Microbiology Quiz on Cholera and Campylobacter

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which of the following is NOT a virulence factor of Vibrio cholerae?

Flagellar proteins

Hemagglutinin

Cholera toxin

Cytotoxins (correct)

What is the primary effect of the Cholera toxin A subunit interacting with cytosolic ARFs?

It blocks the CFTR channel

It promotes Cl and Na absorption

It activates the Gsa subunit (correct)

It inhibits adenylate cyclase

In severe cases of Cholera, which clinical feature is most characteristic?

Constipation with bloody stools

Fever and localized abdominal pain

Rice water stool with fishy odor (correct)

Formation of crypt abscesses

Which disease exhibits mucosal and intraepithelial infiltrates, as well as cryptitis and crypt abscesses?

C. difficile colitis (B) Signup and view all the answers

Which of the following best describes the pathogenesis of Cholera in the small intestine?

Toxin induced hypersecretion of fluids and electrolytes, without invasion (D) Signup and view all the answers

What is the role of hemagglutinin in the pathogenesis of Cholera?

It is responsible for bacterial detachment and shedding (A) Signup and view all the answers

What is a key morphological feature that distinguishes Cholera from C. difficile colitis?

Minimal histological alterations (D) Signup and view all the answers

Which of these best describes the primary reservoir for Campylobacter jejuni?

Poultry, sheep, and pigs. (C) Signup and view all the answers

What is the initial step in the pathogenesis of Campylobacter jejuni infection, once in the host?

Attachment and proliferation on the enterocyte surface. (C) Signup and view all the answers

Which of the following is a hallmark histopathological finding in Campylobacter enterocolitis?

Cryptitis and crypt abscesses. (C) Signup and view all the answers

What is a potential extraintestinal complication associated with Campylobacter jejuni infection?

Reactive arthritis and Guillain-Barré syndrome. (D) Signup and view all the answers

In the context of the provided information, what is a major difference in the pathogenesis of Campylobacter jejuni compared to Yersinia infection? (as shown in the text).

Campylobacter's pathogenesis involves bacterial endocytosis and exocytosis which is not mentioned for Yersinia. (C) Signup and view all the answers

What is the most likely setting for a Campylobacter jejuni infection to occur?

Ingestion of improperly cooked poultry. (C) Signup and view all the answers

Which of the following cell types is involved in the host response in both Campylobacter and Yersinia infections?

Macrophages. (A) Signup and view all the answers

What is a clinical sign that can be associated with both Campylobacter and Yersinia infections based on the text provided?

Dysentery (bloody diarrhea). (A) Signup and view all the answers

In contrast to EHEC O157:H7 infection, what specific feature regarding host cells is described in the pathogenesis of Campylobacter?

Apoptosis of macrophages that have engulfed the bacteria. (B) Signup and view all the answers

Which of the following is a characteristic feature of Enteroinvasive E. coli (EIEC) infection?

Normal crypt architecture with abundant intraepithelial neutrophils (C) Signup and view all the answers

What is the primary reservoir for Shigella species?

Humans (B) Signup and view all the answers

What is the significance of M cells in the pathogenesis of Shigella infection?

They act as entry points for the bacteria into the host tissue. (A) Signup and view all the answers

Which of the following is NOT a virulence factor of Shigella species?

Flagellin (C) Signup and view all the answers

What is a typical symptom associated with Shigella infection?

Bloody diarrhea with possible pseudomembranes (C) Signup and view all the answers

What is the most appropriate treatment approach for Salmonella enteritidis infection?

Supportive care and allowing the infection to resolve on its own (C) Signup and view all the answers

How does Salmonella enteritidis enter host cells in the small intestine?

By inducing endocytosis in M cells and enterocytes. (C) Signup and view all the answers

What effect does bacterial flagellin have during a Salmonella infection?

It activates TLR5, leading to a high inflammatory response. (C) Signup and view all the answers

Which site is primarily affected by Shigella infection?

The colon and ileum (A) Signup and view all the answers

Which of these is a potential complication of Shigella infection?

Reactive arthritis and hemolytic uremic syndrome (A) Signup and view all the answers

Which of the following is NOT a typical symptom associated with Yersinia infections?

Dehydration (D) Signup and view all the answers

What is the primary function of the iron uptake system in Yersinia species?

To capture and transport iron (C) Signup and view all the answers

What is the direct effect of the heat-labile toxin (LT) produced by pathogenic bacteria?

Activation of adenylate cyclase leading to increased cAMP (D) Signup and view all the answers

Which of the following factors contributes to enhanced Yersinia virulence, stimulating systemic dissemination?

High non-heme iron levels (A) Signup and view all the answers

Which of the following methods of transmission is NOT primarily associated with Yersinia infections according to the text?

Consumption of undercooked chicken (C) Signup and view all the answers

What is the primary route of transmission for S. typhi in endemic regions?

Contaminated food and water (A) Signup and view all the answers

Which organ is a reservoir for S. typhi, leading to potential reinfection?

Gallbladder (D) Signup and view all the answers

What is a common complication associated with Salmonellosis resulting from S. typhi?

Encephalopathy and seizure (D) Signup and view all the answers

Which of the following is a characteristic histological finding in the liver during a S. typhi infection?

Typhoid nodules replacing hepatocytes (B) Signup and view all the answers

Which of the following is a distinguishing feature of S. paratyphi infections compared to S. typhi?

More common in travelers (A) Signup and view all the answers

Which of the following best describes the initial febrile phase of S.typhi?

Sustained high fevers for about two weeks (A) Signup and view all the answers

What is the significance of B-1 integrins in the context of Yersinia infection?

They are the host cell receptors that bind to Yersinia (C) Signup and view all the answers

In addition to the ileum and right colon, which other site is commonly affected by Yersinia infection?

Appendix (B) Signup and view all the answers

Which of the following conditions can Yersinia infection mimic?

Acute appendicitis (D) Signup and view all the answers

What are common animal reservoirs for Yersinia infections?

Pigs, cows, puppies, and cats (B) Signup and view all the answers

Study Notes

Bacterial Enterocolitides

Cholera:
- Agent: Vibrio cholerae
- Morphology: Minimal histologic alterations, no invasion, remains in the lumen.
- Pathogenesis: Flagellar proteins cause motility and attachment, cholera toxin (A and B) causes disease, toxin B binds to GM1 ganglioside, toxin A subunit interacts with cytosolic proteins, activating adenylate cyclase, increasing cAMP, blocking CFTR, and leading to Cl and Na absorption, accumulation of Cl ions, secretion of bicarbonate and Na, and massive diarrhea.
- Clinical features: Mostly asymptomatic in mild cases, severe cases present with rice water stool with a fishy odor.
- Location: Endemic in India and Africa, transmission through contaminated water and fecal-oral contact. Shellfish and plankton are reservoirs.
Campylobacter enterocolitis:
- Agent: Campylobacter jejuni
- Pathogenesis: Flagella, cytotoxins, invasion. Organisms attach and proliferate, endocytosis, exit, and invasion of next enterocyte.
- Clinical features: Acute self-limiting colitis, food poisoning, traveler's diarrhea, possibly dysentery. In severe cases, may show symptoms matching conditions like reactive arthritis, erythema nodosum, and Guillain-Barré syndrome (flaccid paralysis) in some patients with HLA-B27.
- Location: Reservoir includes chicken, sheep, pigs, cattle; Transmission: ingestion of improperly cooked chicken.
Shigellosis:
- Agent: Shigella spp.
- Morphology: Mucosa hemorrhagic and granular.
- Pathogenesis: Virulence factors, invasion, and inflammation cascade.
- Clinical features: Affected site: Left colon and ileum, reservoir: Humans.
- Location: Reservoir: Humans.

Other Bacterial Infections

Salmonellosis:
- Agent: Salmonella enteritidis
- Pathogenesis: Virulence factors (flagella, bacterial LPS), bacterial growth in endosomes, activation of TLR5 and TLR4, intense inflammation, and mucosal damage.
- Clinical features: Commonly, self-limiting infection. Severe cases can lead to complications like osteomyelitis in susceptible populations.
- Location: Reservoir: humans, animals; transmission: food, raw meat, poultry.
Typhoid fever:
- Agent: Salmonella enterica (S. typhi, S. paratyphi)
- Pathogenesis: Organisms taken up by M cells, invasion of M cells, and systemic reactive hyperplasia of phagocytes. S. typhi reside in the gallbladder.
- Clinical features: Initial dysentery, followed by asymptomatic phase, bacteremia in severe cases, possible complications like abdominal tenderness, rose spots.
- Location: Reservoir: humans, Transmission: contaminated food or water, person to person.

Viral Gastroenteritis

Norovirus:
- Single-stranded RNA.
- Common cause of nonbacterial gastroenteritis.
- Self-limiting in immunocompetent individuals.
- Transmission: Contaminated food, water, airborn droplets
Rotavirus:
- Double-stranded RNA.
- Most common cause of severe childhood diarrhea.
- Low infective dose, in some regions, maternal antibodies are ineffective in the first six months of a child's life.
Adenovirus:
- Most common cause of pediatric diarrhea, often self-limiting.
Ascaris lumbricoides:
- Parasitic infection, if disseminated, can result in hepatic abscesses, potentially leading to pneumonia.
- Transmission: human fecal-oral, contaminated water.

Further Bacterial Infections

Yersinia:
- Agent: Y. enterocolitica, Y. pseudotuberculosis, Y.. pestis
- Pathogenesis:Yersinia binds to B-1 integrins, iron uptake system mediates iron capture and transport.
- Clinical Feature Mimic acute appendicitis, extraintestinal symptoms, Pharyngitis, arthritis, Erythema nodosum, Chronic anemia, and hemochromatosis.
- Reservoirs: Cattle, Pigs, and other mammals, transmitted through contaminated food or water.
Enterotoxigenic E. coli (ETEC):
- Pathogenesis: Heat-labile toxin (LT), and heat-stable toxin (ST), activates adenylate cyclase, increased cAMP and cGMP, leads to fluid secretion.
- Clinical Features: Watery diarrhea.
- Reservoirs: Cows, transmission: contaminated food.
Enteropathogenic E. coli (EPEC):
- Pathogenesis: Adherent effacing (A/E) lesions, proteins in the cytoplasm to attach to cells.
- Clinical Features: Infant's diarrhea.
Enterohemorrhagic E. coli (EHEC):
- Pathogenesis: Shiga-like toxins (STx) activate adenylate cyclase.
- Clinical Features: Bloody diarrhea (possible HUS in some cases), ischemic colitis.
- Reservoirs: Cows
Enteroinvasive E. coli (EIEC):
- Pathogenesis: Invasion of epithelial cells.
- Clinical Features: Bloody diarrhea.
Enteroaggregative E. coli (EAEC):
- Pathogenesis: Attachment to enterocytes, similar to Shigella.
- Clinical Features: Non-bloody diarrhea.

Protozoal Infections

Cryptosporidium:
- Agent: Cryptosporidium spp.
- Pathogenesis: Oocyst, secretes proteases, releases sporozoites, damages brush-border. Na malabsorption, secretion of Cl leads to diarrhea.
- Clinical Features: Self-limiting diarrhea in immunocompetent persons; Chronic diarrhea in immunocompromised persons.
- Transmission: Contaminated drinking water, fecal-oral transmission
Strongyloides:
- Agent: Strongyloides spp.
- Pathogenesis: Filariform larvae is infective stage. Self-sustaining infection, auto-infection
- Clinical Features: Mucosal damage, iron deficiency anemia, intense irritation, and pruritus, bloody diarrhea.
- Transmission: Fecal-oral, ingestion
Schistosoma:
- Agent: Schistosoma spp.
- Pathogenesis: Cercariae from snails can penetrate skin, granulomatous reaction.
- Clinical Features: Granulomatous reaction, bleeding and obstruction.
Diphyllobothrium latum:
- Pathogenesis: Larval stage, infection persists, mucosal damage, possible vitamin B12 deficiency.
- Clinical Features: Megaloblastic anemia in severe cases possible, possible obstruction/bleeding.
Taenia solium:
- Pathogenesis: Cysticercus stage.
- Clinical Feature: Gravid proglottids in feces, presence of cysticerci in muscles of pork, can lead to neurological complications.
Hymenolepis nana:
- Pathogenesis: Eggs passed in feces.
- Clinical Features: Cysticercoid in arthropods (in some cases).
Entamoeba histolytica:
- Pathogenesis: Flask shaped ulcer, invasion and destruction of the colonic epithelium.
- Clinical Features: Amebiasis, potentially life-threatening.
Giardia lamblia:
- Pathogenesis: Duodenal trophozoites, cysts.
- Clinical Features: Diarrhea, usually self-limiting.

Pseudomembranous Colitis

Agent: Clostridium difficile
Pathogenesis: Antibiotics disrupt normal colonic flora leading to C. difficile overgrowth, toxin release damaging epithelial cells, inflammation and pseudomembrane formation.
Clinical Features: Antibiotic-associated colitis/diarrhea, protein loss, hypoalbuminemia, watery diarrhea.

Whipple Disease

Agent: Tropheryma whipplei
Pathogenesis: Distended foamy macrophages with PAS-positive granules.
Clinical Features: Arthritis, fever, lymphadenopathy.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge with this quiz focusing on the virulence factors, pathogenesis, and clinical features of Cholera and Campylobacter infections. Dive into the specifics of toxins, histopathology, and key characteristics that distinguish these pathogens. Perfect for students studying microbiology or infectious diseases.