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PHARM 232 Midterm 1 > Gram positive bacteria > Flashcards

Gram positive bacteria Flashcards

1
Q

What are characteristics of of all STAPHYLOcocci
Gram?
Catalase?
Structure?

A
  • Gram-positive
  • Catalase: positive
  • Structure: grape-like
  • Non motile
  • Facultative anaerobes
  • Salt-tolerant
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2
Q

Which is the most virulent staphylococci?

A

Staph. Aureus

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3
Q

Staph. Aureus
Found in:
Coagulase?

A

Found in: normal flora of nose, nasopharynx, perineal skin

Coaglulase: positive

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4
Q

What 3 features of pathogenicity does Staph. aureus result from

A
  1. Production of enzymes
  2. Structures/enzymes that enable to escape phagocytosis
  3. Production of toxins
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5
Q

How does staph aureus escape phagocytosis (3)

A
  1. Protein A:
    - provides high affinity for Fe receptor of IgG molecules –> decreases clearance of the bacteria from site of infection
  2. Coagulase:
    - fibrin coat protects cells
  3. Bacterial capsule
    - facilities attachment to surfaces –> inhibits phagocytosis
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6
Q

Which Staph. Aureus enzymes increase virulence? (4)

A
  1. Coagulase
  2. Hyaluronidase (spreading factor)
  3. Staphylokinase
    - Fibrinolysis: forms plasmin to digest fibrin clots
    - allows you to bleed quicker
  4. Beta-lactamase
    - provides resistance to B-lactam antibiotics (penicilinns, cephalosporins)
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7
Q

What are examples of Staph. aureus exotoxins (4)

A
  1. Hemolysins
  2. Exfoliative toxins:
    - cause staphylococcal scaled skin syndrome (SSSS); desquamtion= skin layer cells comes off in scales or flakes
  3. Toxic-shock syndrome toxin
    - cause fever, desquamation/hypotension leading to shock and death
  4. Enterotoxins: important causes of food poisoning
    - S. aureus grows in carbohydrate and proteins foods
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8
Q

Staph Epidermidis
Location?
Catalase?
Coagulase?

A

Location?
- Normal flora of skin and mucosa

Catalase?
- Positive

Coagulase?
- Negative

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9
Q

Which Staph is an opportunistic pathogen?

A

Staph. epidermidis

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10
Q

What are the virulence factors of Staph. Epidermidis (2)

A

Exopolysaccharide slime: adherence to medical devices (catheters etc..)

Exotoxins

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11
Q

Staph saprophyticus
Location
Catalase
Coagulase
Virulence factors

A

Location
- normal flora of: skin, mucous membranes, genitourinary tracts

Catalase
- positive

Coagulase
- negative

Virulence factors
- None

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12
Q

Which staph is a common cause of UTI

A

Staph saprophyticus

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13
Q

What is common of all streptococci
Gram?
Structure?
Catalase?

A

Gram positive
Structure: pairs or chains
Catalase: negative

Mostly facultative anaerobes

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14
Q

How do we classify streptococci (5)

A
  1. Colony morphology/hemolytic reactions
  2. Presence of lancefield antitgens: to divide Beta-hemolytic streptococci
  3. Biochemical reactions/resistance to physical + chemical factors
  4. Ecologic features (niche)
  5. Molecular genetics
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15
Q

Strept. Pyogens
Group
Formation
Location

A

Group: A
Formation: pairs or chains
Location: not part of normal flora

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16
Q

Virulence of Strept. pyogens (6)

A
  1. Capsule
  2. M protein: anti-phagocytic
  3. Pyrogenic exotoxins/erthrogenei
    - toxic shock syndrome, scarlet fever
  4. Streptokinase (fibrinolysis)
    - digests blood clots –> allows bacteria to escape
  5. Hemolysins: lyse erythrocyte membranes
  6. Hyalurodinase (spreading factor)
17
Q

What are examples of infections with Strept. Pyogens (6)

A
  1. Acute paharyngitis: Strep throat
  2. Imeptigo: common in 2-5 yrs
  3. Cellulitis: skin swelling
  4. Necrotizing fasciitis: “flesh eating bacteria” destroys tissue in skin
  5. Bacteremia: infection in organs
  6. Post-streptococcal disease: auto-immune disorders after this infection
18
Q

Strept agalactiae
Group
Location
Virulence factors

A

Group: B
Location: vaginal flora
Virulence factors:
- capsule

19
Q

What are examples of infections for strep. agalactiae infections

A

Most common in neonates

Adults:
- post-partum (birth) infections
- immunocomprimised individuals

20
Q

Enterococci
Group
Location
Virulence factors

A

Group: D
Location: GI tract, female genitourinary tract
Virulence factors:
- Adhesions
- Cytolysins

resistant to many antimicrobial agents
- first bacteria to develop vancomycin resistance

21
Q

What infections are caused my enterocci

A

UTI
- Intra-abdominal infections

22
Q

Strept Pneumococci
Group
Formation
Location

A

Group: alpha-hemolytic
Formation: Pairs or chains
Location: Upper respiratory

23
Q

Strept. Pnemoniae infections caused?

A

bacteremia
meningitis
bacterial pneumonia
acute otitis media in children

24
Q

What are the virulence factors of strep. pneumoniae?

A
  • Polysaccharide capsule
  • IgA protease
  • Pneumolysin: intracellular killing
25
Q

Viridans streptococci
Group
Location
Virulence factor

A

Group: alpha-hemolytic or non-hemolytic
Location: Oral cavity, GI tract, female genital tract

Virulence factor
- Production of extracellular complex polysaccharides
- low virulence (opportunistic)

26
Q

Infections caused by viridans strept.

A
  • bacteremia
  • Endocarditis
27
Q

Corynebacterium (gram-positive bacilli, non spore-forming)
Location
Shape
Oxidase
Catalase
Virulence factors/infections

A

Location
- non-infectious species, skin, resp tract, urinary tract, conjunctiva

Shape
- clubbed or irregularly shaped

Oxidase
- negative

Catalase: Positive

Virulence factors
- Diphtheria toxin

Inflection
- diphtheria vaccine

28
Q

Listeria monocytogenes (gram-positive bacilli, non spore-forming)
Location
Shape
Catalase

A

Location:
- can survive in wide range of conditions

Shape
- Rod or sphere

Catalase
- positive

29
Q

Listeria monocytogenes virulence factors (4)

A

Adhesion proteins: attachment
Internalins: induce phagocytosis–> survival
Listeriolysin O: facilitates escape from phagocytes
ACtA: facillitates cell-to-cell spread

30
Q

What infections do listeria monocytogenes cause?

A

Meningitis
Food borne: listeriosis

31
Q

Lactobacilli (gram-positive bacilli, non spore-forming)
Location
Shape
Catalase

A

Location: Vagina
Shape: Rods
Catalase: NEGATIVE

32
Q

Bacillus anthracis (gram-positive bacilli, spore-forming)
Hemolytic?
Catalase?

A

non-Hemolytic
Catalase: positive

33
Q

Bacillus anthracis virulence factors (2)

A

Capsule
Anthrax toxin consists of 3 proteins
1. Protective antigen (mediates the entry of the other 2 factors into cell)
2. Edema factor
3. Lethal factor (death)

Need protective antigen + 1 of the factors

34
Q

What are the infections caused by bacillus anthracis

A
  • Most diseases caused in herbivores
  • Humans: through contact with infected animals/animal products
    Anthrax: cutaneous, GI, pulmonary
35
Q

Bacillus cereus (gram-positive bacilli, spore-forming)
Hemolytic?
Catalase?
Virulence factors?
Disease?

A

Beta-hemolytic
Catalase positive

Virulence
- Enterotoxins
- pyogenic toxins
**opportunistic pathogen

Disease: food poisoning

36
Q

Clostridium (gram-positive bacilli, spore-forming)
Catalase?
Spores?
Virulence?

A

Catalase: NEGATIVE
Spores: wider than original bacilli
Virulence:
- decompose proteins from toxins

37
Q
A

PHARM 232 Midterm 1 (6 decks)

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