Bacteroides fragilis: Microbiota and Infections
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Questions and Answers

What is the optimal growth temperature for Bacteroides fragilis?

  • 25°C
  • 37°C (correct)
  • 60°C
  • 45°C
  • What is the pH range for optimal growth of Bacteroides fragilis?

  • 3-5
  • 5-7 (correct)
  • 7-9
  • 9-11
  • What structures does B. fragilis use for adhesion to other molecular structures?

  • Cilia
  • Lipopolysaccharide chains
  • Flagella
  • Peritrichous fimbriae (correct)
  • What type of bacterium is Bacteroides fragilis?

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

    What type of metabolism does Bacteroides fragilis have in the gut microbiome?

    <p>Aerotolerant, anaerobic chemoorganotroph</p> Signup and view all the answers

    How does B. fragilis survive the volatile intestinal micro-environment?

    <p>By utilizing outer membrane vesicles</p> Signup and view all the answers

    What is the role of cytochrome bd oxidase in B. fragilis?

    <p>It is essential for oxygen consumption and can allow other obligate anaerobes to survive in the oxygen-reduced microenvironment.</p> Signup and view all the answers

    What does the environmental-sensory system of B. fragilis effectively handle?

    <p>Bacteriocins secretion and resistance, bile salt resistance, and oxidative stress response</p> Signup and view all the answers

    What is the main attributed factor for the high resistance to antibiotics of B.fragilis?

    <p>Genetic plasticity</p> Signup and view all the answers

    What is a characteristic feature of the antibiotic resistance mechanisms in members of the genus Bacteroides?

    <p>High resistance rates amongst anaerobic bacteria</p> Signup and view all the answers

    Which organism is the most prevalent in the B. fragilis group?

    <p>B. fragilis</p> Signup and view all the answers

    What do animals lacking gut bacteria require to maintain body mass?

    <p>30% more caloric intake</p> Signup and view all the answers

    What do Bacteroides species accumulate in their gastrointestinal tract?

    <p>A variety of antibiotic/antimicrobial resistance genes</p> Signup and view all the answers

    Which enzymes are utilized by B. fragilis to resist the degrading effects of bile salts?

    <p>Bile salt hydrolase</p> Signup and view all the answers

    What permits growth in the presence of nanomolar concentrations of O2?

    <p>Catalase, superoxide dismutase, &amp; alkyl hydroperoxide reductase</p> Signup and view all the answers

    What permits B. fragilis to survive/adapt in the ever-changing human gut microbiome?

    <p>The complex environmental-sensory system</p> Signup and view all the answers

    What is the cofactor required for Haemophilus species growth, known as the V factor?

    <p>NAD+</p> Signup and view all the answers

    Which agar is an excellent growth medium for Haemophilus due to increased accessibility to the required factors?

    <p>Chocolate agar</p> Signup and view all the answers

    In the 'Staph streak' technique for culturing Haemophilus, what produces the necessary blood factor byproducts required for Haemophilus growth?

    <p>Staphylococcus colonies</p> Signup and view all the answers

    Which species is an exception to the requirement of X and V factors and can grow well on both blood and chocolate agars?

    <p>Haemophilus haemoglobinophilus</p> Signup and view all the answers

    What is the main attribute of the 'V factor' for Haemophilus species growth?

    <p>Nicotinamide adenine dinucleotide</p> Signup and view all the answers

    What is the primary function of the 'Staph streak' technique in culturing Haemophilus organisms?

    <p>To enhance Haemophilus growth</p> Signup and view all the answers

    What do most species of the genus Haemophilus require for growth on blood agar plates?

    <p>Both hemin and nicotinamide adenine dinucleotide</p> Signup and view all the answers

    What prevents the growth of many Haemophilus species on blood agar plates?

    <p>Absence of X-factor bound to the blood cells</p> Signup and view all the answers

    Why are Haemophilus bacteria categorized as pleomorphic?

    <p>Because of their wide range of shapes</p> Signup and view all the answers

    Which genus includes significant pathogenic species such as H. influenzae and H. ducreyi?

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

    Where do Haemophilus organisms typically inhabit?

    <p>Upper respiratory tract, mouth, vagina, and intestinal tract</p> Signup and view all the answers

    What prevents most species of the genus Haemophilus from growing on blood agar plates?

    <p>Absence of blood factors for growth</p> Signup and view all the answers

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