Gram-Negative Bacteria
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Questions and Answers

What is a characteristic of the genus Escherichia?

  • Obligate anaerobic
  • Facultative anaerobic (correct)
  • Microaerophilic
  • Obligate aerobic

    • What is a virulence factor of E. coli?

  • Endotoxin (correct)
  • Exotoxin
  • Hemolysin
  • Cytotoxin

    • What is a habitat of Salmonella?

  • Gut of animals (correct)
  • Human skin
  • Soil
  • Fresh water

    • What is a characteristic of Vibrio?

    <p>Gram-negative</p> Signup and view all the answers

    What is a symptom of Salmonella infection?

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

    What is a transmission route of E. coli?

    <p>Food-borne</p> Signup and view all the answers

    What is a characteristic of S. typhi?

    <p>Water-borne</p> Signup and view all the answers

    What is a characteristic of E. coli's flagella?

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

    Which of the following bacteria can cause meningitis?

    <p>Neisseria meningitis</p> Signup and view all the answers

    What is a characteristic of Rickettsia?

    <p>It is an aerobic, G-ve coccobacillus</p> Signup and view all the answers

    How is Rickettsia typically transmitted?

    <p>Through arthropod bites</p> Signup and view all the answers

    What is a common symptom of meningitis?

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

    What is a characteristic of Rickettsia prowazekii?

    <p>It causes typhus fever</p> Signup and view all the answers

    What type of stain is used to visualize Neisseria gonorrhoeae?

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

    What is the primary characteristic of Vibrio cholerae that enables it to cause severe diarrhoea?

    <p>Production of exotoxin</p> Signup and view all the answers

    Which of the following is a characteristic of Pseudomonas aeruginosa?

    <p>Low membrane permeability</p> Signup and view all the answers

    What is the primary mode of transmission of Vibrio cholerae?

    <p>Through contaminated food and water</p> Signup and view all the answers

    What is the primary function of the capsule in Neisseria species?

    <p>Evasion of immune response</p> Signup and view all the answers

    Which of the following is NOT a characteristic of Vibrio cholerae?

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

    What is the primary function of fimbriae in Neisseria species?

    <p>Adhesion to tissues</p> Signup and view all the answers

    What is the primary reason for Pseudomonas aeruginosa being an opportunistic pathogen?

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

    What is the primary source of Pseudomonas aeruginosa infections?

    <p>Soil and water</p> Signup and view all the answers

    Study Notes

    Gram-Negative Bacteria

    Proteobacteria

    • Escherichia (E. coli) is a heterotrophic, facultative anaerobic, Gram-negative rod-shaped bacterium that inhabits the gut of humans and animals.

    • It can cause diarrhea, fever, and produces endotoxin and enterotoxin (in some strains).

    • E. coli is part of the Enterobacteriaceae family and has peritrichous flagella for motility.

    • Most strains are normal flora, but some can be pathogenic, with infection occurring through animal contact or contaminated food (e.g., 0157, 0111).

    • Salmonella (S. enterica) is a heterotrophic, facultative anaerobic, Gram-negative rod-shaped bacterium that is a normal flora in animal gut.

    • It can cause food-borne infections and self-limiting diarrhea, with endotoxin and enterotoxin production.

    • S. typhi is a water-borne infection that causes typhoid fever, which can be fatal.

    Vibrio

    • Vibrio (V. cholera) is a heterotrophic, facultative anaerobic, Gram-negative curved rod-shaped bacterium that is mainly found in marine environments.
    • It can cause gut infections, cholera, and severe diarrhea, with exotoxin production.
    • V. cholera is often found in sewage contamination and can cause seafood-borne disease.

    Pseudomonas

    • Pseudomonas (P. aeruginosa) is a heterotrophic, aerobic, Gram-negative curved rod-shaped bacterium that is commonly found in soil and water.
    • It can cause hospital-acquired infections, such as burns and contact lenses infections, and has innate antibiotic resistance.
    • P. aeruginosa has low membrane permeability, produces haemolysin, and proteases, and has a large genome (6mb) making it metabolically versatile.

    Neisseria

    • Neisseria is a heterotrophic, aerobic, Gram-negative diplococci bacterium that inhabits mammalian mucous membranes.
    • It has a capsule that aids in evading the immune response and fimbriae that allows adhesion to tissues.
    • N. gonorrhoeae causes gonorrhoea (STD) and N. meningitis causes meningitis (meningococcal disease).

    Rickettsia

    • Rickettsia is a heterotrophic, aerobic, Gram-negative coccobacillus bacterium that is dependent on host metabolism and cannot be grown in vitro.
    • It causes various fever diseases, such as arthropod-borne diseases, and produces phospholipase.
    • R. prowazekii causes diseases with symptoms like headache, fever, and rash.

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    Gram-Negative Bacteria PDF

    Description

    Learn about the characteristics and symptoms of Gram-negative bacteria, including Proteobacteria and E. coli.

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