Gram Positive Cocci: Staphylococci and Streptococci
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Questions and Answers

What is a characteristic of Staphylococci?

  • Motile
  • Gram-negative
  • Spore-forming
  • Non-motile (correct)

    • Which of the following is a characteristic of Staphylococcus aureus?

  • Coagulase negative
  • β-hemolysin negative
  • White pigmentation of colonies
  • Coagulase positive (correct)

    • What is a normal habitat of Staphylococcus aureus?

  • Skin and mucosal surfaces (correct)
  • Oral cavity
  • Anterior nares
  • Intestines

    • How do Staphylococci survive on dry surfaces?

    <p>Due to thickened peptidoglycan layer</p> Signup and view all the answers

    What is a common infection caused by Staphylococcus saprophyticus?

    <p>Urinary tract infections</p> Signup and view all the answers

    How are Staphylococci transmitted?

    <p>Through direct contact or contaminated fomites</p> Signup and view all the answers

    What is a characteristic of Staphylococcus epidermidis?

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

    What is a common habitat of Staphylococcus epidermidis?

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

    What is the effect of Teichoic Acid on Staphylococcus aureus?

    <p>Helps in attachment</p> Signup and view all the answers

    Which virulence factor is responsible for Staphylococcal Scalded Skin Syndrome (SSSS)?

    <p>Exfoliative Toxins (ETA, ETB)</p> Signup and view all the answers

    What is the effect of Peptidoglycan on Staphylococcus aureus?

    <p>Inhibits phagocytosis</p> Signup and view all the answers

    Which virulence factor is responsible for Necrotizing Pneumonia?

    <p>Panton Valentine Leukocidin (PVL)</p> Signup and view all the answers

    What is the effect of Protein A on Staphylococcus aureus?

    <p>Inhibits phagocytosis</p> Signup and view all the answers

    What is the effect of Enterotoxins (A-E, G-I) on the body?

    <p>Increases intestinal peristalsis and fluid loss, as well as nausea and vomiting</p> Signup and view all the answers

    Which Gram Positive Cocci is most likely responsible for Scalded Skin Syndrome in neonate?

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

    Which Gram Positive Cocci is most likely responsible for Neonatal meningitis?

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

    Which Gram Positive Cocci is Optochin sensitive?

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

    Which Gram Positive Cocci is most likely responsible for Endocarditis in patient with artificial heart valve?

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

    Which Gram Positive Cocci is most likely responsible for Urinary tract infection in a 25-year-old female?

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

    Which Gram Positive Cocci is most likely responsible for Pharyngitis in young adult?

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

    Which of the following is a risk factor for Staphylococcal infections?

    <p>Presence of a foreign body</p> Signup and view all the answers

    S. epidermidis is responsible for which of the following diseases?

    <p>Endocarditis and UTIs</p> Signup and view all the answers

    Which of the following is a common disease caused by S. aureus?

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

    Intravenous drug abuse is a risk factor for infections with which of the following?

    <p>S. epidermidis</p> Signup and view all the answers

    Use of antibiotics can lead to an increased risk of Staphylococcal infections due to the suppression of:

    <p>Normal microbiota flora</p> Signup and view all the answers

    Which of the following is NOT a disease caused by S. aureus?

    <p>Cystic fibrosis</p> Signup and view all the answers

    What is the main difference between folliculitis and furuncles?

    <p>Folliculitis is a superficial infection, while furuncles are deep-seated</p> Signup and view all the answers

    Which of the following is a characteristic of impetigo?

    <p>It is a superficial infection that affects mostly children</p> Signup and view all the answers

    What is the main difference between Staphylococcal Scalded Skin Syndrome and Staphylococcal Toxic Shock Syndrome?

    <p>SSSS is a multisystem intoxication, while STSS is a dissemination of epithelium in infants</p> Signup and view all the answers

    Which of the following is NOT a pyrogenic infection?

    <p>Staphylococcal Food poisoning</p> Signup and view all the answers

    What is the main cause of Staphylococcal Food poisoning?

    <p>Consumption of contaminated food with heat-stable enterotoxin</p> Signup and view all the answers

    Which of the following is characterized by a honey-colored crust with a moist erythematous base?

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

    What is the main difference between carbuncles and furuncles?

    <p>Carbuncles affect multiple hair follicles, while furuncles affect a single hair follicle</p> Signup and view all the answers

    Which of the following is a characteristic of Staphylococcal Scalded Skin Syndrome?

    <p>Disseminated desquamation of epithelium in infants</p> Signup and view all the answers

    Study Notes

    Gram Positive Cocci - Staphylococci

    • Staphylococci are gram-positive, non-motile, non-spore forming cocci that form grape clusters or clumps.
    • They are facultative anaerobes, β-haemolytic, and catalase-positive, which distinguishes them from Streptococci.

    Human Pathogens

    • Staphylococcus aureus is responsible for a broad spectrum of clinical syndromes.
    • Staphylococcus epidermidis is associated with medical device-related infections.
    • Staphylococcus saprophyticus is responsible for urinary tract infections.

    Staphylococcus Species

    • Staphylococcus aureus:
      • Coagulase-positive
      • Golden pigmentation of colonies grown on rich media
      • β-hemolytic
    • Staphylococcus epidermidis:
      • Coagulase-negative
      • White pigmentation of colonies
      • Associated with medical device-related infections
    • Staphylococcus saprophyticus:
      • Coagulase-negative
      • Colonies can be white or golden depending on the strain
      • Responsible for 20% of urinary tract infections

    Staphylococci as Normal Human Flora

    • Staphylococci are normal flora on human skin and mucosal surfaces.
    • They can survive on dry surfaces for long periods due to their thickened peptidoglycan layer and absence of outer membrane.
    • Person-to-person spread can occur through direct contact or exposure to contaminated fomites.
    • S. aureus is a common inhabitant of anterior nares and can also be found in other areas of the body.
    • S. epidermidis is a common inhabitant of skin.

    Diseases Caused by Staphylococci

    • Staphylococcus aureus:
      • Skin infections
      • Endocarditis
      • Osteomyelitis
      • Pneumonia
      • Meningitis
      • Food-borne diseases (toxin-mediated)
    • Staphylococcus epidermidis:
      • Bacteraemia
      • Endocarditis
      • Surgical wounds
      • UTIs
      • Opportunistic infections of catheters, shunts, plastic implants, and prosthetic devices
    • Staphylococcus saprophyticus:
      • Urinary tract infections

    Staphylococcus aureus Virulence Factors

    • Peptidoglycan: abscess formation, inhibits phagocytosis
    • Teichoic acid: helps in attachment
    • Protein A: inhibits antibody-mediated clearance, inhibits phagocytosis
    • Panton Valentine Leukocidin (PVL): necrotizing pneumonia
    • Exfoliative Toxins (ETA, ETB): Staphylococcal Scalded Skin Syndrome (SSSS)
    • Enterotoxins (A-E, G-I): superantigens, stimulating proliferation of T cells and release of cytokines
    • Toxic Shock Syndrome Toxin-1: superantigen, produces leakage or cellular destruction of endothelial cells

    Specific Diseases Due to S. aureus

    • Cutaneous disease:
      • Folliculitis
      • Furuncle or boil
      • Carbuncle
    • Toxin-mediated disease:
      • Staphylococcal Scalded Skin Syndrome (SSSS)
      • Staphylococcal Toxic Shock Syndrome (STSS)
      • Staphylococcal food poisoning
    • Pyrogenic infections/ Invasive Staphylococcal Diseases:
      • Abscesses
      • Impetigo
      • Wound infections
      • Pneumonia
      • Mastitis
      • Osteomyelitis
      • Septicaemia

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    Gram Positive Cocci - Staphylococci 2023 PDF

    Description

    Identify the Gram positive cocci responsible for specific conditions, such as pharyngitis in young adults, skin infections, and others. This quiz covers Staphylococcus and Streptococcus species.

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