eMedicine Specialties > Gastroenterology > Colon

Gastroenteritis, Bacterial

Author: Jennifer Lynn Bonheur, MD, Attending Physician, Division of Gastroenterology, Lenox Hill Hospital
Coauthor(s): Mukul Arya, MD, Associate Professor of Internal Medicine, Assistant Director of Therapeutic Endoscopy, Department of Gastroenterology and Internal Medicine, Wyckoff Heights Medical Center/Weill Medical College; Richard E Frye, MD, PhD, Assistant Professor, Departments of Pediatrics and Neurology, University of Texas Health Science Center at Houston; M Akram Tamer, MD, Program Director, Professor, Department of Pediatrics, University of Miami
Contributor Information and Disclosures

Updated: Feb 19, 2009

Introduction

Background

Bacterial gastroenteritis is a very common disorder. It has many causes, can range from mild to severe, and usually manifests with symptoms of vomiting, diarrhea, and abdominal discomfort. Other causes of some of these symptoms include viral infections, improper diet, malabsorption syndromes, various enteropathies, and inflammatory bowel disease. Bacterial gastroenteritis is usually self-limited, but improper management of an acute infection can lead to a protracted course. By far, the most common complication is dehydration.^1,2,3,4

For excellent patient education resources, visit eMedicine's Esophagus, Stomach, and Intestine Center and Public Health Center. Also, see eMedicine's patient education articles Gastroenteritis and Foreign Travel.

Related eMedicine topics:
Campylobacter Infections
Escherichia Coli Infections
Gastroenteritis, Viral
Salmonella Infection
Shigellosis

Pathophysiology

Bacteria employ several mechanisms to invoke a pathologic response. Invasive bacteria cause mucosal ulceration and abscess formation with a subsequent inflammatory cascade. Bacterial toxins control enteral and extraenteral cellular processes. For example, the heat-labile and heat-stable enterotoxins of Escherichia coli activate enteral adenylate cyclase and guanylate cyclase.
 
Verotoxin, which enterohemorrhagic E coli and Shigella species produce, causes systemic disorders such as seizures and hemolytic-uremic syndrome (HUS). Other noninvasive bacteria adhere to the gut wall, causing inflammation. Organisms such as E coli and Clostridium species are normal enteric flora, pathogenic strains of which can cause gastroenteritis.

Frequency

United States

Bacterial gastroenteritis is a very common problem in primary care and emergency department settings, especially for children younger than 5 years.^3,4 Diarrhea accounts for as many as 5% of pediatric office visits and 10% of hospitalizations in this age group. Very often, gastroenteritis is underreported in the adult population.

Each year, gastroenteritis affects adults and accounts for 8 million doctor visits and 250,000 hospitalizations. Episodes of gastroenteritis do not occur at random but usually occur in outbreaks. Traveler's diarrhea affects 20-50% of people traveling from industrialized to developing countries.^4,5,6

International

Worldwide, millions of children and adults are affected by diarrhea each year. In developing countries, where sanitation is suboptimal, epidemics of bacterial gastroenteritis can develop and cause significant mortality.^2,4,5,6,7

Mortality/Morbidity

Diarrhea and vomiting are so commonplace that nonphysicians usually underappreciate the potential mortality and morbidity of bacterial gastroenteritis. In the United States each year, several hundred people die from complications of bacterial gastroenteritis; the majority are elderly people.

Many developing countries do not have the resources to properly treat diarrhea and vomiting associated with bacterial gastroenteritis, leading to a disproportionately high mortality rate. Gastroenteritis-causing pathogens are the second leading cause of morbidity and mortality worldwide.

Race

It has been reported that the preparation and ingestion of chitterlings, common among some blacks, especially during the holiday season, may pose an increased risk of infection with Yersinia enterocolitica serotype O:3.^8,9

Sex

Most infectious diarrheas do not affect one sex more than the other; however, females have a higher incidence of Campylobacter infections and hemolytic-uremic syndrome (HUS).

Age

Yersinia species infect children younger than 1 year almost exclusively, and Aeromonas species are a significant cause of bacterial gastroenteritis in young children. Very young children are particularly susceptible to secondary dehydration and malabsorption.

Clinical

History

• Stool characteristics
  • Diarrhea is defined as daily stools with a mass greater than 15 g/kg for children younger than 2 years and greater than 200 g for children aged 2 years and older. Adult stool patterns vary from 1 stool every 3 days to 3 stools per day; therefore, consider individual stool patterns.
  • Consistency, color, volume, and frequency are very important in determining whether the stool source is from the small or large bowel. Below, Table 1 outlines these characteristics and demonstrates that an index of suspicion can be generated easily for a specific set of organisms.

Table 1. Stool Characteristics and Determining Their Source

Open table in new window

HPF = high-power field; WBC = white blood cell.

• Associated systemic symptoms can guide empiric therapy. Some enteric infections have characteristic systemic symptoms, whereas the associated systemic features of others do not occur reliably. Below, Table 2 outlines the frequency of these symptoms with various organisms.
• Symptom onset and duration characteristics can narrow the differential diagnosis of the organism (see Differential Diagnoses). The onset of symptoms within 6 hours of exposure to the bacterial source indicates a preformed toxin, probably produced by Staphylococcus or Bacillus species. Table 2 outlines the incubation and duration characteristics of common bacteria.

Table 2. Organisms and Frequency of Symptoms

Open table in new window

• Particular foods are associated with certain bacteria. Ingestion of raw or contaminated food, particularly raw milk and meat, is a common cause of bacterial gastroenteritis. The following list outlines organisms that cause food poisoning:
  • Dairy -Campylobacter, Salmonella, Listeria, and Staphylococcus species
  • Eggs -Salmonella species
  • Meats -C perfringens and Salmonella, Aeromonas, Campylobacter, and Staphylococcus species
  • Ground beef - Enterohemorrhagic E coli
  • Poultry -Campylobacter species
  • Pork -C perfringens and Y enterocolitica
  • Seafood -Aeromonas, Plesiomonas, and Vibrio species and astrovirus
  • Oysters -Plesiomonas and Vibrio species and calicivirus
  • Vegetables -Aeromonas species and C perfringens
  • Alfalfa sprouts - Enterohemorrhagic E coli and Salmonella species
  • Fried rice -Bacillus species
  • Custards, mayonnaise -Staphylococcus species
• Water is a major reservoir for many organisms that cause diarrhea. Swimming pools have been associated with outbreaks of Shigella organisms, and Aeromonas species are associated with exposure to the marine environment.
• Travel history is an important and useful clue in determining bacterial etiology. Enterotoxigenic E coli is the leading cause of traveler's diarrhea. Rotavirus and Shigella, Salmonella, and Campylobacter species are prevalent worldwide and need to be considered, regardless of specific travel history.Other organisms that are prevalent in particular parts of the world are listed below. The risk of contracting diarrhea while traveling is highest in travel to Africa. Travel to Portugal, Spain, and Eastern European countries is also associated with a relatively high risk. Organisms associated with travel to particular locations are as follows:
  • Nonspecific - Enterotoxigenic E coli and Aeromonas, Giardia, Plesiomonas, Salmonella, and Shigella species
  • Underdeveloped tropics -C perfringens
  • Africa -Entamoeba species and V cholerae
  • Americas (South and Central) -Entamoeba species and V cholerae
  • Asia -V cholerae
  • Australia -Yersinia species
  • Canada -Yersinia species
  • Europe -Yersinia species
  • India -Entamoeba species and V cholerae
  • Japan -Vibrio parahaemolyticus
  • Mexico -Aeromonas, Entamoeba, Plesiomonas, and Yersinia species
  • New Guinea -Clostridium species
• Animals can transmit particular bacteria. Exposure to young dogs or cats is associated with Campylobacter transmission. Exposure to turtles is associated with Salmonella transmission.
• Preexisting medical conditions can predispose for infections with particular organisms. The following list outlines such medical conditions and their associated organisms:
  • C difficile - Hospitalization with antibiotic administration
  • Plesiomonas species - Liver diseases or malignancy
  • Salmonella species - Intestinal dysmotility, malnutrition, achlorhydria, hemolytic anemia (especially sickle cell disease), immunosuppression, and malaria
  • Rotavirus - Hospitalization
  • Giardia species -Agammaglobulinemia, chronic pancreatitis, achlorhydria, and cystic fibrosis
  • Cryptosporidia - Immunocompromise and immunosuppression
• Outbreaks are caused by particular bacteria, including enterohemorrhagic E coli O157:H7, Listeria monocytogenes, C perfringens, and Salmonella species.

Physical

• Dehydration is the primary cause of morbidity and mortality in cases of gastroenteritis. Assess every patient for signs, symptoms, and severity of dehydration. Lethargy, depressed consciousness, dry mucous membranes, sunken eyes, poor skin turgor, and delayed capillary refill should raise the suspicion of dehydration.
• Malnutrition is typically a sign of a chronic process. Reduced muscle and fat mass is found. This is usually due to development of secondary carbohydrate intolerance.
• Abdominal pain is a common symptom in gastroenteritis. Nonspecific, nonfocal abdominal pain and cramping are common with some organisms. This pain usually does not increase with palpation. Focal abdominal pain worsened by palpation, rebound tenderness, or guarding should alert the clinician to possible complications or to another noninfectious gastrointestinal diagnosis.
• Borborygmi, defined as a significant increase in peristaltic activity with small bowel diarrhea, can cause an audible and/or palpable increase in bowel activity.
• Perianal erythema results from many stools causing a constantly wet area. Failure to properly dry the buttocks and perianal area results in erythema and skin breakdown.

Causes

• Salmonella, Shigella, and Campylobacter species are the top 3 leading causes of bacterial diarrhea worldwide, followed closely by Aeromonas species.
• Aeromonas and Shigella infection have a higher incidence in summer and fall, and Campylobacter infection usually occurs in summer months.
• Yersinia infection occurs most frequently in winter months and colder climates.

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