Introduction
Diarrhea is defined as any change in normal bowel movements characterized by an increase in frequency (≥3 bowel movements within 24 hours), water content, volume of stools or with bloody stools. The usual stool output is 10 g/kg/day. Infectious diarrhea is defined as diarrhea of infectious origin and is usually associated with symptoms of nausea and vomiting, fever, and abdominal cramps.
Epidemiology
Bacterial gastroenteritis usually affects children >2 years of age. Diarrheal disease is the third leading cause of mortality in children <5 years of age globally.
Cholera causes an estimated 1.3–4.0 million cases and 21,000–143,000 deaths annually, with incidence increasing significantly since 2021. The disease remains endemic in about 50 countries, particularly in Africa, South and Southeast Asia, and in the Western Hemisphere. Campylobacter infection is the second leading cause of clinically significant foodborne infections in the United States, with a reported incidence of 18.2 infections per 100,000 persons in 2023. Campylobacter infections seem to predominate as the cause of traveler’s diarrhea in North Africa and Southeast Asia. Shigellosis remains one of the top three causes of bacterial gastroenteritis worldwide.
Etiology
Gastroenteritis - Bacterial_Disease BackgroundCommon pathogens causing pediatric bacterial gastroenteritis include Escherichia coli, Salmonella sp, Shigella sp, Clostridioides difficile, Campylobacter jejuni, and Yersinia enterocolitica. Escherichia coli, Salmonella and Shigella sp are common in children 6-10 years of age.
Traveler’s Diarrhea
Causes of acute traveler’s diarrhea will vary from one geographical area to another. Enterotoxigenic E coli is one of the most frequently identified organisms. Other common bacterial causes are enteroaggregative E coli (EAEC), Salmonella, Shigella sp, and C jejuni.
Watery Diarrhea
Severe dehydration with severe watery diarrhea is most likely caused by Vibrio cholerae subgroup O1. Vibrio O139, other non-O1 vibrios and occasionally Vibrio parahaemolyticus, Aeromonas sp and enteropathogenic or enterotoxigenic E coli can cause a similar clinical picture; though diarrhea from these organisms usually causes milder forms of diarrheal illness.
Bloody Diarrhea
Shigella sp and C jejuni cause bloody diarrhea. Shigella dysenteriae and Shigella flexneri may cause a more severe disease with high fever. Shigella boydii and Shigella sonnei cause a milder disease. Salmonella enteritidis, Yersinia enterocolitica, C difficile, Balantidium coli, Plesiomonas, enterohemorrhagic E coli (EHEC) and enteroinvasive E coli (EIEC) can produce bloody diarrhea.
Pathophysiology
Bacterial gastroenteritis is transmitted through the fecal-oral route, ingestion of contaminated meat, or exposure to poultry and other farm animals.
The pathogenesis of foodborne gastroenteritis involves the following main mechanisms: Ingestion of pathogens with preformed toxins already present in food (eg S aureus, B cereus), production of toxins within the gastrointestinal tract after ingestion (eg C perfringens, enterotoxigenic E coli [ETEC]), and direct invasion of the bowel wall by pathogens (eg Salmonella, Shigella, C jejuni), leading to epithelial damage and inflammatory diarrhea.
Infections caused by preformed toxins are due to the noninflammatory effects of toxins already present in contaminated food, and these commonly present with nausea and vomiting. Some bacteria cause disease by adhering to the intestinal epithelium and secreting toxins after colonization, leading to secretory diarrhea without invasion of the intestinal mucosa. Fever and bloody stools are typically absent. Invasive intestinal infections occur when bacteria penetrate the gastrointestinal mucosa, resulting in inflammatory diarrhea characterized by abdominal pain, fever, and the presence of pus, blood, or both in the stool.
Risk Factors
Epidemiological Risk Factors
Epidemiological risk factors for bacterial gastroenteritis include travel to developing or underdeveloped areas; daycare attendance; ingestion of unsafe foods such as unpasteurized dairy products, raw or undercooked meats, and seafood; and swimming in or drinking untreated freshwater. Poor personal and public hygiene practices (eg seldom practice of handwashing), visits to farms or contact with pets with diarrhea, knowledge of other ill persons, recent or regular use of medications (eg antibiotics), and underlying medical conditions (eg acquired immunodeficiency syndrome [AIDS], immunosuppressants) also increase the risk of disease transmission.
Classification
Types of Diarrhea by Duration
The types of diarrhea by duration include acute and chronic diarrhea. Acute diarrhea is diarrhea lasting for ≤14 days' duration, while chronic diarrhea is diarrhea lasting for >14 days.