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CMOD > Gram Positive Bacterial Infections > Flashcards

Gram Positive Bacterial Infections Flashcards

1
Q

Name the Gram Positive Cocci

A
  1. Staphylococci
    2.Streptococci
    (non-motile, non-spore formers)
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2
Q

Shape of Staphylococci

A

“grape-like clusters” of cocci

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3
Q

Shape o Streptococci

A

“Chainz” of cocci

two chaaaainz

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4
Q

Catalase status of Staph

A

catalase positive

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5
Q

Catalase status of Strep

A

catalase negative

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6
Q

Name the Clinically important types of Staphylococci (3 of them that we have studied)

A
  1. Staph. aureus
  2. Staph epidermis
  3. Staph. saprophyticus
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7
Q

Most Clinically important Staph species

A

Staph. aureus

aureus refers to gold pigment produced

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8
Q

Prominent (general types of ) diseases associated with Staph (there are two types)

A
  1. pyogenic inflammation (abscesses)

2. Toxigenic

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9
Q

Local pyogenic diseases associated with Staph. aureus

A
  1. impetigo

2. wound infections

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10
Q

Disseminated pyogenic diseases associated with Staph. aureus

A
  1. endocarditis
  2. pneumonia
  3. osteomyelitis
  4. septic arthritis
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11
Q

Toxigenic diseases associated with Staph aureus

A
  1. food poisoning
  2. toxic shock syndrome
  3. scalded skin syndrome
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12
Q

Key Virulence factors of Staph aureus

A
  1. . coagulase (+)–> clot formation impart antiphagocytic properties
  2. Protein A–>binds IgG and disrupts compliment pathway
  3. Some strains produce a capsule
  4. Cell wall with endotoxic properties–>sepsis
  5. numerous enzymes and toxins–> skin damage
  6. super antigens (both exotoxins)
    a. heat resistance causes food poisoning
    b. TSST causes toxic shock syndrome
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13
Q

Prominent Diseases assocoated with Staph. epidermis

A

pyogenic infection of in-dwelling catheters

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14
Q

Staph epi is almost always aquired in the ______

A

Hospital

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15
Q

Key virulence factor of Staph epidermis

A
  1. biofilm (glycocalyx)

2. coagulase negative

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16
Q

Exotoxins produced by Staph epi

A

NONE

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17
Q

Prominent diseases associated with Staph. saprophyticus

A

UTI’s related to sexual activity

behind e. coli

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18
Q

Key virulence factors of Staph saprophyticus

A

coagulase negative

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19
Q

Antibiotic resistances commonly seen in Staph aureus and Staph. epi

A
  1. beta lactamases (penicillin G resistance)
  2. Methicillin resistance due to altered PBP’s
  3. Vancomycin resistance due to altered peptide sequence D-ala-Dala—> Dala-D-lac
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20
Q

Characteristic of Strep bugs MOA

A

hemolysis (break down of red blood cells)

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21
Q

Alpha hemolysis

A

cause oxidization of iron in hemoglobin molecules within red blood cells, giving it a greenish color on blood agar
*(pneumoniae and viridans)

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22
Q

Beta Hemolysis

A

causes complete rupture of red blood cells. On blood agar, this appears as wide areas clear of blood cells surrounding bacterial colonies
(pyogenes and agalactiae)

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23
Q

Gamma hemolysis

A

no hemolysis

enterococci

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24
Q

Carbohydrate antigen, displayed on bacterial cell wall that is important for typing Strep bugs, especially beta hemolytic strains

A

Lancefield antigen

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25
Q

Clinically important Lancefield groups

A

A, B, D or not-typed

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26
Q

Classification of Strep pyogenes

A

Group A

beta hemolytic

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27
Q

Primenent pyogenic diseases of Strep Pyogenes (GAS)

A

pyogenic

  1. pharyngitis–> STREP THROAT
  2. cellulitis
  3. impetigo
  4. necrotizing fascitis
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28
Q

Prominent toxigenic diseases associated with Strep pyogenes

A

Scarlet fever

TSS

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29
Q

Immune mediated diseases associated with Strep pyogenes

A
  1. Rheumatic fever (M protein cross reactive Ab’s to heart and joint capsule)
  2. acute glomerulonephritis (ab-antigen complexes accumulate in glomeruli)
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30
Q

Key virulence factors associate with Strep pyogenes

A
  1. M protein
  2. Inflammation-related enzymes
  3. Toxins and Hemolysis
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31
Q

M protein associated virulence factors of Strep. pyogenes

A
  1. antiphagocytic,

2. specific serotypes associated with rehumatiogenic or nephritogenic peroperties

32
Q

Inflammation-related enzymes that are virulence factors for Strep pyogenes

A

hylauronidase–promotes cellulitis)
(streptokinase–> dissolves clots)
(DNAse

33
Q

Toxins and hemolysins that are virulence factors for Strep. pyogenes

A

Streptolysin O–> Oxygen-labile
Strepstolysis S–> Oxygen stable
Exotoxin A–> TSS
Exotoxin B–> protease causing necrotizing fascitis

34
Q

Clinically significant Streptococci species

A 
Strep. pyogenes
Strep agalactiae
Strep pneumonia
Strep viridans
Enterococci
35
Q

Strep agalactiae classification

A

beta hemolytic, groub B (GBS)

36
Q

Strep agalactiae mainly found in

A

genital tract of some women

37
Q

Prominent diseases associate with Strep. agalactiae

A

neonatal sepsis and meningitis (pyogenic)

38
Q

Virulence factor for Strep agalactiae

A

polysaccharide capsule

39
Q

Classification of Strep. pneumoniae (pneumococcus)

A

alpha hemolytic, not Lancefield typed

40
Q

Prominent diseases with Strep. pneumoniae

A
  • all Pyogenic
    1. lobar pneumonia
    2. meningitis
    3. otitis media (middle ear infection)
41
Q

Virulence factor for Strep pneumoniae

A

polysaccharide capsule (over 85 serotypes)

42
Q

Classification of Strep. viridans

A

alpha hemolytic, not Lancefield typed

43
Q

Normal flora of the oropharynx

A

Strep viridans as well as Strep mutans

44
Q

Prominent diseases associated with Strep. viridans

A
  1. pyogenic endocarditis follow dental procedure

2. Dental caries (tooth decay)

45
Q

Key virulence factor of Strep. viridans

A

Biofilm (glycocalyx) production in endocarditis

46
Q

Enterococci classification

A

alpha OR beta hemolytic, Lancefield group D

  • note they are not a species of streptococcus but are very difficult to differntiate from strep by physical characteristics alone and were originally classed as group D strep
  • facultative anaerobic bacteria incapable of forming spores
  • WIKIPEDIA SAYS IT IS GAMMA HEMOLYTIC?
47
Q

Normal Flora of the colon

A

Enterococci

48
Q

Prominent diseases associated with enterococci

A
  1. pyogenic UTI’s
  2. Pyogenic endocarditis
  3. diverticulitis
  4. meningitis
49
Q

Virulence factor of enterococci

A

*resistant to many key antibiotics

not sure if this is a good thing or a bad thing

50
Q

Unique characteristics of pneumococci (thankfully for us)

A

produce no beta lactamases &
still reasonably sensitive to Pen G
also sensitive to ampicillin and Vanc

51
Q

Source of Vancomycin resistance for many bacteria

A

enterococci

52
Q

Spore-Forming Gram Positive Rods

A
  1. Bacillus anthracis (fucking bio-terrorism)

2. Bacillus cereus

53
Q

B. Anthracis types of modes of infection/ resultant disease

A
  1. cutaneous anthrax (black “eschar” lesions
    a. introduction of spore into wound
    b. untreated–> pulmonary infection
  2. Inhalation anthrax (wool-sorter’s disease)
    a. not transmitted human to human
    b caused by inhalation of fine spores
    c. fatal if untreated
54
Q

Key virulence factors of Bacillus anthracis

A
  • two A-B exotoxins that share common Beta subunit
    1. edema factor-anenylate cyclase that spurs fluid secretion
    2. lethal factor- protease that inhibits cell growth
55
Q

Types of Clostridium

A

C. perfringens
C. difficile
C. tetani
C. botulinum

56
Q

All clostridium are _____

A

anaerobes

57
Q

C. perfringes causes

A
  1. gas gangrene–> spore invasion of wounds, Alpha exotoxin is a lecithinase that damages cell membranes
  2. Food poisoning–> spores germinate during cooking to release enterotoxin (targets the intestines specifically)
58
Q

Most common cause of nasocomial diarrhea

A

C. diff.

59
Q

Disease associated with C. diff.

A

Antibiotic associated pseudomembranous colitis

  1. C. diff. is very antibiotic resistant
  2. depltion of normal flora creates an environment where C. Diff can thrive
60
Q

Key virulence factors of C. diff

A

Exotoxin A and B

(leads to depolymerization of actin–> cell death

61
Q

C. tetani disease

A

Sporatic paralysis–> spores enter a wound and release an exotoxin (tatnus toxin) resulting in tetanus

62
Q

Tetanus Toxin MOA

A

Alpa-Beta exotoxin that cleaves snares, preventing the release of GABA

63
Q

C. botulinum intoxication vs infection

A

intoxication–> consumption of preformed exotoxin__ the result of spors germinating in improperly prepared (usually canned) foods

64
Q

C. botulinum disease and MOA

A

Flaccid paralysis–>A-B exotoxin cleaves SNAREs to block release of ACH

65
Q

Tx of Botulinum and Tetaus exotoxins

A

antitoxins

66
Q

C. tetani spore appearance

A

polar endospore that results in “tennis racket” appearance

67
Q

NON-spore forming Gram positive rods

A
  1. Corynebacterium diphtheria (club shaped rods)

2. Listeria monocytogenes

68
Q

Disease caused by C. diphtheria

A

diphtheria (an URT illness)

69
Q

Characteristics of the disease diphtheria

A
  1. severe pharyngitis that forms a pseudomembrane at the back of the throat
  2. human-human transmission is rare bc of vaccine
70
Q

MOA for C. diphtheria

A

A-B exotoxin produced form lysogenic ADP ribosylates EF-2, inhibiting translation

71
Q

Tx for diphtheria

A
  1. antitoxins

2. antibiotics

72
Q

Listeria monocytogenes causes

A

listeria (watery diarrhea)

73
Q

primary manner of infection with L. monocytogenes

A

unpasteurized cheese or deli meats

74
Q

Pregnancy complications with L. monocytogenes

A

pregnant females are particularly susceptible due to suppressed cell mediated–> may exhibit flu-like symptoms
*major concern is sepsis or meningitis in newborns from infected mother

75
Q

Non-pathogenic Corynebacterium are opportunistic commensals referred to as __________

A

diphtheroids

76
Q

What is a superantigen

A

Causes non-specific activation of t cells–> resulting in polyclonal T cell activation and a coinciding MASSIVE CYTOKINE RELEASE

CMOD (19 decks)

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