Systemic Bacteriology II
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Questions and Answers

Which of the following bacteria is associated with scarlet fever and impetigo?

  • Streptococcus progenies (correct)
  • Clostridium difficile
  • Staphylococcus aureus
  • Enterococcus

    • Which bacteria is the most common cause of skin, soft tissue, and wound infections?

  • Clostridium difficile
  • Enterococcus
  • Staphylococcus aureus (correct)
  • Streptococcus pneumoniae

    • Which bacteria is associated with nosocomial infections and is commonly found on foreign devices like catheters?

  • Staphylococcus epidermis (correct)
  • Enterococcus
  • Clostridium difficile
  • Streptococcus pneumoniae

    • Which bacteria is part of the normal bowel flora and can cause problems if it enters a normally sterile area?

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

    Which bacteria produces endotoxins that can cause severe tissue damage and is part of the normal bowel flora?

    <p>Clostridium difficile</p> Signup and view all the answers

    Which bacteria is associated with antibiotic-associated diarrhea, especially in the elderly?

    <p>Clostridium difficile</p> Signup and view all the answers

    Which bacteria is identified by its golden appearance and clump formation, resembling grapes?

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

    Which bacteria is associated with ⍺-hemolysis and causes pneumonia?

    <p>Streptococcus pneumoniae</p> Signup and view all the answers

    Which bacteria is associated with 𝛾-hemolysis and is part of the normal bowel flora?

    <p>Clostridium difficile</p> Signup and view all the answers

    Which bacteria is associated with numerous diseases, including scarlet fever and impetigo?

    <p>Streptococcus pyogenes</p> Signup and view all the answers

    Which of the following best defines the term 'virulence'?

    <p>The capacity of a microbe to cause damage to its host</p> Signup and view all the answers

    What is the purpose of the coagulase test?

    <p>To differentiate between Staph. aureus and coagulase negative Staph.</p> Signup and view all the answers

    What happens during sepsis?

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

    Which of the following is the most common cause of bacterial meningitis?

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

    What are gut commensal coliforms?

    <p>Organisms that are part of the normal bowel flora- gram negative cocci associated with GI tract</p> Signup and view all the answers

    Which antibiotic is the first line treatment for infections caused by coliforms?

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

    What is the purpose of the haemolysis test?

    <p>To differentiate between Streptococci</p> Signup and view all the answers

    What is an opportunistic pathogen?

    <p>An organism that causes infection when opportunity/change in natural immunity arises</p> Signup and view all the answers

    What is the definition of a pathogen?

    <p>A harmful organism that produces a disease in the host</p> Signup and view all the answers

    What is the purpose of the coagulase test?

    <p>To differentiate between Staph. aureus and coagulase negative Staph.</p> Signup and view all the answers

    What is the most common cause of skin, soft tissue, and wound infection?

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

    What is the definition of a pathogen?

    <p>A microorganism that can cause disease</p> Signup and view all the answers

    What bacteria is commonly found on foreign devices like catheters?

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

    What bacteria is associated with nosocomial infections?

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

    What bacteria is associated with scarlet fever and impetigo?

    <p>Group A streptococcus (GAS)</p> Signup and view all the answers

    What bacteria produces endotoxins that can cause severe tissue damage?

    <p>Clostridium spp.</p> Signup and view all the answers

    What bacteria causes antibiotic-associated diarrhea, especially in the elderly?

    <p>Clostridium difficile</p> Signup and view all the answers

    What bacteria is part of the normal bowel flora and can cause problems if it enters a normally sterile area?

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

    What is the definition of virulence?

    <p>The capacity of a microbe to cause damage to its host.</p> Signup and view all the answers

    Define commensal.

    <p>An organism that is part of the normal flora, often in a mutualistic relationship.</p> Signup and view all the answers

    What is an opportunistic pathogen?

    <p>An organism that causes infection when opportunity/change in natural immunity arises.</p> Signup and view all the answers

    What is the purpose of the coagulase test?

    <p>To differentiate between Staph. aureus and coagulase negative Staph. (including Staph epidermis).</p> Signup and view all the answers

    What is the purpose of the haemolysis test?

    <p>To differentiate between Streptococci.</p> Signup and view all the answers

    What happens during sepsis?

    <p>Small blood vessels become 'leaky' and lose fluid into tissues, decreased blood volume, poor tissue perfusion, blood clotting system activated.</p> Signup and view all the answers

    What are gut commensal coliforms?

    <p>Many coliforms that are part of the normal bowel flora.</p> Signup and view all the answers

    Which antibiotic is the first line treatment for infections caused by coliforms?

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

    What are the associated diseases of coliform infections?

    <p>Coliform infections can cause urinary tract infections, bloodstream infections, and infections in other parts of the body</p> Signup and view all the answers

    Which of the following diseases is NOT associated with Group A streptococcus infections?

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

    What are the common infections caused by Group A streptococcus?

    <p>Skin infections</p> Signup and view all the answers

    Which of the following is a bacterial infection caused by Group A streptococcus?

    <p>Strep throat</p> Signup and view all the answers

    What are some diseases associated with Group A streptococcus infections?

    <p>Scarlet fever, impetigo, strep throat.</p> Signup and view all the answers

    What are the steps in the process of how fever is induced in the body?

    <ol> <li>Antigen/LPS interacts with macrophages</li> <li>Macrophages release cytokines into bloodstream</li> <li>Cytokines travel to anterior hypothalamus</li> <li>Prostaglandin E released - increases body’s thermal set point</li> <li>Body perceives it as cold - starts to ‘shiver’</li> <li>FEVER</li> </ol> Signup and view all the answers

    Which cells release cytokines into the bloodstream during the process of inducing fever?

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

    What is the role of prostaglandin E in the induction of fever?

    <p>Prostaglandin E is released and increases the body's thermal set point, causing the body to perceive it as cold and initiate shivering, leading to the onset of fever</p> Signup and view all the answers

    What are some common gram-negative bacteria?

    <p>Neisseria meningitidis, Neisseria gonorrhoea, Haemophilia influenza, Escherichia coli (E. coli), Klebsiella, Pseudomonas aeruginosa, Salmonella</p> Signup and view all the answers

    What are some common gram-positive bacteria?

    <p>Streptococcus, Staphylococcus, Enterococcus, Clostridium, Fusobacterium</p> Signup and view all the answers

    Which of the following best describes coliforms?

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

    How can Escherischia coli be differentiated from each other?

    <p>By their biochemical reactions and antigenic structure</p> Signup and view all the answers

    Where are coliforms commonly found in the body?

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

    What are coliforms and how are they identified?

    <p>Coliforms are a sub group of enterobacteria that are Gram negative bacilli. They are identified by their appearance on gram film and blood agar, resembling Escherischia coli.</p> Signup and view all the answers

    How can Escherichia coli be differentiated from each other?

    <p>Escherichia coli can be differentiated from each other by biochemical reactions, antigenic structure of cell wall (serotype), and O antigens that have cell wall and H antigens that have flagella.</p> Signup and view all the answers

    Where are coliforms commonly found in the body?

    <p>Coliforms are commonly found in the normal bowel flora.</p> Signup and view all the answers

    Which bacteria is the most significant pathogenic streptococci?

    <p>Group A streptococcus</p> Signup and view all the answers

    What are the common infections caused by Group A streptococcus?

    <p>Streptococcal sore throat and necrotising fasciitis</p> Signup and view all the answers

    What is puerperal sepsis?

    <p>An infection of pregnant and postnatal women</p> Signup and view all the answers

    What are the clinical manifestations of Group A streptococcus infections?

    <p>The clinical manifestations of Group A streptococcus infections include streptococcal sore throat (scarlet fever), invasive diseases like necrotising fasciitis, and puerperal sepsis.</p> Signup and view all the answers

    What is puerperal sepsis?

    <p>Puerperal sepsis is the infection of pregnant and postnatal women caused by Group A streptococcus.</p> Signup and view all the answers

    What is the specific type of infection caused by Clostridioides perfringens?

    <p>Gas gangrene</p> Signup and view all the answers

    What illness is caused by Clostridium tetani?

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

    Study Notes

    Key Definitions

    • Virulence: Ability of a microbe to damage the host.
    • Pathogen: Organism that causes disease.
    • Commensal: Normal flora organism, often in a mutualistic relationship, potentially leading to endogenous infections.
    • Opportunistic Pathogen: Causes infection when there is a change in host immunity.

    Diagnostic Tests

    • Coagulase Test: Differentiates Staphylococcus aureus from coagulase-negative Staphylococci, such as Staphylococcus epidermidis.
    • Haemolysis: Differentiates Streptococcus species based on their ability to lyse red blood cells.

    Sepsis

    • Characterized by increased permeability of small blood vessels leading to fluid loss into tissues, reduced blood volume, and increased workload on the heart.
    • Results in poor tissue perfusion and subsequent shutdown of blood supply to less essential organs.
    • Activation of the blood clotting system increases the risk of hemorrhage.
    • Gram-negative Sepsis: Rapid deterioration due to endotoxin release upon Gram-negative bacteria death.

    Fever Induction Process

    • Antigen/LPS interacts with macrophages.
    • Macrophages secrete cytokines into the bloodstream.
    • Cytokines target the anterior hypothalamus.
    • Prostaglandin E is released, raising the body's thermal set point.
    • Body responds with shivering, leading to fever.

    Key Gram-negative Pathogens

    • Neisseria meningitidis: Leading cause of bacterial meningitis.
    • Neisseria gonorrhoeae: Causative agent of gonorrhea.
    • Coliforms: Part of normal bowel flora; infections (e.g., UTIs) occur when they enter sterile sites.
    • Gentamicin: First-line antibiotic used for coliform infections.

    Key Gram-positive Pathogens

    • Streptococcus spp.: Identified via haemolysis; Group A Streptococcus (GAS) is linked to various diseases like scarlet fever and impetigo.
    • Streptococcus pneumoniae: Causes pneumonia, and is alpha-haemolytic.
    • Staphylococcus epidermidis: Nosocomial infections associated with medical devices.
    • Staphylococcus aureus: Most common cause of skin infections; coagulase positive, appears golden.
    • Enterococcus: Normally part of bowel flora but can cause infections if introduced into sterile areas.
    • Clostridium spp.: Includes Clostridium difficile, known for antibiotic-associated diarrhea, proliferating when normal flora is disrupted.

    Invasive Streptococcus Infections

    • Group A Streptococcus can lead to severe conditions like necrotizing fasciitis and puerperal sepsis in women.
    • Clostridioides perfringens: Causes gas gangrene, a severe infection resulting from wound contamination.
    • Clostridium tetani: Causes tetanus, a fatal paralytic illness.

    Common Gram-negative and Gram-positive Bacteria

    • Gram-negative: Neisseria meningitidis, Neisseria gonorrhoeae, Haemophilus influenzae, Escherichia coli (E. coli), Klebsiella, Pseudomonas aeruginosa, Salmonella.
    • Gram-positive: Streptococcus, Staphylococcus, Enterococcus, Clostridium, Fusobacterium.

    Coliforms Overview

    • Subgroup of enterobacteria; resembles E. coli on Gram stain.
    • Part of normal bowel flora; can grow anaerobically and aerobically.
    • Differentiated by biochemical reactions, serotype, and presence of O and H antigens.

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    Description

    Test your knowledge of key definitions in systemic bacteriology II, including virulence, pathogens, commensals, and opportunistic pathogens. Challenge yourself and improve your understanding of these important concepts in microbiology.

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