GRAM-POSITIVE COCCI

Question 1

3 Genera (prural ng Genus) of Gram Positive Cocci

Answer 1

Staphylococci
Streptococci
Enterococci

Question 2

Clusters

Answer 2

Staphylococcus

Question 3

Chains

Answer 3

Steptococcus
Enterococcus

Question 4

Catalase positive (may bubbles)

Answer 4

Staphylococcus

Question 5

Catalase negative (no bubbles)

Answer 5

Streptococcus
Enterococcus

Question 6

• gram-positive spherical cells arranged in grapelike irregular clusters
• aerobic or microaerophilic
• produce catalase, which converts H2O2 to H2O and O2
• slowly ferment many carbohydrates, producing lactic acid but not gas
• relatively resistant to drying, heat (withstand 50°C for 30 minutes), and
  10% NaCl

Answer 6

STAPHYLOCOCCI

Question 7

Expose the microorganism to peroxide

Answer 7

Catalase test

Question 8

Catalyst is the enzyme that neutralizes what reactive oxygen species?

Answer 8

hydrogen peroxide (H2O2)

Question 9

Products of peroxide- intoxification by catalyst

Answer 9

Water (H2O) and oxygen (dioxide/O2)

Question 10

AS human what we ferment?

Answer 10

lactic acid

Question 11

Fungi ferment nya

Answer 11

Ethanol

Question 12

3 Staphylococci

Answer 12

Staphylococcus aureus
Staphylococcus epidermidis
Staphylococcus saprophyticus

Question 13

Blood Agar Plate (BAP) hemolysis
S. aureus
S. epidermidis
S. saprophyticus

Answer 13

S. aureus - Beta
S. epidermidis- Gamma
S. saprophyticus- Gamma

Question 14

Coagulase of
S. aureus
S. epidermidis
S. saprophyticus

Answer 14

S. aureus- Positive
S. epidermidis- Negative
S. saprophyticus- Negative

Question 15

Mannitol-Salt Agar (MSA fermentation)
S. aureus
S. epidermidis
S. saprophyticus

Answer 15

S. aureus- Positive Golden yellow colonies (pink to yellow)
S. epidermidis- Negative (no fermenting)
S. saprophyticus- Both pos. and neg.

Question 16

Mannitol Salt Agar

Answer 16

Contains high salt concentration
Staphylococci grows in high-salt concentration
7.5% Sodium chloride
Selective medium-salt content
Differential medium- mannitol content

Question 17

Virulence factors associated with S. aureus
S. aureus Enzymes

Answer 17

-Coagulase
* clots oxalated or citrated plasma
* binds to prothrombin to enzymatically activate and initiate fibrin
polymerization
* alters ingestion by phagocytic cells or their destruction
-Clumping Factor
* adheres organism to fibrinogen and fibrin

Question 18

S. aureus Toxins

Answer 18

Hemolysins
Exfoliative Toxins
Toxic Shock Syndrome Toxin-1 (TSST-1)
Enterotoxins

Question 19

• lyse many cells e.g., RBCs and WBCs
• creates pores that cause release of inflammatory mediators e.g., IL-8,
  leukotriene, and histamine, which are responsible for necrosis and severe inflammation

Answer 19

Hemolysins

Question 20

• superantigens
• produce the generalized desquamation of staphylococcal scalded skin
  syndrome by dissolving the mucopolysaccharide matrix of the epidermis

Answer 20

Exfoliative Toxins

Question 21

• a superantigen
• binds to MHCII molecules, resulting in T-cell stimulation, which promotes
  the manifestations of toxic shock syndrome (fever, shock, desquamative
  skin rash)

Answer 21

Toxic Shock Syndrome Toxin-1 (TSST-1)

Question 22

• heat stable and resistant to gut enzymes
• causes food poisoning

Answer 22

Enterotoxins

Question 23

S. aureus Transmission

Answer 23

• members of the normal microbiota of skin and respiratory tract and GIT
• nasal carriage of S. aureus occurs in 20–50% of humans
• direct and indirect contact

Question 24

S. aureus Clinical Findings

Answer 24

• Furuncle/Carbuncle
• Impetigo/Pyoderma
• Bacteremia
• Food Poisoning
• Toxic Shock Syndrome
• Scalded Syndrome

Question 25

* localized abscess * Groups of S. aureus established in a hair follicle lead to tissue necrosis. * Coagulase coagulates fibrin, resulting in wall formation. * Within the center of the lesion, liquefaction occurs (enhanced by delayed hypersensitivity).

Answer 25

Furuncle/Carbuncle

Question 26

Honey yellow colored crust * local infection of superficial layers of skin, especially in children * superficial vesicles → pustules → erosions covered with pus → yellow- brown honey-colored crust * highly communicable, especially in hot, humid climates

Answer 26

Impetigo/Pyoderma

Question 28

* Inc. period: 1-8 hrs *N/V, diarrhea, (-) fever

Answer 28

Food poisoning

Question 29

* abrubt onset of high fever, vomiting, diarrhea, myalgia, scarlatiniform rash, and hypotension with cardiac and renal failure in most severe cases * often w/n 5 days after the onset of menses in young women who use high-absorbency tampons

Answer 29

Toxic Shock Syndrome

Question 30

redness and tenderness of the central face, neck, trunk, and intertriginous zones short-lived flaccid bullae and exfoliation of superficial epidermis (+) Nikolsky Sign crusted areas around mouth in a radial pattern

Answer 30

Scalded Skin Syndrome

Question 31

S. aureus Treatment * Furuncles/Carbuncles * Bacteremia and Dissemination

Answer 31

- Furuncles/Carbuncles * Antisepsis *Drainage - Bacteremia and Dissemination * IV β-lactamase-resistant (antistaphylococcal) penicillins- Methicillin * MRSA: vancomycin * VRSA: linezolid, streptogramins