Question 1

All of the following staphylococci are coagulase-positive, except

Accepted Answer

A)  Staphylococcus aureus. 
B)  S. saprophyticus. 
C)  S. intermedius. 
D)  S. delphini. 
A)  Staphylococcus aureus. 
B)  S. saprophyticus. 
C)  S. intermedius. 
D)  S. delphini.

Question 2

A young, healthy woman was rushed to the hospital with a high fever, hypotension, and shock. She had not been feeling well that day, but her condition progressively worsened throughout the day. She was feeling fine until a couple of days after she started menstruating. What condition could this woman be exhibiting?

Accepted Answer

A)  Scalded skin syndrome 
B)  Toxic epidermal necrolysis 
C)  TSS 
D)  Food poisoning 
A)  Scalded skin syndrome 
B)  Toxic epidermal necrolysis 
C)  TSS 
D)  Food poisoning

Question 3

What are the effects of the Panton-Valentine toxin produced by Staphylococcus aureus?

Accepted Answer

A)  It acts on sphingomyelin in the plasma membrane of red blood cells. 
B)  It kills leukocytes. 
C)  It kills epithelial cells. 
D)  It lyses red blood cells, damages platelets and macrophages, and can cause severe tissue damage. 
A)  It acts on sphingomyelin in the plasma membrane of red blood cells. 
B)  It kills leukocytes. 
C)  It kills epithelial cells. 
D)  It lyses red blood cells, damages platelets and macrophages, and can cause severe tissue damage.

Question 4

The two species of coagulase-negative staphylococci most often isolated in clinical laboratories are

Accepted Answer

A)  Staphylococcus aureus and S. epidermidis. 
B)  S. capitus and S. lugdunensis. 
C)  S. epidermidis and S. saprophyticus. 
D)  S. saccharolyticus and S. epidermidis. 
A)  Staphylococcus aureus and S. epidermidis. 
B)  S. capitus and S. lugdunensis. 
C)  S. epidermidis and S. saprophyticus. 
D)  S. saccharolyticus and S. epidermidis.

Question 5

What are the effects of the $\alpha$-hemolysin produced by Staphylococcus aureus?

Accepted Answer

A)  It acts on sphingomyelin in the plasma membrane of red blood cells. 
B)  It kills polymorphonuclear leukocytes. 
C)  It kills macrophages. 
D)  It lyses red blood cells, damages platelets and macrophages, and can cause severe tissue damage. 
A)  It acts on sphingomyelin in the plasma membrane of red blood cells. 
B)  It kills polymorphonuclear leukocytes. 
C)  It kills macrophages. 
D)  It lyses red blood cells, damages platelets and macrophages, and can cause severe tissue damage.

Question 6

All of the following virulence factors are associated with Staphylococcus aureus, except

Accepted Answer

A)  enterotoxins. 
B)  cytolytic toxins. 
C)  protein A. 
D)  endotoxins. 
A)  enterotoxins. 
B)  cytolytic toxins. 
C)  protein A. 
D)  endotoxins.

Question 7

Staphylococcus aureus food poisoning is most commonly caused by these two enterotoxins.

Accepted Answer

A)  A and D 
B)  A and B 
C)  B and C 
D)  B and D 
A)  A and D 
B)  A and B 
C)  B and C 
D)  B and D

Question 8

What is the mechanism by which toxic shock syndrome toxin-1 (TSST-1) causes TSS?

Accepted Answer

A)  The bacteria release the toxin into the blood and it goes to the hypothalamus to produce an extremely high fever. 
B)  The bacteria release the toxin into the gastrointestinal system where phagocytes engulf the bacteria, leaving a pseudomembrane that irritates the colon. 
C)  The toxin is a superantigen that stimulates T-cell proliferation with production of large amounts of cytokines. 
D)  All of the above 
A)  The bacteria release the toxin into the blood and it goes to the hypothalamus to produce an extremely high fever. 
B)  The bacteria release the toxin into the gastrointestinal system where phagocytes engulf the bacteria, leaving a pseudomembrane that irritates the colon. 
C)  The toxin is a superantigen that stimulates T-cell proliferation with production of large amounts of cytokines. 
D)  All of the above

Question 9

This staphylococcus produces wide zones of beta hemolysis on 5% sheep blood agar.

Accepted Answer

A)  Staphylococcus epidermidis 
B)  S. aureus 
C)  S. intermedius 
D)  S. saprophyticus 
A)  Staphylococcus epidermidis 
B)  S. aureus 
C)  S. intermedius 
D)  S. saprophyticus

Question 10

Why do staphylococci spread so easily when infecting the skin?

Accepted Answer

A)  They produce hyaluronidase, which hydrolyzes hyaluronic acid present in the intracellular ground substance that makes up connective tissue. 
B)  They produce lipase, which melts the fat under the skin, making it easier to spread. 
C)  The hemolysins kill the white and red blood cells; then the protease liquefies the skin protein, allowing easy penetration for the bacteria. 
D)  All of the above 
A)  They produce hyaluronidase, which hydrolyzes hyaluronic acid present in the intracellular ground substance that makes up connective tissue. 
B)  They produce lipase, which melts the fat under the skin, making it easier to spread. 
C)  The hemolysins kill the white and red blood cells; then the protease liquefies the skin protein, allowing easy penetration for the bacteria. 
D)  All of the above

Question 11

Automated antimicrobial susceptibility testing methods are not reliable in detecting staphylococci resistant to this agent.

Accepted Answer

A)  Vancomycin 
B)  Erythromycin 
C)  Clindamycin 
D)  All of the above 
A)  Vancomycin 
B)  Erythromycin 
C)  Clindamycin 
D)  All of the above

Question 12

What is the most common causative agent of pyoderma?

Accepted Answer

A)  Staphylococcus aureus 
B)  Neisseria gonorrhoeae 
C)  Clostridium perfringens 
D)  Haemophilus influenzae 
A)  Staphylococcus aureus 
B)  Neisseria gonorrhoeae 
C)  Clostridium perfringens 
D)  Haemophilus influenzae

Question 13

How is Staphylococcus saprophyticus presumptively identified?

Accepted Answer

A)  Latex agglutination test for clumping factor 
B)  Rabbit plasma test for coagulase 
C)  Novobiocin susceptibility 
D)  All of the above 
A)  Latex agglutination test for clumping factor 
B)  Rabbit plasma test for coagulase 
C)  Novobiocin susceptibility 
D)  All of the above

Question 14

What is the function of protein A in the cell wall of Staphylococcus aureus?

Accepted Answer

A)  To keep the structural integrity of the cell wall and keep out antimicrobial agents 
B)  To bind IgG and prevent phagocytosis 
C)  To bind IgM and inactivate natural killer cells 
D)  To block the activation of the complement cascade 
A)  To keep the structural integrity of the cell wall and keep out antimicrobial agents 
B)  To bind IgG and prevent phagocytosis 
C)  To bind IgM and inactivate natural killer cells 
D)  To block the activation of the complement cascade

Question 15

A young man goes to his physician complaining of large, raised, suppurative abscesses on his neck. The man denies having a fever or the chills. What is the name of the lesions on his neck, and what organism causes this type of lesions?

Accepted Answer

A)  Staphylococcus epidermidis and boils 
B)  S. aureus and furuncles 
C)  S. saprophyticus and carbuncles 
D)  S. sciuri and folliculitis 
A)  Staphylococcus epidermidis and boils 
B)  S. aureus and furuncles 
C)  S. saprophyticus and carbuncles 
D)  S. sciuri and folliculitis

Exam 14: Staphylococci

All of the following staphylococci are coagulase-positive, except

What are the effects of the Panton-Valentine toxin produced by Staphylococcus aureus?

The two species of coagulase-negative staphylococci most often isolated in clinical laboratories are

What are the effects of the α\alphaα -hemolysin produced by Staphylococcus aureus?

All of the following virulence factors are associated with Staphylococcus aureus, except

Staphylococcus aureus food poisoning is most commonly caused by these two enterotoxins.

What is the mechanism by which toxic shock syndrome toxin-1 (TSST-1) causes TSS?

This staphylococcus produces wide zones of beta hemolysis on 5% sheep blood agar.

Why do staphylococci spread so easily when infecting the skin?

Automated antimicrobial susceptibility testing methods are not reliable in detecting staphylococci resistant to this agent.

What is the most common causative agent of pyoderma?

How is Staphylococcus saprophyticus presumptively identified?

What is the function of protein A in the cell wall of Staphylococcus aureus?

A young man goes to his physician complaining of large, raised, suppurative abscesses on his neck. The man denies having a fever or the chills. What is the name of the lesions on his neck, and what organism causes this type of lesions?

Bacterial Cell Structure, Physiology, Metabolism, and Genetics

Hostparasite Interaction

The Laboratory Role in Infection Control

Control of Microorganisms

Performance Improvement in the Microbiology Laboratory

Specimen Collection and Processing

Microscopic Examination of Materials From Infected Sites

Use of Colony Morphology for the Presumptive Identification of Microorganisms

Biochemical Identification of Gram-Negative Bacteria

Immunodiagnosis of Infectious Diseases

Applications of Molecular Diagnostics

Antimicrobial Agent Mechanisms of Action and Resistance Mechanisms

Antimicrobial Susceptibility Testing

Streptococcus, Enterococcus, and Other Catalase-Negative, Gram-Positive Cocci

Aerobic Gram-Positive Bacilli

Neisseria Species and Moraxella Catarrhalis

Haemophilus, Hacek, Legionella, and Other Fastidious Gram-Negative Bacilli

Enterobacteriaceae

Vibrio, Aeromonas, and Campylobacter Species

Nonfermenting and Miscellaneous Gram-Negative Bacilli

Anaerobes of Clinical Importance

The Spirochetes

Chlamydia, Rickettsia, and Similar Organisms

Mycoplasma and Ureaplasma

Mycobacterium Tuberculosis and Nontuberculous Mycobacteria

Medically Significant Fungi

Diagnostic Parasitology

Clinical Virology

Agents of Bioterror and Forensic Microbiology

Biofilms: Architects of Disease

Upper and Lower Respiratory Tract Infections

Skin and Soft Tissue Infections

Gastrointestinal Infections and Food Poisoning

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Bacteremia and Sepsis

Urinary Tract Infections

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What are the effects of the $\alpha$ -hemolysin produced by Staphylococcus aureus?