Bacterial Gastroenteritis Clinical Presentation

Stool characteristics

Diarrhea is defined as daily stools with a mass greater than 15g/kg for children younger than 2 years and greater than 200 g for children 2 years or 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. Table 1, below, 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 Sources (Open Table in a new window)

Systemic symptoms

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. Table 2, below, outlines the frequency of these symptoms with various organisms.

The characteristics of symptom onset and symptom duration can narrow the differential diagnosis of the organism. The onset of symptoms within 6 hours of exposure to the bacterial source indicates a preformed toxin, probably produced by a species of Staphylococcus or Bacillus. Table 2 outlines the incubation periods and durations of common bacteria.

Table 2. Symptoms and Their Characteristics (Open Table in a new window)

Food-borne bacteria

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

A study by Calbo et al reported a foodborne nosocomial outbreak due to extended-spectrum β-lactamase (ESBL)–producing Klebsiella pneumoniae.^[14] This may be the first reported hospital outbreak that provides evidence that food can be a transmission vector for ESBL K pneumoniae.

Water-borne bacteria

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.

Animal-borne bacteria

Animals can transmit particular bacteria. Exposure to young dogs or cats is associated with Campylobacter transmission. Exposure to turtles is associated with Salmonella transmission.

Travel-associated infections

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.

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
• Developing tropics -C perfringens
• Africa -Entamoeba species and Vibrio 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 -V parahaemolyticus
• Mexico -Aeromonas, Entamoeba, Plesiomonas, and Yersinia species
• New Guinea -Clostridium species

Bacteria associated with preexisting conditions

Preexisting medical conditions can predispose patients 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

Outbreaks are caused by particular bacteria, including enterohemorrhagic E coli O157:H7, Listeria monocytogenes, C perfringens, and Salmonella species.

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 for dehydration.

Malnutrition is typically a sign of a chronic process. Reduced muscle and fat mass is found. This is usually due to the 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.