Staphylococcus spp.

Question 1

Staphylococcus spp. characteristics

Answer 1

• gram (+); in singly, pairs, majority on cluster
  CLUSTERS/ BUNDLES OF GRAPES
• Non-motile, non-sporeforming
  aerobic or facultatively anaerobic
  (except for S. saccharolyticus —obligate anaerobe)

Question 2

Catalase test

Answer 2

used to differentiate Staphylococcus from Streptococcus

Question 3

what does staphylococcus ferment

Answer 3

glucose

Question 4

coccis that are not gram (+)

Answer 4

Neisseria branhamella and veillonella

Question 5

Culture media for Staphylococcus

Answer 5

BAP - to see specific hemolytic pattern

Question 6

Staphylococcus colonies

Answer 6

Cream-colored, white or rarely light
gold (staphylococcus aureus) and
“buttery-looking” have larger
colonies compared to Streptococcus

Question 7

Species of Staphylococcus

Answer 7

• aures
• epidermidis
• saprophyticus

Question 8

S. aureus characteristics

Answer 8

✦ most virulent species
✦ Can be recovered from almost any
clnical specimen
✦ Important cause of nosocomial
infections
✦ Chiefly responsible for various skin,
wound, and deep tissue infection.

Question 9

S. aureus culture characteristics

Answer 9

Medium to large, smooth, most
colonies pigmented creamy yellow;
most colonies are beta-hemolytic

Question 10

2 types of staphylococcus virulence factors

Answer 10

toxins and enzymes

Question 11

Virulence factors ( toxins )

Answer 11

• enterotoxins
• toxic shock syndrome 1
• exfoliative toxins ( A nd B)
• cytolytic toxins ( Hemolysin and leukocidins)
• panton - valentine leukocidin

Question 12

Enterotoxins

Answer 12

• Heat stable exotoxins responsible
for vomiting and diarrhea

• Stable at 100C for 30 minutes

• Resistant to hydrolysis by the
gastric and intestinal enzymes;
cant be easily destroyed once
ingested by patients

• Enterotoxins A to E and G to J

• Staphylococcal food poisoning-
common cause, A, B, and D.

• Enterotoxin B- linked to
staphylococcal enterocolitis

Question 13

Toxic Shock syndrome Toxin-I

Enterotoxin F / Pyrogenic exotoxin C

Answer 13

• Causes nearly all cases of
menstruating and
nonmenstruating-associated TSS
(prolonged tampon used)
• Superantigen

Question 14

Exfoliative toxins (A and B)

Answer 14

•Causes scalded skin syndrome
(Ritter’s disease)
• Serine protease

Question 15

Cytolytic toxins (Hemolysin and
Leukocidins)

Answer 15

• alpha hemolysin
• beta hemolysin
• delta hemolysin
• gamma hemolysin

Question 16

Alpha hemolysin

Answer 16

• Lysing RBCs, damage platelets,
macrophages and cause severe
tissue damage.

Question 17

Beta hemolysin

sphingomyelinase C

Answer 17

• Acts on sphingomyelin in the
plasma membrane of RBC
• “Hot-cold” lysin
• Exhibited in CAMP test for Group
B Streptococci identification

Question 18

Delta Hemolysin

Answer 18

Less toxic to cell structure

Question 19

Gamma Hemolysin

Answer 19

• Destroys RBCs
• Associated with Panton-Valentin
Leukocidin (PVL)

Question 20

Panton-Valentin Leukocidin (PVL)

Answer 20

• Exotoxin lethal to PMN leukocytes
• Associated with severe cutaneous
infections and necrotizing
pneumonia.

• Associated with community-
acquired staphylococcal infection.

Question 21

Virulence factors (enzymes)

Answer 21

• staphylocoagulace
• hyaluronidase
• lipase
• staphylokinase
• protease
• DNAse and Phosphatase
• Beta-lactamase
• Protein A

Question 22

staphylocoagulace

Answer 22

• Virulence marker
• Coagulates fibrinogen in plasma
• 2 types:
 A. Cell bound coagulase/clumping
factor
B. Unbound/extracellular coagulase

Question 23

hyaluronidase

Answer 23

Hydrolyzes hyaluronic acid present in the
intracellular ground substance that
makes up connective tissues, permitting
the spread of bacteria during infection.

Question 24

lipase

Answer 24

• Acts on the lipids present on the
surface of the skin, particularly fats
and oil secreted by the sebaceous
glands
• Important in the formation of furuncles,
carbuncles, and boils.

Question 25

staphylokinase

Answer 25

• It has fibrinolytic activity that | dissolves fibrin clot.

Question 26

protease

Answer 26

Capable of destroying tissue and may facilitate the spread of infection to adjoining tissues.

Question 27

DNAse and Phosphatase

Answer 27

Lowers viscosity of exudates, giving the pathogen more mobility. Exudates should be sticky but turns it to be more viscous infecting other tissues.

Question 28

Beta-lactamase

Answer 28

• It breaks down penicillin and other beta-lactam drugs. Can cause resistance to antibiotics

Question 29

Protein A

Answer 29

• It has the ability to bind to the Fe portion of IgG — neutralized IgG and can block phagocytosis.

Question 30

Pathogenesis of S. aureus

Answer 30

``` 1. Skin and wound infections • Folliculitis in the hair follicles • Furuncles (boils) • Carbuncles cluster of boils • Bullous impetigo — highly contagious infection ; manifests blisters in the skin that’s worse. 2. Scalded Skin Syndrome • Ritter’s disease • Exfoliative dermatitis 3. Toxic Shock Syndrome • Prolonged tampon use • Fever, desquamation, hypotension • Erythemasus/rashes 4. Toxic Epidermal Necrolysis 5. Food poisoning — heat stable • Enterotoxin A (78%), D (38%), B(10%) ```

Question 31

S. epidermidis characteristics

Answer 31

``` ✦ Normal flora buy may cause bacteremia, UTI, stitch abscess, meningitis, and endocarditis ✦ Causes nosocomial infections from instrumentation procedures such as catheterization, medical implantation, and immunosuppresive therapy. ✦ Coagulase (-); does not ferment mannitol ✦ DNAse and maltose (-) ✦ Sensitive to n ```

Question 32

S. epidermidis colonies

Answer 32

Grows on CNA ✦ Non-hemolytic white creamy, raised growth on BAP

Question 33

S. saphrophyticus characteristics

Answer 33

``` ✦ Primarily associated with nosocomial infections ✦ Causes community-acquired UTI in young, sexually active females. — second most common cause of UTI next to E. coli. ✦ May be found in lower numbers (<10,000 CFU/mL), and still considered significant. ✦ Coagulase (-); does not ferment mannitol ✦ DNAse (-) and maltose (+) ✦ Resistant to novobiocin. ```

Question 34

S. lugdunesis characteristics

Answer 34

``` ✦ Coagulase negative staphylococci ✦ Can cause both community and nosocomial infections ✦ Known to contain the gene mecA that encodes oxallin resistance. ✦ Infective endocarditis, septicemia, meningitis, skin and soft tissue infection, UTI, septic shock. ```