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MICROBIOLOGY > Staphylococcus spp. > Flashcards

Staphylococcus spp. Flashcards

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Biology 101 flashcards
1
Q

Staphylococcus spp. characteristics

A
  • 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)
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2
Q

Catalase test

A

used to differentiate Staphylococcus from Streptococcus

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3
Q

what does staphylococcus ferment

A

glucose

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4
Q

coccis that are not gram (+)

A

Neisseria branhamella and veillonella

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5
Q

Culture media for Staphylococcus

A

BAP - to see specific hemolytic pattern

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6
Q

Staphylococcus colonies

A

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

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7
Q

Species of Staphylococcus

A
  • aures
  • epidermidis
  • saprophyticus
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8
Q

S. aureus characteristics

A 
✦ 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.
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9
Q

S. aureus culture characteristics

A

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

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10
Q

2 types of staphylococcus virulence factors

A

toxins and enzymes

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11
Q

Virulence factors ( toxins )

A
  • enterotoxins
  • toxic shock syndrome 1
  • exfoliative toxins ( A nd B)
  • cytolytic toxins ( Hemolysin and leukocidins)
  • panton - valentine leukocidin
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12
Q

Enterotoxins

A

• 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

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13
Q

Toxic Shock syndrome Toxin-I

Enterotoxin F / Pyrogenic exotoxin C

A 
• Causes nearly all cases of
menstruating and
nonmenstruating-associated TSS
(prolonged tampon used)
• Superantigen
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14
Q

Exfoliative toxins (A and B)

A

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

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15
Q 
Cytolytic toxins (Hemolysin and
Leukocidins)
A
  • alpha hemolysin
  • beta hemolysin
  • delta hemolysin
  • gamma hemolysin
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16
Q

Alpha hemolysin

A

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

17
Q

Beta hemolysin

sphingomyelinase C

A 
• Acts on sphingomyelin in the
plasma membrane of RBC
• “Hot-cold” lysin
• Exhibited in CAMP test for Group
B Streptococci identification
18
Q

Delta Hemolysin

A

Less toxic to cell structure

19
Q

Gamma Hemolysin

A

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

20
Q

Panton-Valentin Leukocidin (PVL)

A

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

• Associated with community-
acquired staphylococcal infection.

21
Q

Virulence factors (enzymes)

A
  • staphylocoagulace
  • hyaluronidase
  • lipase
  • staphylokinase
  • protease
  • DNAse and Phosphatase
  • Beta-lactamase
  • Protein A
22
Q

staphylocoagulace

A 
• Virulence marker
• Coagulates fibrinogen in plasma
• 2 types:
 A. Cell bound coagulase/clumping
factor
B. Unbound/extracellular coagulase
23
Q

hyaluronidase

A

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

24
Q

lipase

A 
• 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.
25
Q

staphylokinase

A

• It has fibrinolytic activity that

dissolves fibrin clot.

26
Q

protease

A

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

27
Q

DNAse and Phosphatase

A

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

28
Q

Beta-lactamase

A

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

29
Q

Protein A

A

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

30
Q

Pathogenesis of S. aureus

A 
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%)
31
Q

S. epidermidis characteristics

A 
✦ 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
32
Q

S. epidermidis colonies

A

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

33
Q

S. saphrophyticus characteristics

A 
✦ 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.
34
Q

S. lugdunesis characteristics

A 
✦ 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.

MICROBIOLOGY (9 decks)

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