Laboratory Diagnosis of Staphylococci 2022

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Questions and Answers

What temperature is the test tube incubated at for the coagulase testing of staphylococcus?

  • 30°C
  • 37°C (correct)
  • 40°C
  • 25°C

If no clotting is observed in the test tube after incubation at 37°C for an hour, what should be done next?

  • Incubate for another hour at 45°C
  • Examine at 30-minute intervals for up to 6 hours (correct)
  • Add more test organism culture
  • Examine the tube under a microscope

Why should citrated blood not be used for the coagulase test?

  • It inhibits clot formation
  • It causes false-negative results
  • It can lead to false-positive results (correct)
  • It accelerates the clotting process

Can coagulase testing be performed using growth from mannitol salt agar?

<p>No, it cannot be performed from growth on mannitol salt agar (A)</p> Signup and view all the answers

How is a DNase test spot inoculation performed?

<p>Touch a colony of the organism with a loop and inoculate onto a small area (A)</p> Signup and view all the answers

What should be done after flooding a DNase test agar plate with 1N Hydrochloric Acid?

<p>Decant excess hydrochloric acid (B)</p> Signup and view all the answers

What happens if Coagulase testing is performed with citrated blood?

<p>It causes false-positive results (C)</p> Signup and view all the answers

Which agar type should not be used for Coagulase testing?

<p><strong>Mannitol Salt Agar</strong> (C)</p> Signup and view all the answers

What property of Staphylococcus aureus contributes to high infection rates and persistence despite treatment?

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

Which of the following is a systemic illness associated with Staphylococcus aureus infections?

<p>Toxic shock syndrome (B)</p> Signup and view all the answers

What plays a role in determining the treatment for Staphylococcus aureus infections?

<p>Antibiotic resistance patterns and co-infection rates (A)</p> Signup and view all the answers

How does Staphylococcus aureus evade host immune responses?

<p>By producing biofilms (A)</p> Signup and view all the answers

Which of the following is NOT a factor in the pathogenesis of Staphylococcus aureus infections?

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

What is the function of coagulase enzymes produced by Staphylococcus aureus?

<p>Help the bacteria evade the human immune response (B)</p> Signup and view all the answers

Which toxin produced by Staphylococcus aureus disrupts the immune system by causing massive activation of host immune cells?

<p>Toxic shock syndrome toxin-1 (TSST-1) (B)</p> Signup and view all the answers

In addition to causing skin and soft tissue infections, what else can Staphylococcus aureus infections lead to?

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

What role do exotoxins produced by Staphylococcus aureus play in causing diseases?

<p>Activate host immune cells (A)</p> Signup and view all the answers

Where can Staphylococcus aureus be found besides infecting humans?

<p>In soil, wildlife animals, and foodstuffs (B)</p> Signup and view all the answers

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