Staphylococci and Related Diseases

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

Which of the following Staphylococcus species are coagulase positive?

  • S. aureus, S. intermedius, S. pseudintermedius (correct)
  • S. lugdunensis, S. schleiferi, S. epidermidis
  • S. aureus, S. epidermidis, S. saprophyticus
  • S. hyicus, S. delphini, S. lugdunensis

Which of the following toxins is considered less toxic to cells?

  • δ-hemolysin (correct)
  • β-hemolysin
  • γ-hemolysin
  • α-hemolysin

What is the mechanism of action of Protein A?

  • It acts on sphingomyelin in the plasma membrane of erythrocytes.
  • It binds to the Fc portion of IgG, inhibiting phagocytosis. (correct)
  • It directly lyses erythrocytes.
  • It binds to the Fab portion of IgG, preventing antibody binding.

Which of the following staphylococcal toxins is lethal to polymorphonuclear leukocytes?

<p>Panton-Valentine leukocidin (PVL) (C)</p> Signup and view all the answers

Which of these is NOT a characteristic of Staphylococci?

<p>Spore-forming (D)</p> Signup and view all the answers

Which of the following staphylococcal species is the most common cause of prosthetic valve endocarditis?

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

Which of the following is a common source of hospital-acquired infections?

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

What is the Greek term for "bunches of grapes" which describes Staphylococci's appearance?

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

Which type of toxin is associated with Ritter disease, a skin condition mainly affecting newborns and infants?

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

Which of the following staphylococcal species is associated with UTIs in young women?

<p>S. saprophyticus (A)</p> Signup and view all the answers

What is the basis of the slide coagulase test?

<p>Clumping factor causing bacterial cells to agglutinate in plasma (A)</p> Signup and view all the answers

What is the name of the test used to identify Staphylococci based on their ability to coagulate plasma?

<p>Coagulase test (D)</p> Signup and view all the answers

Which of these toxins is associated with Staphylococcal pseudomembranous enterocolitis?

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

Which of these is NOT a type of hemolysin produced by S. aureus?

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

Which of these is a potential consequence of TSS caused by Staphylococci?

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

Which of these is a common characteristic of both Staphylococci and Micrococci?

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

Which of the following is NOT a characteristic of Staphylococcus aureus?

<p>Is typically less virulent than other <em>Staphylococcus</em> species. (D)</p> Signup and view all the answers

What is the mechanism by which Staphylococcus aureus develops resistance to methicillin?

<p>Production of an altered penicillin-binding protein (PBP) called PBP2a. (C)</p> Signup and view all the answers

Which of the following statements is TRUE about Staphylococcus lugdunensis?

<p>It can cause both community-associated and hospital-acquired infections. (A)</p> Signup and view all the answers

What is the name of the gene responsible for methicillin resistance in Staphylococcus aureus?

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

What is the 'gold standard' method for detecting methicillin resistance in Staphylococcus aureus?

<p>Detection of the <em>mecA</em> gene by molecular methods. (C)</p> Signup and view all the answers

Which of the following is a TRUE statement about Staphylococcus saprophyticus?

<p>It is a common cause of urinary tract infections in young women. (B)</p> Signup and view all the answers

Which of the following statements is TRUE regarding the treatment of methicillin-resistant Staphylococcus aureus (MRSA)?

<p>Vancomycin remains the primary treatment option. (B)</p> Signup and view all the answers

What is the most appropriate test for determining methicillin resistance in Staphylococcus aureus isolates?

<p>A molecular test for the <em>mecA</em> gene. (D)</p> Signup and view all the answers

Flashcards

Food poisoning

Illness caused by consuming contaminated food, often linked to staphylococci.

Toxic Shock Syndrome Toxin-1 (TSS Toxin-1)

A toxin linked to staphylococcal infections causing toxic shock syndrome, especially in menstruating women.

Staphylococci

Gram-positive cocci, often appear in clusters, catalase-positive, and can cause various infections.

Exfoliative Toxin

Toxins from staphylococci that cause skin to slough off, leading to conditions like Ritter disease.

Signup and view all the flashcards

Ritter Disease

A skin condition caused by exfoliative toxins, primarily affecting newborns and infants.

Signup and view all the flashcards

Micrococci

Catalase-positive, coagulase-negative, gram-positive cocci found in the environment and on skin.

Signup and view all the flashcards

Coagulase

An enzyme produced by some bacteria that causes blood plasma to clot; indicates pathogenic staphylococci.

Signup and view all the flashcards

Cytolytic Toxins

Toxins produced by some bacteria that cause damage to cell membranes, leading to cell lysis.

Signup and view all the flashcards

Staphylocoagulase

An enzyme produced by coagulase-positive staphylococci that causes blood plasma to clot.

Signup and view all the flashcards

Alpha-Hemolysin

A toxin that lyses (breaks down) red blood cells and can damage platelets.

Signup and view all the flashcards

Beta-Hemolysin

Sphingomyelinase C, a hemolysin that acts on sphingomyelin in erythrocyte membranes.

Signup and view all the flashcards

Panton-Valentine leukocidin (PVL)

An exotoxin lethal to polymorphonuclear leukocytes, associated with certain strains of staphylococci.

Signup and view all the flashcards

Protein A

A surface protein in staphylococci that binds the Fc portion of IgG, blocking phagocytosis.

Signup and view all the flashcards

Clumping Factor

A protein that causes staphylococci to agglutinate in plasma; basis of slide coagulase test.

Signup and view all the flashcards

Staphylococcus epidermidis

A normal skin bacterium that can cause hospital-acquired infections and is often a contaminant in blood cultures.

Signup and view all the flashcards

Staphylococcus saprophyticus

A staphylococcus species commonly associated with urinary tract infections (UTIs) in young women.

Signup and view all the flashcards

Staphylococcus lugdunensis

A virulent bacteria causing community and hospital infections, known for mecA gene for resistance.

Signup and view all the flashcards

Staphylococcus aureus

The most clinically significant species causing skin infections and toxic conditions.

Signup and view all the flashcards

Cutaneous infections

Skin infections like impetigo, cellulitis, and carbuncles caused by bacteria.

Signup and view all the flashcards

Enterotoxins

Heat-stable toxins causing diarrhea and vomiting, linked with food poisoning.

Signup and view all the flashcards

Methicillin-resistant Staphylococci

Bacteria resistant to nafcillin or oxacillin, often treated with vancomycin.

Signup and view all the flashcards

mecA gene

Gene encoding for penicillin-binding protein PBP2a, responsible for methicillin resistance.

Signup and view all the flashcards

Toxin-induced diseases

Diseases caused by toxins like food poisoning, scalded skin syndrome, and toxic shock syndrome.

Signup and view all the flashcards

Oxacillin-salt agar plate

Medium used to screen for methicillin-resistant Staphylococcus aureus (MRSA).

Signup and view all the flashcards

Study Notes

Staphylococci

  • Gram-positive cocci, arranged in clusters ("bunches of grapes")
  • Nonmotile, non-spore-forming, aerobic or facultatively anaerobic
  • Catalase-positive
  • Several species, including S. aureus, S. epidermidis, S. saprophyticus, S. lugdunensis
  • Important in human infections, often causing food poisoning, skin infections, and other diseases.
  • S. aureus is the most common and clinically significant species

Staphylococcal Diseases

  • Food poisoning: Caused by heat-stable enterotoxins
  • Scalded skin syndrome (SSS): Caused by exfoliative toxins
  • Toxic shock syndrome (TSS): Caused by toxic shock syndrome toxin-1 (TSST-1)
  • Impetigo: Superficial skin infection, can progress deeper
  • Cellulitis: Skin infection, can progress deeper
  • Carbuncles: Deep skin abscesses

Staphylococcal Toxins

  • Enterotoxins: Heat-stable, cause vomiting and diarrhea (A-E, G-J groups)
  • Exfoliative toxins: Cause scalded skin syndrome
  • Toxic shock syndrome toxin-1 (TSST-1): Causes toxic shock syndrome
  • Cytolytic toxins (hemolysins and leukocidins): Damage cells
  • Panton-Valentine leukocidin (PVL): Toxin lethal to polymorphonuclear leukocytes

Coagulase

  • Enzyme produced by some staphylococci
  • Positive test results in clot formation in plasma

Differentiation Between Staphylococci and Micrococci

  • Use tests like modified oxidase, anaerobic acid production from glucose/glycerol, resistance to bacitracin, lysosome/lysostaphin assay.

Antimicrobial Susceptibility

  • Testing crucial for S. aureus and S. lugdunensis infections
  • Testing of S. saprophyticus from urine not usually required

Methicillin-Resistant Staphylococci (MRSA)

  • Isolates resistant to nafcillin or oxacillin
  • Vancomycin often the treatment of choice for MRSA and MRSE
  • Screening for MRSA involves oxacillin-salt agar plate and/or detection of the mecA gene

Vancomycin-Resistant Staphylococci

  • Vancomycin often the drug of choice
  • Infections may require different approaches, emphasizing prompt testing

Macromolecule Resistance

  • Modified disk diffusion tests used to assess resistance
  • Resistance mechanisms can affect treatment pathways

Diagnostic Procedures

  • Gram stains, catalase tests, coagulase tests
  • Differentiating tests used to identify specific staphylococcal and micrococcal species

Studying That Suits You

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

Quiz Team

Related Documents

Clinical Bacteriology Lab Chapter 14 PDF

More Like This

Staphylococcus Infections Overview
10 questions

Staphylococcus Infections Overview

InnocuousChiasmus avatar
InnocuousChiasmus
Les Infections à Staphylococcus aureus
27 questions

Les Infections à Staphylococcus aureus

WonderfulBliss avatar
WonderfulBliss
Microbiology Chapter 5: Bacterial Skin Infections
16 questions

Microbiology Chapter 5: Bacterial Skin Infections

FashionablePeony avatar
FashionablePeony
Overview of Bacterial Infections
31 questions

Overview of Bacterial Infections

EquitableRhodochrosite avatar
EquitableRhodochrosite
Use Quizgecko on...
Browser
Open
Browser
Browser