Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

microbiology > staphylococcus > Flashcards

staphylococcus Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

gram staining

A

§ Reflects a fundamental differentiation based on permeability, presence or absence of outer membrane and cell wall thickness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

4 typical cell types, which are common with one another?

A

Gram (+) rods
Gram (+) cocci
Gram (-) rods
Gram (-) cocci

• Gram positive rods have more in common with gram positive cocci than with gram negative rods

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Gram positive cocci types

A

staphylococcus and streptococcus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Staphylococci types
where found?
often associated with?

A

S. aureus; S. saprophyticus; S. epidermidis

§ Found in many body sites; primarily skin infections &wounds; carbuncles; abscesses; leading to life threatening deep tissue infections: osteomyelitis,
endocarditis

§ Severe intoxications; Food poisoning

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Streptococci
groups?
O2 use?

A

§ Alpha or beta hemolysis
Alpha: S. pneumoniae
Beta: Groups A-T; Group A most prevalent in human disease

§ faculative anaerobes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Bacteroides fragilis

A

ü Most common organism in the human intestine.
ü Can cause serious disease when deposited into deep tissues.
(abscesses)
ü Can be also be found in gingival pockets
ü Very stinky

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q 
Staphylococcus aureus 
gram?
shape?
color?
catalase?
A

Gram +
cocci
gold
catalase +

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

S. aureus cell wall

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Variations in oxygen requirement and tolerance for S. aureus

A

Facualtive anaerobe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Virulence Factors of staphylococci (10 total)

A 
catalase 
coagulase 
clumping factor 
protein A
leukocidin 
digestive enzymes
staphylokinase 
B-lactamase
hemolysins
secreted exotoxins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

catalase

A

Reduces the potential of phagocytes to kill, conversion H2O2 to water and o2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

coagulase
how does it relate to tissue invasive potential?
what strain is it in?
what action does it have?

A

The tissue-invasive potential of staphylococcal infections is directly proportional to coagulase production (S.aureus; not in other Staph. species).

coagulase binds prothrombin: fibrinogen is cleaved anti-phagocytic fibrin coating on bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

clumping factor

A

fibrinogen-binding protein: cell surface proteins that bind to foreign materials (like sutures) and to extracellular matrix.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

protein A action

on what species?

A

Anti-phagocytic, competes with neutrophils for Fc portion of opsonizing IgGs
on cell surface of S.aureus but not on other staphylococcal strains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

leukocidins
how they work
major factor in the formation of what?

A

secretion: inhibits phagocytosis by forming pores in
phagosomal membranes which kills phagocytes.
Major factor in pus formation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

digestive enzymes

A

proteases, DNase, nuclease, lipases, hyaluronidase (spreading factor: digests extracellular matrix)

17
Q

staphylokinase functions

additional function?

A

converts plasminogen to plasmin, increasing invasion by digesting fibrin clots
also cleaves C3b and IgG to inhibit phagocytosis

18
Q

β-lactamase

A

Enzymatic digestion of penicillins (90% strains have plasmid-based antibiotic resistance)

19
Q

hemolysins

A

α-, β-, γ-, and δ-toxins are all hemolysins: lyse erythrocytes (lab phenomenon)

20
Q

alpha hemolyisns
kill what cells?
destroy what strucutre?
paralysis?

A

α-hemolysins (pores) are hemolytic and leukocytic

will destroy skin, cause smooth muscle paralysis

21
Q

beta hemolysins

A

β-hemolysins are cytolytic sphingomyelinases that destroy nerves

22
Q

γ-hemolysins

A

lyse like related leukocidin on neutrophil lysosomal membranes

23
Q

hemolysins seen in which species

A

S. aureus

24
Q

impetigo
caused by what strain?
affects what tissues?
accumulation of?

A

caused by S. aureus

skin and deeper tissue infection, accumulation of pus due to cell death

25
Q

Empyema:

A

Collection of pus in a naturally existing anatomical cavity e.g. lungs, may be due to impetigo

26
Q

pyogenic infections:

A

pus-forming (massive amounts of neutrophils and other leukocytes are lysed by bacterial factors (e.g. leukocidin) and release their lysosomal contents in attempting phagocytic killing of the staphylococci

27
Q

folliculitis progression

A
28
Q

Secreted exo-toxins of staphylcocci

A

super Ag: enterotoxins and TSST

others: exfoliative toxin

29
Q

enterotoxins

A

super Ag
Heat-stable (cooking doesnt help!)
cause of gastrointestinal upset typical of food poisoning

30
Q

TSST

A

super Ag

mass activation of T cells leads to large production of inflammatory cytokines

31
Q

exfoliative toxin
heat?
causes what disorder?
production local? effects?

A

exfoliative toxin (heat-stable, chromosomal), B (heat-labile, plasmid) : SSSS
(staphylococcal scalded-skin syndrome)
toxin is produced locally but is distributed and acts systemically

32
Q

TSS: Toxic Shock Syndrome

A

Increased oxygenation of vagina by tampons, and foreign surface adhesion, caused massive growth
allow aureus to grow and produce toxins

33
Q

SSSS, what agents cause this?
cause loss of?
resolved with?

A

Ø exfoliative toxins A, B cause loss of layers of the skin in SSSS
resolved with Neutralizing Ab, recover without scarring

34
Q

Nosocomial Staphylococci, what is the common species? coagulase + or -?

A

surgery, implant & instrument risk

often coagulase-negative S.epidermidis

35
Q

endocarditis, species involved?

dental risk?

A
  • acute: 60% S.aureus
  • if artificial heart valves: 80% S.epidermidis

S.epidermidis: dental extraction risk

36
Q

most frequent cause of bacterial arthrirts

A

S. aureus in all age groups

37
Q

Epidemiology of S. aureus
found?
surface survival/hospitals?
temp/salt resistance?

A

found on skin, mucosa and aerosols
good surface survival (hospitals= nosocomial)
high temp and salt resistant too

38
Q

resistances found in S. aureus

A

β-lactamase (plasmid): >90% penicillin resistant
penicillin-binding protein 2a (chromosomal): causes Methicillin Resistance
50% of hospital strains are MRSA; 20% of community strains are MRSA
VRSA possible

39
Q

coagulase - strains
cell walls/capsules?
secrete?
where they are a problem?

A

Other Staphylococci like S.epidermidis or S.saprophyticus
• Thick cell wall, slime capsule, (S.saprophyticus: urease secretion → acute cystitis
• Opportunistic hospital pathogens (instruments, catheters, heart valves)

microbiology (42 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions