Gastroenterology Quiz: Diarrheal Diseases

Gastroenteritis/Toxin-mediated Gastroenteritis

• This presentation is about Gastroenteritis/Toxin-mediated Gastroenteritis
• The date of the presentation is November 27, 2024
• The speaker is Prof. Dr. Necla Tülek

Learning Objectives

• List important causes of food poisoning
• Identify the most common bacteria that can cause food poisoning
• Describe the main modes for transmitting infectious agents that cause food poisoning
• Describe the pathogenesis of toxin-mediated diarrhea
• Explain the mechanisms of damage from enterotoxin, cytotoxins, and invasive organisms
• Describe the clinical findings in food poisoning
• Differentiate an invasive infection vs. a toxin-mediated illness based on clinical findings
• Describe the diagnostic techniques used to identify organisms causing toxin-mediated diarrhea
• Understand the prevention of toxin-mediated gastrointestinal infections

Introduction

• "Gastroenteritis" comes from Greek words meaning stomach and small intestine
• Gastroenteritis is inflammation of the stomach and intestines
• Gastroenteritis is a diarrhea disease with or without vomiting, fever, and abdominal pain
• Enterocolitis involves both the colon and small intestine, including stomach inflammation
• Frequent passing of formed stools isn't diarrhea; loose, "pasty" stools from breastfed babies isn't diarrhea
• Diarrhea is defined as 3 or more watery or loose bowel movements in 24 hours or at least 200 grams of stool per day

Diarrheal Disease

• Diarrheal disease is the second leading cause of death in children under five
• It kills around 525,000 children annually
• It's preventable and treatable
• Globally, there are nearly 1.7 billion cases of childhood diarrheal disease annually
• It's a leading cause of malnutrition in children under five

Duration of Symptoms

• Symptoms can be acute, persistent, chronic, or recurrent
• Acute: 14 days or fewer
• Persistent: More than 14 but fewer than 30 days
• Chronic: More than 30 days
• Recurrent: Diarrhea that recurs after 7 days without diarrhea

Types of Diarrhea

• Acute watery diarrhea (lasts hours to days, including cholera)
• Acute bloody diarrhea (also called dysentery)

Watery Diarrhea

• The most common form of gastrointestinal infection
• Characterized by frequent, watery bowel evacuations, potentially with nausea, vomiting, fever, and abdominal pain
• Damage results from pathogenic mechanisms that attack the small intestine, responsible for 90% of fluid absorption

Dysentery

• Characterized by frequent, smaller-volume bowel evacuations
• Stool contains blood and pus
• Symptoms include fever, abdominal pain, cramps, and tenesmus (straining to defecate)
• Vomiting is less common
• Pathogens cause inflammatory/destructive changes in the colon

Causes of Infectious Diarrhea

• Vary by geographic region, depending on co-morbidities and host immune status
• Viruses (norovirus, rotavirus, adenovirus) are most common
• Bacteria (Clostridium perfringens, enterotoxigenic Escherichia coli [ETEC]) can cause severe cases

Overview of Causes

• Infectious or noninfectious causes
• Infections categorized by the affected portion of the intestine
• Small bowel: fluid- and nutrient-absorbing; dysregulation causes large-volume watery diarrhea, abdominal cramping, gas, and weight loss; fever less significant
• Large bowel: fluid and salt absorption and potassium excretion; present with frequent, regular, small-volume bowel movements often painful, possibly bloody or mucoid stools; fever and inflammatory cells often present

Bacterial Gastroenteritis

• Bacteria are less common than viral causes
• Bacteria cause gastroenteritis by several mechanisms (e.g. production of toxins)
• Common bacteria include Campylobacter, Clostridioides difficile, Escherichia coli (especially serotype O157:H7), Salmonella, Shigella, Staphylococci (food poisoning)

Gastroenteritis Pathogens

• Mechanisms, location, illness, stool findings, and examples of pathogens are detailed in a table

Staphylococcal Food Poisoning

• An acute intoxication caused by a bacterial toxin
• Results from consuming food contaminated with enterotoxin from Staphylococcus aureus
• Common cause of gastroenteritis worldwide
• Contamination often due to cross-contamination of food or by a contaminated food handler

Staphylococcus

• The genus includes over 50 species
• Staphylococcus aureus is of particular note due to golden-colored colonies
• Staphylococcal enterotoxins (SEs) cause illness

Staphylococcal Enterotoxins

• Water-soluble, structurally stable, secreted polypeptides
• 17 types; Type A is most common in food poisoning
• Heat-stable; survive boiling for up to 30 minutes
• Resistant to drying, freezing, and gut enzymes
• Produced when S. aureus grows on carbohydrate and protein foods

Epidemiology and Transmission

• S. aureus must be present in the food and the food must be stored at incorrect temperatures for toxin production
• About 25% of people carry S. aureus on their skin or in their nose
• Contamination can occur from food handlers or by coughing/sneezing
• Growth and enterotoxin production require temperatures between 7°C and 48°C; optimal at ~37°C

Foods Implicated

• Poultry, egg products, cooked meat (e.g., ham, corned beef), milk and milk products, canned foods, bakery products, sliced meats, puddings, pastries, potato salads, raw salads, ice creams, salted foods, and sandwiches

Food Poisoning Pathogenesis

• Production of one or more exotoxins by pathogens in the gastrointestinal tract, such as enterotoxins and neurotoxins.
• Enterotoxins directly affect the secretory mechanisms of the intestinal mucosa.
• Neurotoxins are produced outside the host and have a faster onset of symptoms.
• Cytotoxins destroy intestinal mucosal cells, causing dysentery with bloody stools.

Clinical Findings (Staphylococcal Food Poisoning)

• Symptoms appear 0.5-8 hours after consumption, averaging 3 hours
• Incubation period can vary by age, with earlier onset in children and teenagers
• Key symptoms: nausea, vomiting, occasionally watery diarrhea, abdominal pain, and mild fever

Diagnosis (Staphylococcal Food Poisoning)

• History and rapid resolution of the clinical findings are key
• Toxin detection in stool, vomit, or food samples using tests like mouse bioassay
• Confirmation using PCR for identifying toxin genes
• Confirmation method is not urgently needed; diagnosis should be based on history and clinical findings

Treatment (Staphylococcal Food Poisoning)

• Fluid therapy and rest
• Intravenous fluids may be necessary in severe cases
• Antibiotics aren't effective as the toxin isn't affected by antibiotics

Prevention (Staphylococcal Food Poisoning)

• Use food thermometers to correctly cook foods
• Properly store hot and cold foods
• Refrigerate or freeze quickly foods handled between steps, or when storing
• Wash hands frequently
• Use appropriate food handler protective clothing
• Cover skin lesions

Bacillus cereus

• A bacterium that can cause food poisoning
• It produces two types of toxins: heat-stable and heat-labile toxins
• Heat-stable toxin leads to emetic syndrome, and heat-labile toxin leads to diarrheal syndrome

Epidemiology (Bacillus cereus)

• Isolated from soil, vegetables, milk, cereals, spices, fried rice, cooked poultry, meats, soups, and desserts
• Present in vending machine foods and improper handling environments

Pathogenicity and Virulence Factors (Bacillus cereus)

• Heat-stable toxin causes emetic syndrome (nausea, vomiting, abdominal cramps, and potentially diarrhea)
• Heat-labile toxin causes diarrheal syndrome (watery diarrhea, nausea, abdominal cramping)

Clinical Findings (Bacillus cereus)

• Emetic type: 1-5 hours from ingestion with fried rice, milk, and pasta
• Diarrheal type: 6-15 hours from meat and sauce ingestion

Diagnosis (Bacillus cereus)

• Specimen collection: feces, vomitus, remaining food, and sometimes eye specimens
• Microscopy, and sometimes serological or molecular methods

Treatment (Bacillus cereus)

• Supportive care in most cases
• Oral rehydration or intravenous fluids for severe dehydration cases
• Antibiotics not recommended

Prevention (Bacillus cereus)

• Appropriate food handling; avoid temps between 10°C and 45°C; good refrigeration practices

Mushroom Poisoning

• Serious complications that can result from eating certain mushrooms
• Diarrhea, abdominal pain, and nausea are possible early symptoms
• Amanita species are the most dangerous; poisoning due to these species can cause liver and kidney failure

Introduction (Botulism)

• Clostridium botulinum is the causative agent of botulism
• It produces dangerous neurotoxins (botulinum toxins) under low-oxygen conditions
• These toxins block nerve functions, causing respiratory and muscle paralysis

Spores of Clostridium botulinum

• Widely found in soil, pond, marine sediments, and isolated from surfaces of vegetables, fruits, and seafood
• Heat-resistant; must be heated to 120°C for five minutes to destroy them

Botulism Toxins

• Potent, lethal substance for humans
• Dose as low as 30-100 ng can be lethal in humans

Botulism Toxin (in general)

• Has no smell or taste
• Absorbed in the stomach and small intestine and large intestine
• Resistant to gastric acid and human enzymes
• Inactivated in chlorinated water after 20 minutes, or destroyed by heating to 100°C for ~15 minutes

Botulism Pathogenesis

• Toxins affect peripheral neuromuscular junction and autonomic synapses
• The effect is primarily weakness
• Other toxins can affect the central nervous system, including a rigidity and spasm effect

Botulism Transmission

• Spores are in soil, sediments, freshwater, and animal intestines
• Improperly canned foods, such as meats and vegetables, can be harboring toxins
• Spores remain in some vegetables or meat when cooked
• Botulism can transfer from an endospore to a healthy host through certain conditions

Botulism Clinical Forms

• Foodborne (ingestion of preformed toxin or ingestion of spores that make toxin)
• Infant (ingestion of spores which then multiply and form toxin)
• Wound (spores germinate in wounds and create toxin)
• Adult intestinal (toxin produced in the intestines)
• iatrogenic (injection of an overdose of toxin while being used for therapeutic purposes)
• inhalational (spores inhalated)

Botulism Progression/Symptoms

• Begins with paralysis in facial muscles
• Related symptoms may include blurred vision, difficulty speaking, trouble swallowing, and dry mouth
• Paralysis may extend to other parts of the body
• Lack of sensory or cognitive deficits
• Respiratory problems often lead to death

Diagnosis (Botulism)

• Detect toxin in serum or other body fluids (e.g., stool or gastric secretions)
• Use mouse assay, enzyme-linked immunosorbent assay (ELISA), and PCR tests.
• A timely diagnosis of botulism is paramount to successful treatment

Treatment (Botulism)

• Administering large doses of botulism antitoxin (which can be from a horse)
• Intensive supportive care, including mechanical ventilation

Botulism Prevention

• Proper food handling and storage to prevent toxin presence in food
• Avoid storing foods at high temperatures
• Proper processes in the making of fermented foods
• Avoiding consuming food from damaged cans or bottles
• Keeping cold food below 5°C and hot food above 80°C
• Using heat treatments that successfully kill the spores

Test your knowledge on diarrheal diseases, including their causes, symptoms, and classifications. This quiz covers important aspects of gastroenteritis, malnutrition in children, and the impact of sanitation and hygiene on health. Challenge yourself and see how well you understand these critical health issues.