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?

Low stomach acidity. Signup and view all the answers

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

Contaminated food and water. Signup and view all the answers

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

1-4 days. Signup and view all the answers

What is the clinical presentation of V. cholerae infection?

Nausea, vomiting, and profuse diarrhea. Signup and view all the answers

What percentage of V. cholerae infections are asymptomatic?

60% Signup and view all the answers

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

Campylobacter species Signup and view all the answers

What is the recommended counterstain for Carbol-fuchsin?

Safranin Signup and view all the answers

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

35°C to 37°C Signup and view all the answers

What is the major cause of type B gastritis?

H. pylori infection Signup and view all the answers

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

50% Signup and view all the answers

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

Microaerophilic atmosphere Signup and view all the answers

What is the specimen of choice for C. fetus?

Blood Signup and view all the answers

What is the characteristic of Campylobacter species?

Oxidase-positive, catalase-positive Signup and view all the answers

What is the primary disease caused by Campylobacter jejuni?

Gastroenteritis Signup and view all the answers

What is the shape of Campylobacter jejuni rods?

Curved rods Signup and view all the answers

How is Campylobacter jejuni often transmitted?

By consumption of contaminated food or water Signup and view all the answers

What is the characteristic of Vibrio species in stools?

Large numbers of Vibrios Signup and view all the answers

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

Profound dehydration, circulatory collapse, and anuria Signup and view all the answers

Which serotype of Campylobacter jejuni is responsible for major pandemics?

O1 and O139 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.