What is Bacterial Gastroenteritis? Pathophysiology and Treatment

Bacterial gastroenteritis is the inflammation of the stomach and intestines (small and large) a result of a bacterial infection or the ingestion of bacterial toxins present in food. It is the cause of most cases of food poisoning or food infection and is prevalent where proper food storage and preparation methods as well as the availability of clean drinking water is lacking. Consuming partially cooked or raw meat as well as raw vegetables may also result in bacterial gastroenteritis. It is frequently seen in traveler’s diarrhea and gastroenteritis after eating at a restaurant or takeout foods.

Bacterial Gastroenteritis Pathophysiology

A host of different bacterial species may cause gastroenteritis (Refer to the Stomach Bug Causes) and will act on the gut in a number of ways :

  • Some bacteria will enter the gastrointestinal tract and attach to the lining (intestinal mucosa) where it will begin to secrete toxins (enterotoxins). These bacteria do not invade the cells of the intestinal mucosa. The toxins will affect nutrient absorption (malabsorption) and cause the mucosal cells to secrete electrolytes and water (secretory diarrhea).  This will be evident as profuse, watery diarrhea with vomiting that usually starts in 12 to 48 hours after ingestion.
  • Other bacteria may invade the mucosal cells leading to ulceration and bleeding. This causes inflammatory diarrhea which is associated with diarrhea that is sometimes bloody and there is significant abdominal pain.
  • Bacterial toxins that are present in foods (exotoxins) tends to result in secretory diarrhea which is profuse and watery with nausea and vomiting that is very prominent. It is fast acting and symptoms may be evident in less than 12 hours after ingesting contaminated food. In some cases, the symptoms may be present in 1 to 6 hours.

This gastrointestinal irritation and inflammation causes the typical signs and symptoms seen in bacterial gastroenteritis – nausea, vomiting, diarrhea, abdominal pain with fever (not always present).

Treatment of Bacterial Gastroenteritis

  • Antibiotics are not necessary in every case of bacterial gastroenteritis. Most cases are self-limiting and will resolve in a few days. If the causative organism has been identified with a stool culture and the symptoms are persisting, then antibiotics may be necessary. Immunocompromised patients may also require antibiotics.
  • Antidiarrheal agents should be avoided unless the symptoms are persisting despite resolution of the infection or if antibiotics have already been commenced. This is dependent on individual cases and should be discussed with a medical doctor before using an antidiarrheal agent.  A persistent diarrhea in this case may also require probiotics.
  • Probiotics containing Saccharomyces boulardii and Lactobacillus casei may be useful in all cases but more so in the event of persistent diarrhea after the infection has been treated or has resolved.
  • Oral rehydration therapy is the cornerstone of infectious gastroenteritis management. The BRAT diet followed by a simple bland diet should be commenced immediately once the vomiting subsides but an oral rehydration solution (ORS) should be continued for as long as the diarrhea is present.

Related Articles

  1. What is Gastroenteritis? Infectious, Allergic, Acute, Chronic
  2. Food Infection, Intoxication – Foods that Cause Gastroenteritis

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