What Is Bacterial Gastroenteritis?

Infection with a bacteria could lead to nausea and vomiting

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Bacterial gastroenteritis is an infection in the digestive system caused by a bacteria (germ). The infection with the bacteria causes symptoms such as vomiting, diarrhea, and pain in the abdomen.

This is a common reason for diarrhea. It can be serious if it causes dehydration from diarrhea and/or vomiting and the symptoms last for several days or weeks.

This article will include information about the causes, symptoms, diagnosis, treatment, and prevention of bacterial gastroenteritis.

A man lying on his side on a couch, clutching his stomach in pain.

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Bacterial vs. Viral Gastroenteritis

Bacteria or viruses could cause gastroenteritis. In addition, bacteria can spread from person to person and from surfaces and contaminated food. Viruses also spread from person to person and from contamination on surfaces.

Gastroenteritis that includes bloody diarrhea, lasts longer than three days, or is causing dehydration may be due to bacteria. Antibiotics may be used for bacterial gastroenteritis, but will not be effective for viral infections. Viral gastroenteritis is often called stomach flu.

Causes

Gastroenteritis is an inflammation of the stomach and the small intestine. It can be caused by viruses, parasites, diseases, or bacteria. In most cases, bacterial gastroenteritis is caused by eating foods contaminated with bacteria (food poisoning).

Many types of bacteria can infect the digestive system and cause symptoms. Some of the more common germs include:

  • Campylobacter: Exposure can occur through poultry, unpasteurized dairy products, travel abroad, puppies, reptiles, or contaminated water.
  • Clostridium difficile: Can be transferred from person to person, especially in hospital settings. It can happen after recent antibiotic use.
  • Escherichia coli: Sources include beef (particularly ground), sprouts, salad greens, or cookie dough, petting zoos, and child care centers.
  • Salmonella: Can be from contaminated eggs, chicken, backyard flocks, or several types of pets, including amphibians and reptiles.
  • Shigella: Sources include eggs, chicken, multiple foods, backyard flocks, and several types of pets, including amphibians and reptiles.

Risk Factors

Anyone can develop gastroenteritis. However, some of the risk factors can include:

  • Age (older people and young children may be at higher risk)
  • Handling raw fish and meat
  • Not washing hands after going to the toilet or changing diapers 
  • Recent travel to areas with water that may be contaminated with bacteria

Symptoms

The symptoms of bacterial gastroenteritis may differ from person to person and with the type of bacteria. In some cases, the symptoms may come on within hours of eating food that's contaminated with bacteria.

The signs and symptoms of bacterial gastroenteritis may include:

  • Abdominal (stomach) cramps and/or pain
  • Dehydration (the rapid loss of too much fluid through vomiting and/or diarrhea)
  • Diarrhea (sometimes with blood)
  • Electrolyte imbalance (losing too much potassium and/or salt from the body)
  • Fever (sometimes high)
  • Loss of appetite 
  • Nausea
  • Vomiting

When to Seek Medical Help

Most bacterial infections will go away on their own. However, bloody diarrhea, vomiting that won’t stop, dehydration, dizziness, or losing consciousness are reasons to seek care from a healthcare provider.

Diagnosis

For many people, infection with bacteria will cause diarrhea and/or vomiting for a few days. Abdominal pain and cramps after eating or drinking and feeling tired are also common. It may not be necessary to see a healthcare provider or to get a diagnosis because the symptoms aren’t severe enough to cause complications and will go away on their own.

For children or babies, it is important to talk to a healthcare provider about diarrhea and vomiting. Kids can get dehydrated and lose water through vomiting and diarrhea quicker than adults, so it’s important to make sure they take in enough fluids.

There won’t be a need for testing in most cases unless the symptoms are going on for a long time. But if testing is done, a stool sample might be needed to check for bacteria. It may take a day or two to get back the stool culture results.

Other tests may be used to look for complications (such as those caused by dehydration) rather than diagnose the bacterial infection. These will be done as determined by a healthcare provider.

Treatment

Treatment usually takes place at home and is usually focused on getting enough fluids to avoid dehydration.

Bacterial gastroenteritis can usually be cared for at home by:

  • Drinking enough fluids
  • Eating small meals as tolerated
  • Replacing electrolytes (eating foods with potassium and salt such as bananas and crackers)

Over-the-counter pain medications may be helpful with cramping and pain in the abdomen. Taking over-the-counter (OTC) antidiarrhea medications might not be helpful. Talk to a healthcare provider before trying antidiarrheal medications.

Things to avoid eating include:

  • Dairy (foods that include cow's milk)
  • Foods with a lot of fiber or sugar
  • Too many foods or liquids at once

Needing care in the hospital is not common for bacterial gastroenteritis. People at higher risk of complications, such as older adults or those who are immunocompromised (have a weakened immune system), may be more likely to need care in the hospital. While in the hospital, treatment might include:

  • Antibiotics (in severe cases)
  • Antinausea medication
  • Intravenous fluids

Prevention

Some foods and water can be contaminated with bacteria which can make people sick. However, there are several steps that people can use to avoid bacterial infections.

These foods and drinks are most often linked to bacterial infections and should be avoided:

  • Raw meat
  • Raw shellfish
  • Unpasteurized milk

It’s also important to wash fruits and vegetables before eating them. Use separate utensils for raw and cooked meat, and store foods at the proper temperature.

Some bacterial infections may be spread from person to person. It’s important to try to avoid passing the infection to other people.

Steps that you can take when you’re sick include:

  • Avoiding close contact with other people 
  • Not cooking or preparing food for others
  • Waiting until symptoms are gone for two days before returning to regular activities
  • Washing hands frequently

Summary

Bacterial gastroenteritis is a common type of infection that causes vomiting and diarrhea. Most infections will get better on their own and treatment is given at home with rest and fluids. For some infections, antibiotic therapy will be needed.

A Word From Verywell

Vomiting and diarrhea from bacterial gastroenteritis can be really intense and lead to several days of feeling really unwell. Some people are not able to keep much food or liquid down in the first few days of feeling unwell.

It’s important to keep an eye out for becoming dehydrated or feeling dizzy or lethargic. If symptoms don’t start to get better after a day or two or they come back again after a few days, it’s time to get medical attention at a prompt care center or an emergency department. 

Frequently Asked Questions

  • Is bacterial gastroenteritis curable?

    Bacterial gastroenteritis is an acute condition. It comes on after an infection with a germ. The body will rid itself of the bacteria and most people will recover from the nausea and vomiting in a few days.

  • How long can bacterial gastroenteritis last?

    It’s not common, but the symptoms of bacterial gastroenteritis can last up to a week, and some people might not feel completely better for two weeks. The length of time symptoms last may be dependent on the type of bacteria that’s causing the infection.

  • Will bacterial gastroenteritis go away on its own?

    Yes, bacterial gastroenteritis will usually go away on its own. Therefore, antibiotics are not usually needed, and for some people, they may not help or could even make the infection worse.

  • How can you tell the difference between viral and bacterial gastroenteritis?

    It may not always be obvious if nausea and vomiting are from a virus or from a bacteria. However, viruses are more commonly spread during the colder months. Bacterial infections, in the United States, usually come from foods that are contaminated and are more common in the warmer months. 

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3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. FoodNet 2015 Surveillance Report (Final Data).

  2. Fleckenstein JM, Matthew Kuhlmann F, Sheikh A. Acute bacterial gastroenteritis. Gastroenterol Clin North Am. 2021;50(2):283-304. doi:10.1016/j.gtc.2021.02.002. 

  3. MedlinePlus. Loperamide.

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