Microbiology: Gram Negative Bacteria
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Questions and Answers

Which of the following bacteria is NOT a member of Enterobacteriaceae?

  • Salmonella
  • Shigella
  • Vibrio (correct)
  • E.coli

    • What is the oxygen requirement of Helicobacter?

  • Facultative anaerobe
  • Microaerophilic (correct)
  • Obligate anaerobe
  • Obligate aerobe

    • Which of the following bacteria is an obligate anaerobe?

  • Bacteroides fragilis (correct)
  • Pseudomonas
  • Campylobacter
  • Vibrio

    • What is the characteristic of Yersinia pestis?

    <p>Causes plague</p> Signup and view all the answers

    Which of the following Escherichia coli strains is associated with hemorrhagic colitis?

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

    Which of the following bacteria is a zoonotic pathogen?

    <p>Salmonella Typhimurium</p> Signup and view all the answers

    What type of respiration does Vibrio undertake?

    <p>Facultatively anaerobic</p> Signup and view all the answers

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

    <p>Direct contact with contaminated surface water</p> Signup and view all the answers

    What is the characteristic shape of Vibrio bacteria?

    <p>All of the above</p> Signup and view all the answers

    What is a unique characteristic of Vibrio bacteria?

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

    How many species of curved rods are present in the genus Vibrio?

    <p>119</p> Signup and view all the answers

    What is the primary reservoir for V.cholerae in areas where the disease is endemic?

    <p>Asymptomatically infected humans</p> Signup and view all the answers

    What is the family name of the genus Vibrio?

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

    How many species of Vibrio are particularly important human pathogens?

    <p>3</p> Signup and view all the answers

    What is the typical pattern of Campylobacter infections?

    <p>Usually sporadic, with incidence rising in March</p> Signup and view all the answers

    Why are patients who use proton pump inhibitors or H2 blockers more susceptible to Campylobacter infection?

    <p>Because C. jejuni is susceptible to hydrochloric acid</p> Signup and view all the answers

    What is a common complication of Campylobacter infections?

    <p>Guillain-Barré syndrome</p> Signup and view all the answers

    Which of the following Campylobacter species is NOT associated with acute enteritis?

    <p>C. difficile</p> Signup and view all the answers

    What is a rare occurrence in Campylobacter infections?

    <p>Secondary transmission from ill persons to others</p> Signup and view all the answers

    Which Campylobacter species is associated with Reiter syndrome?

    <p>C.</p> Signup and view all the answers

    What is the ideal temperature range for the growth of Vibrio cholera?

    <p>From 14° C to 40° C</p> Signup and view all the answers

    What is the name of the pilus that helps Vibrio cholerae colonize the small intestine?

    <p>Toxin co-regulated pilus</p> Signup and view all the answers

    What is the name of the toxin that is functionally similar to the heat-labile enterotoxin of Escherichia coli?

    <p>Complex A-B toxin</p> Signup and view all the answers

    What is the typical duration between ingestion of Vibrio cholerae and the onset of symptoms?

    <p>2 to 3 days</p> Signup and view all the answers

    What is the characteristic appearance of the stool in severe cholera cases?

    <p>Colorless, odorless, and free of protein</p> Signup and view all the answers

    What is the consequence of severe fluid loss in cholera?

    <p>Metabolic acidosis</p> Signup and view all the answers

    How many serogroups of Vibrio cholerae are there?

    <p>More than 200</p> Signup and view all the answers

    What is the name of the flagella that helps Vibrio cholerae pass through the stomach?

    <p>Polar flagella</p> Signup and view all the answers

    What is the name of the biotype of Vibrio cholerae that is responsible for the majority of cholera cases?

    <p>El Tor</p> Signup and view all the answers

    When should specimens for Vibrio cholerae culture be collected?

    <p>Early in the disease</p> Signup and view all the answers

    What is the function of the surface (S)-layer protein in Campylobacter?

    <p>It acts as a capsule</p> Signup and view all the answers

    What is the primary goal of management in Campylobacter gastroenteritis?

    <p>Replacement of lost fluids and electrolytes</p> Signup and view all the answers

    Which of the following media is used for the culture of Campylobacter species?

    <p>Skirrow's medium</p> Signup and view all the answers

    What is the characteristic of the O side chain of Helicobacter pylori?

    <p>It is antigenically similar to the Lewis blood group antigens</p> Signup and view all the answers

    Which of the following is NOT a step in the laboratory diagnosis of Campylobacter infection?

    <p>Polymerase chain reaction for gene expression analysis</p> Signup and view all the answers

    What is the primary antibiotic used to treat Campylobacter gastroenteritis?

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

    What type of atmosphere is required for the growth of Campylobacter species?

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

    Which of the following is a category of Helicobacter species?

    <p>Enterohepatic helicobacters</p> Signup and view all the answers

    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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    Vibrio, Campylobacter, Helicobacter PDF

    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.

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