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?

It can occur from eating honey containing spores. Signup and view all the answers

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

Infant botulism involves toxin production in the gastrointestinal tract from spores. Signup and view all the answers

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

Severe vomiting Signup and view all the answers

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

3–6 hours Signup and view all the answers

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

Within 24 hours Signup and view all the answers

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

Diarrhoea Signup and view all the answers

What is NOT a typical characteristic of superantigen activity?

Symptoms lasting more than 48 hours Signup and view all the answers

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

Food borne via reheated meat Signup and view all the answers

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

It promotes cell membrane disruption Signup and view all the answers

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

Increased immunity response Signup and view all the answers

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

Double zone hemolysis Signup and view all the answers

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

Endothelial cells Signup and view all the answers

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

Watery diarrhea Signup and view all the answers

Which strain is known to cause Pigbel necrotizing disease?

Type C strain Signup and view all the answers

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

Supportive treatment Signup and view all the answers

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

Metronidazole and penicillin Signup and view all the answers

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

Self-limiting and noninflammatory Signup and view all the answers

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

220,000 cases Signup and view all the answers

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

13,000 deaths Signup and view all the answers

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

Hospitalized patients Signup and view all the answers

What distinguishes toxigenic CDI from non-toxigenic CDI?

Production of toxins Signup and view all the answers

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

5.9% Signup and view all the answers

What is the primary treatment for adults diagnosed with botulism?

Polyvalent antitoxin and intensive supportive therapy Signup and view all the answers

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

Human-derived botulism immune globulin Signup and view all the answers

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

Gram-positive rods, spore former, nonmotile Signup and view all the answers

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

It is a Gram-negative rod Signup and view all the answers

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

Polyvalent antitoxin and supportive therapy Signup and view all the answers

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

Metronidazole Signup and view all the answers

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

Foul-smelling, fatty stools Signup and view all the answers

Which method is essential for diagnosing Giardia intestinalis infections?

Microscopic examination of stool Signup and view all the answers

What characterizes the life cycle of Giardia intestinalis?

Binary fission and cyst formation Signup and view all the answers

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

Patients with IgA deficiency Signup and view all the answers

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

Ham Signup and view all the answers

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

Staphylococcus aureus Signup and view all the answers

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

Trivalent antitoxin Signup and view all the answers

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

Anaerobic Gram-positive rods Signup and view all the answers

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

Fried rice Signup and view all the answers

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

Typically self-limited without treatment Signup and view all the answers

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

Can cause toxic shock syndrome Signup and view all the answers

What is a symptom associated with toxin in leftover food?

Flaccid paralysis Signup and view all the answers

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

Children younger than 2 years Signup and view all the answers

Which subtype of enteric adenovirus is the most common?

Subtype A Signup and view all the answers

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

Acute onset with projectile vomiting Signup and view all the answers

Which diagnostic method is used to detect enteric adenovirus infection?

PCR or ELISA methods Signup and view all the answers

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

Salmonella Signup and view all the answers

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

Produces toxins that lead to watery diarrhea Signup and view all the answers

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

Fluid and salt replacement Signup and view all the answers

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

It leads to no inflammation or invasion Signup and view all the answers

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

Permanent activation of adenylate cyclase Signup and view all the answers

Which culture method is preferred for diagnosing cholera?

TCBS agar Signup and view all the answers

What condition is strongly contraindicated in cases of EHEC?

Fluids and electrolytes replacement Signup and view all the answers

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

Hydrogen sulfide production Signup and view all the answers

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

Tetracycline Signup and view all the answers

What clinical manifestation is associated with Vibrio cholera infection?

Watery 'rice water' stools Signup and view all the answers

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

Cholera is transmitted through contaminated water, while parahaemolyticus is through seafood. Signup and view all the answers

What symptom is most likely associated with severe cholera infection?

Metabolic acidosis Signup and view all the answers

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

Inhibition of protein synthesis Signup and view all the answers

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

Inhibiting protein synthesis Signup and view all the answers

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

Stacked brick formation Signup and view all the answers

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

Hemolytic-uremic syndrome (HUS) Signup and view all the answers

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

Consumption of undercooked beef Signup and view all the answers

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

Stimulates fluid secretion Signup and view all the answers

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

Inhibits phagocytosis Signup and view all the answers

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

Profuse watery diarrhea Signup and view all the answers

What is the primary method of transmission for Entamoeba histolytica?

Fecally contaminated food or drink Signup and view all the answers

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

Localized ulcers in the colon Signup and view all the answers

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

Presence of mucus, pus, and blood in stools Signup and view all the answers

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

Entamoeba histolytica and Giardia intestinalis Signup and view all the answers

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

Presence of many polymorphs and macrophages in Shigella Signup and view all the answers

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

Inverted flask-shaped ulcers Signup and view all the answers

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

Indirect fluorescent antibody technique (IFAT) Signup and view all the answers

What is a common treatment for acute Entamoeba histolytica infection?

Metronidazole or tinidazole Signup and view all the answers

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 germinate➔ 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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Description

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.