Untitled Quiz
20 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What type of hemolysis is exhibited by Streptococcus pneumoniae?

  • Alpha-hemolytic (correct)
  • Beta-hemolytic
  • Gamma-hemolytic
  • None of the above
  • Which of the following diseases is caused by Streptococcus pyogenes?

  • Scarlet fever (correct)
  • Meningitis
  • Pneumonia
  • Neonatal pneumonia
  • What is the primary virulence factor responsible for adherence to host cells in Streptococcus pyogenes?

  • Streptokinase
  • Streptolysin O
  • M protein (correct)
  • Hyaluronidase
  • Which of the following is a characteristic of viridans streptococci?

    <p>Commonly found in the mouth</p> Signup and view all the answers

    What type of organism is Streptococcus agalactiae primarily known to cause infections in?

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

    What culture conditions are optimal for Neisseria species?

    <p>Facultative anaerobes with 5-10% CO2</p> Signup and view all the answers

    Which of the following is NOT a disease caused by Streptococcus pyogenes?

    <p>Dental caries</p> Signup and view all the answers

    What is the mode of transmission for Neisseria gonorrhoeae?

    <p>Sexual contact</p> Signup and view all the answers

    Which type of hemolytic streptococci is responsible for complete hemolysis?

    <p>Beta-hemolytic</p> Signup and view all the answers

    Which organism is known to cause infective endocarditis?

    <p>Viridans streptococci</p> Signup and view all the answers

    What is the primary characteristic of coagulase-positive Staphylococci?

    <p>They are most pathogenic among Staphylococci.</p> Signup and view all the answers

    Which of the following is a virulence factor of Staphylococcus aureus?

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

    What type of infections is primarily associated with Staphylococcus aureus?

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

    Streptococci can be differentiated based on what criterion?

    <p>Their hemolytic activity on blood agar</p> Signup and view all the answers

    What is a characteristic of Staphylococcus epidermidis?

    <p>It is part of the normal skin flora.</p> Signup and view all the answers

    What type of bacteria are Staphylococci classified as?

    <p>Gram positive cocci</p> Signup and view all the answers

    Which toxin is responsible for scalded skin syndrome caused by Staphylococcus aureus?

    <p>Epidermolytic toxin</p> Signup and view all the answers

    Which of the following statements about Staphylococci is true?

    <p>Staphylococci can grow on nutrient agar and blood agar.</p> Signup and view all the answers

    Which Streptococcus species is known for forming chains and is associated with pyogenic infections?

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

    Which disease is NOT caused by Staphylococcus aureus?

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

    Study Notes

    Lecture 6: Medical Bacteriology (I) - Cocci Bacteria

    • Types of Bacteria:
      • Pathogenic: Cause disease in humans
      • Commensal: (Normal flora/human microbiome): Normally inhabit the human body

    Gram-Positive Cocci (Staphylococci)

    • Morphology: Gram-positive cocci arranged in grape-like clusters
    • Culture & Biochemical Characteristics:
      • Facultative anaerobes
      • Grow at 37°C
      • Grow on nutrient agar and blood agar
      • All Staphylococci are catalase-positive

    Classification of Staphylococci

    • Coagulase-positive:

      • Staphylococcus aureus (Most pathogenic)
    • Coagulase-negative:

      • Staphylococcus epidermidis (Normal skin flora)
      • Staphylococcus saprophyticus

    Virulence Factors of Staphylococcus aureus

    • Toxins:

      • Epidermolytic (exfoliative) toxin
      • Enterotoxin
      • Toxic shock syndrome toxin
      • Hemolysin
    • Enzymes:

      • Coagulase
      • Staphylokinase
      • Catalase
      • Proteases, Lipase, DNase

    Diseases Caused by Staphylococcus aureus

    • Suppurative (pyogenic):

      • Skin infections: Boils, Folliculitis, Impetigo
      • Bacteremia
      • Endocarditis, Osteomyelitis, Pneumonia, Urinary tract infections
    • Toxigenic Diseases:

      • Scalded skin syndrome
      • Food poisoning
      • Toxic Shock Syndrome

    2- Streptococci

    • Morphology: Gram-positive cocci arranged in pairs (e.g., S. pneumoniae) or in chains (e.g., S. pyogenes)
    • Some strains are capsulated
    • Culture & Biochemical Characteristics:
      • Facultative anaerobes
      • Grow at 37°C
      • Catalase-negative.
      • Grow on blood agar

    Classification of Streptococci (hemolytic activity)

    • Alpha-hemolytic: (partial hemolysis) - S. pneumoniae, S. viridans
    • Beta-hemolytic: (complete hemolysis) - Group A Streptococci (S.Pyogenes), Group B Streptococci (S. agalactiae)
    • Gamma-hemolytic: (no hemolysis) - Enterococcus faecalis

    Virulence Factors of Streptococcus pyogenes

    • M protein: Adherence to cells; resistance to phagocytosis
    • Enzymes: Streptokinase, Streptodornase, Hyaluronidase, Streptolysins (S & O)
    • Exotoxins: Erythrogenic toxin

    Diseases Caused by Streptococcus pyogenes

    • Suppurative infections: Pharyngitis, Tonsillitis, Sinusitis, Otitis media, Impetigo, Cellulitis, Bacteremia, Puerperal sepsis, Endocarditis, Osteomyelitis
    • Toxigenic diseases: Scarlet fever, Streptococcal toxic shock-like syndrome, (due to erythrogenic toxin)
    • Post-streptococcal sequelae: Acute rheumatic fever, Acute glomerulonephritis

    Other Streptococci and Bacteria

    • Streptococcus agalactiae: (normal flora of the vagina); Neonatal meningitis, Neonatal pneumonia

    • Viridans Streptococci: (normal flora of the mouth); Dental caries, Infective endocarditis

    • S. pneumoniae: Pneumonia, Meningitis

    • Enterococcus faecalis: Normal flora in GIT → Urinary tract infection (UTI)

    • Gram-negative cocci (Neisseria species):

      • Morphology: Gram-negative cocci arranged in pairs (diplococci)
      • Culture conditions: Facultative anaerobes, grow at 37°C, Capnophilic (need 5-10% CO2), grow best on chocolate agar and Thayer-Martin agar (selective media)
    • Important species of Neisseria:

      • Neisseria meningitidis: Mode of transmission - inhalation of infected droplets; Diseases: Meningitis
      • Neisseria gonorrhoeae: Mode of transmission - sexually transmitted disease; Diseases: Gonorrheal urethritis or cervicitis, Ophthalmia neonatorum

    Case Study

    • Case: 1-year-old with fever and generalized convulsion, mild throat inflammation, neck rigidity, clear lungs, Gram-negative diplococci in CSF
    • Most likely Causative Pathogen: Neisseria meningitidis

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    More Like This

    Untitled Quiz
    6 questions

    Untitled Quiz

    AdoredHealing avatar
    AdoredHealing
    Untitled Quiz
    55 questions

    Untitled Quiz

    StatuesquePrimrose avatar
    StatuesquePrimrose
    Untitled Quiz
    18 questions

    Untitled Quiz

    RighteousIguana avatar
    RighteousIguana
    Untitled Quiz
    50 questions

    Untitled Quiz

    JoyousSulfur avatar
    JoyousSulfur
    Use Quizgecko on...
    Browser
    Browser