Skin, Bone, and Soft Tissue Infections
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Questions and Answers

What is the approximate surface area of human skin?

  • 1.5-2.0 m² (correct)
  • 3.5-4.0 m²
  • 0.5-1.0 m²
  • 2.5-3.0 m²

    • Which type of bacteria are most abundant in normal skin flora?

  • Gram-negative bacteria
  • Anaerobic bacteria
  • Acid-fast bacteria
  • Gram-positive bacteria (correct)

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

  • Coagulase positive and catalase positive (correct)
  • Coagulase positive and catalase negative
  • Coagulase negative and catalase positive
  • Coagulase negative and catalase negative

    • Which of the following best describes the morphology of staphylococci?

    <p>Grape-like clusters of cocci (A)</p> Signup and view all the answers

    What role do sweat glands and hair follicles play in the skin's bacterial ecosystem?

    <p>They help to reestablish the bacterial flora. (B)</p> Signup and view all the answers

    Which characteristic is NOT associated with Staphylococcus aureus?

    <p>Catalase-negative reaction (B)</p> Signup and view all the answers

    What type of hemolysis is associated with Streptococcus pyogenes?

    <p>Beta (β)-hemolysis (A)</p> Signup and view all the answers

    Which of the following describes the catalase test result for all streptococci?

    <p>Catalase-negative (C)</p> Signup and view all the answers

    Which of the following does NOT produce coagulase?

    <p>Both <em>Staphylococcus epidermidis</em> and <em>Streptococcus pyogenes</em> (A)</p> Signup and view all the answers

    Which of the following is associated with partial hemolysis of red blood cells?

    <p>Alpha (α)-hemolysis (C)</p> Signup and view all the answers

    According to the Lancefield classification, which group does Streptococcus pyogenes belong to?

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

    What is the shape of Streptococcus bacteria?

    <p>Spherical (cocci) in chains (C)</p> Signup and view all the answers

    Which of the following is a characteristic of an anaerobic bacteria as noted in this content?

    <p>Grows in the absence of oxygen. (A)</p> Signup and view all the answers

    Which of the following is a characteristic of a vesicle?

    <p>A small, fluid-filled lesion in the epidermis (C)</p> Signup and view all the answers

    Which bacterial species would likely be found in an infection of necrotic tissue?

    <p>Bacteroides fragilis (B)</p> Signup and view all the answers

    What is a key differentiating factor between cellulitis and erysipelas?

    <p>Erysipelas shows prominent lymphatic involvement and is a type of superficial cellulitis. (A)</p> Signup and view all the answers

    A patient presents with a deep inflammatory nodule that developed from a previous folliculitis infection. Which condition is most likely?

    <p>Furuncle (A)</p> Signup and view all the answers

    Which of the following is a characteristic of a bulla?

    <p>A large, fluid-filled lesion in the epidermis. (A)</p> Signup and view all the answers

    Which of these bacteria is NOT classified as an anaerobe?

    <p>Escherichia coli (C)</p> Signup and view all the answers

    What is the initial presentation of impetigo?

    <p>Vesicular superficial infection. (A)</p> Signup and view all the answers

    Which condition is associated with a generalized sunburn-like eruption alongside an acute febrile illness?

    <p>Staphylococcal Toxic Shock Syndrome (A)</p> Signup and view all the answers

    Which of the following is the primary causative agent of gas gangrene?

    <p>Clostridium perfringens (B)</p> Signup and view all the answers

    What is the primary characteristic of necrotizing fasciitis?

    <p>Severe infection of subcutaneous soft tissue and fascia (D)</p> Signup and view all the answers

    Which of these conditions is specifically caused by a Staphylococcus aureus strain that produces an exfoliative exotoxin?

    <p>Staphylococcal Scalded Skin Syndrome (A)</p> Signup and view all the answers

    What predisposing factor is commonly associated with necrotizing fasciitis?

    <p>Diabetes (B)</p> Signup and view all the answers

    Which of the following is NOT a common causative organism of diabetic foot infections?

    <p>Mycobacterium tuberculosis (A)</p> Signup and view all the answers

    Which of the following is a common location for septic arthritis?

    <p>Joint spaces (D)</p> Signup and view all the answers

    Which of these factors primarily increases the risk of osteomyelitis in a diabetic patient?

    <p>Vascular disease impairing blood supply (D)</p> Signup and view all the answers

    What is the primary treatment for necrotizing fasciitis?

    <p>Surgical debridement and antibiotics (C)</p> Signup and view all the answers

    Study Notes

    Skin, Bone, and Soft Tissue Infections

    • Skin infections are a significant health concern, affecting skin, soft tissues, and bones.
    • Normal skin flora is primarily gram-positive bacteria, including Staphylococcus spp., Micrococcus spp., Corynebacterium spp., and Cutibacterium (Propionibacterium) acnes.
    • Vigorous washing reduces but does not fully eliminate normal skin flora. Sweat glands and hair follicles help re-establish the bacterial flora after washing.
    • Staphylococcus aureus is a spherical, gram-positive coccus that forms grape-like clusters.
    • It forms pale to golden-yellow colonies on blood agar. All Staphylococci are catalase positive, breaking down hydrogen peroxide.
    • Staphylococcus aureus is also coagulase positive.
    • Coagulase is a specific enzyme that causes rabbit plasma to coagulate (clotting). Subtypes of staphylococcus are categorized based on coagulase activity (positive or negative).
    • Staphylococcus aureus produces multiple virulence factors, including coagulase, hemolysins (various types of toxins that destroy red blood cells), enterotoxins, and pyrogenic (febrile) toxins. Also, exfoliatins, leukocidin, and protein A
    • Streptococcus species are spherical, gram-positive cocci that form chains.
    • They are catalase negative and are broadly classified by their hemolytic activity (alpha, beta, or gamma).
    • Alpha-hemolytic species partially lyse red blood cells; beta-hemolytic species completely lyse red blood cells; and gamma-hemolytic species do not lyse red blood cells. Examples of these species include Streptococcus pyogenes (beta-hemolytic) and Streptococcus pneumoniae (alpha-hemolytic).
    • Group A Streptococcus (GAS) is a gram-positive bacteria in short chains, hemolytic, and does not produce coagulase.
    • Anaerobes are bacteria that thrive in the absence of oxygen. These include facultative species (e.g., Staphylococcus aureus), obligate species (e.g., Bacteroides fragilis), and Fusobacterium species.
    • Common species of gram-positive and gram-negative cocci and bacilli are listed for anaerobes.
    • Skin lesions are described via different morphological terms, including vesicles (small fluid-filled blisters), bullae (larger fluid-filled blisters), macules, and papules (raised lesions). Pustules are sores that have pus inside.
    • Bacterial skin diseases include folliculitis (infection of hair follicles), impetigo (superficial skin infection), cellulitis (spreading skin infection), erysipelas (superficial cellulitis with lymphatic involvement), furuncles (deep, inflamed nodules), carbuncles (more extensive than furuncles, involving subcutaneous fat), staphylococcal toxic shock syndrome (sudden onset fever, sunburn rash), and scalded skin syndrome (widespread and painful blisters).
    • Organisms associated with these specific skin diseases are also listed
    • Soft-tissue infections (e.g., necrotizing fasciitis, myositis, gas gangrene) may cause significant tissue damage.
    • Necrotizing fasciitis is a severe infection of the connective tissue.
    • Myositis is an infection of skeletal muscle.
    • Gas gangrene results from the infection of Clostridium bacteria.
    • Bone infections, including septic arthritis (infection of joint spaces) and osteomyelitis (infection of the bone), are also discussed.
    • Diabetic foot infections are a significant complication of diabetes. Infections may involve cellulitis, bone infections (osteomyelitis), and soft-tissue infections.
    • The risk factors include vascular disease, peripheral neuropathy, and poor foot care.
    • The infectious organisms that cause foot infections are also noted.

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    Skin, Bone, and Soft Tissue Infections PDF

    Description

    Explore the significance of skin, bone, and soft tissue infections, with a focus on the role of normal skin flora and the characteristics of Staphylococcus aureus. This quiz covers the types of bacteria involved, their enzymatic activity, and how they interact within the human body. Test your knowledge on infection mechanisms and bacterial classifications.

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