What is bacterial gastroenteritis?
Bacterial gastroenteritis is a type of gastroenteritis – a common condition sometimes called stomach flu or food poisoning. Gastroenteritis is the result of irritation and inflammation in the stomach and intestines. It can be caused by infection with a virus, such as rotavirus, bacteria or parasites, among other things. When caused by bacteria, it is called bacterial gastroenteritis. While it can be very unpleasant, most cases of bacterial gastroenteritis can be treated at home, and clear up within a few days without causing complications.
Symptoms of bacterial gastroenteritis can range from mild to severe, and vary depending on the type of bacteria that has caused the infection. The main symptom tends to be diarrhea. Other symptoms may include:
- Abdominal (belly) pain or cramps
- Loss of appetite
- Nausea and vomiting
- In severe cases, blood in the stool (feces)
Bacterial gastroenteritis can be caused by a number of different types of bacteria, including Campylobacter, Salmonella, Shigella, Escherichia coli (E.coli) and Clostridium difficile. Sometimes these bacteria are transmitted directly from one person to another, but they are most often spread through contaminated food and beverages. Depending on the source of infection, a large group of people may develop bacterial gastroenteritis, or food poisoning, at the same time.
- Resting at home
- Drinking plenty of fluids to avoid dehydration
- When necessary, taking medication to relieve nausea and diarrhea
In some cases, where a person is not able to keep fluids down and is becoming dehydrated, replacement of fluids through an intravenous (IV) drip at a hospital may be necessary. Antibiotics are only recommended for more severe types of bacterial gastroenteritis.
Generally, people make a full recovery, and a bout of bacterial gastroenteritis does not cause any complications. However, if it occurs in a person with a weakened immune system, someone who is pregnant, very young or elderly, or someone with a chronic condition such as diabetes, bacterial gastroenteritis can be serious, and medical advice should be sought without delay. In addition, anyone experiencing severe symptoms should see a doctor immediately.
Furthermore, if symptoms are mild but do not improve within a few days, medical advice should also be sought. In cases where a person has returned from a trip overseas, they may have developed traveler’s diarrhea (see below).
Bacterial gastroenteritis can affect adults and children. It is contagious and can be spread easily. For this reason, it is important for people who have bacterial gastroenteritis to take steps to avoid passing it on to others, such as practicing good personal hygiene and avoiding the preparation of food for other people. In general, the following can help to reduce the likelihood of developing bacterial gastroenteritis:
- Washing one’s hands well after using the toilet
- Taking precautions to ensure food is prepared, cooked and stored properly
- Avoiding consumption of inadequately treated water
Symptoms of bacterial gastroenteritis
- Abdominal (belly) discomfort, pain or cramps
- Loss of appetite
- Nausea and vomiting
- Fever and chills
- Body aches
- Feeling of weakness
- In severe cases, blood in the stool (feces)
Symptoms may be mild or more severe, and vary depending on the type of bacteria.
If symptoms are severe or do not improve within 2-3 days, it is important to contact a doctor without delay. Furthermore, medical attention should be sought immediately if:
- There are any indications of severe dehydration, such as passing little to no urine or dizziness that does not go away
- There is blood, pus or a black color in the diarrhea
- There is constant vomiting that makes it impossible to keep down fluids
- There is very intense abdominal pain
- There is a fever over 38 degrees Celsius (101 F), in adults or children
In addition, a doctor should be contacted urgently if the affected person:
- Is pregnant
- Is a very young child
- Is an elderly person
- Has a weakened immune system
- Has a chronic condition such as inflammatory bowel disease or diabetes
Causes of bacterial gastroenteritis
- Escherichia coli (E.coli)
- Clostridium difficile
In some cases, the bacteria may be transmitted directly from one person to another, but they are typically spread through contaminated food and water. Sources of bacterial gastroenteritis include:
- Unhygienic food preparation, e.g. a cook not washing their hands after going to the toilet, or using the same cutting boards for both meat and salads
- Raw or undercooked meat, eggs and fish
- Unpasteurized dairy and juices
- Inadequately-treated drinking water
It can also be spread through food that is not stored properly, e.g. poor refrigeration that leads to food spoiling, as well as from raw fruits and vegetables that are not thoroughly washed in clean water. Contact with reptiles, birds and amphibians can also be a route of transmission for Salmonella bacteria.
Bacterial gastroenteritis is a common cause of traveler’s diarrhea, a condition which frequently affects overseas travelers, particularly in developing countries. It is often the result of inadequate food hygiene at local restaurants and food outlets. For more information on traveler’s diarrhea, see the FAQ below.
Bacterial gastroenteritis caused by exotoxins
Some cases of bacterial gastroenteritis are not caused by bacteria themselves, but instead by toxins that they release. The harmful byproducts of certain types of bacteria can contaminate food, causing food poisoning when ingested. These byproducts are called exotoxins, and they usually cause symptoms within 12 hours of consuming the contaminated food. This type of gastroenteritis typically clears up within 36 hours.
Diagnosis of bacterial gastroenteritis
When symptoms are mild, a diagnosis of bacterial gastroenteritis can often be made without seeing a doctor, and the condition can be treated at home. However, if there is any uncertainty or concern over the condition, or symptoms are severe, seeing a doctor is very important.
A doctor will take the person’s medical history and perform a physical examination, taking care to rule out other gastrointestinal conditions such as gastritis. In most cases, it will not be necessary to order tests to confirm the diagnosis of gastroenteritis. However, in cases that are severe or long lasting, a doctor may request blood and/or stool tests.
Bacterial gastroenteritis treatment
Most cases of bacterial gastroenteritis clear up without specific medical treatment. As long as symptoms are not severe and there are no signs of dehydration, a person can generally treat bacterial gastroenteritis in an adult or child at home.
- Bed rest
- Consuming plenty of fluids in the form of water or oral rehydration drinks; at the very least, small sips should be taken between being sick or having bowel movements
- Eating light meals when the appetite returns; plain foods like bread and rice may be helpful
- Taking an antidiarrheal medication, e.g. loperamide, only when necessary and there is no fever, and no blood or mucus is present in the stool
- Taking antiemetic (anti-nausea) medication for nausea and vomiting, when necessary
- Taking probiotics may slightly shorten the duration of diarrhea
If a person is unable to keep any fluids down or shows signs of dehydration (see below), they may need to be treated with an IV drip at a hospital.
Antibiotics for bacterial gastroenteritis
In mild cases of bacterial gastroenteritis, antibiotics are typically not considered necessary and will not be prescribed. Antibiotic medication is generally only recommended in severe cases, or when a person has a weakened immune system.
Complications of bacterial gastroenteritis
Generally, a bout of bacterial gastroenteritis clears up completely, without causing any complications. In a few cases, there may be complications. The risk of developing complications from bacterial gastroenteritis is highest in very young children, elderly people, and people who have a chronic condition such as diabetes, or who have a weakened immune system.
Dehydration may present with the following signs and symptoms in adults:
- Muscle cramps
- Urinating less and dark colored urine
- Dry mouth
- Eyes appear sunken in the head
Additional signs which may help to identify dehydration in children include:
- Drowsiness or irritability
- Increased heart rate
- Fewer wet nappies
- No tears when crying
If signs and symptoms of dehydration do not go away with the replacement of lost fluids, or if a person is unable to keep fluids down, a doctor should be seen immediately. Dehydration can be extremely serious.
- Reduced effectiveness of medications, e.g. birth control pills or diabetes medicine
- Temporary intolerance to lactose, the sugar in cow’s milk
- Irritable bowel syndrome
- Reactive inflammation in other parts of the body, causing conditions like reactive arthritis
- The infection spreading to other parts of the body, e.g. the bones, joints, gallbladder, or the tissue around the brain and spinal cord (meninges)
- Persistent diarrhea
- Hemolytic uremic syndrome, a serious condition characterized by anemia and kidney failure
- Bleeding in the gastrointestinal tract
- Guillain-Barre syndrome, a serious condition in which the body’s immune system mistakenly attacks the nerves
Prevention of bacterial gastroenteritis
Good personal hygiene and food preparation hygiene, as well as safe food storage and the use of water only from clean, adequately-treated sources, can help to reduce the risk of developing bacterial gastroenteritis.
- Always wash your hands well with soap and water, or use an alcohol-based hand sanitizer, after using the toilet
- Always wash your hands well before preparing food, and after handling any raw meat or fish
- Wash fruit and vegetables in clean water before using them
- Use different chopping boards for meat and vegetables, and clean them thoroughly with a disinfectant after use
- Regularly clean kitchen work surfaces with a disinfectant
- Cook all meat and fish well
- Store food in clean containers at appropriate temperatures; throw out anything that seems to have spoiled
- When traveling to other countries, drink only bottled water or water that has been boiled for at least 10 minutes; and only eat food that has been well cooked and fruit that can be peeled
- Wash your hands well with soap and water, or use an alcohol-based hand sanitizer, after using the toilet
- Clean the toilet and bathroom thoroughly with disinfectant on a daily basis
- Avoid sharing cutlery, towels, clothing and linen; also wash your items separately in hot water, with bleach if possible
- Avoid preparing food for other people for at least two days after the vomiting or diarrhea has cleared up
- Stay off work or school, if possible, until at least two days after the vomiting or diarrhea has cleared up
- Avoid swimming for two weeks after the vomiting or diarrhea has cleared up
Bacterial gastroenteritis FAQs
Q: Is bacterial gastroenteritis contagious?
A: Yes, bacterial gastroenteritis is contagious, which means that it can be spread directly from person to person. However, it is most often spread via contaminated food and water. Practicing good hygiene, such as washing one’s hands with soap and water or using an alcohol-based hand sanitizer after going to the toilet and before eating, can help to reduce the risk of developing bacterial gastroenteritis.
Q: How can I tell if it is bacterial gastroenteritis or viral gastroenteritis?
A: In most cases of gastroenteritis, it is not necessary to find out whether the cause is viral or bacterial, as the treatment is largely the same and is aimed at providing relief from symptoms. However, in some cases, if symptoms are severe or do not clear up, a doctor may recommend tests to identify the cause and prescribe a specific treatment, such as antibiotics.
Q: Should I be worried about “traveler’s diarrhea”?
A: Traveler’s diarrhea is a name given to episodes of gastroenteritis, most commonly bacterial gastroenteritis, which develop during or shortly after travel abroad. The main symptom is diarrhea, which is typically watery, though nausea, vomiting and abdominal pain may also occur. Most cases of traveler's diarrhea are relatively mild and can be managed without the need for medical advice. Dehydration is the main risk, so it is important to consume plenty of fluids and get sufficient rest. Medical advice should be sought in any of the following situations:
- A fever is present
- There is blood in the stool
- There is difficulty replacing fluids because of frequent bouts of diarrhea or vomiting
- There are signs and symptoms of dehydration
- Symptoms last for more than 2-3 days
- Antibiotics have been prescribed, but symptoms have not improved within three days
- The person is a young child, is elderly or has an underlying medical condition
- The person is pregnant
Other names for bacterial gastroenteritis
Bacterial gastroenteritis is sometimes also known as:
- Stomach flu
- Stomach bug
- Traveler’s diarrhea
- Infectious diarrhea
- Montezuma’s revenge (may be considered inappropriate)
- Food poisoning or foodborne illness
American Journal of Epidemiology. “Incidence of Guillain-Barré Syndrome following Infection with Campylobacter jejuni.” March 15, 2001. Accessed June 19, 2018. ↩
Emergency Medicine Journal. “Acute bacterial gastroenteritis: a study of adult patients with positive stool cultures treated in the emergency department.” 2003. Accessed June 18, 2018. ↩
Best Practice Journal. “Assessment and management of infectious gastroenteritis.” 2009. Accessed June 18, 2018. ↩