staph strep micro entero

Question 1

What is the Gram reaction and morphology of Staphylococcus species?

Answer 1

Gram-positive cocci in clusters.

Question 2

What enzyme differentiates Staphylococcus from Streptococcus?

Answer 2

Catalase (Staphylococcus is catalase-positive).

Question 3

Which Staphylococcus species is coagulase-positive?

Answer 3

Staphylococcus aureus.

Question 4

What is the main virulence factor of Staphylococcus aureus that inhibits phagocytosis?

Answer 4

Protein A.

Question 5

What enzyme produced by S. aureus allows it to clot plasma?

Answer 5

Coagulase.

Question 6

Which Staphylococcus species is a major cause of hospital-acquired infections?

Answer 6

Staphylococcus epidermidis.

Question 7

What infections are commonly caused by Staphylococcus saprophyticus?

Answer 7

Urinary tract infections (UTIs), particularly in young women.

Question 8

Which enzyme allows S. aureus to break down penicillin?

Answer 8

Beta-lactamase (Penicillinase).

Question 9

What toxin is responsible for Staphylococcal Toxic Shock Syndrome?

Answer 9

Toxic shock syndrome toxin-1 (TSST-1).

Question 10

Which Staphylococcus species is associated with catheter-related infections?

Answer 10

Staphylococcus epidermidis.

Question 11

What is the significance of mecA in Staphylococcus?

Answer 11

Encodes PBP2a, which confers methicillin resistance (MRSA).

Question 12

Which test is used to differentiate Staphylococcus aureus from CoNS?

Answer 12

Coagulase test (S. aureus is coagulase-positive).

Question 13

What agar is selective for Staphylococcus species?

Answer 13

Mannitol salt agar (MSA).

Question 14

How does S. aureus appear on mannitol salt agar?

Answer 14

Yellow colonies due to mannitol fermentation.

Question 15

What is the function of hemolysins in S. aureus infections?

Answer 15

Lyse red blood cells and contribute to tissue destruction.

Question 16

What is the difference between hospital-acquired MRSA (HA-MRSA) and community-acquired MRSA (CA-MRSA)?

Answer 16

CA-MRSA is more virulent and can affect healthy individuals, while HA-MRSA is usually multidrug-resistant.

Question 17

What is the Gram reaction and morphology of Micrococcus species?

Answer 17

Gram-positive cocci in tetrads or irregular clusters.

Question 18

How do Micrococcus species differ from Staphylococcus?

Answer 18

Micrococcus is oxidase-positive and bacitracin-sensitive, while Staphylococcus is oxidase-negative and bacitracin-resistant.

Question 19

Which test differentiates Micrococcus from Staphylococcus?

Answer 19

Microdase test (Micrococcus is positive).

Question 20

Are Micrococcus species considered pathogenic?

Answer 20

Generally no, but they can cause opportunistic infections in immunocompromised patients.

Question 21

What pigment do some Micrococcus species produce?

Answer 21

Yellow or orange pigments.

Question 22

What is the Gram reaction and morphology of Streptococcus species?

Answer 22

Gram-positive cocci in chains or pairs.

Question 23

What test differentiates Streptococcus from Staphylococcus?

Answer 23

Catalase test (Streptococcus is catalase-negative).

Question 24

Which Streptococcus species belongs to Group A?

Answer 24

Streptococcus pyogenes.

Question 25

Which test is used to identify Streptococcus pyogenes?

Answer 25

Bacitracin sensitivity test (Group A Streptococcus is sensitive).

Question 26

What major virulence factor does S. pyogenes use to evade the immune system?

Answer 26

M protein.

Question 27

What is the function of Streptolysin O?

Answer 27

Destroys red and white blood cells; oxygen-labile.

Question 28

What are the major infections caused by S. pyogenes?

Answer 28

Pharyngitis, scarlet fever, rheumatic fever, necrotizing fasciitis.

Question 29

Which Streptococcus species is associated with neonatal sepsis and meningitis?

Answer 29

Streptococcus agalactiae (Group B Streptococcus).

Question 30

What test is used to identify Group B Streptococcus?

Answer 30

CAMP test (Group B Streptococcus enhances hemolysis).

Question 31

Which species of Streptococcus is optochin-sensitive?

Answer 31

Streptococcus pneumoniae.

Question 32

What type of hemolysis does Streptococcus pneumoniae exhibit?

Answer 32

Alpha-hemolysis (partial hemolysis, greenish color).

Question 33

What is the Gram reaction and morphology of Enterococcus species?

Answer 33

Gram-positive cocci in pairs or short chains.

Question 34

What test differentiates Enterococcus from Streptococcus?

Answer 34

Bile esculin test (Enterococcus is positive).

Question 35

Which Enterococcus species is most commonly associated with infections?

Answer 35

Enterococcus faecalis and Enterococcus faecium.

Question 36

What type of infections are caused by Enterococcus?

Answer 36

Urinary tract infections, endocarditis, bacteremia.

Question 37

Which test differentiates Enterococcus from other Streptococcus species?

Answer 37

Growth in 6.5% NaCl (Enterococcus can grow).

Question 38

What is the major concern regarding Enterococcus infections?

Answer 38

They are often resistant to antibiotics, including vancomycin (VRE).

Question 39

What is VRE?

Answer 39

Vancomycin-resistant Enterococcus, a major hospital-acquired infection concern.