Vibrio Cholerae Infection and Diagnosis
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Questions and Answers

What is the primary reason why direct person-to-person spread of V. cholerae is rare?

  • The infectious dose is low.
  • The infectious dose is high. (correct)
  • The organisms are susceptible to acid.
  • The organisms are not susceptible to acid.

    • Why are fewer organisms required to cause infection when the vehicle is food?

  • The acidic environment of the stomach increases the infectious dose.
  • The buffering capacity of food decreases the infectious dose. (correct)
  • The alkaline environment of the intestine decreases the infectious dose.
  • The buffering capacity of food increases the infectious dose.

    • What is the optimal timing for culturing stool specimens for V. cholerae diagnosis?

  • Early in the course of the disease. (correct)
  • During the incubation period.
  • After symptoms have resolved.
  • Late in the course of the disease.

    • What increases a person's susceptibility to V. cholerae infection?

    <p>Low stomach acidity.</p> Signup and view all the answers

    What is the primary mode of transmission of V. cholerae?

    <p>Contaminated food and water.</p> Signup and view all the answers

    What is the typical incubation period of V. cholerae infection?

    <p>1-4 days.</p> Signup and view all the answers

    What is the clinical presentation of V. cholerae infection?

    <p>Nausea, vomiting, and profuse diarrhea.</p> Signup and view all the answers

    What percentage of V. cholerae infections are asymptomatic?

    <p>60%</p> Signup and view all the answers

    Which species of bacteria can be identified based on their growth at 42°C?

    <p>Campylobacter species</p> Signup and view all the answers

    What is the recommended counterstain for Carbol-fuchsin?

    <p>Safranin</p> Signup and view all the answers

    What is the ideal temperature for incubating a specimen for H. pylori?

    <p>35°C to 37°C</p> Signup and view all the answers

    What is the major cause of type B gastritis?

    <p>H. pylori infection</p> Signup and view all the answers

    What is the estimated percentage of the population worldwide infected with H. pylori?

    <p>50%</p> Signup and view all the answers

    What is the ideal atmosphere for incubating a specimen for Campylobacter?

    <p>Microaerophilic atmosphere</p> Signup and view all the answers

    What is the specimen of choice for C. fetus?

    <p>Blood</p> Signup and view all the answers

    What is the characteristic of Campylobacter species?

    <p>Oxidase-positive, catalase-positive</p> Signup and view all the answers

    What is the primary disease caused by Campylobacter jejuni?

    <p>Gastroenteritis</p> Signup and view all the answers

    What is the shape of Campylobacter jejuni rods?

    <p>Curved rods</p> Signup and view all the answers

    How is Campylobacter jejuni often transmitted?

    <p>By consumption of contaminated food or water</p> Signup and view all the answers

    What is the characteristic of Vibrio species in stools?

    <p>Large numbers of Vibrios</p> Signup and view all the answers

    What is the consequence of rapid loss of fluid and electrolytes in Campylobacter jejuni infection?

    <p>Profound dehydration, circulatory collapse, and anuria</p> Signup and view all the answers

    Which serotype of Campylobacter jejuni is responsible for major pandemics?

    <p>O1 and O139</p> Signup and view all the answers

    Study Notes

    Cholera

    • Direct person-to-person spread is rare due to high infectious dose
    • Stomach acids kill most Vibrio cholerae organisms
    • Normal gastric acidity requires ingestion of 1000+ V.cholerae to become infected through contaminated water
    • Food buffering capacity reduces the infectious dose to 102-104 organisms
    • Diagnosis involves microscopic examination and stool culture
    • Medications or conditions reducing stomach acidity increase susceptibility to infection
    • Fluid and electrolyte replacement are crucial for treatment
    • Antibiotics such as doxycycline, trimethoprim-sulfamethoxazole, or furazolidone are administered
    • About 60% of infections are asymptomatic
    • Improved hygiene is critical for control
    • Incubation period is 1-4 days

    Campylobacter

    • Sudden onset of nausea, vomiting, and profuse diarrhea with abdominal cramps
    • Organisms exhibit darting motility on hanging drop preparations or phase contrast microscopy
    • Most clinically relevant species are C.jejuni subsp.jejuni, C.coli, and C.fetus subsp
    • Inoculation of specimen to campylobacter blood agar and incubation in microaerophilic atmosphere
    • Oxidase-positive, catalase-positive campylobacter species can be differentiated based on growth at 42°C
    • Stools resemble rice water and contain mucus, epithelial cells, and large numbers of Campylobacter
    • Rapid loss of fluid and electrolytes leads to dehydration, circulatory collapse, and anuria
    • Often transmitted by contaminated water and animals, especially poultry and carcasses
    • Campylobacter fetus is the causative agent of bacteremia

    Helicobacter

    • Identified in 80% of gastric ulcer patients
    • Estimated that 50% of the population worldwide is infected with H.Pylori
    • Higher incidence attributed to poor sanitary conditions, with infection occurring early in life
    • Major cause of type B gastritis, a chronic condition formerly associated with stress and chemical irritants

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    Description

    This quiz explores the transmission and diagnosis of Vibrio cholerae infection, including the effects of stomach acid and the limitations of microscopic examination of stool.

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