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Block 7 Week 2 Colt > Soft Tissue Infections I: Strep and Staph - Kozel > Flashcards

Soft Tissue Infections I: Strep and Staph - Kozel Flashcards

1
Q

What is the most common bug in non-bullous impetigo?

A

S. aureus

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2
Q

What is the second most common cause of non-bullous impetigo?

A

strep pyogenes

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3
Q

T/F: impetigo can be caused by an infection of more than one bug

A

true

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4
Q

What is this?
Begins as erythematous papules that turn to vesicles then pustules then rupture. Dries to HONEY COLORED crusts, heals without scarring

A

impetigo

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5
Q

What bug and toxin causes bullous impetigo?

A

S. aureus producing exfoliating toxin

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6
Q

What is an ulcerative pyoderma that is a deeper form of impetigo?

A

Ecthyma

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7
Q

What gives you echtyma>?

A

insect bites or minor traumas

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8
Q

T/F: ecthyma can be caused by the same bugs as impetigo

A

true

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9
Q

T/F: ecthyma scars

A

false

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10
Q

T/F: a cutaneous abscess is restricted to the epiderm

A

false; goes to the dermis and deeper

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11
Q

What is pyoderma in a hair follicle?

A

folliculitis

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12
Q

What is an inflammatory nodule extending into subcutaneous tissue; follows folliculitis

A

furuncle (boil)

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13
Q

What is a coalescent process involving multiple follicles

A

carbuncle

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14
Q

what bug causes folliculitis, carbuncles, and furuncles

A

S aureus

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15
Q

Bacillus anthracis, treponema pallidum, Haemophilus ducreyi, F. tularensis, M ulcerans and M marinum all present with what type of lesion?

A

chancriform

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16
Q

T/F: Erysipelas and cellulitis both describe diffuse, superficial spreading skin infections

A

true

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17
Q

T/F: cellulitis is associated with pus

A

false

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18
Q

what layers of tissues does cellulitis involve?

A

upper derm and subQ fat

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19
Q

When doing your preliminary physical exam of cellulitis, what are you going to notice? Think latin!

A

Rubor, tumor, calor, dalor!

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20
Q

What bugs cause cellulitis?

A

Group A strep and sometimes S. aureus

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21
Q

What differentiates erysipelas from cellulitis?

A

lymphatic involvement

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22
Q

What is characterstic about the appearance of erysipelas?

A

sharp, painful demarcation of the rash

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23
Q

What bug is basically the only thing that causes erysipelas?

A

S. pyogenes

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24
Q

What tissues does necrotizing fasciitis affect?

A

all tissue between skin and muscle

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25
Q

T/F: necr. fasc. is often polymicrobial

A

true

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26
Q

T/F: necr. fasc. can result in systemic toxicity

A

true

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27
Q

What are the four most common bugs causing necrotizing fasciitis?

A

S pyogenes
S aureus
V vulnificus
Aeromonas hydrophila

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28
Q

Synergistic necrotizing cellulitis
Clostridial anaerobic cellulitis
are subtypes of (blank)

A

subcutaneous tissue infections

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29
Q

What is readily visible in a systemic bacterial infection?

A

skin rash

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30
Q

Bacteremia ,Leptospirosis (Weil’s disease), Rat-bite fever – Annular erythema – Lyme disease,
Rocky mountain spotted fever are all examples of rash producing (blank)

A

systemic infections

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31
Q

scarlet fever is induced by (blanks) released by group A strep

A

toxins

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32
Q

scarlet fever follows what initial presentation

A

pharyngitis

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33
Q

What toxin is responsible for scarlet fever?

A

SpeA of strep pyogenes

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34
Q

What toxin is responsible for scalded skin syndrome? What bug?

A

exfoliating toxin of staph

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35
Q

What bug and toxin causes toxic shock syndrome?

A

staph aureus, TSST-1 super ag

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36
Q

A violaceous lesion will present with infection of what bug after contact with infected fish, marine animals, swine, or poultry?

A

E. rhusiopathiae

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37
Q

Cat scratch disease shows what types of lesions?

A

pustular

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38
Q

What bug infects surgical wounds?

A

serratia marcesens

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39
Q

What bug infects cuts from FRESH ONLY water?

A

Aeromonas

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40
Q

What bug infects cuts from FRESH AND SALT water?

A

Vibrio parahaemolyticus

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41
Q

What bug infects cuts from SALT WATER ONLY?

A

Vibrio vulnificus

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42
Q

What bug infects battlefield injuries?

A

A. baumanii

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43
Q

What bug infects post human bite or fist fights?

A

E. corrodens

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44
Q

what is the name for pus within a muscle?

A

pyomyositis

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45
Q

What causes pyomyositis 90 percent of the time?

A

S. aurues

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46
Q

where in the world do we commonly see pyomyositis?

A

the tropics

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47
Q

Myonecrosis or gas gangrene happens after contamination with soil or other material containing (blank)

A

spores

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48
Q

What is the most common bug causing gas gangrene?

A

Clostridium perfringens

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49
Q

What is the discoloration associated with gas gangrene?

A

yellowish-bronze

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50
Q

T/F: most streptococci are facultative anaerobes

A

true

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51
Q

strep is catalase (pos/neg)

A

negative

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52
Q

what are the three ways that strep is classified?

A

hemolytic patterns, lancefield grouping, and bch properties

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53
Q

(B/ a and g) hemolytic strept are classified by lancefield groups

A

B

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54
Q

(B/a and g) hemolytic strep are classified by bch properties

A

alpha and gamma hemolytic

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55
Q

What type of hemolysis is partial and turns the agar green?

A

alpha

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56
Q

What type of hemolysis is complete creating a clear zone?

A

beta

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57
Q

what type hemolysis doesn’t actually cause hemolysis?

A

gamma

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58
Q

Streptolysins O and s are associated with which hemolytic group?

A

beta

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59
Q

S. salivaris and S. mitis are what type of hemolytic group?

A

alpha

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60
Q

The normal flora of the mucous membranes is what (a/b) hemolytic

A

alpha

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61
Q

C carbohydrate is found in what hemolytic group?

A

Beta

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62
Q

Group A includes (blank) and most human pathogens

A

strep pyogenes

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63
Q

Groups B C F G H KL are found on what types of bugs?

A

normal flora of mucous membranes, occasionally on pathogens

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64
Q

Groups E M N CHOs are found where?

A

in most lower animals

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65
Q

Group D ag is found on what specific bug?

A

enterocccus faecalis

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66
Q

T/F: strep with C carbohydrate are only B hemolytic

A

false; can by a b or g

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67
Q

What bug causes this: pharyngitis, pyoderma, rheumatic fever

A

strep pyogens

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68
Q

What bug causes this: neonatal sepsis and meningitis

A

s. agalactiae

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69
Q

What bug causes this: puerperal sepsis and endocarditis

A

Strep anginosus and equi

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70
Q

What bug causes this: endocarditis, UTI

A

enterococcus, strep bovans, s. equinus

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71
Q

What bug causes this: penumonia, otitis media, meningitis

A

strep pneumoniae

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72
Q

What bug causes this: subacute endocarditis

A

S. mutans, salivaris, or mitis

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73
Q

T/F: Strep pneumoniae has no serological group

A

true

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74
Q

S. anginosus and equi are what group?

A

group C

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75
Q

What streps are in the Viridans group?

A

mutans, salivaris, and mitis

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76
Q

Which strep groups are Beta hemolytic>?

A

A, B, C, D

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77
Q

Which strep groups are alpha hemolytic?

A

D, S. pneumoniae, and viridans

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78
Q

which groups of strep may be non-hemolytic?

A

D and Viridans

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79
Q

(blank) is a Polymer of rhamnose and N-acetyl-glucosamine

A

lancefield CHO or C CHO

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80
Q

The M protein subdivides group (blank) into over 100 types

A

group A

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81
Q

(blank) induces type-specific protective immunity to GAS

A

M protein

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82
Q

What three extracellular enzymes are present in S. pyogenes?

A

streptolysin O, DNase, hyaluronidase

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83
Q

Impetigo, Erysipelas, Cellulitis, myositis and necr. fasc. are caused by group (A/D) strep

A

A

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84
Q

What is the function of lipoteichoic acid?

A

adhesion to epithelial cells

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85
Q

F protein/strept fibronecting binding protein binds to what type of epithelial cells?

A

nasopharyngeal

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86
Q

(M protein/hyaluronic acid capsule) is essential for early colonization and adhesion to nasal mucosa

A

hyaluronic acid capsule

87
Q

T/F: M protein is involved in both adherence and avoiding phagocytosis

A

true

88
Q

What step pyogenes virulence factor is a target for vaccine development?

A

M protein

89
Q

Erythrogenic toxin and scarlet fever toxin are two types of (blank) toxin

A

strep pyrogenic exotoxins aka Spe

90
Q

Spe super-ags stimulate the release of which cytokines?

A

IL1, IL2, IL6, TNFa, IFNg

91
Q

(Spe/Spa) is coded by the lysogenic bacteriophage

A

Spe

92
Q

(blank) activates steps in inflammation and septic shock, e.g., complement cascade, cytokine secretion, coagulation cascade in GAS

A

lipoteichoic acid

93
Q

streptolysin O is what class of protein?

A

porin

94
Q

Streptolysin O is oxygen (labile/stable)

A

labile

95
Q

Streptolysin (O/S) is antigenic

A

O is antigenic

S is non-antigenic

96
Q

Streptolysin (O/S) is oxygen stable

A

S

97
Q

(Streptokinase/streptornase) converts plasminogen to plasmin and lyses blood clots

A

streptokinase

98
Q

(Streptokinase/streptornase) reduces viscosity of abscess material

A

streptornase

99
Q

T/F: Hyaluronidase function as a virulence factor by avoiding phagocytosis

A

false; causes tissue damage

100
Q

A strawberry tongue with enlarged fungiform papillae, red cheeks with a pale area around the mouth and a fine, red and rough textured rash that blanches upon pressure is classic for what non-purulent strep based disease?

A

Scarlet fever

101
Q

Are live streptococci necessary to cause AGN or rheumatic fever?

A

no, can be secondary to the first infection

102
Q

Is prior sensitization necessary for both AGN and rheumatic fever?

A

ONLY FOR RHEUMATIC FEVER; you can get AGN from your first exposure to streptococci

103
Q

What is the site of infection of rheumatic fever?

A

pharynx

104
Q

what is the site of infection of AGN?

A

skin!

105
Q

is it common for an infant to get rheumatic fever? AGN?

A

rare for rheumatic fever, not uncommon for AGN

106
Q

T/F: prophylaxis is mandatory in rheumatic fever

A

true

107
Q

T/F: there is no prophylaxis for AGN

A

true

108
Q

Describe the M protein types for rheumatic fever and for AGN?

A

rheumatic fever: rheumatogenic strains

AGN: nephritogenic strains

109
Q

Are complement levels decreased in rheumatic fever or AGN? why does this make sense?

A

AGN; you are getting kidney damage from large molecule depostion–all that complement is stuck in the kidneyu

110
Q

What is mechanism for rheumatic fever?

A

cytotoxic Ab

111
Q

what is the mechanism for AGN?

A

immune complex disregulation

112
Q

What does the quick strep test detect?

A

lancefield carbohydrate ag

113
Q 
Describe the status of strep pyogenes for the following tests:
Gram stain
Hemolysis
Catalase production
Bacitracin sensitivity
Lancefield group
A 
Gram pos
B hemolytic
Catalase neg
Bacitracin sensitive
Lancefield will tell what type of B hemoltic strep
114
Q

What are the systemic effects of SpeA toxin?

A

Fever, rash, and systematic effects

115
Q

What is the mechanism of the SpeA toxin?

A 
Superag causing cyotkine release of :
IL1
IL2
IL6
TNFa
IFNg
116
Q

Serological tests for GAS are used for a (blank)-type diagnosis

A

retrospective

117
Q

The anti-streptolysin O assay is (neg/pos) in skin infections

A

negative

118
Q

Anti-streptolysin O is useful for diagnosis of (rheumatic fever/AGN)

A

rheumatic fever; NOT HELPFUL for AGN

119
Q

Anti-DNase assay is (neg/pos) in skin infections

A

positive

120
Q

Anti-DNase assay is useful for Dx of (rheumatic fever/AGN)

A

AGN

121
Q

T/F: anti streptolysin O and anti-DNase imply immunity to the infection

A

FALSE

122
Q

strep pharyngitis is transmitted via (blank)

A

airborne droplets

123
Q

strep skin infections can be controlled by good (blank)

A

hygeine

124
Q

What percent of the population can be asymptomatic carriers of strep infections?

A

5-20%

125
Q

what is the reservoir for transmission of strep?

A

asymptomatic carriers

126
Q

Decades-long immunity to strep is given via the (blank) protein

A

M protein

127
Q

What is the firstline drug for strep?

A

Penicillin

128
Q

T/F: all strains of strep are sensitive to PCN

A

true

129
Q

Why is it essential that a strep infection be treated QUICKLY and COMPLETELY?

A

reduces the Ab response and limits the chance of progression in the future to RF or AGN

130
Q

If you have a mixed infection of strep and staph aureus, what abx is your choice?

A

vancomycin or oxacillin

131
Q

What is the abx for necrotizing fasciitis?

A

High dose PCN with clindamycin

132
Q

What must you do besides give abx to control necrotizing fasciitis?

A

drainage and surgical treatment

133
Q

If someone has a PCN allergy and has necrotizing fasciitis, the fuck are you supposed to give them??

A

clindamycin or a narrow specture cephalosporin, or maybe even a macrolide

134
Q

T/F: MRSA without any other simultaneous infections is a common cause of necrotizing fasciitis

A

false1!

135
Q

Staph aureus is coagulase (neg/pos)

A

NEGATIVE

136
Q

staph aureus presents in (blank) like clusters

A

grape like

137
Q

Staph is coagulase negative and catalase (blank)

A

POSITIVE

138
Q

What color pigment may staph aureus have?

A

GOLD; AUreus, hellooooo

139
Q

t/F: staph aureus may be non-hemolytic

A

true, also may be beta

140
Q

T/F: staph aureus is sensitive to physical and chemical agents

A

false; resistant

141
Q

Staph aureus carries multiple (blank or blank) that give it PCNase activity along with toxin production

A

plasmids and bacteriophages

142
Q

What percent of the staph genome is a conserved core genome?

A

80%

143
Q

20% of the staph genome is made of mobile genetic elements including bacteriophages, plasmids, transposons, and (blanks), which act like transposons

A

staph chromosomal cassettes

144
Q

What are the two huge important functions of the staph mobile genetic elements?

A

virulence factors and antibiotic resistance

145
Q

Regulation of the staph mobile genetic elements is (blank)-like, and is exemplified by the accessory gene regulator agr that allows for quorum sensing

A

operon-like

146
Q

staph aureus accounts for 80% of bullous and pustular forms of (blank)

A

impetigo; S. pyogenes alone or in conjunction with S aureus for the remainder

147
Q

Abscesses, folliculitis, furuncles, and carbuncles are caused by (s. aureus/ s. pyogenes0

A

aureus

148
Q

T/F: staph aureus can cause osteomyelitis

A

true

149
Q

T/F: staph aureus can cause pneumonia and septic arthritis

A

true

150
Q

staphylococcal (blank) follows broad spectrum abx use

A

enterocolitis

151
Q

Staph (blanks) cause food poisoning, scalded skin syndrome, bullous impetigo, and TSS

A

toxins

152
Q

Staph aureus is (weakly/strongly) virulent

A

weakly!! the minimal dose to get an infection is LARGE

153
Q

Unlike strep, Skin lesions with staph areus cause (blank), irreversible tissue damage and scarring

A

PUS FORMATION AKA SUPPURATION

154
Q

75% of clinical cases of staph have a type 5 or 8 antiphagocytic (blank)

A

capsule

155
Q

What two components of the capsule in staph contribute to the inflammation?

A

PDG layer and lipoteichoic acid

156
Q

Protein A in the staph capsule has a high affinity for the Ig(blank) Fc fragment

A

IgG

157
Q

Coagulase in staph converts (blank to blank) and helps localize lesions and is a marker for other species

A

fibrinogen to fibronectin

158
Q

Catalase in staph facilitates (blank)

A

intracellular survival

159
Q

T/F: staph carries PCNase

A

true

160
Q

What are the cytotoxins that staph aureus codes for?

A

alpha, beta, delta, and gamma along with PV leukocidin

161
Q

staph cytotoxins are toxic via mechanisms for what three cell types?

A

erythrocytes, leukocytes, and platelets

162
Q

what two toxins lead to scalded skin syndrome?

A

exfoliating toxin a and b

163
Q

Pyrogenic exotoxins of s aureus are coded by (blanks) for the enterotoxins or (blanks) for TSST

A

plasmids for enterotoxins

bacteriophage for TSST

164
Q

T/F: Superags are pyrogenic exotoxins

A

true

165
Q

T/F: superags have toxic effects that are different than the superag effects

A

true

166
Q

SEA, SEB, SEC, SED, and SEE are what class of staph toxins?

A

enterotoxins

167
Q

what are the five classes of staph toxins?

A
  1. cytotoxins
  2. exfoliating toxins
  3. pyrogenic toxins
  4. enterotoxins
  5. toxic shock syndrome toxin
168
Q

T/F: staph is resistant to extended boiling and gastric acids

A

true

169
Q

what is the incubation time for staph food poisoing?

A

1-6 hours

170
Q

staph food poisoning targets *(blank) of the smooth muscle of the intestine

A

sensory nerve endings

171
Q

How long is it until staph food poisoning passes?

A

24 hours

172
Q

Exfoliative skin disease is aka

A

scalded skin syndrome

173
Q

Bullous impetigo is the local form of:

A

scalded skin syndrome

174
Q

The toxin in scalded skin syndrome is a (blank) protease

A

serine

175
Q

the toxin in scalded skin syndrome cleaves the (blank) junction to form fragile, thin-roofed vesicopustules

A

derm-epiderm

176
Q

scalded skin syndrome is usually seen in (kids/elderly)

A

kids

177
Q

desqumation is a complication seen in:

A

scalded skin syndrome

178
Q

toxic shock syndrome gives you an increased susceptibility to (blank)

A

endogenous exotoxin

179
Q

T/F: toxic shock syundrome has a direct effect on vascular endothelial cells

A

true

180
Q

When is TSST-1 stimulated in staph infections?

A

poor growth conditions; one hell of a “fuck you”

181
Q

T/F: blood cultures are usually negative in TSS

A

true, super wierd

182
Q

Superags will bind the MHC (blank) to the tCR

A

MHC II

183
Q

T/F: TSST-1 froms staph and SpeA from strep elicit the same systemic symptoms and cytokine release

A

true!!!!

184
Q

Direct examination of what two fluids will show you staph?

A

pus and CSF

185
Q

what type of special media is needed to isolate staph?

A

mannitol salt agar

186
Q

Coagulase (pos/neg) distinguishes s aureus from other staph strains

A

coag pos

187
Q

T/F: Staph aureus ferments mannitol

A

true, that’s why you use mannitol salt agar

188
Q

What special media do you need to culture MRSA and what two abx do you use for sensitivity testing?

A

chromogenic media with disks of oxacillin or cefotoxin

189
Q

Dx of MRSA via PCR is looking for the (blank) gene

A

mecA

190
Q

T/F: Abx sensitivity testing is essential for the Dx of staph

A

true

191
Q

When do you do subspecies typing of staph?

A

for epidemic strains

192
Q

Antibiograms, biotyping, phage typing, and nucleic acid analysis are used to determine the (blank) for epidemic strains

A

subtype

193
Q

What is the primary reservoir of staph aureus and where does it reside in the reservoir?

A

MAN, normal flora of lower large bowel, skin, anterior nares

194
Q

T/F: staph aureus infection can be transmitted via aerosol

A

true

195
Q

T/F: staph aureus infections can be endogenous

A

true

196
Q

what is the carrier rate of staph in the normal pop?

A

30%

197
Q

What is used for decontamination of nasal carriers of staph?

A

mupirocin

198
Q

T/f: there is no immunity made against staph, allowing for multiple reinfections

A

true

199
Q

What must the PCN based drugs have to be effective against MRSA?

A

must be PCNase resistant

200
Q

What are the most commonly used abx against MRSA?

A 
Penicillinase-resistant penicillins, e.g., oxacillin
Clindamycin
TMP-SMX
Doxycycline
Linezolid
Vancomycin
Daptomycin
201
Q

T/F: PCNase producing staph is uncommon except in the hospital setting

A

false; very common

202
Q

What type of staph has a thicker, more disorganized cell wall with free ala-ala groups as decoys for vancomycin?

A

VISA

203
Q

the vanA gene operon encodes for ala-lactate production in what strain of staph?

A

VRSA

204
Q

T/F: VRSA is still rather rare

A

true

205
Q

what is the cassette that codes for MRSA abx resistance?

A

SCCmec

206
Q

SCCmec codes for a (pos/neg) repressor operon and mecA which codes for (blank)

A

negative repressor operon and mecA which codes for PBP 2a which has low affinity for b-lactam abx

207
Q

What are the risk factors associated with HCA-MRSA?

A

surgery, indwelling catheters

208
Q

HCA-MRSA is (multi/Pauci) resistant

A

multi

209
Q

T/F: community acquired MRSA has no risk factors

A

true

210
Q

What is the most common cause of soft tissue infection in the community?

A

MRSA

211
Q

CA-MRSA carries (blank) leukocidin

A

PV leukocidin

212
Q

CA-MRSA is (blank) resistant

A

Pauci resistant

213
Q

How do you decolonize MRSA colonzied patients?

A

1 week of body washing with chlorhexidine and use of nasal mupirocin

Block 7 Week 2 Colt (4 decks)

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