10. Infectious Diarrheas
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Questions and Answers

What causes food-borne botulism in adults?

  • Spores ingested from honey
  • Toxin production in the gastrointestinal tract
  • Toxins pre-fabricated and ingested in home-canned food (correct)
  • Infection through wounds

What is a common symptom of infant botulism?

  • High fever
  • Floppy baby syndrome (correct)
  • Severe abdominal pain
  • Persistent vomiting

How does wound botulism occur?

  • By inhaling spores
  • By consuming honey contaminated with spores
  • Through ingestion of contaminated food
  • By spores being implanted in a wound (correct)

Which of the following statements is true about infant botulism?

<p>It can occur from eating honey containing spores. (A)</p> Signup and view all the answers

What is the key difference between food-borne and infant botulism?

<p>Infant botulism involves toxin production in the gastrointestinal tract from spores. (D)</p> Signup and view all the answers

What is a common symptom associated with superantigen activity after consumption?

<p>Severe vomiting (C)</p> Signup and view all the answers

How soon after consumption do symptoms typically appear in cases of superantigen activity?

<p>3–6 hours (C)</p> Signup and view all the answers

What is the expected recovery time after experiencing symptoms of superantigen activity?

<p>Within 24 hours (A)</p> Signup and view all the answers

Which of the following symptoms may accompany severe vomiting in cases of superantigen activity?

<p>Diarrhoea (B)</p> Signup and view all the answers

What is NOT a typical characteristic of superantigen activity?

<p>Symptoms lasting more than 48 hours (B)</p> Signup and view all the answers

What is the primary method of transmission for the bacteria associated with gas gangrene?

<p>Food borne via reheated meat (D)</p> Signup and view all the answers

What is the role of alpha toxin in the context of gas gangrene?

<p>It promotes cell membrane disruption (C)</p> Signup and view all the answers

Which of the following is NOT a consequence of alpha toxin activity?

<p>Increased immunity response (C)</p> Signup and view all the answers

What type of hemolysis is associated with the bacteria causing gas gangrene?

<p>Double zone hemolysis (B)</p> Signup and view all the answers

Which cells are primarily affected by the action of alpha toxin in gas gangrene?

<p>Endothelial cells (D)</p> Signup and view all the answers

What kind of diarrhea is commonly associated with type A strain enterotoxin production?

<p>Watery diarrhea (B)</p> Signup and view all the answers

Which strain is known to cause Pigbel necrotizing disease?

<p>Type C strain (B)</p> Signup and view all the answers

What is the supportive treatment used for self-limiting noninflammatory watery diarrhea?

<p>Supportive treatment (A)</p> Signup and view all the answers

In the case of necrotizing enteritis, what are the preferred treatments?

<p>Metronidazole and penicillin (C)</p> Signup and view all the answers

Which of the following best describes the nature of the diarrhea caused by type A strain?

<p>Self-limiting and noninflammatory (D)</p> Signup and view all the answers

What is the estimated number of nosocomial infections caused by CDI in the USA?

<p>220,000 cases (D)</p> Signup and view all the answers

How many deaths are attributed to nosocomial infections caused by CDI in the USA?

<p>13,000 deaths (A)</p> Signup and view all the answers

Which group is primarily affected by nosocomial infections caused by CDI?

<p>Hospitalized patients (D)</p> Signup and view all the answers

What distinguishes toxigenic CDI from non-toxigenic CDI?

<p>Production of toxins (D)</p> Signup and view all the answers

What percentage of CDI cases lead to severe outcomes such as death?

<p>5.9% (D)</p> Signup and view all the answers

What is the primary treatment for adults diagnosed with botulism?

<p>Polyvalent antitoxin and intensive supportive therapy (C)</p> Signup and view all the answers

Which type of immune globulin is used in the treatment of infant botulism?

<p>Human-derived botulism immune globulin (A)</p> Signup and view all the answers

What is the gram stain result and morphology of Clostridium perfringens?

<p>Gram-positive rods, spore former, nonmotile (D)</p> Signup and view all the answers

Which of the following is NOT a characteristic of Clostridium perfringens?

<p>It is a Gram-negative rod (A)</p> Signup and view all the answers

Which combination of treatments is essential for managing botulism in adults?

<p>Polyvalent antitoxin and supportive therapy (D)</p> Signup and view all the answers

Which treatment is commonly used for infections caused by Giardia intestinalis?

<p>Metronidazole (B)</p> Signup and view all the answers

What is a primary symptom associated with an infection by Giardia intestinalis?

<p>Foul-smelling, fatty stools (C)</p> Signup and view all the answers

Which method is essential for diagnosing Giardia intestinalis infections?

<p>Microscopic examination of stool (C)</p> Signup and view all the answers

What characterizes the life cycle of Giardia intestinalis?

<p>Binary fission and cyst formation (C)</p> Signup and view all the answers

Which population is particularly susceptible to severe symptoms from Giardia intestinalis infections?

<p>Patients with IgA deficiency (C)</p> Signup and view all the answers

What is a common food source associated with flaccid paralysis symptoms?

<p>Ham (C), Cream pastries (D)</p> Signup and view all the answers

Which bacterium is characterized as Gram-positive cocci in clusters?

<p>Staphylococcus aureus (D)</p> Signup and view all the answers

Which type of treatment is indicated for patients with foodborne illness symptoms related to specific toxins?

<p>Trivalent antitoxin (A)</p> Signup and view all the answers

What type of bacteria is associated with anaerobic and spore-forming characteristics?

<p>Anaerobic Gram-positive rods (D)</p> Signup and view all the answers

Which food source is associated with a higher risk of bacterial growth leading to toxin production?

<p>Fried rice (B), Potato salad (C)</p> Signup and view all the answers

Which of these statements is accurate regarding recovery from bacterial foodborne illnesses?

<p>Typically self-limited without treatment (A)</p> Signup and view all the answers

What is a likely characteristic of the bacteria associated with superantigen activity?

<p>Can cause toxic shock syndrome (A)</p> Signup and view all the answers

What is a symptom associated with toxin in leftover food?

<p>Flaccid paralysis (D)</p> Signup and view all the answers

What is the common age group predominantly affected by gastroenteritis associated with enteric adenovirus?

<p>Children younger than 2 years (C)</p> Signup and view all the answers

Which subtype of enteric adenovirus is the most common?

<p>Subtype A (A)</p> Signup and view all the answers

What is a significant characteristic of the diarrhea caused by rotavirus?

<p>Acute onset with projectile vomiting (B)</p> Signup and view all the answers

Which diagnostic method is used to detect enteric adenovirus infection?

<p>PCR or ELISA methods (C)</p> Signup and view all the answers

Which of the following bacteria is classified as invasive and associated with PMN in stool?

<p>Salmonella (A)</p> Signup and view all the answers

What is a key feature of Enterotoxigenic E. coli (ETEC)?

<p>Produces toxins that lead to watery diarrhea (B)</p> Signup and view all the answers

What type of treatment is essential for life-threatening diarrhea caused by rotavirus?

<p>Fluid and salt replacement (D)</p> Signup and view all the answers

What characteristic differentiates Enteropathogenic E. coli (EPEC) from other enteric bacteria?

<p>It leads to no inflammation or invasion (B)</p> Signup and view all the answers

What is the primary mechanism of cholera toxin in causing symptoms?

<p>Permanent activation of adenylate cyclase (B)</p> Signup and view all the answers

Which culture method is preferred for diagnosing cholera?

<p>TCBS agar (C)</p> Signup and view all the answers

What condition is strongly contraindicated in cases of EHEC?

<p>Fluids and electrolytes replacement (A)</p> Signup and view all the answers

What is a characteristic feature of Salmonella that helps differentiate it from Shigella?

<p>Hydrogen sulfide production (D)</p> Signup and view all the answers

Which treatment option is typically first-line for cholera if resistant?

<p>Tetracycline (B)</p> Signup and view all the answers

What clinical manifestation is associated with Vibrio cholera infection?

<p>Watery 'rice water' stools (A)</p> Signup and view all the answers

In what way does the transmission of Vibrio parahaemolyticus primarily differ from that of Vibrio cholerae?

<p>Cholera is transmitted through contaminated water, while parahaemolyticus is through seafood. (C)</p> Signup and view all the answers

What symptom is most likely associated with severe cholera infection?

<p>Metabolic acidosis (C)</p> Signup and view all the answers

Which feature allows Enterohemorrhagic E. coli (EHEC) to cause severe symptoms?

<p>Inhibition of protein synthesis (B)</p> Signup and view all the answers

What is the primary mechanism of action for the shiga-like toxins produced by E. coli?

<p>Inhibiting protein synthesis (C)</p> Signup and view all the answers

What characteristic of Enteroaggregative E. coli (EAEC) contributes to its adherence mechanism?

<p>Stacked brick formation (A)</p> Signup and view all the answers

What complication is commonly associated with Enterohemorrhagic E. coli infections?

<p>Hemolytic-uremic syndrome (HUS) (C)</p> Signup and view all the answers

Which of the following is a significant risk factor for infection by Enterohemorrhagic E. coli?

<p>Consumption of undercooked beef (D)</p> Signup and view all the answers

What effect does the heat-labile enterotoxin have on intestinal cells?

<p>Stimulates fluid secretion (B)</p> Signup and view all the answers

How does the capsule of certain E. coli strains benefit the bacteria?

<p>Inhibits phagocytosis (B)</p> Signup and view all the answers

What symptom is NOT typically associated with infections caused by Enterohemorrhagic E. coli?

<p>Profuse watery diarrhea (B)</p> Signup and view all the answers

What is the primary method of transmission for Entamoeba histolytica?

<p>Fecally contaminated food or drink (D)</p> Signup and view all the answers

Which of the following is a consequence of E. histolytica invasion of the intestine?

<p>Localized ulcers in the colon (B)</p> Signup and view all the answers

What is a characteristic symptom of amoebic dysentery caused by E. histolytica?

<p>Presence of mucus, pus, and blood in stools (C)</p> Signup and view all the answers

Which two organisms are notably involved in the cause of diarrhea?

<p>Entamoeba histolytica and Giardia intestinalis (D)</p> Signup and view all the answers

Which of the following describes a differentiation between Shigella and Entamoeba histolytica in stool analysis?

<p>Presence of many polymorphs and macrophages in Shigella (A)</p> Signup and view all the answers

What type of lesions are associated with E. histolytica infection within the intestine?

<p>Inverted flask-shaped ulcers (A)</p> Signup and view all the answers

Which diagnostic technique is used to identify active E. histolytica infection in stool samples?

<p>Indirect fluorescent antibody technique (IFAT) (D)</p> Signup and view all the answers

What is a common treatment for acute Entamoeba histolytica infection?

<p>Metronidazole or tinidazole (A)</p> Signup and view all the answers

Flashcards

Food-borne botulism

A type of botulism where pre-formed toxins are ingested from improperly canned food.

Infant botulism

A type of botulism where C. botulinum spores are ingested by infants and produce toxins in their gut.

Wound botulism

A type of botulism where C. botulinum spores or toxins are introduced into a wound.

Clostridium botulinum (C. botulinum)

The bacterium responsible for botulism.

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Botulinum toxins

The toxins produced by C. botulinum that cause botulism.

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Superantigen activity

A type of immune response where a superantigen triggers the activation of a large number of T cells, leading to a massive immune response.

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VβTCR (Variable beta chain of the T cell receptor)

A specific type of T cell receptor that is targeted by superantigens, leading to their widespread activation.

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Severe vomiting (projectile)

A severe and rapid onset of vomiting, usually occurring within 3-6 hours after consuming contaminated food or water. It is a common symptom of superantigen-induced illness .

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Diarrhea (loose stools)

Loose and watery stools, frequently a symptom of superantigen-induced illness. Often accompanied by severe vomiting.

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Recovery within 24 hours

The recovery period after superantigen-induced illness is typically short, with most symptoms resolving within 24 hours.

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Anaerobe

A type of bacteria that can survive and thrive in the absence of oxygen.

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Double zone hemolysis

A distinctive pattern of hemolysis on blood agar plates where a clear zone of complete hemolysis is surrounded by a narrow zone of partial hemolysis.

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Gas gangrene

A severe bacterial infection that can occur after trauma or eating contaminated food. Characterized by tissue damage, gas production, and rapid spread.

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Alpha toxin (C-Lecithinase)

A toxin produced by Clostridium perfringens, the bacteria responsible for gas gangrene. This toxin breaks down cell membranes, leading to tissue destruction and other complications.

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Transmission

The spread of an infection from one person to another. In the case of Clostridium perfringens, this can happen through contaminated food or wounds.

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Clostridium botulinum

A type of bacteria responsible for botulism, a serious illness affecting the nervous system.

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Adult botulism treatment

Treatment for adult botulism involves polyvalent antitoxin and intensive supportive therapy.

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Infant botulism treatment

Human-derived botulism immune globulin is used to treat botulism in infants.

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Clostridium perfringens

A rod-shaped bacteria with a positive gram stain, capable of forming spores and unable to move.

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Gram (+) rod, spore former, nonmotile

A type of bacteria categorized by its shape (rod), its reaction to Gram staining (positive), spore formation ability, and lack of motility.

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Self-limiting noninflammatory C. perfringens Diarrhea

A type of Clostridium perfringens infection causing watery diarrhea. It's often linked to the type A strain producing an enterotoxin, which disrupts the gut.

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Enterotoxin

The specific toxin released by Clostridium perfringens type A strain that causes watery diarrhea.

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Necrotizing Enteritis

A rare type of Clostridium perfringens infection characterized by severe, life-threatening inflammation and tissue death in the intestines, particularly the small intestines.

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Type C Clostridium perfringens Infection

A type of Clostridium perfringens infection often associated with the type C strain, resulting in a severe inflammatory reaction that damages the intestines.

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Beta-toxin

A potent toxin associated with the type C strain of Clostridium perfringens and responsible for the tissue damage seen in pigbel.

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Toxigenic Clostridium difficile (CDI)

A type of Clostridium difficile infection that produces toxins, causing severe diarrhea and other complications.

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Non-toxigenic Clostridium difficile

A type of Clostridium difficile infection that does not produce toxins, typically causing milder symptoms or no symptoms at all.

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Nosocomial Clostridium difficile Infection

A type of hospital-acquired infection caused by Clostridium difficile.

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Nosocomial Infection

An infection acquired in a hospital setting, often affecting hospitalized patients.

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220,000 Nosocomial Clostridium difficile cases (USA)

The number of Clostridium difficile cases reported in US hospitals annually, highlighting the prevalence of this serious infection.

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What is Botulism?

Botulism is a severe paralytic illness caused by a neurotoxin produced by the bacterium Clostridium botulinum. It's often associated with improperly canned foods.

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What are the different types of botulism?

Botulism can manifest in three main forms: food-borne botulism, infant botulism, and wound botulism.

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What are the symptoms of botulism?

The symptoms of botulism include muscle weakness, blurred vision, difficulty swallowing, and respiratory distress.

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How is botulism treated?

Botulism is often treated with antitoxin, a medication that neutralizes the botulinum toxin.

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What is Clostridium perfringens?

C. perfringens is a gram-positive, spore-forming bacterium that can cause various infections, including food poisoning and gas gangrene.

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What is C. perfringens food poisoning?

C. perfringens food poisoning is a common illness characterized by watery diarrhea and abdominal cramps. It typically resolves within 24 hours.

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What is gas gangrene?

Gas gangrene is a serious infection caused by C. perfringens that can lead to tissue death and gas production in the infected area.

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What is Clostridium difficile?

C. difficile is a bacterium that can cause severe diarrhea, particularly in hospital settings. It is known for producing toxins that damage the lining of the intestines.

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Enterotoxigenic E. coli (ETEC)

A type of E. coli that produces toxins, leading to watery diarrhea, especially common in travelers' diarrhea.

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Enteropathogenic E. coli (EPEC)

A type of E. coli that attaches to intestinal cells and causes inflammation, resulting in prolonged diarrhea, particularly in infants.

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Invasive bacteria

A category of bacteria that invade the intestinal lining, causing inflammation and often bloody diarrhea. Examples include Shigella, Salmonella, Campylobacter, and EIEC.

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Toxigenic bacteria

A category of bacteria that produce toxins, causing diarrhea without invading the intestinal lining. Examples include ETEC, V. cholerae, Cl. perfringens, and EHEC.

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Enterohemorrhagic E. coli (EHEC)

A type of E. coli that produces toxins that attach to intestinal cells, causing watery diarrhea.

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Enteroaggregative E. coli (EAEC)

A type of E. coli linked to acute, profuse diarrhea and vomiting, commonly associated with swine industry.

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Enteroaggregative E. coli (EAEC)

A type of E. coli that causes bloody diarrhea and can lead to hemolytic uremic syndrome (HUS).

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E.coli

A group of bacteria that can cause various types of diarrhea in humans.

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What is ETEC?

Enterotoxigenic Escherichia coli (ETEC) is a type of E. coli that produces toxins that cause diarrhea. It is often associated with traveler's diarrhea and is generally considered a milder form of E. coli infection.

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How does ETEC cause diarrhea?

ETEC causes diarrhea through the production of two main types of toxins: heat-labile toxin (LT) and heat-stable toxin (ST). LT is similar to cholera toxin and causes fluid secretion in the intestines, while ST is a smaller toxin that also triggers fluid loss.

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How is ETEC acquired and what are the symptoms?

ETEC infection is typically acquired through contaminated food or water, and it is common in areas with poor sanitation. Symptoms usually start within 1-3 days after exposure and can include watery diarrhea, abdominal cramps, and sometimes fever.

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How is ETEC treated?

Treatment for ETEC usually involves fluid replacement to compensate for fluid loss. Antibiotics are generally not recommended, but in severe cases, they may be considered.

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What is Vibrio cholerae?

Vibrio cholerae is a comma-shaped bacterium that causes cholera, a severe diarrheal illness. It is spread through contaminated water and food and is a serious threat in areas with poor sanitation.

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How does Vibrio cholerae cause cholera?

The cholera toxin produced by Vibrio cholerae is responsible for the severe diarrhea characteristic of cholera. This toxin binds to intestinal cells and triggers a cascade of events that leads to a massive outpouring of fluids.

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What are the complications of cholera and how is it treated?

Cholera can lead to severe dehydration, electrolyte imbalance, and even death if left untreated. Prompt rehydration with fluids and electrolytes is crucial for managing cholera. Antibiotics may also be used to reduce the severity and duration of the illness.

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What is Salmonella Non-Typhoidal?

Salmonella non-typhoidal is a type of bacteria that frequently causes food poisoning. It is often found in poultry and dairy products, and transmission typically happens through contaminated food or water.

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Bundle-forming pili (BFP)

These pili are located on the bacterial surface and attach to the host cell by binding to the host cell's receptors, leading to colonization and the formation of a "bundle" of bacteria. These bacteria, in turn, can trigger the release of toxins or cause damage to the host cell.

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Intimin

This protein is a key virulence factor in enterohemorrhagic Escherichia coli (EHEC). It helps to create an intimate attachment between the bacteria and the host cell, leading to the formation of "attaching-effacing lesions" on the surface of the intestinal lining.

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Translocated intimin receptor (Tir)

This receptor protein is encoded by the bacteria and is directly inserted into the host cell membrane by EHEC. Acting as a 'bridge,' it allows the bacteria to attach more tightly to the host cell, contributing to the formation of attaching-effacing lesions and causing damage.

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Heat-labile enterotoxin (LT)

This toxin, produced by some strains of E. coli, causes severe diarrhea by stimulating the production of cyclic AMP (cAMP). cAMP interferes with the normal absorption of water and electrolytes in the intestines, leading to watery diarrhea.

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Heat-stable enterotoxin (ST)

Similar to LT, this toxin affects the intestines but works by triggering the production of cyclic GMP (cGMP). cGMP results in increased fluid secretion into the gut, causing severe diarrhea.

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Verotoxin (Shiga-like toxin)

A major virulence factor in EHEC, this toxin (also known as Shiga-like toxin) disrupts protein synthesis in the host cell. This can lead to cell damage and death. Its presence can cause Hemolytic-Uremic Syndrome (HUS): a serious condition characterized by hemolysis, thrombocytopenia, and acute kidney failure.

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Enteropathogenic Escherichia coli (EPEC)

This type of Escherichia coli infection is characterized by an attaching-effacing (A/E) mechanism. The bacteria produce an 'intimate attachment' with the intestinal lining, leading to the destruction of microvilli and diarrhea. They are known to cause severe diarrhea, especially in infants.

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Hemorrhagic colitis (HC)

A specific type of diarrhea caused by EHEC. Known for its 'bloody' appearance and often accompanies intense stomach cramping.

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Giardia intestinalis

A microscopic parasite with two life stages: the trophozoite (active form) and the cyst (dormant form), both spread through contaminated water or fecal-oral route.

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Cryptosporidium Hominis

A protozoan parasite that infects the intestinal tract, often causing diarrhea, especially in immunocompromised individuals.

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Diloxanide furoate

An antiparasitic drug used to treat intestinal amoebiasis, effectively targeting amoebae in the gut lumen.

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Metronidazole

A common antiparasitic drug used to treat a variety of intestinal parasitic infections, including those caused by Giardia.

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Nitazoxanide

An antiparasitic drug used to treat intestinal infections, specifically targeting Giardia and Cryptosporidium.

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Entamoeba histolytica

A parasitic protozoan responsible for invasive amoebiasis, characterized by bloody diarrhea, liver abscesses, and potential extraintestinal complications. It is spread through contaminated water and food.

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Trophozoite

The active, feeding stage of an ameba, capable of reproducing and invading host tissues.

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Cyst

The dormant, resistant stage of an ameba, capable of surviving outside the host and transmitting infection.

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Excystation

The process of an ameba transitioning from a cyst to a trophozoite, typically occurring within the small intestine.

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Flask-shaped ulcer

A characteristic lesion formed by Entamoeba histolytica in the intestinal mucosa, resembling an inverted flask.

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Liver abscess

A common complication of Entamoeba histolytica infection, characterized by inflammation and pus formation in the liver.

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Study Notes

GI Tract Infections - Infectious Diarrheas

  •  GI tract infections include food poisoning and infectious diarrhea
  •  Transmission methods and associated etiologies are identified
  • Pathogenesis mechanisms of involved infectious agents are recalled
  • Relevant clinical data is analyzed and integrated to reach a diagnosis
  • First line and gold standard diagnostic methods and key outcomes are identified
  • Treatment focus for infectious agents is recalled
  • All pathogens are ingested

Objectives

  •  Identify common etiologies for food poisoning and infectious diarrhea
  •  List transmission methods for food poisoning and infectious diarrhea
  •  Recall the pathogenesis mechanisms of infectious agents
  •  Analyze and integrate clinical data to reach a diagnosis
  •  Identify first-line and gold-standard diagnosis methods
  •  Recall the treatment focus for infectious agents

Definitions

  •  Gastroenteritis: GI symptoms including nausea, vomiting, diarrhea, abdominal discomfort
  •  Diarrhea: Abnormal fecal discharge, characterized by frequent, fluid stool, and increased fluid and electrolyte loss
  •  Dysentery: Inflammatory disorder of the GI tract, involving blood and pus in stools, with pain, fever, and abdominal cramps, affecting large intestine
  •  Enterocolitis: Inflammation of both small and large intestines' mucosa

All Pathogens

  • All pathogens are ingested
  • Diarrhea without blood and pus is enterotoxin production
  • Blood and/or pus cells indicate invasive infection with mucosal destruction
  • Pathogens are acquired through faecal-oral route through fecally contaminated food or fluids, or through fingers

Bugs Causing Food-Borne Illness

  • S aureus and B cereus food poisoning onset is quick and resolves quickly
  • Bacteria, Bacterial toxins, Parasites, Viruses, and Protozoa
  • Sources of infection for each bacteria are listed
    • S Aureus: reheated foods, potato salad, cream-filled pastries
    • B cereus: fried rice, reheated rice (emetic form); meats, milk, veggies, fish, sauces/gravies (diarrheal form)
    • C botulinum: improperly canned, preserved foods (toxins), raw honey (spores)
    • C perfringens: reheated meats (Watery diarrhea, B-type C-strain, beta-toxin-pigbel necrotizing disease)
    • E coli O157:H7: undercooked ground beef, unpasteurized milk, contaminated water
    • L monocytogenes: unpasteurized milk, soft cheeses, raw milk
    • Salmonella: poultry, eggs, pets, turtles, unpasteurized milk, undercooked/ contaminated food
    • Shigella: human contact, poultry, undercooked food, water
    • S aureus, raw and undercooked foods or unpasteurized milk
    • V vulnificus: raw/undercooked seafood
  • V parahaemolyticus: raw/undercooked seafood - associated with wound infections from contaminated water or shellfish

Bacterial Toxin Diarrhea

  • Staphylococcus Aureus is gram +, clustered cocci, catalase positive

  • Heat-stable and resistant to destruction in GI tract

  • Severe vomiting (3-6 hours after consumption); usually within 24 hours.

  • Human carriers can contaminate through skin and nose

  • Bacillus Cereus is gram +, spore producer

  • Emetic toxin (heat-stable)- ingested preformed in foods high in carbohydrates (like fried rice) and causes vomiting

  • Diarrheal toxin (heat-labile) → ingested spores in foods with high protein content (meat, sausages) causing diarrhea

  • Antibiotic treatment is not indicated

  • Clostridium Botulinum is gram + and anaerobic, spore-former

  • Neurotoxins (A-G most common E, F to humans and heat-labile)

  • Preformed toxins in the gut inhibit neurotransmitter release.

  • Foodborne botulism: contaminated or reheated foods

  • In food-borne botulism, eating home-canned foods or inadequate heat processing causes the release of neurotoxins.

  • Flaccid paralysis is the main symptom

Clostridium Perfringens

  • Gram-positive rod, spore-former, non-motile, anaerobe
  • Transmission: foodborne (reheated meat), trauma
  • Watery diarrhea, B-type C-strain, beta-toxin-pigbel necrotizing disease
  • Spore germinateâž” vegetative C. perf in GI
  • Symptoms include cramps, watery diarrhea, less than 24 hours, and self-limiting

Clostroides Difficile- Antibiotic Associated Diarrhoea

  • Gram-positive bacilli; anaerobe; spore former
  • Reservoir: human colon
  • Nosocomial infections (220,000 cases annual, 13,000 deaths)
  • Clindamycin, Tetracycline, Fluoroquinolones, 2nd generation penicillins, and macrolides are involved.
  • Recolonization happens with S. aureus/yeasts (Candida)
  • Increased toxin production causes direct and indirect cytopathic effects → colonocyte death, loss of intestinal barrier function, colitis.
  • Glucosylation of rho proteins by the toxins results in colonic epithelial cell rounding, fluid leakage, cell death
  • Toxins A & B; Increased toxin production causes direct and indirect cytopathic effects; Glucosylation of rho proteins results in cell death (rounding, fluid loss)

Viral Causes of Diarrhea

  • Faecal-oral transmission is the main mode of transmission

  • Noroviruses: naked, ss linear, RNA

  • Highly infectious, spreads rapidly (common in closed environments, cruise ships).

  • Clinical manifestations include acute onset of vomiting, watery diarrhea, cramping, and fever

  • Lab diagnosis: PCR

  • Rotavirus: ds RNA reovirus

  • Most important cause for infants

  • Transmission is fecal oral

  • Peak during cooler months

  • Symptoms include acute onset of vomiting, projectile, and diarrhea lasting 4-7 days.

Adenovirus

  • ds, DNA linear, non-enveloped
  • Transmission: fecal-oral, respiratory, and direct contact
  • Long incubation period (8-10 days)
  • Less infectious vs rotavirus or norovirus
  • Associated with myocarditis and intussusception

Bacterial Causes of Diarrhea

  • Salmonella: Gram-negative rods. Facultative intracellular, lactose fermenter

  • Campylobacter: S-shaped Gram-negative rods, polar flagellated

  • Person-to-person spread is rare

  • Transmitted via consumption of undercooked/contaminated food, or contact with animals, milk bottles

  • Clinical manifestations are typically similar to Salmonella and Shigella: frank dysentery to watery diarrhea to asymptomatic excretion

  • Tx: usually recovery without antibiotic treatment or azithromycin for severe diarrhea, invasive infections require fluoroquinolones

  • Yersinia enterocolitica: Gram-positive pleomorphic rods, cocobacillus

  • Food-associated infection and winter months

  • Acute bloody diarrhea

  • Reactive arthritis in adults

  • Can be mistaken for acute appendicitis (especially in children)

  • Symptoms include cramping, diarrhea, chills, and fever.

Parasites

  • Transmission routes are more complex and include food or water contaminated with eggs/larvae, picked up directly, or animal products

  • Eating contaminated animal products can cause various stages of infections (from mild to chronic)

  • Typical symptoms include diarrhea, cramps, and fever.

  • Entamoeba histolytica: Protozoan amebae

  • E. histolytica is invasive, E. dispar is not pathogenic and non-invasive

  • Transmission through contaminated food or drink (fecal contamination)

  • Inflammatory response to the pathogen results in red blood cells, mucus, and pus in the stool

  • Giardia intestinalis: Protozoan, flagellated

  • Transmission is waterborne and fecal-oral

  • Inflammatory response leads to malabsorption and diarrhea

  • Symptoms include loose, foul-smelling, and fatty stools.

  • Self-limiting, with 7-10 days being the usual course, can develop into malabsorption.

  • Giardia needs to be cultured or recognized through a microscope by examining cysts or trophozoites.

  • Cryptosporidium hominis: Protozoan

  • Transmission is through contaminated food or water and can be fecal oral

  • Transmission is common in daycare centers and among male homosexual individuals, through person-to-person contact

  • Symptoms include watery diarrhea, which may be severe in immunocompromised persons.

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Test your knowledge on the causes and symptoms of food-borne botulism in adults and infants. This quiz also covers superantigen activity and its effects on the body. Dive into the details to understand the distinctions and transmission methods of these serious conditions.

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