Questions and Answers
Which of the following bacteria is NOT a member of Enterobacteriaceae?
What is the oxygen requirement of Helicobacter?
Which of the following bacteria is an obligate anaerobe?
What is the characteristic of Yersinia pestis?
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Which of the following Escherichia coli strains is associated with hemorrhagic colitis?
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Which of the following bacteria is a zoonotic pathogen?
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What type of respiration does Vibrio undertake?
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What is the primary mode of transmission of V.cholerae?
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What is the characteristic shape of Vibrio bacteria?
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What is a unique characteristic of Vibrio bacteria?
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How many species of curved rods are present in the genus Vibrio?
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What is the primary reservoir for V.cholerae in areas where the disease is endemic?
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What is the family name of the genus Vibrio?
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How many species of Vibrio are particularly important human pathogens?
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What is the typical pattern of Campylobacter infections?
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Why are patients who use proton pump inhibitors or H2 blockers more susceptible to Campylobacter infection?
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What is a common complication of Campylobacter infections?
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Which of the following Campylobacter species is NOT associated with acute enteritis?
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What is a rare occurrence in Campylobacter infections?
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Which Campylobacter species is associated with Reiter syndrome?
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What is the ideal temperature range for the growth of Vibrio cholera?
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What is the name of the pilus that helps Vibrio cholerae colonize the small intestine?
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What is the name of the toxin that is functionally similar to the heat-labile enterotoxin of Escherichia coli?
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What is the typical duration between ingestion of Vibrio cholerae and the onset of symptoms?
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What is the characteristic appearance of the stool in severe cholera cases?
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What is the consequence of severe fluid loss in cholera?
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How many serogroups of Vibrio cholerae are there?
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What is the name of the flagella that helps Vibrio cholerae pass through the stomach?
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What is the name of the biotype of Vibrio cholerae that is responsible for the majority of cholera cases?
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When should specimens for Vibrio cholerae culture be collected?
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What is the function of the surface (S)-layer protein in Campylobacter?
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What is the primary goal of management in Campylobacter gastroenteritis?
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Which of the following media is used for the culture of Campylobacter species?
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What is the characteristic of the O side chain of Helicobacter pylori?
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Which of the following is NOT a step in the laboratory diagnosis of Campylobacter infection?
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What is the primary antibiotic used to treat Campylobacter gastroenteritis?
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What type of atmosphere is required for the growth of Campylobacter species?
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Which of the following is a category of Helicobacter species?
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Study Notes
Gram-Negative Bacteria
- Bacteroides fragilis and Pseudomonas are examples of Gram-negative bacteria that can be aerobic, anaerobic, or microaerophilic.
Enterobacteriaceae
- Examples of Enterobacteriaceae include E. coli, Salmonella, Shigella, Yersinia, and others.
Vibrio
- Vibrio bacteria are Gram-negative, facultatively anaerobic, straight, curved, or comma-shaped rods that are motile and halophilic.
- There are 119 species of Vibrio, three of which are particularly important human pathogens: Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus.
Epidemiology of V. cholerae
- Cholera is associated with poor sanitation and direct contact with contaminated surface water.
- Asymptomatically infected humans can be an important reservoir for V. cholerae in endemic areas.
Physiology and Structure of V. cholerae
- V. cholerae can grow on simple media without additional salt and within a broad temperature range (14°C to 40°C).
- V. cholerae is susceptible to stomach acids.
- There are over 200 serogroups of V. cholerae, with V. cholerae O1 and V. cholerae O139 being the most important.
Life Cycle of V. cholerae
- V. cholerae has a life cycle that involves passage through the stomach via polar flagella, colonization of the small intestine via toxin co-regulated pilus, and secretion of cholera toxin.
Pathogenesis of V. cholerae
- Cholera toxin is a complex A-B toxin that promotes chloride ion secretion, decreased absorption by villous cells, and increased cAMP, leading to water moving from epithelial cells into the bowel lumen.
- Clinical manifestations of cholera begin with abrupt onset of watery diarrhea and vomiting, followed by dehydration, metabolic acidosis, hypokalemia, and hypovolemic shock.
Laboratory Diagnosis of V. cholerae
- Specimen collection should be done early in the disease, and inoculated promptly onto culture media.
Campylobacter
- Campylobacter is a worldwide zoonosis, with outbreaks usually occurring in the spring and fall.
- Campylobacter infections are usually sporadic, and secondary transmission from ill persons is rare.
Clinical Diseases Caused by Campylobacter
- GI infections caused by C. jejuni, C. coli, and C. upsaliensis can lead to acute enteritis, acute colitis, and abdominal pain mimicking acute appendicitis.
- Extraintestinal infections can lead to bacteremia, hepatitis, and urinary tract infections.
- Campylobacter can also cause Guillain-Barré syndrome, reactive arthritis, and Reiter syndrome.
Laboratory Diagnosis of Campylobacter
- Specimen collection involves fecal specimens, which are transported in alkaline peptone water with thioglycolate or Stuart medium.
- Direct examination involves microscopy, antigen detection, and nucleic acid-based tests.
- Culture involves the use of Skirrow's, Campy-BAP media, and requires a microaerobic atmosphere.
Treatment, Prevention, and Control of Campylobacter
- Campylobacter gastroenteritis is typically self-limited and managed by replacing lost fluids and electrolytes.
- Antibiotics such as erythromycin or azithromycin may be used.
Helicobacter
- Helicobacter can be classified into gastric helicobacters and enterohepatic helicobacters.
- H. pylori has an O side chain that is antigenically similar to the Lewis blood group antigens.
- There is no evidence of animal-to-human transmission of H. pylori.
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Description
This quiz covers the characteristics of gram negative bacteria, including Vibrio, Campylobacter, and Helicobacter. It also explores the different types of anaerobic and aerobic bacteria.
