when germination of the organism and spores can flourish.

Discussion 

As this case shows, a simple “sick” call turned out to have some interesting pathophysiology. In this unfortunate era of terrorism, the crew was absolutely correct to look at other “outside the box” causes for vomiting in multiple patients.

Carbon monoxide exposure, particularly in the colder months when a space heater is used, definitely must be considered when multiple patients complain of similar symptoms. Travel history and possible exposure to chemicals also needs to be determined as part of the evaluation.

Although the management of such food poisoning cases is limited from the prehospital perspective, this case is an interesting one to remind providers of some of the causes of gastrointestinal disturbances that may be encountered.