Bacterial Diarrhea (Diarrhea)

What is Bacterial Diarrhea (Diarrhea)?

Diarrhea is a common medical condition characterized by passing loose, watery stools multiple times a day, typically more than three. However, specific definitions can vary depending on different studies or populations. While mild cases might not need medical help, it’s still important for all health care providers to know about it.

Among the causes of diarrhea, bacterial diarrhea is particularly serious and often more severe. Therefore, knowing about this cause and distinguishing it from less serious causes is crucial. Treatment involves deciding if diagnostic stool testing is needed and when antibiotics should be used. In the United States, most cases of bacterial diarrhea are foodborne.

What Causes Bacterial Diarrhea (Diarrhea)?

Diarrhea can be split into three types depending on how long it lasts: acute (less than two weeks), persistent (between 2 to 4 weeks), and chronic (more than a month).

Chronic diarrhea could be a symptom of a health condition like irritable bowel syndrome, chronic diseases like inflammatory bowel disease, digestion problems or side effects from certain medication. It’s usually not caused by infectious diseases, but some chronic bacterial or protozoa infections can lead to chronic diarrhea. For example, infections with organisms like Clostridiodes difficile, Giardia, Entamoeba, Cryptosporidium, or Isospora can cause it. Those especially at risk are young children, the elderly, people with weakened immune systems, and international travelers.

Acute diarrhea usually comes from an infection, most often a viral one. Common viruses include norovirus, rotavirus, and adenovirus. The primary treatment is to ensure the patient stays hydrated, especially with children, who can get very sick or even die from severe dehydration. In developing countries, diarrhea is a big health threat for young children, but prompt treatment with solutions that replenish the water and electrolytes lost can save many lives.

Sometimes, bacterial infections cause intense forms of acute diarrhea. When diarrhea contains blood (and sometimes mucus), it is called dysentery, and it indicates a severe infection. The most frequent bacteria causing this type of diarrhea include Escherichia coli (most common globally), Shigella, Salmonella, Campylobacter (most common in children), Yersinia, and Clostridium spp.

Finally, traveler’s diarrhea is often caused by bacteria like Shiga-toxin producing E. coli (STEC), as well as Shigella, Salmonella, Entamoeba histolytic, Giardia, Cryptosporidium, Cyclospora, and certain viruses.

Risk Factors and Frequency for Bacterial Diarrhea (Diarrhea)

Every year, there are 1.7 billion cases of diarrhea in children, making it the second leading cause of death in children under five. This results in around 525,000 child deaths annually. Often, these deaths could be prevented with access to medical care and rehydration treatment. After recovering from the illness, children may still face complications such as malabsorption, which can impact their growth.

In the United States, there are about 5.2 million cases of bacterial diarrhea each year. Roughly 80% of these cases come from eating contaminated food.

• Out of all types of diarrhea, between 10 to 25% are caused by E.coli,
• 10% are caused by Shigella,
• and 3% are caused by Salmonella.

Between 3 to 6% of diarrheal cases are caused by Campylobacter. These different forms of bacterial diarrhea make up about 31% of all diarrhea cases in the U.S.

• In the U.S., the different bacteria in food that cause diarrhea include: Salmonella (15.4%),
• Campylobacter (11.8%),
• Shigella (4.6%),
• and Shiga-toxin producing E. coli (around 3%).

Signs and Symptoms of Bacterial Diarrhea (Diarrhea)

What you eat and when you eat it can help diagnose food poisoning. If you’ve traveled recently, other pathogens might need to be considered. Other factors like your job, hobbies, pets, where you live, and your medications can all impact the diagnosis. Almost all drugs can cause diarrhea, but some more commonly include antacids, laxatives, anti-inflammatory drugs, antibiotics, chemotherapy drugs, and metformin. Antibiotics in particular can lead to diarrhea associated with a bacterium called Clostridiodes difficile.

Details about your stool, like the number of bowel movements, consistency, volume, and other characteristics, can be informative. For instance, diarrhea from the small intestine is typically high volume and watery, and comes with abdominal discomfort, bloating and pain. Diarrhea from the large intestine is less voluminous and often comes with painful bowel movements and minimal abdominal discomfort. Certain bacteria affect these parts of the bowel differently.

• Fever
• Blood in the stool
• Mucus in the stool

These symptoms are usually a sign of disease in the colon. For instance, if there’s clear red blood in the stool, it’s likely due to a specific strain of E. coli, which starts with watery diarrhea that becomes bloody in 1 to 5 days. This comes with severe cramping and frequent bowel movements. In children, it’s a common cause of kidney failure and a serious condition called hemolytic uremic syndrome.

Your general health history is also important. If you have a weakened immune system, or a compromised health state like cancer, having had a transplant, or HIV etc, this can increase your risk of certain pathogens or worsen the severity of the illness. Certain bacteria are also associated with certain health conditions or risk factors, like the bacteria Vibrio with liver disease, Yersinia with a blood condition called hemochromatosis, or Listeria with pregnancy.

Some foods are commonly associated with certain bacterial infections. For instance, reheated fried rice can lead to Bacillus cereus infection, raw beef like hamburger can cause E. coli, raw milk can carry Salmonella as well as Campylobacter, seafood such as shellfish can be contaminated with Vibrio cholerae or V. parahemolyticus, and undercooked pork can cause diarrhea from Yersinia spp. People with HIV have an increased risk of diarrhea caused by other types of pathogens. Listeriosis is particularly associated with a weak immune system as well as with pregnancy.

As well as antibiotics, other medications like laxatives, antacids, colchicine, and chemotherapy have all been tied to diarrhea. Problems like microscopic colitis or radiation colitis can also cause this symptom. A physical examination focusing on vital signs and signs of dehydration can be important. The abdominal exam should evaluate for bloating, tenderness, normal bowel sounds or lack thereof, and clinical signs of irritation of the peritoneum.

A Clostridiodes difficile infection usually manifests as watery diarrhea, nausea, fever, and loss of appetite after recent antibiotic use. This can happen up to 10 weeks after using the antibiotic. Fluoroquinolones, penicillins, and clindamycin are the antibiotics most often linked to this. Very low potassium levels can also present in this infection.

Salmonella usually comes from poultry, eggs, and milk. Enteric fever results from specific types of Salmonella and manifests as an illness with abdominal pain, fever, slow heart rate, a pulse-temperature mismatch, rose-colored spots, enlarged liver and spleen, anemia, and decreased white blood cells. Diarrhea is usually from other types of Salmonella, which are commonly found in diarrheal stool. The course of this illness is typically self-limited and includes diarrhea, fever, cramps, and nausea. Antibiotics aren’t usually recommended unless the host is immunocompromised.

Shigellosis manifests with abdominal cramps, high fever, bloody diarrhea with mucus, tenesmus, and an unusually high white blood cell count. It lasts for up to seven days and is usually self-limited, but complications like reactive arthritis, seizures, hemolytic-uremic syndrome, rectal prolapse, enlarged colon, obstruction, and perforation can occur.

Yersiniosis presents with lower right abdominal pain, fever, vomiting, diarrhea, increased white blood cells, and can be easily mistaken for appendicitis. There’s a phenomenon known as “epidemic appendicitis” which describes the sudden appearance of many cases of appendicitis-like patients due to a yersinia epidemic.

Testing for Bacterial Diarrhea (Diarrhea)

While not all cases of diarrhea require laboratory tests, these assessments are recommended if symptoms persist for several days or if initial treatments have failed. It’s particularly important to conduct tests for severe cases, cases that don’t respond to treatment, or in cases involving people at high risk.

One of the main tests involves analyzing a fresh stool sample. The presence of white blood cells in the stool might suggest inflammation, but this test isn’t completely accurate. There are other components in your stool, like calprotectin and lactoferrin, which can indicate the activity of specific immune cells and help differentiate between inflammatory and non-inflammatory diarrhea. These tests are more accurate.

If there are red blood cells in the stool, it points towards a disease that’s causing bleeding in your gut. The presence of eggs or parasites in the stool can confirm these as the source of infection. A test to see if there is excess fat in the stool can help diagnose cases where nutrients aren’t being absorbed properly by the gut.

There’s also an advanced technique that can detect the genetic material of infectious organisms. What’s great about this method is that it pinpoints the source of the infection within a few hours, compared to the days it takes using standard culture techniques. A stool culture is another test that can confirm specific bacteria and guide treatment.

For diagnosing a specific infection called C. difficile, there’s a method called nucleic acid amplification. It starts with initial screening tests looking for specific toxins in the stool. Imaging or endoscopy, to visualize the inside of the colon, can also be useful in this diagnosis.

Treatment Options for Bacterial Diarrhea (Diarrhea)

The primary way to treat bacterial diarrhea is through rehydration. This can be done by orally or intravenously providing fluids. It is often recommended for patients to receive small, regular amounts of a rehydration solution that contains sodium, potassium, and glucose, if they can handle it. Intravenous rehydration is typically used when oral rehydration doesn’t work.

Once dehydration is properly managed, patients should eat nutrient-rich foods to recover from diarrhea, instead of restricting their diet. Where possible, breastfed infants should continue with usual feedings. Zinc supplements might be considered for severe cases, as they have been reported to decrease both the volume and frequency of stools by 30 percent.

Diets such as BRAT (banana, rice, apple, and toast) or a bland diet have been suggested to help improve the condition as they could be easier to tolerate. However, these recommendations are based on limited studies or personal experiences, since no reliable data or prospective studies confirm this. Similarly, avoiding certain foods, like dairy products, is not evidence-based. A comprehensive review has found little evidence to support dietary restrictions during diarrhea. Resuming a normal diet should be based on individual tolerance.

Medications that treat symptoms by reducing gut movement (i.e. antimotility agents) should be avoided as they can delay the clearing of bacteria and toxins from the gut and potentially worsen the disease. While these agents reduce stool volume, they should not be used as a replacement for rehydration therapy.

Antibiotic therapy might be necessary in some cases of bacterial diarrhea. This is particularly true when the patient appears critically ill, experiences dysentery, or has a compromised immune system. When available, local data of bacteria and their resistance patterns should guide the initial choice of antibiotics, with stool test results then informing any adjustments to therapy.

Probiotics such as Lactobacillus GG and Saccharomyces boulardii may be used in cases of infectious diarrhea and traveler’s diarrhea, but their effect tends to be minimal. The type, dose, and duration of such treatment are not definitively established.

Hospital admission may be necessary if the patient has severe dehydration, shock, intense nausea and vomiting, a need for intravenous antibiotics, complication risk, or on an individual basis. Several scoring systems have been proposed to identify severe cases of diarrhea, looking at factors such as temperature, blood pressure, white blood cell count, and the presence of white cells in the stool.

Vaccinations against cholera and typhoid might be recommended for specific travelers, depending on their travel destination and country of origin. There is also a vaccine available for infants to protect against the rotavirus.

What else can Bacterial Diarrhea (Diarrhea) be?

When a person suddenly falls ill with diarrhea, several potential causes need to be considered by medical professionals. This list of possible causes includes:

• Illnesses caused by viruses, including stomach flu or other systemic viral infections like adenovirus and influenza.
• Diseases caused by small microorganisms called protozoa, such as Giardia or Cryptosporidium. These can cause similar symptoms to bacterial diarrhea.
• In regions where they are commonly found, mosquito-borne illnesses and malaria also need to be weighed up as potential reasons.

However, not all causes of diarrhea are due to infection. There are also non-infectious causes that need to be ruled out. These include:

• Conditions that cause inflammation in the gut, such as inflammatory bowel disease (IBD) or irritable bowel syndrome (IBS).
• Diseases causing issues with nutrient absorption like celiac disease or Whipple’s disease.
• Cystic fibrosis, a genetic disorder affecting the lungs and digestive system.
• Carcinoid tumor, a specific type of cancer.
• Intolerance to certain ingredients in food like lactose.
• Conditions affecting hormone production such as hyperthyroidism.
• Diarrhea induced by the use of antibiotics.

A proper diagnosis will take into account these considerations and appropriate tests will be conducted.

What to expect with Bacterial Diarrhea (Diarrhea)

The outlook is typically very positive in developed countries with the right support, fluids, and antibiotics. However, in developing areas where healthcare access may be restricted, the risk of disease and death may increase, especially for the more vulnerable groups.

Possible Complications When Diagnosed with Bacterial Diarrhea (Diarrhea)

Several complications can come from the disease, depending on what kind of bacteria caused it. Complications can include:

• Toxic megacolon (a rare, life-threatening complication of inflammation of the colon)
• Gastrointestinal perforation (an opening in the wall of the stomach, small intestine, or large bowel)
• Reactive arthritis (joint inflammation triggered by an infection)
• Persistent diarrhea
• Bacteremia (bacteria in the blood) and sepsis (a serious infection spreading throughout the body)
• Hemolytic-uremic syndrome (a condition causing destruction of blood cells, kidney injury, and low platelets)
• Guillain-Barre syndrome (a rare neurological disorder that can cause muscle weakness)

Preventing Bacterial Diarrhea (Diarrhea)

The World Health Organization (WHO) actively supports and funds efforts to treat and control diarrhea in developing nations. In more developed areas, this work is carried out by both local and national health departments. These groups play a crucial role in spreading awareness and understanding about diarrhea to the general public and those particularly at risk. In addition, they offer necessary training for healthcare professionals and implement programs designed for specific regions to help limit the spread of bacterial diarrhea.