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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
Clinically important Lancefield groups
A, B, D or not-typed
26
Classification of Strep pyogenes
Group A | beta hemolytic
27
Primenent pyogenic diseases of Strep Pyogenes (GAS)
pyogenic 1. pharyngitis--> STREP THROAT 2. cellulitis 3. impetigo 4. necrotizing fascitis
28
Prominent toxigenic diseases associated with Strep pyogenes
Scarlet fever | TSS
29
Immune mediated diseases associated with Strep pyogenes
1. Rheumatic fever (M protein cross reactive Ab's to heart and joint capsule) 2. acute glomerulonephritis (ab-antigen complexes accumulate in glomeruli)
30
Key virulence factors associate with Strep pyogenes
1. M protein 2. Inflammation-related enzymes 3. Toxins and Hemolysis
31
M protein associated virulence factors of Strep. pyogenes
1. antiphagocytic, | 2. specific serotypes associated with rehumatiogenic or nephritogenic peroperties
32
Inflammation-related enzymes that are virulence factors for Strep pyogenes
hylauronidase--promotes cellulitis) (streptokinase--> dissolves clots) (DNAse
33
Toxins and hemolysins that are virulence factors for Strep. pyogenes
Streptolysin O--> Oxygen-labile Strepstolysis S--> Oxygen stable Exotoxin A--> TSS Exotoxin B--> protease causing necrotizing fascitis
34
Clinically significant Streptococci species
``` Strep. pyogenes Strep agalactiae Strep pneumonia Strep viridans Enterococci ```
35
Strep agalactiae classification
beta hemolytic, groub B (GBS)
36
Strep agalactiae mainly found in
genital tract of some women
37
Prominent diseases associate with Strep. agalactiae
neonatal sepsis and meningitis (pyogenic)
38
Virulence factor for Strep agalactiae
polysaccharide capsule
39
Classification of Strep. pneumoniae (pneumococcus)
alpha hemolytic, not Lancefield typed
40
Prominent diseases with Strep. pneumoniae
* all Pyogenic 1. lobar pneumonia 2. meningitis 3. otitis media (middle ear infection)
41
Virulence factor for Strep pneumoniae
polysaccharide capsule (over 85 serotypes)
42
Classification of Strep. viridans
alpha hemolytic, not Lancefield typed
43
Normal flora of the oropharynx
Strep viridans as well as Strep mutans
44
Prominent diseases associated with Strep. viridans
1. pyogenic endocarditis follow dental procedure | 2. Dental caries (tooth decay)
45
Key virulence factor of Strep. viridans
Biofilm (glycocalyx) production in endocarditis
46
Enterococci classification
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
Normal Flora of the colon
Enterococci
48
Prominent diseases associated with enterococci
1. pyogenic UTI's 2. Pyogenic endocarditis 3. diverticulitis 3. meningitis
49
Virulence factor of enterococci
*resistant to many key antibiotics | not sure if this is a good thing or a bad thing
50
Unique characteristics of pneumococci (thankfully for us)
produce no beta lactamases & still reasonably sensitive to Pen G also sensitive to ampicillin and Vanc
51
Source of Vancomycin resistance for many bacteria
enterococci
52
Spore-Forming Gram Positive Rods
1. Bacillus anthracis (fucking bio-terrorism) | 2. Bacillus cereus
53
B. Anthracis types of modes of infection/ resultant disease
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
Key virulence factors of Bacillus anthracis
* 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
Types of Clostridium
C. perfringens C. difficile C. tetani C. botulinum
56
All clostridium are _____
anaerobes
57
C. perfringes causes
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
Most common cause of nasocomial diarrhea
C. diff.
59
Disease associated with C. diff.
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
Key virulence factors of C. diff
Exotoxin A and B | (leads to depolymerization of actin--> cell death
61
C. tetani disease
Sporatic paralysis--> spores enter a wound and release an exotoxin (tatnus toxin) resulting in tetanus
62
Tetanus Toxin MOA
Alpa-Beta exotoxin that cleaves snares, preventing the release of GABA
63
C. botulinum intoxication vs infection
intoxication--> consumption of preformed exotoxin__ the result of spors germinating in improperly prepared (usually canned) foods
64
C. botulinum disease and MOA
Flaccid paralysis-->A-B exotoxin cleaves SNAREs to block release of ACH
65
Tx of Botulinum and Tetaus exotoxins
antitoxins
66
C. tetani spore appearance
polar endospore that results in "tennis racket" appearance
67
NON-spore forming Gram positive rods
1. Corynebacterium diphtheria (club shaped rods) | 2. Listeria monocytogenes
68
Disease caused by C. diphtheria
diphtheria (an URT illness)
69
Characteristics of the disease diphtheria
1. severe pharyngitis that forms a pseudomembrane at the back of the throat 2. human-human transmission is rare bc of vaccine
70
MOA for C. diphtheria
A-B exotoxin produced form lysogenic ADP ribosylates EF-2, inhibiting translation
71
Tx for diphtheria
1. antitoxins | 2. antibiotics
72
Listeria monocytogenes causes
listeria (watery diarrhea)
73
primary manner of infection with L. monocytogenes
unpasteurized cheese or deli meats
74
Pregnancy complications with L. monocytogenes
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
Non-pathogenic Corynebacterium are opportunistic commensals referred to as __________
diphtheroids
76
What is a superantigen
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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